BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Vacuum Pressure Considerations on the Performance and Lifetime of Penning Ion Sources DTSTART;VALUE=DATE-TIME:20200904T173000Z DTEND;VALUE=DATE-TIME:20200904T193000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1926@indico.inp.nsk.su DESCRIPTION:Speakers: Scott Lawrie (STFC ISIS Neutron Source)\nThe ISIS pu lsed spallation neutron and muon facility uses a Penning surface-plasma io n source to deliver high current\, high repetition rate\, long pulse H- be ams for accelerator operations. Several variations of the Penning source h ave been tested\, primarily with a view to higher duty-cycle operation in future facilities. It has been noted that the different source configurati ons vary in their operational stability and wear patterns\, despite using the same power supplies\, gas feed-rates\, magnetic fields\, temperature s ettings etc. It is proposed that the vacuum chamber setup contributes to t he observed performance variations. Therefore temporally-resolved vacuum s imulations were made of the different setups. The pressure profiles output were used in conjunction with collision cross sections to estimate stripp ing losses along the beam’s flight path. It was found that up to 20% dif ference in H- stripping can occur depending on the vacuum environment. The refore caution must be used when comparing perveance scans of transported beam current from different ion sources and different experimental setups. In addition\, the stripped positive ions can back-stream into the ion sou rce\, increasing anode wear.\n\nhttps://indico.inp.nsk.su/event/28/contrib utions/1926/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1926/ END:VEVENT BEGIN:VEVENT SUMMARY:Experimental results of 40kW\, 1 MHz Solid State High Frequency Po wer Supply with Inductively Coupled Plasma DTSTART;VALUE=DATE-TIME:20200903T082000Z DTEND;VALUE=DATE-TIME:20200903T084000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1957@indico.inp.nsk.su DESCRIPTION:Speakers: Sandip Gajjar (ITER-India\, Inst. for Plasma Researc h)\nA Solid State High Frequency (HF) 1MHz\, 40kW source is intended for p lasma formation in neutral beam source by inductive coupling of RF power. An important design feature of such a HF source is its ability to sustain large transient swings of load(due to impedance transition in microseconds time scale). A 40kW High Frequency Power Supply( HFPS) has been configur ed with multiple Class-D H-Bridge inverters modules by using latest genera tion switching semiconductors\; each capable of delivering 3kW Power\, mag netic combiners\, LC tuning network to provide 1 MHz sinusoidal output at 50 Ω standard Load. The developed prototype power supply has been couple d to a single driver RF ion source test bed ROBIN in IPR to characterize t he system with actual load conditions. \nIn recent experimental campaign\, tuning of matching network parameters helped to strike and sustain plasma over the range of 1Pa to 0.42 Pa pressure with forward power of 37kW to 2 2kW. Additional impedance matching network was implemented to map the powe r supply impedance(50Ω) with impedance offered from source(>90Ω seen at PS end). Configurable frequency with resolution(~1kHz) helped to achiev e Power factor close to unity. Experiments helped to study the behavior of power supply in scenarios of dynamic (plasma) impedance. Auto tunable fre quency for matching the varying load is being implemented in the HF power supply.\n\nhttps://indico.inp.nsk.su/event/28/contributions/1957/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1957/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantifying the Cesium and H- Densities Inside the LANSCE H- Ion S ource with Laser Absorption Techniques DTSTART;VALUE=DATE-TIME:20200904T162000Z DTEND;VALUE=DATE-TIME:20200904T164000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1955@indico.inp.nsk.su DESCRIPTION:Speakers: David Kleinjan (Los Alamos National Laboratory)\nThe Los Alamos Neutron Science Center (LANSCE) H- ion source (LHIS) has provi ded stable output for decades of LANL mission needs. While operationally well understood\, the internal relationship between the LHIS plasma\, cesi um distribution (the catalyst for producing H- ions)\, and produced H- bea m remains a mystery\, only explored indirectly with models.\n\nWe will dev elop fast\, accurate\, and non-invasive diagnostics techniques to measure the Cs and H- densities inside LHIS. These diagnostics are based on optica l absorption spectroscopy that have been developed in the last decade for fusion based H- ion sources that can readily be applied to the accelerator based LHIS. A refined form of optical absorption spectroscopy\, the lase r absorption technique (LAT)\, utilizes lasers tuned to a given atomic spe cies to measure its density. In this case a laser tuned to the D2 line of cesium will be used to determine its density inside LHIS. Similarly\, a refined version of LAT called the cavity ring-ring down spectroscopy (CRDS ) technique utilizes a laser tuned to H- photo-detachment to measure the H - densities at inside LHIS.\n\nWith successful development of these diagno stic techniques\, any hidden or dormant capabilities in LHIS will be found and capitalized upon\, both in its modeling and operation. Also\, its pot ential benefit to LANSCE and LANL future needs will be realized. More gen erally\, this will be the first use of these plasma diagnostic techniques on an accelerator based H- ion sources. We will present on the preliminar y status of the diagnostic setup.\n\nhttps://indico.inp.nsk.su/event/28/co ntributions/1955/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1955/ END:VEVENT BEGIN:VEVENT SUMMARY:Beam Extraction and Optics of 200keV beam accelerator for neutral beam injection in China DTSTART;VALUE=DATE-TIME:20200902T074000Z DTEND;VALUE=DATE-TIME:20200902T080000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1963@indico.inp.nsk.su DESCRIPTION:Speakers: Fei Song (Huazhong University of Science and Technol ogy)\nA Negative-ion based Neutral Beam Injection (NNBI) prototype is unde r conceptual design in Southwestern Institute of Physics for China Fusion Engineering Test Reactor (CFETR). The aim in the first stage is to extract an H- beam >3A for 1000s and acquire an energy of 200keV. In this present ation\, a single beamlet model for optimization of the CFETR NNBI prototyp e accelerator’s beam optics is developed. The boundary between plasma an d beam\, namely the meniscus\, is calculated with a self-consistent method accomplished in Comsol environment. The optimum perveance is found\, whic h guarantees beam the minimum divergence angle. Magnetic field produced by permanent magnets in the extraction grid is verified to deflect the major ity of co-extracted electrons\, while inducing a slight offset of the ion beam. As a conclusion\, the system is capable to operate as required.\n\nh ttps://indico.inp.nsk.su/event/28/contributions/1963/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1963/ END:VEVENT BEGIN:VEVENT SUMMARY:Recent Achievements in Studies of Negative Beam Formation and Acce leration in the Tandem Accelerator at Budker Institute DTSTART;VALUE=DATE-TIME:20200909T030000Z DTEND;VALUE=DATE-TIME:20200909T032000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1928@indico.inp.nsk.su DESCRIPTION:Speakers: Andrey Sanin (Budker Institute of Nuclear Physics)\n A continuous-wave surface-plasma negative hydrogen ion source is used to i nject a negative ion beam into tandem accelerator with vacuum insulation a t Budker Institute of Nuclear Physics since 2006. In the ion source\, Penn ing discharge with plasma injection from hollow cathodes and cesium seedin g is applied to generate a negative ion beam with a current up to 10 mA at 25 KV acceleration voltage. Due to several updates to the ion source and the tandem\, maximum output proton beam current of up to 8 mA at 2 MeV is obtained. The results obtained recently in studies of ion beam formation and acceleration in the tandem accelerator are discussed\n\nhttps://indico .inp.nsk.su/event/28/contributions/1928/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1928/ END:VEVENT BEGIN:VEVENT SUMMARY:Velocity distribution functions of hydrogen atoms in ion source di scharges DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1986@indico.inp.nsk.su DESCRIPTION:Speakers: Tatsuhiro Tokai (Graduate School of Science and Engi neering\, Doshisha University\, Kyotanabe\, Kyoto Japan.Graduate School of Science and Engineering\, Doshisha University\, Kyotanabe\, Kyoto Japan.) \nMany types of negative hydrogen (H$^-$) ion sources are operated by inje cting cesium (Cs) into the discharge. The injected Cs reduces the surface work function of the extraction electrode to enhance negative ion current and reduce coextracted electron current. The high H$^-$ ion density in th e vicinity of the beam extraction hole is believed to be realized by negat ive ionization of incoming flux to the electrode including atomic hydrogen (H$^0$) produced from the ion source discharge. The production efficienc y of this surface produced H$^-$ ion component should be highly dependent upon the velocity distribution of H$^0$ atoms striking the extraction elec trode. A system to measure the change in the H$^0$ velocity distribution functions depending upon the method to excite the plasma has been designed \, built and being improved the performance.\n\n The system equips a rotat ing blade neutral beam chopper to modulate the intensity of the neutral fl ux passing through the skimmer that separates the downstream chamber for t ime of flight analysis from the ion source discharge. After about 45 cm f ree flying vacuum space an electron impact type ionizer converts neutral p articles to ions. A magnetic deflection type mass separator guides the pr oduced protons to a secondary electron multiplier detector. The system ex hibits the existence of a high-speed component in the H$^0$ velocity distr ibution when it was tested with an ECR plasma source. The current problem is the detector life that limits the signal accumulation. The ion to ele ctron conversion plate degrades rapidly for the positive hydrogen ion impa ct and reduces the signal pulse height in several hours. The correlation between the discharge power and the observed time-of-flight spectrum is di scussed.\n\nhttps://indico.inp.nsk.su/event/28/contributions/1986/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1986/ END:VEVENT BEGIN:VEVENT SUMMARY:High-speed Emittance Measurements for Beams Extracted from J-PARC RF Ion Source DTSTART;VALUE=DATE-TIME:20200909T012000Z DTEND;VALUE=DATE-TIME:20200909T014000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1936@indico.inp.nsk.su DESCRIPTION:Speakers: Takanori Shibata (J-PARC)\nOscillation of emittance and Twiss parameters in the negative ion $(\\text{H}^-)$ beam from the J-P ARC 2MHz RF ion source is measured by applications of a double-slit emitta nce monitor located at the RFQ (Radio Frequency Quadrupole) entrance. The emittance monitor is equipped with a newly-developed 60 MS/s data acquisit ion system\, so that beam current oscillation in a few MHz can be observed with enough time resolution.\n\nFrom the measurement\, it is shown that t he beam phase space consists of (1) a DC component in the beam core\, (2) a 2MHz oscillating component which takes place both in the beam core and t he halo and (3) a doubled RF frequency (4 MHz) oscillation which slightly exists in the beam halo. The major component is the 2 MHz component\, whic h resultantly decides the beam emittance oscillation frequency. A typical value of the beam emittance in the present experiment is 0.34 $\\pi$ mm-m rad\, while the amplitude of the 2MHz oscillation is around 0.04 $\\pi$ mm -mrad. The results indicate that the high-frequency oscillation component occupying about ten-percent of the beam from the RF source travels a few m eters passing through a magnetic lens focusing system.\n\nhttps://indico.i np.nsk.su/event/28/contributions/1936/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1936/ END:VEVENT BEGIN:VEVENT SUMMARY:NIBS'20 Summary DTSTART;VALUE=DATE-TIME:20200910T104000Z DTEND;VALUE=DATE-TIME:20200910T110000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1994@indico.inp.nsk.su DESCRIPTION:https://indico.inp.nsk.su/event/28/contributions/1994/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1994/ END:VEVENT BEGIN:VEVENT SUMMARY:NIBS'20 Award Lecture DTSTART;VALUE=DATE-TIME:20200910T102000Z DTEND;VALUE=DATE-TIME:20200910T104000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1995@indico.inp.nsk.su DESCRIPTION:Speakers: Mieko Kashiwagi and QST N-NBI Team ()\nhttps://indic o.inp.nsk.su/event/28/contributions/1995/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1995/ END:VEVENT BEGIN:VEVENT SUMMARY:Welcome to NIBS'22 DTSTART;VALUE=DATE-TIME:20200910T110000Z DTEND;VALUE=DATE-TIME:20200910T111000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1996@indico.inp.nsk.su DESCRIPTION:https://indico.inp.nsk.su/event/28/contributions/1996/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1996/ END:VEVENT BEGIN:VEVENT SUMMARY:The Cs-free Negative Hydrogen Ion Source Project at KAERI: A New C oncept Multi-Pulsed Ion Source DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1951@indico.inp.nsk.su DESCRIPTION:Speakers: Sung-Ryul Huh (Korea Atomic Energy Research Institut e)\nDue to reliability issues in using cesium (Cs) for efficient hydrogen negative ion production in ion sources for neutral beam injection (NBI) sy stems in fusion research\, many researchers have explored Cs-free alternat ives to Cs for a future DEMOnstration power station (DEMO) NBI system. The Korea Atomic Energy Research Institute (KAERI) recently launched a new pr oject in collaboration with Seoul National University (SNU) in order to id entify an efficient Cs-free negative ion source based on the volume produc tion mechanism\, not only for fusion application\, but for other applicati ons (e.g.\, semiconductor\, space propulsion\, and accelerator). In this p roject\, we attempt to improve efficiency of the volume negative ion sourc e by introducing plasma pulsing. The plasma pulsing\, which is also called temporal filter\, refers to a method of modulating power that sustains th e plasma and consequently the electron energy. Supplying negative ions at high densities by the pulsing is\, however\, inherently transient and its duration is short. In view of a future DEMO\, a significant drawback of th e pulsing is being unable to continuously supply the negative ions to an e xtraction system. To remedy the drawback\, and consequently to develop a n ovel promising Cs-free alternative\, we devised a multi-pulsed ion source. The multi-pulsed ion source included more than two plasma sources and mag netic filters operates with an alternating pulsing sequence of the plasma sources. The temporal and magnetic filters named spatiotemporal filters ma y enable this ion source to continuously supplying the negative ions\, lea ding to the development of the efficient Cs-free negative ion source. In t his presentation\, the overview of the Cs-free negative hydrogen ion sourc e project at KAERI\, the new ion source concept\, and its preliminary expe rimental results will be presented and discussed in detail.\n\nhttps://ind ico.inp.nsk.su/event/28/contributions/1951/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1951/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigation of the negative ionization of hydrogen particles on metal surfaces with low work function DTSTART;VALUE=DATE-TIME:20200903T092000Z DTEND;VALUE=DATE-TIME:20200903T094000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1941@indico.inp.nsk.su DESCRIPTION:Speakers: Ivan Gainullin (Faculty of Physics\, Moscow State Un iversity)\nThis work addresses the negative ionization of hydrogen particl es on metal surfaces with low work function\, which is an important for th e field of the surface plasma negative ion sources. The theoretical model for the calculation of the negative ionization probability which takes int o account the component of atom/ion velocity\, parallel to the surface is described. The influence of parallel velocity on the negative ionization p robability for the case of surfaces with low work function is of interest\ , because for ordinary metal surfaces the parallel velocity effect can enh ance the negative ionization probability by order of magnitude. The calcul ated ionization probabilities quantitatively fit to experimental data for wide range of ion energies. The theoretical analysis reveals\, that in the case of low work function converter surfaces\, the parallel velocity effe ct can enhance the negative ionization probability up to ~33%.\n\nhttps:// indico.inp.nsk.su/event/28/contributions/1941/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1941/ END:VEVENT BEGIN:VEVENT SUMMARY:Prediction of negative hydrogen ion density in permanent magnet-b ased helicon ion source (HELEN) using deep learning techniques DTSTART;VALUE=DATE-TIME:20200909T040000Z DTEND;VALUE=DATE-TIME:20200909T042000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1970@indico.inp.nsk.su DESCRIPTION:Speakers: Vipin Shukla (PANDIT DEENDAYAL PETROLEUM UNIVERSITY) \nIn the present work\, a deep learning model is developed for a permanent magnet-based helicon plasma source. The non-invasive cavity ring-down spe ctroscopy (CRDS) characterizes the HELEN ion source as a negative hydrogen ion source. This paper discusses different deep learning techniques for m odelling the ion source and subsequently predicts the ion source density. The experiments were conducted for measuring the plasma density for the di fferent range of gas pressure (mTorr)\, magnetic field (B-Field) and RF-po wer. Consequently\, experimental data trains deep learning models. The per formance of various deep learning models has been assessed by the root mea n squared error and the coefficient of determination values. The deep lear ning techniques also develop a correlation between the electron temperatur e and plasma densities which reasonably mimics the behaviour of HELEN ion source and can classify the helicon plasma generation at high power range (800-850 W). Also\, the influence of other input parameters such as gas pr essure and the magnetic field is assessed using the correlation matrix.\n\ nhttps://indico.inp.nsk.su/event/28/contributions/1970/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1970/ END:VEVENT BEGIN:VEVENT SUMMARY:Development of the directional Langmuir probe for the charged part icle flow measurement DTSTART;VALUE=DATE-TIME:20200902T060000Z DTEND;VALUE=DATE-TIME:20200902T062000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1935@indico.inp.nsk.su DESCRIPTION:Speakers: Shingo Masaki (National Institute for Fusion Science )\nFlow of charged particles near the plasma grid in negative ion sources affects the extraction efficiency of negative hydrogen / deuterium (H- / D -) ion beams [1][2]. In our previous research\, the flow of the charged pa rticles was measured with a four-pin directional Langmuir probe by rotatin g the tips around the center axis of the tips [3]. In the case of the four -pin probe\, spatial resolution is determined by the distance between the probe tips\, while plasma state changes with the direction and strength of Electron Deflection Magnetic (EDM) field. Furthermore\, the field directi on becomes opposite within the distance of the probe tips at some position close to the plasma grid. To resolve the problem of spatial resolution\, a single-pin directional Langmuir probe equipped rotatable flap co-axially to shield charged-particle flow around the tip was newly developed and in stalled to the NIFS R&D Negative Ion Source (NIFS-RNIS). The probe is avai lable to apply for a usual photodetachment Langmuir probe as well as usual electrostatic one. The first data obtained with the directional photodeta chment Langmuir probe with the rotatable flap are going to be introduced.\ n\n[1] M. Kisaki et al.\, Rev. Sci. Instrum. 85\, 02B131 (2014).\n[2] H. N akano et al.\, AIP Conf. Proc. 1515\, 237 (2013).\n[3] S. Geng et al.\, Re v. Sci. Instrum. 87\, 02B103 (2016).\n\nhttps://indico.inp.nsk.su/event/28 /contributions/1935/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1935/ END:VEVENT BEGIN:VEVENT SUMMARY:Development of External RF Antenna based Cusp Free High Duty Facto r Pulsed Negative Hydrogen Ion Source DTSTART;VALUE=DATE-TIME:20200902T080000Z DTEND;VALUE=DATE-TIME:20200902T082000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1952@indico.inp.nsk.su DESCRIPTION:Speakers: Dharmraj Ghodke (Raja Ramanna Centre for Advanced Te chnology)\nAn external RF antenna based cusp free negative H ion source ha s been designed and developed as shown in figure 1. This source is operate d at 10% duty factor and the key experimental result is shown in figure 2. The extracted H- ion beam current is 11 mA with 2 ms pulse duration and 5 0 Hz repetition rate at 50 kV beam energy. Operation of the H- ion source at high duty factor results in temperature rise in components\, which lead s to failure of electronic components and vacuum joints of plasma chamber\ , igniter chamber and burn out of extraction electrodes. In order to keep the operating temperature within limits\, water cooling arrangement was de signed and incorporated for (i) the 2 MHz RF antenna operating at 80 A RMS at 7 kVAC. (ii) the extraction electrodes\, which is operating at maximum voltage of 15 kVDC (iii) the plasma chamber (made of Aluminium Nitride\, transparent to RF field with high thermal conductivity) (iv) the Faraday c up for H- ion current measurement. Forced air cooling was used for RF base d pulsed igniter\, operating at 13.56 MHz and various current stabilizing electrode biasing networks and RF impedance matching networks. Simulations were carried out on the main components and results obtained were satisfa ctory.\nMore details of the H- ion source and experimental results will be presented in the manuscript. The content of manuscript will include therm al\, vacuum and electrical simulation and experimental results.\n\nFigure 1 link :[Experimental test setup of high duty factor RF based negative hyd rogen ion source][1]\n\nFigure 2 link :[Recorded pulsed negative hydrogen ion beam current ~ 11 mA (2 ms pulse width at 50 Hz repetition rate\, 10 % duty factor) at 50 kVDC accelerating voltage\, Scale :X-axis : 0.4 ms/div . and Y-axis : 2.0 mA/div.][2]\n\nFull doc document link :[Abstract of the Paper in doc][3]\n\nFull PDF document link : [Abstract of paper in pdf][4 ]\n\n \n\n\n [1]: https://drive.google.com/file/d/1jI70VQ3Bnf1A6vcCjNxV-5 uUMinNXyO5/view?usp=sharing\n [2]: https://drive.google.com/file/d/19gmcK mc-jrNLa0xzUTRwdKpHbavb1Ssu/view?usp=sharing\n [3]: https://drive.google. com/drive/folders/1ud5LEBrloOWew3q8ClDsVN5ydDP9imHB?usp=sharing\n [4]: ht tps://drive.google.com/file/d/1mbC7MXVHPWsD4ao0Krm6wZYlyyI0QO2h/view?usp=s haring\n\nhttps://indico.inp.nsk.su/event/28/contributions/1952/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1952/ END:VEVENT BEGIN:VEVENT SUMMARY:Analysis of the DEMO-FNS magnetic field passive reduction and neut ral beam injectors shielding methods DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1972@indico.inp.nsk.su DESCRIPTION:Speakers: Sergey Ananyev (NRC Kurchatov institute (НИЦ Ку рчатовский институт))\nSteady-state operation mode of a fusion neutron source (FNS) will require plasma heating and maintaining th e current in it by fast atoms beam injecting. The DEMO-FNS project [1] ass umes the use of six injectors providing additional heating power up to 30 MW at an atomic energy of 500 keV. As a prototype for the DEMO-FNS injecto r\, an injector developed in detail for the ITER project can be used\, wit h the injector layout retained\, but changes in individual components\, wh ich is caused by the difference in beam energy and power [2]. Inside these components\, there are very strict restrictions on the magnetic field mag nitude (the flux density should be below a certain value along the path of ion movement and even lower in the neutralization region) [3]. To achieve these characteristics in an environment with a high scattered field due t o the magnetic system of the facility\, which includes the coils of the po loidal and toroidal fields\, the central solenoid and the plasma itself\, additional shielding of the injectors is provided. At this stage\, we expe ct that the proposed design will allow obtaining the required magnetic fie ld values only by passive injector(s) shielding due to a case made of a fe rromagnetic material with a high magnetic permeability index. An electroma gnetic analysis of the effectiveness of such a screen was performed using 3D modeling using the ANSYS code. For this\, a computational finite-elemen t model DEMO-FNS was created\, which includes a vacuum volume in which an electromagnetic system is located and one of 6 heating injectors. The magn etic field components values on the injection axis were calculated without shielding the injector region. It was shown that the vertical field compo nent Bz in the injector region is maximum and is in the range of 300 G at the input (from the side of the torus) to 150 G at the other end of the sh ielded case. Variants of single-layer shielding using various materials\, and multilayer ones: two-\, three- and four-layer with different layer thi cknesses and vacuum gaps between them were considered. By choosing the opt imal thicknesses of layers and gaps\, the projection of the magnetic induc tion vector on the plane perpendicular to the beam direction was suppresse d to acceptable values in the region of the injector components. The BTR c ode was used to calculate the motion of particles in the conditions of the obtained magnetic fields\, taking into account reionization along the ent ire injection path length. The distributions of loads and power losses on the injector components and the transverse beam power dynamics are obtaine d. Loads calculations have shown that for a given magnetic field distribut ion\, the loads on the duct are significantly uneven\, which together with the reionized particles fluxes focusing in magnetic fields\, is the great est danger for heat removal. These results will be used later in the inje ctor case and the duct engineering design.\n1. Y. S. Shpanskiy\, “Progre ss in the design of the DEMO-FNS hybrid facility\,” Nucl. Fusion\, vol. 59\, no. 7\, p. 076014\, Jul. 2019\n2. S.S. Ananyev\, E.D. Dlougach\, A.I. Krylov\, A. A.Panasenkov and B. V. Kuteev\, Concept of Plasma Heating and Current Drive Neutral Beam System for Fusion Neutron Source DEMO-FNS — Physics of Atomic Nuclei\, 2019\, Vol. 82\, No. 7\, pp. 981–990\, DOI: 1 0.1134/S1063778819070020\n3. S.S. Ananyev\, E. D. Dlugach\, B.V. Kuteev\, A.A. Panasenkov\, Modeling and optimization of neutral beam injectors for fusion neutron source DEMO-FNS - VANT. Ser. Thermonuclear fusion\, 2018\, vol. 41\, no. 3\, DOI: 10.21517 / 0202-3822-2018-41-3-57-79\n\nhttps://ind ico.inp.nsk.su/event/28/contributions/1972/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1972/ END:VEVENT BEGIN:VEVENT SUMMARY:Impact of operational parameters on single beamlet deflection in a negative ion source for NBI applications DTSTART;VALUE=DATE-TIME:20200903T102000Z DTEND;VALUE=DATE-TIME:20200903T104000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1953@indico.inp.nsk.su DESCRIPTION:Speakers: Andrew Hurlbatt (Max-Planck-Institut für Plasmaphys ik)\nFor current and future large scale tokamaks\, neutral beams for heati ng and current drive are generated from the neutralisation of large negati ve ion beams with powers up to 40 MW and energies up to 1 MeV. These beams are created by electrostatically extracting negative ions from a low temp erature/pressure hydrogen or deuterium plasma\, and accelerating them thro ugh a series of grids\, resulting in a beam comprised of many hundreds of beamlets. Due to their negative charge\, electrons are also extracted from this plasma. Were they to undergo acceleration to the full energy\, these co-extracted electrons would reduce efficiency due to the additional acce lerated current\, and cause high heat loads on beamline components. To pre vent this\, permanent magnets are embedded in the second grid\, the field of which deflects co-extracted electrons out of the beam at a low energy. This field also affects the negative ions as they are accelerated\, causin g beamlets to exit the grid system with a residual offset and deflection a ngle. Due to the alternating orientation of the magnetic field\, this alte rnates row-by-row\, and causes an observable zig-zag pattern of the beamle ts in many ion sources. This adversely affects the overall divergence of t he beam\, and compensation is foreseen in future devices.\n\nMeasurements of the residual deflection of a single beamlet have been carried out at th e BATMAN Upgrade test facility by calculating relative beamlet angles from beam emission spectroscopy (BES) spectra\, and through the use of one-dim ensional carbon fibre composite (1D-CFC) tile calorimetry to find beamlet positions. In this work\, the amount of beamlet deflection is shown to cha nge significantly\, by up to 0.7° (12 mrad)\, depending on the operationa l parameters used. As is to be expected from a simple theoretical treatmen t\, the beamlet deflection angle is observed to be affected by changes to the voltages of the acceleration system. However\, the beamlet deflection angle is also observed to change with RF power\, which\, to a first approx imation\, should only affect beamlet divergence\, and not the deflection. Other source parameters that should only affect the plasma are also demons trated to impact the beamlet deflection angle\, but it was not yet possibl e to determine which of the source filling pressure\, filter field strengt h\, or plasma grid bias current play a role and to which extent.\n\nWhiche ver are the underlying reasons for changes to the beamlet deflection angle with operational parameters that\, to first approximation\, should only a ffect the plasma\, it is clear that the deflection is not constant. This h as implications for devices that are planning to use compensation methods for beamlet deflection\, as these methods may not be effective outside of a narrow operational space.\n\nThis work has been carried out within the f ramework of the EUROfusion Consortium and has received funding from the EU RATOM research and training programme 2014-2018 and 2019-2020 under grant agreement No. 633053. The views and opinions expressed herein do not neces sarily reflect those of the European Commission.\n\nhttps://indico.inp.nsk .su/event/28/contributions/1953/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1953/ END:VEVENT BEGIN:VEVENT SUMMARY:Hydrogen negative ion beam extraction with Cs DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1981@indico.inp.nsk.su DESCRIPTION:Speakers: Min Park (National Fusion Research Institute (NFRI)) \nA negative ion beam source of 200 keV / 0.5 A has been under development at National Fusion Research Institute (NFRI). Recently\, a Cs dispenser w as equipped to feed the Cs to enhance the source performance. To see the C s seeding effect\, preliminary short-pulse beam extraction experiments wer e carried out with 50 keV accelerator prior to the installation of 200 keV accelerator. It was confirmed that the performance of Cs dispenser was ma intained for more than 2 hours and the beam currents were increased by abo ut 2 times. The co-extracted electron currents were drastically decreased. It is necessary to find optimum operational conditions such as the curren t waveform of Cs dispenser to control the Cs feeding rate and particularly the plasma grid (PG) temperature which is the main factor for the deposit ion rate or the thickness of Cs on the PG surface.\n\nhttps://indico.inp.n sk.su/event/28/contributions/1981/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1981/ END:VEVENT BEGIN:VEVENT SUMMARY:Initial results of a plasma grid comparison experiment between NIF S and ITER-like types at BATMAN Upgrade DTSTART;VALUE=DATE-TIME:20200902T050000Z DTEND;VALUE=DATE-TIME:20200902T052000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1927@indico.inp.nsk.su DESCRIPTION:Speakers: Haruhisa Nakano (National Institute for Fusion Scien ce\, National Institutes of Natural Sciences)\nLarge-scale sources for neg ative hydrogen (or deuterium) ions are used in some present and many futur e fusion devices in neutral beam injectors (NBI). Several test facilities contribute to the development of the RF source for the ITER-NBI in order t o achieve simultaneously the ITER requirements\, e.g. beam pulse of 3600 s \, beam current density of 286 A/m2 and co-extracted electron current lowe r than the ions in deuterium operation at ITER-relevant sources: among the m are BATMAN Upgrade (BUG) and ELISE at IPP. Filament-arc (FA) negative io n sources are routinely operated at the NBIs of the Large Helical Device a t NIFS. Beside the discharge type\, these sources differ in their required parameter range as well as in certain parts of their design\, e.g. the ex istence of a bias plate\, magnetic field configurations\, and the design o f the extraction system\, in which the plasma grid (PG) is the plasma-faci ng component.\n In order to gain a better understanding of the influenc e of the PG design on the plasma and beam properties\, a comparison betwee n the NIFS and ITER-like PGs at IPP was started at BUG by a NIFS-IPP inter national collaboration. The NIFS-type PG is thinner (4 mm) and has a shall ower conus around the extraction apertures compared to the ITER-like PG no rmally used at BUG (thickness of 9 mm and deeper conus). The distance betw een the PG and the second grid (extraction grid\, EG) is kept constant. He nce\, due to the different thickness of the PGs\, the field strength of th e electron deflection magnets (EDM\, mounted in the EG) in the plasma clos e to the PG is stronger for the NIFS-PG. Thus\, an influence on the co-ext racted electron current is expected. The different conus geometry may impa ct the transport of negative ions in the plasma as well as the formation o f the plasma meniscus (i.e. the transition between plasma and extracted be am)\, and thus impact the beam optics. For this comparison\, source plasma parameters were measured at 32 mm and 27 mm distance upstream of the PG s urface in the NIFS and ITER-like PG cases\, respectively (difference resul ts from the different PG thickness). This position is outside of the EDM f ield loop. Initial results have been successfully obtained in hydrogen ope ration. Similar source plasma parameters with only minor differences were observed\, such as local positive ion density in the range of 1x1017 m-3 ( measured by Langmuir probes) and line-averaged negative-ion density of 3 t o 4x1016 m-3 (measured by Cavity Ring-Down Spectroscopy) for both PGs at a filling pressure of 0.3 Pa\, discharge power of 64 kW\, extraction voltag e of 5 kV\, acceleration voltage of 32.5 kV\, PG filter current of 1.5 kA (approximately 3 mT on the PG upstream surface)\, and bias current of 5 A. The extracted ion current density is with 125 A/m2 similar for both PGs\, as well as the divergence\, measured by Beam Emission Spectroscopy collec ting signal from many beamlets. Consequently\, it needs to be considered t hat the respective value of the divergence is strongly affected by the row -wise zig-zag-deflection caused by the EDM field. In contrast\, the co-ext racted electron current with the NIFS-PG was approximately three times hig her than that with the ITER-like PG. An increase of the PG current by appr oximately 1 kA is necessary for the NIFS-PG to obtain an equivalent co-ext racted electron current as for the ITER-like PG. Further systematic invest igations will follow\, among them also a comparison in deuterium operation \, within the scope of the NIFS-IPP international collaboration.\n\nThis s tudy was supported by JSPS KAKENHI Grant number 19H01883 and 18KK0080\, an d NIFS (KEIN1606 and UFEX105).\n\nhttps://indico.inp.nsk.su/event/28/contr ibutions/1927/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1927/ END:VEVENT BEGIN:VEVENT SUMMARY:Recent performance of the SNS H- ion source with a record long run DTSTART;VALUE=DATE-TIME:20200904T152000Z DTEND;VALUE=DATE-TIME:20200904T154000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1937@indico.inp.nsk.su DESCRIPTION:Speakers: Baoxi Han (Oak Ridge National Laboratory)\nThe Spall ation Neutron Source (SNS) accelerator system includes a 65-keV H- injecto r\, a 2.5-MeV RFQ\, a 1-GeV linac series\, and an accumulator ring. The H- injector consists of an RF-driven\, Cs-enhanced H- ion source and a compa ct\, two-lens electrostatic LEBT. SNS routinely operates at 1.4 MW average beam power for three run cycles per year. In the recent two run cycles (F Y20A and FY20B)\, due to conservative operation of the RFQ with reduced po wer\, the H- injector had to deliver >50 mA to the RFQ to achieve ~35 mA l inac current required for 1.4 MW. For FY20A\, we ran two sources each serv ing about 60 days. For FY20B\, we ran a single source for the entire cycle spanning 116 days. A single dose of cesiation was conducted in the startu p which yielded ~54 mA for the entire run with little adjustments of RF po wer and Cs collar temperature. After service inspections revealed no signi ficant tear or damage that would have limited further operation of the sou rce.\n\nhttps://indico.inp.nsk.su/event/28/contributions/1937/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1937/ END:VEVENT BEGIN:VEVENT SUMMARY:Plasma Electrode Shape Suitable for Negative Hydrogen Ion Producti on DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1985@indico.inp.nsk.su DESCRIPTION:Speakers: Keita Bito (Graduate School of Science and Engineeri ng\, Doshisha University)\nIntroduction of cesium (Cs) into an ion sources enhances the production of negative hydrogen (H$^-$) ions while suppresse s the co-extracted electron current by reducing the work function of the p lasma grid surface [1-2]. However\, cesium injection into an ion sources should require periodical maintenance and can add serious complexity in op eration in a strong neutron /gamma radiation environment. Thus\, the deve lopment of Cs-free H$^-$ / D$^-$ sources is desirable. \n\nWe have been in vestigating the amount of H$^-$ current and the amount of co-extracted ele ctron current when C12A7 electride or molybdenum (Mo) were used for the Pl asma electrode (PE) in a compact ECR ion source with an exchangeable PE. T he C12A7 electride has a low work function\, and it is expected to increas e the amount of H$^-$ ion current and suppress the co-extracted electron c urrent when used as the PE material [3]. In this study\, we focus on the H$^-$ ion extraction and electron coextraction due to the shape of the PE of a H$^-$ ion source. Two materials: Mo and C12A7 electride are examined for a search of extraction structure suitable for a Cs-free ion source.\n \nhttps://indico.inp.nsk.su/event/28/contributions/1985/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1985/ END:VEVENT BEGIN:VEVENT SUMMARY:High-intensity polarized and un-polarized H- sources and injector development at BNL DTSTART;VALUE=DATE-TIME:20200903T084000Z DTEND;VALUE=DATE-TIME:20200903T090000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1924@indico.inp.nsk.su DESCRIPTION:Speakers: Anatoli Zelenski (BNL)\nThe AGS-RHIC injector comple x includes: high-intensity (magnetron type) H- ion source and Optically Pu mped Polarized Ion Source (OPPIS)\; 750 keV RFQ and 200 MeV Linac. In this paper we will focus on the recent Linac LEBT upgrade with three sources: two magnetron sources and OPPIS. This LEBT configuration can be a good pro totype of very reliable H- ion beam injectors for the accelerator complexe s with the high down time cost. We also present the recent magnetron devel opment to higher duty factor and reliability. The results of the beam prod uction with the new LEBT configuration will be presented. Both magnetron s ources produce 120 mA current (600-1000 us pulse duration \, 7 Hz repetit ion rate). The LEBT improvement resulted in beam intensity increase (after RFQ at 750 keV) to 80 mA (maximum 90 mA). The polarized beam efficiency t ransport will be also improved due to shorter LEBT line and replacement el ectrostatic Einzel lenses with the magnetic quadrupole lenses.\n\nhttps:// indico.inp.nsk.su/event/28/contributions/1924/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1924/ END:VEVENT BEGIN:VEVENT SUMMARY:Noise Mitigation Techniques in Thermocouple signals in Negative io n sources with RF and HV transients DTSTART;VALUE=DATE-TIME:20200909T034000Z DTEND;VALUE=DATE-TIME:20200909T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1964@indico.inp.nsk.su DESCRIPTION:Speakers: Himanshu Tyagi (ITER-India\, IPR)\nNegative Ion base d inductively coupled plasma sources operate in a high RF power and HV env ironment for plasma production and beam transport. Due to plasma power cou pling dynamics\, RF power mismatch causes large reflected fields which aff ect all the diagnostic signals by degrading the signal to noise ratio. In addition to RF disturbances\, during the beam extraction and acceleration\ , the diagnostic signals are also prone to suffer during HV breakdowns due to high dV/dt associated with fast turn off and turn on of HV system. The breakdowns cause generation of HV transients which in turn disturb the en tire signal reference system.\nSuch operational environment poses challeng es for front end electronics design for low voltage signals like the one f rom thermocouple sensors\, which are the most important diagnostic element s in such sources. The surface mounted thermocouples referenced to floati ng potential pick up noise from HV transients and RF noise. A signal condi tioning system [1\,2] is therefore needed to arrest the noise sources and provide clean signals for acquisition and control system . Such signal con ditioning needs specific RF filters and PCB design. Special attention is a lso required for shielding and grounding to help reducing noise interferen ce. \nThe present work discusses the measurements in light of the improvem ents made to the front end electronics for the thermocouples used on the R OBIN [3] RF based negative ion source test bed. The source operates at 1 M Hz RF and with HV power supplies of rating 11 kV 35 A for extraction and 3 5 kV 15 A for acceleration for which mismatch fields of the order of 90 V/ m have been observed. The overall signal chain from field to presentation layer shall be presented with the measures undertaken to solve the noise i nterference. \nReferences:\n\n[1] Henry Ott\, Noise Reduction Techniques\, Wiley \n[2] L.K. Bansal\, et. al.\,” Noise Mitigation in Thermocouple S ignal Conditioning System for Neutral Beam Calorimeter for NBI SST-1”\, IEEE Trans on Plasma Sciences\, Volume: 42\, Issue: 6\, June 2014\n[3] K P andya et. al.\, “First results from negative ion beam extraction in ROBI N in surface mode”\, AIP Conference proceedings 1869 (2017)\, p. 030009\ n\nhttps://indico.inp.nsk.su/event/28/contributions/1964/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1964/ END:VEVENT BEGIN:VEVENT SUMMARY:Numerical modeling of the electrons confinement in the multicusp m agnetic trap DTSTART;VALUE=DATE-TIME:20200903T094000Z DTEND;VALUE=DATE-TIME:20200903T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1939@indico.inp.nsk.su DESCRIPTION:Speakers: Viktor Klenov (INR)\nA charge-exchange target for ne utralizing a negative ion beam with energies up to 10 MeV and higher requi res the development of a highly efficient plasma trap which allows to form and confine plasma with a linear density up to 1017 cm-2 and higher.\n The magnetic systems in which the condition of magnetohydrodynamic stabili ty of the plasma is satisfied are most interesting to obtain a high-densit y plasma. \n The electron confinement efficiency in a magnetic trap with a quasi-spherically symmetric multicusp magnetic field geometry with a "m inimum B" at the center of the system\, in which all cusps are point-type cusps is studied using numerical methods.\n The results of numerical expe riments are compared with a collisionless model of particle motion in a tr ap.\n\nhttps://indico.inp.nsk.su/event/28/contributions/1939/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1939/ END:VEVENT BEGIN:VEVENT SUMMARY:Modeling filaments in H- ion source from the first principles DTSTART;VALUE=DATE-TIME:20200904T164000Z DTEND;VALUE=DATE-TIME:20200904T170000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1988@indico.inp.nsk.su DESCRIPTION:Speakers: Nikolai Yampolsky (Los Alamos Natonal Laboratory)\nW e report on the progress in modeling performance of the H-ion source at LA NSCE. We have developed a numerical model describing key physics processes from the first principles. The model accurately describes degradation of tungsten filaments and predicts their life time as well as the change in t he performance. The model has been benchmarked against experimental data a nd shows good agreement in various regimes of operation. The model has bee n used to provide real time information for the degradation of the filamen ts in the 2019 production cycles at LANSCE. A table with estimates for the filament lifetime depending on the output ion source current has been gen erated.\n\nhttps://indico.inp.nsk.su/event/28/contributions/1988/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1988/ END:VEVENT BEGIN:VEVENT SUMMARY:Primary electron analysis to improve the negative ion uniformity t oward ITER-class long pulse and high power negative ion sources DTSTART;VALUE=DATE-TIME:20200909T014000Z DTEND;VALUE=DATE-TIME:20200909T020000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1989@indico.inp.nsk.su DESCRIPTION:Speakers: Yuji Shimabukuro (National Institute for Quantum and Radiological Science and Technology)\nThe multi-cusp negative ion source with a unique end-plug\, so-called Eclair ion source\, has been designed f or high power negative ion sources required in fusion devices such as ITER and JT-60SA. This Eclair ion source shows one of the ideal magnetic field configurations designed by the detailed fast electron analysis to achieve both uniform negative ion production and reduction of a co-extracted elec tron in large negative ion source with over 1m long.\nThe non-uniformity o f negative ions was widely observed in the large negative ion sources in t he world. This is a critical issue in the long pulse beam acceleration bec ause this causes excess grid heat loads. In this study\, the magnetic fiel d configurations were examined by referring the semi-cylindrical ion sourc e with 1.2 m long and 0.6 m in diameter used for JT-60SA (500 keV\, 22 A d euterium negative ion beams for 100 s in the requirement). In order to pro duce uniform plasma as a seed of negative ions and reduce the co-extracted electrons in the whole extraction area\, fast electrons should be not onl y well confined but also distributed throughout the driver region. Origina lly\, a tent-shaped filter field was designed and demonstrated to make the uniform distribution of negative ions and electrons instead of the conven tional plasma grid current filter (PG filter). The previous study utilizin g the tent-shaped filter system showed that the uniform and intense negati ve ions in 80 % of the longitudinal extraction region. However\, co-extrac ted electrons detected at the EXG (extraction grid) was two times larger t han the case of the PG filter\, which is not acceptable for the long pulse operation. In this study\, the fast electron trajectory is analyzed to un derstand a route cause of the large electron current and produce uniform n egative ions.\nThe fast electrons emitted from cathode filaments were movi ng in the longitudinal direction due to the grad-B drift of the filter fie ld but were leaking around the corners of the ion source. It was expected that the electron leak at the corner was occurred by the weak magnetic fie ld there because the magnets are arranged with the 90 degrees of the angle at the corners\, and the magnetic field becomes weaker. Although addition al magnets were mounted at the corners to suppress the electron leak and e nhance the magnetic field\, the numbers of leaked electrons to PG were inc reased contrary to our expectations. This result indicated that the electr on leak was influenced by a discontinuous magnetic field at the corner reg ion. Firstly\, the proper magnet positions were examined to make smooth an d continuous magnetic field respect to the tent-shaped filter configuratio n. Finally\, hemisphere end-plug and magnet locations were designed to cir culate the fast electrons efficiently at the corner region. The electron l eak to the PG was completely suppressed with the Eclair shaped source cham ber and continuous magnet arrangement. The plasma uniformity with the Ecla ir shaped ion source can be estimated by the experimental results based up on the fast electron trajectories as 21% and 20% improvements in the later al and longitudinal directions\, respectively.\nAs a result\, the new magn etic field geometry with the Eclair type may contribute to the improvement of the negative beam uniformity and the reduction of co-extracted electro ns by comparing with conventional PG and tent-shaped filters.\n\nhttps://i ndico.inp.nsk.su/event/28/contributions/1989/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1989/ END:VEVENT BEGIN:VEVENT SUMMARY:Work function behavior of C12A7 electride materials in low tempera ture hydrogen plasmas DTSTART;VALUE=DATE-TIME:20200904T173000Z DTEND;VALUE=DATE-TIME:20200904T193000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1990@indico.inp.nsk.su DESCRIPTION:Speakers: Adrian Heiler (Max-Planck-Institut fuer Plasmaphysik )\nSince present-day high-power negative hydrogen ion sources are based on the surface conversion mechanism of atomic and ionic hydrogen species\, t hey rely on a low work function converter surface. Currently\, the alkali metal Cs (bulk work function of 2.14 eV) is continuously evaporated onto r efractory metals during the ion source operation to generate low work func tion coatings by chemisorption. However\, the high chemical reactivity and volatility of Cs coatings are major drawbacks in terms of a stable and lo ng-term reliable ion source performance. Thus\, Cs-free alternatives for t he H$^-$ converter surface are highly desirable and an active research top ic in ion source development. Since the material requirements for an imple mentation in ion sources are demanding\, i.e.\, machinability and stabilit y at ambient conditions as well as resilience against the plasma load whil e providing an efficient H$^-$ conversion yield\, no viable alternative to Cs has been found so far [1\,2].\n\nA promising candidate possibly fulfil ling the requirements for an ion source converter surface is the ceramic [ Ca$_{24}$Al$_{28}$O$_{64}$]$^{4+}$(e$^-$)$_4$\, known as C12A7:e$^-$ [3]. It is the first reported electride which is chemically and thermally stabl e in ambient atmosphere and the pure surface provides an intrinsic low wor k function of 2.4 eV at ultra-high vacuum conditions [4]. However\, it is well known that the surface work function of this material is particularly sensitive to impurities\, and it is very challenging to prepare chemicall y pure surfaces [4\,5]. Thus\, C12A7:e$^-$ samples from different manufact urers (Fraunhofer IKTS and AGC Inc.) were investigated at the laboratory e xperiment ACCesS [6]\, which provides vacuum and plasma conditions compara ble to those close to the converter surface in H$^-$ sources for fusion. A t the setup\, the surface work function can be measured absolutely via the photoelectric effect [7]. Campaigns regarding the work function dependenc e on the surface temperature and plasma exposure time in H$_2$ and D$_2$ w ith and without bias have been performed. It is shown that the work functi on can be reduced by vacuum heat treatment. The application of hydrogen pl asma leads to a further decrease of the work function\, and a quick regene ration after surface degradation due to residual gas adsorption. Long-term plasma exposure exhibits a steady-state work function below 3 eV. Biasing has shown a work function dependence from the polarity and the applied bi as potential. In general\, the C12A7:e$^-$ materials have demonstrated pro mising properties in terms of plasma resilience\, but the reached work fun ction is still substantially higher than what is achieved with the state-o f-the-art technique of *in situ* caesiation.\n\n**References**\n[1] U. Kur utz\, R. Friedl\, and U. Fantz\, Plasma Phys. Control. Fusion 59 (2017)\, 075008.\n[2] U. Fantz\, C. Hopf\, R. Friedl\, S. Cristofaro\, B. Heinemann \, S. Lishev\, and A. Mimo\, Fusion Eng. Des. 136 (2018)\, 340.\n[3] S. Ma tsuishi\, Y. Toda\, M. Miyakawa\, K. Hayashi\, T. Kamiya\, M. Hirano\, I. Tanaka\, and H. Hosono\, Science 301 (2003)\, 626.\n[4] Y. Toda\, H. Yanag i\, E. Ikenaga\, J. J. Kim\, M. Kobata\, S. Ueda\, T. Kamiya\, M. Hirano\, K. Kobayashi\, and H. Hosono\, Adv. Mater. 19 (2007)\, 3564.\n[5] Y. Toda \, Y. Kubota\, M. Hirano\, H. Hirayama\, and H. Hosono\, ACS Nano 5 (2011) \, 1907.\n[6] R. Friedl\, S. Cristofaro\, and U. Fantz\, AIP Conf. Proc. 2 011 (2018)\, 050009.\n[7] R. Friedl\, Rev. Sci. Instrum. 87 (2016)\, 04390 1.\n\n**Acknowlegdements**\nThe authors would like to thank the Fraunhofer IKTS (Institute for Ceramic Technology and Systems\, Germany) and AGC Inc . (Japan) for providing the C12A7:e$^-$ electride samples.\nThis work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-20 18 and 2019-2020 under grant agreement No 633053. The views and opinions e xpressed herein do not necessarily reflect those of the European Commissio n.\n\nhttps://indico.inp.nsk.su/event/28/contributions/1990/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1990/ END:VEVENT BEGIN:VEVENT SUMMARY:Improvements of stable negative ion production for long pulse beam operation toward the negative ion source for JT-60SA DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1932@indico.inp.nsk.su DESCRIPTION:Speakers: Masahiro Ichikawa (National Institutes for Quantum a nd Radiological Science and Technology)\nToward the coming JT-60SA tokamak operation\, negative ion sources producing 500 keV and 22 A (130 A/m$^2$) H-/D- beams for 100 s are being developed for the JT-60SA neutral beam in jector. So far\, the extraction of 15 A H$^-$ beams for 100 s has been ach ieved\, however\, there are two remaining issues related to the unclear Cs behavior in the large size negative ion source (~1.2 m x 0.68 m x 0.55 m) during long pulse operation around 100 s. One of the issues is a limitati on of available negative ion current due to arcing on filaments in the arc source for the long pulse operation with Cs. Another issue is the slow de gradation of negative ion current during a long pulse due to the unexpecte d Cs flux to the plasma grid (PG) from the Cs-accumulated chamber wall (~8 g\, ~2.8 m$^2$) around 100 $^o$C\, although the PG temperature is control led by around 200 $^o$C. \nTo achieve higher arc power for the negative io n current during the long pulse with Cs\, the protection of the filaments is most important. For this purpose\, a prototype of fast arcing detection /cutoff system using Field Programmable Gate Array (FPGA) has been develop ed for a group with 6 filaments. By optimizing the time resolution of the system and the logic of arcing detection\, the cutoff time has been reduce d to 100 $\\mu$s\, which is 1/10 faster than the previous system in the po wer supply and is enough short to reduce the damage to the filament. By ap plying this prototype\, the stable production of negative ion beam with 50 0 keV\, 154 A/m$^2$\, 118 s has been achieved for the first time. During t his experiment\, even in the operational Cs amount of 5 g\, 3 times longer life time of filaments were demonstrated. This result has been applied to the JT-60SA ion source by modifying the prototype to detect the arcing in 8 groups with 48 filaments for JT-60SA. \nAs for the slow degradation of the negative ion current during long pulse\, the balance of the Cs layer o n the PG surface is a key for the long pulse operation. This time\, increa se of PG temperature up to 300$^o$C is considered to accept the larger Cs flux to the PG according to the previous R&D. So far\, the PG temperature was controlled by the high temperature fluorinated fluid whose limit is ar ound 200 $^o$C due to the boiling point. In order to realize the PG temper ature more than 250$^o$C during long pulse\, the coolant was changed to th e compressed air whose heat transfer coefficient is about 1/10 of the fluo rinated fluid. In the preliminary tests\, designed temperature of 300 $^o$ C was sustained during 300 s up to a half of nominal arc power with heat f lux of 30 kW/m$^2$. Based on the results\, the PG temperature control syst em will be modified toward the JT-60SA ion source.\n\nhttps://indico.inp.n sk.su/event/28/contributions/1932/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1932/ END:VEVENT BEGIN:VEVENT SUMMARY:110 mA Operation of J-PARC Cesiated RF-Driven Hˉ Ion Source DTSTART;VALUE=DATE-TIME:20200909T010000Z DTEND;VALUE=DATE-TIME:20200909T012000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1940@indico.inp.nsk.su DESCRIPTION:Speakers: Akira UENO (J-PARC)\nAbstract. The Japan Proton Acce lerator Research Complex (J-PARC) cesiated RF-driven Hˉ ion source has be en stably operated for about six years. The J-PARC 400 MeV LINAC successfu lly accelerated the 60 mA beam required for the J-PARC\, when a 72 mA beam was injected from the source. The high intensity beam with transverse emi ttances suitable for the RFQ is produced with several unique measures\, su ch as\, slight water molecules addition into hydrogen plasma\, low tempera ture (about 70ºC) operation of 45º-tapered plasma electrode with a 16-mm thickness\, impurity (argon and/or nitrogen) elimination in the hydrogen plasma along with filter-field optimization\, and so on. A 65 keV 110 mA H ˉ ion beam\, whose about 103 mA has transverse emittances used for a comm on RFQ design\, was stably operated with a duty factor of 4.5 % (1 ms x 45 Hz). Since the 52.5 keV beam energy (WT) was required to produce an Hˉ i on beam intensity (IH-) of 72 mA\, the interesting relationship of IH-(65) ~IH-(52.5)x(65/52.5)^2 was derived. The source is the benchmark one for th e next generation high intensity and high energy Hˉ LINACs.\n\nhttps://in dico.inp.nsk.su/event/28/contributions/1940/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1940/ END:VEVENT BEGIN:VEVENT SUMMARY:Negative ion source fundamentals DTSTART;VALUE=DATE-TIME:20200901T081500Z DTEND;VALUE=DATE-TIME:20200901T084500Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-2008@indico.inp.nsk.su DESCRIPTION:Speakers: Motoi Wada (Doshisha University)\nhttps://indico.inp .nsk.su/event/28/contributions/2008/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/2008/ END:VEVENT BEGIN:VEVENT SUMMARY:Ion source technologies for accelerators DTSTART;VALUE=DATE-TIME:20200901T084500Z DTEND;VALUE=DATE-TIME:20200901T091500Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-2009@indico.inp.nsk.su DESCRIPTION:Speakers: Dan Faircloth (STFC)\nhttps://indico.inp.nsk.su/even t/28/contributions/2009/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/2009/ END:VEVENT BEGIN:VEVENT SUMMARY:Ion source technologies for fusion DTSTART;VALUE=DATE-TIME:20200901T091500Z DTEND;VALUE=DATE-TIME:20200901T094500Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-2010@indico.inp.nsk.su DESCRIPTION:Speakers: Ursel Fantz (Max-Planck-Institut fuer Plasmaphysik)\ nhttps://indico.inp.nsk.su/event/28/contributions/2010/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/2010/ END:VEVENT BEGIN:VEVENT SUMMARY:Extraction of negative ions DTSTART;VALUE=DATE-TIME:20200901T094500Z DTEND;VALUE=DATE-TIME:20200901T101500Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-2011@indico.inp.nsk.su DESCRIPTION:Speakers: Scott Lawrie (STFC ISIS Neutron Source)\nhttps://ind ico.inp.nsk.su/event/28/contributions/2011/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/2011/ END:VEVENT BEGIN:VEVENT SUMMARY:NIBS2020 Opening DTSTART;VALUE=DATE-TIME:20200901T080000Z DTEND;VALUE=DATE-TIME:20200901T081000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-2012@indico.inp.nsk.su DESCRIPTION:Speakers: Yasuhiko Takeiri (National Institute for Fusion Scie nce)\, Dan Faircloth (STFC)\, Yuri Belchenko (Institute of Nuclear Physics )\nhttps://indico.inp.nsk.su/event/28/contributions/2012/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/2012/ END:VEVENT BEGIN:VEVENT SUMMARY:Operational experience with the ELENA Ion Source DTSTART;VALUE=DATE-TIME:20200904T173000Z DTEND;VALUE=DATE-TIME:20200904T193000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-2013@indico.inp.nsk.su DESCRIPTION:Speakers: Davide Gamba (CERN)\nThe Extremely Low ENergy Antipr oton (ELENA) is a compact ring that was recently installed to complement t he antimatter factory at CERN. A local H-/p source has been installed in E LENA for commissioning purposes of the ring and subsequent electrostatic t ransfer lines toward experiments\, allowing to progress with the commissio ning phase also in the absence of antiprotons. The ELENA source can produc e pulses of H-\, with a length of a few us and an intensity of approximate ly 50 uA at 100 keV\, to mimic the antiproton pulse at extraction energy. In addition\, the source can deliver proton pulses\, if need be.\nAfter a few years of operation\, several observations have been collected that wil l be presented in this work. Of particular interest is the observation of a fast (about 1 MHz) intra-pulse instability for H-\, which resulted in po or charge stability of the H- beam injected into ELENA. Possible ways of s tabilising the beam pulse have been found and will also be presented.\n\nh ttps://indico.inp.nsk.su/event/28/contributions/2013/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/2013/ END:VEVENT BEGIN:VEVENT SUMMARY:Reference Sheets DTSTART;VALUE=DATE-TIME:20200904T173000Z DTEND;VALUE=DATE-TIME:20200904T193000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-2014@indico.inp.nsk.su DESCRIPTION:Speakers: Tiago Morais Sarmento (Isis Neutron Source)\nhttps:/ /indico.inp.nsk.su/event/28/contributions/2014/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/2014/ END:VEVENT BEGIN:VEVENT SUMMARY:Transport of a negative ion beam through a hydrogen plasma DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1930@indico.inp.nsk.su DESCRIPTION:Speakers: Enrique Henestroza (Los Alamos National Laboratory)\ nThe Los Alamos Neutron Science (LANSCE) linear accelerator provides an 80 0 MeV beam of\nnegative hydrogen ions (H-) to several facilities\, e.g.\, pRad\, a proton radiography studies facility\nand the PSR\, a proton stora ge ring which accumulates ions to be delivered to a target at the\nLujan C enter for the production of neutrons by spallation.\nThe negative ion bran ch of LANSCE starts at an ion source which produces H- ions by surface\nco nversion of hydrogen atoms. This process takes place inside a chamber whic h contains a\nhydrogen plasma created by an arc-discharge of molecular hyd rogen gas. Located inside the\nchamber there is a negatively biased conver ter where the actual conversion of hydrogen atoms\ninto negatively charged ions takes place. The production of H- ions is enhanced by the addition\n of Cesium gas into the plasma chamber.\nThe H- ions produced at the negati vely biased converter flow towards the grounded plasma\nelectrode which pr ovides an aperture for the extraction of the H- beam by a positive potenti al.\nAs the H- ions flow through the hydrogen plasma there are several kin etic reactions which may\nprovide a destruction mechanism. The main reacti ons are (i) electron detachment\, (ii) mutual\nneutralization with positiv ely charge plasma components and Cs ions\, (iii) associative and nonassoci ative neutralization by neutral hydrogen gas components.\nSince the amount of H- current that can be extracted from this source depends on the amoun t\nof H- ions that survive at the extraction aperture\, it is therefore of the utmost importance to\ncalculate the rate of H- extinction as they mov e through the plasma environment.\nWe will present Particle-in-Cell calcul ations of the H- beam transport through the hydrogen\nplasma including cha rged and neutral components\, taking into account the kinetic reactions\nm entioned above.\n\nhttps://indico.inp.nsk.su/event/28/contributions/1930/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1930/ END:VEVENT BEGIN:VEVENT SUMMARY:Electrostatic Simulation and Analysis of Transmission Line Corner Section for the CFETR NNBI test platform DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1976@indico.inp.nsk.su DESCRIPTION:Speakers: Rixin Wang (Institute of Plasma Physics\, Chinese Ac ademy of Sciences；University of Science and Technology of China)\nThe Ga s Insulated Transmission Line (GITL)\, which is an important link between radio frequency negative ion source and the power supply system\, carries all the Ion Source and the Extraction Power Supplies (ISEPS) conductors at -400kV with respect to ground\, from High Voltage Deck (HVD) to the beam source and the intermediate potentials of acceleration grids. The corner s ection\, which is inevitable in the GITL\, is easy to discharge if the des ign is unreasonable\, so the insulation design should be considered in the design of the corner section. In this paper three insulation schemes are put forward. Through the finite element analysis\, only one scheme meets t he design requirements. In this analysis\, the relationships between the d esign parameters (the radius and angle of the corner section) and the desi gn indexes (maximum electric field strength and equivalent distributed cap acitance) are analyzed. The preliminary design parameters of the corner se ction: the radius of the corner section can change from 50 mm to 150 mm an d the angle of the corner section is chosen as 90°. In this case\, the ma ximum electric field strength of the GITL decreases from 3.18 kV/mm to 3.0 6 kV/mm\, the maximum electric field strength of the inner surface of the grounding shell decreases from 1.08 kV/mm to 0.73 kV/mm\, the electric fie ld non-uniformity coefficient decreases from 2.21 to 2.15 and the equivale nt distributed capacitance increases from 82.12 pF to 94.70 pF. The simula tion results provide a theoretical basis for the engineering design of the corner section of the GITL.\n\nhttps://indico.inp.nsk.su/event/28/contrib utions/1976/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1976/ END:VEVENT BEGIN:VEVENT SUMMARY:Different characteristics of plasma meniscus formation between pos itive and negative beam extraction DTSTART;VALUE=DATE-TIME:20200902T054000Z DTEND;VALUE=DATE-TIME:20200902T060000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1949@indico.inp.nsk.su DESCRIPTION:Speakers: Kenichi Nagaoka (National Institute for Fusion Scien ce/Nagoya University)\nPlasma meniscus is widely believed to be formed in negative ion beam extraction boundary as well as positive ion beam extract ion boundary\, because very similar perveance dependence of beam divergenc e is generally observed. However\, several difference properties of plasma meniscus formation were revealed in recent studies of negative ion beam f ocusing. In this talk\, the different responses between negative and posit ive ion meniscus to externally applied perturbation [1-2] and unique phase space structure of negative ion beam [3] are reported. It was also found that the electron current does not affect the beam divergence/meniscus for mation [4]. Based on these results\, new physical picture of meniscus form ation of negative ion beam extraction will be discussed.\n\nThis study was supported by JSPS KAKENHI Grant number 17H03002\, 17K14903\, 19H01883 and 18KK0080\, and NIFS (NIFS18ULRR702\, NIFS19ULRR031\, NIFS20KLER103).\n\n[ 1] K. Takahashi\, T. Imagi\, et al.\, New Journal of Physics 21\, 093043\, 2019.\n[2] Y. Haba\, K. Nagaoka\, et al.\, Japanese Journal of Applied Ph ysics 59\, SHHA01\, 2020.\n[3] Y. Haba\, K. Nagaoka\, K. Tsumori\, et al.\ , New Journal of Physics 22\, 023017\, 2020.\n[4] M. Kisaki\, K. Ikeada\, Plasma and Fusion Research 13\, 1205110\, 2018.\n\nhttps://indico.inp.nsk. su/event/28/contributions/1949/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1949/ END:VEVENT BEGIN:VEVENT SUMMARY:Study of population dynamics of excited atomic hydrogen in negativ e hydrogen ion sources base on collisional radiative model DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1973@indico.inp.nsk.su DESCRIPTION:Speakers: Zengshan Li ()\nCollisional radiative (CR) models ar e useful to analyze the dynamic process of excited states and are in favor of optical emission spectroscopy (OES) in negative hydrogen ion source pl asma. In this paper\, a CR model of atomic hydrogen containing excitation of H\, dissociative excitation by H2 and dissociative recombination by H2+ is developed. The above three channels account for the main contribution for an excited H in cesium free negative hydrogen ion source. Then\, the p opulation and depopulation mechanisms of excited atomic hydrogen states ar e presented for each channel. Furthermore\, the influence of electron ener gy distribution function with a depleted or overheated tail is discussed. Finally\, above CR model is used to obtain plasma parameters by OES in hy drogen ICP discharge\, with electron density 4.9E16 m-3 and electron tempe rature 2.2 eV at a source pressure of 2.3 Pa and power of 600 W.\n\nhttps: //indico.inp.nsk.su/event/28/contributions/1973/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1973/ END:VEVENT BEGIN:VEVENT SUMMARY:BTR Application for Beam Slowing-down Analysis DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1975@indico.inp.nsk.su DESCRIPTION:Speakers: Eugenia Dlougach (NRC Kurchatov Institute\, Russia)\ nBTR code\, which is generally used for NBI beamlines design and optimizat ions\, is applied to calculate the injected beam stopping in plasma\, beam deposition and shine-through power in a fusion neutron source DEMO-FNS ( R = 3.2m\, a = 1m\, k = 2\, B = 5T\, Eb = 500keV\, PNBI ≈ 30MW). Beam-p lasma model calculates the detailed beam spatial and angular distributions with account of injector and tokamak operation parameters. The cross-sect ion fits by Janev-Suzuki are used for beam ionization\, and beam power dep osition in axial and normal beam planes\, including shine-through power in the far wall (FW) plane are obtained for different geometries. The influe nce of beam size and beamlets angular distribution (focusing and divergenc e) is found essential. Thin\, rectangular and focused beam geometries are compared. It is shown that neutral power decay aberrations in toroidal pla sma target lead to power profiles asymmetry\, which is high enough for tan gentially injected thick and divergent beams. BTR beam model allows more precise evaluation of beam losses in plasma\, shine-through power profile s and beam power and current deposition in plasma.\n\nhttps://indico.inp.n sk.su/event/28/contributions/1975/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1975/ END:VEVENT BEGIN:VEVENT SUMMARY:Profile of the LHD negative ion beam source at the plasma meniscus from numerical beam calculation based on experimental onservation DTSTART;VALUE=DATE-TIME:20200902T062000Z DTEND;VALUE=DATE-TIME:20200902T064000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1959@indico.inp.nsk.su DESCRIPTION:Speakers: Jelle Slief (Eindhoven University of Technology)\nGo od understanding of negative ion beam optics is crucial to the development of the ITER NBI system. The Large Helical Device (LHD) has such a negativ e ion beam. Recently\, an unexplained splitting of the beam in the horizon tal\, but not the vertical\, direction has been observed in the emittance diagram. This indicates a large influence of the plasma meniscus on the ne gative ion beam optics. As part of a larger set of parametric sweeps\, a s can of the beam source arc power has been carried out inside the NIFS Neut ral Beam Test Stand (NIFS-NBTS)\, while a Pepper-pot-type phase space anal yser (PPSA) has been used to characterize the beam in six-dimensional posi tion-momentum phase space. In this way\, the effect of varying the beam so urce condition on the optics of the beam downstream is investigated. Numer ical simulations of beam particle trajectories are carried out based on th e phase space measurements to obtain beam intensity profiles and phase spa ce structures (PSSs) at the location of the plasma meniscus. This provides a first step in understanding meniscus structure and formation and its in fluence on the extracted beam. \n\nAnalysis of the PSS observed in the exp eriment indicates that different beam sub-components after splitting origi nate from different physical locations on the meniscus. The results motiva te further research into negative ion plasma and plasma meniscus modeling and into negative ion beam focusing.\n\nhttps://indico.inp.nsk.su/event/28 /contributions/1959/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1959/ END:VEVENT BEGIN:VEVENT SUMMARY:Controlling the Shape of the ISIS H- Penning Ion Source Beam Pulse DTSTART;VALUE=DATE-TIME:20200903T112000Z DTEND;VALUE=DATE-TIME:20200903T114000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1921@indico.inp.nsk.su DESCRIPTION:Speakers: Tiago Morais Sarmento (Isis Neutron Source)\nThe Pen ning ion source serving the ISIS Pulsed SpallationNeutron and Muon facilit y routinely delivers55 mAbeamof negative hydrogen ions (H−) in250μspuls es at50 Hzrep-etition rate. The Front End Test Stand (FETS) specifications require60 mA\,2 ms\, pulses at50 Hz. Extending the ionsource discharge pul se length to2.2 mswill need overcomethe observed beam current droop caused by thermal tran-sients in long pulse operation. Recent experiments at25 H zhave demonstrated square60 mAbeam pulses up to1.2 mswith the permanent ma gnet version of the ISIS source and100 mApulses up to1.65 mswith the same source equippedwith a double-width extraction slit. Droop was compen-sated by ramping up the discharge current during the beampulse. The physical ph enomena underlying the droop and itscountermeasures are discussed\, and fu rther technical devel-opments that are necessary to reach the FETS specifi cationsare described. In addition\, various experimental shapes ofthe ion source discharge pulses and H−beam pulses wereachieved by controlling th e ion source discharge currentand accelerated through the ISIS70 MeVlinac. The tech-nique allows almost arbitrary shaping of the H−beam pulsesfor injection studies into the800 MeVrapid cycling protonsynchrotron\n\nhttps: //indico.inp.nsk.su/event/28/contributions/1921/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1921/ END:VEVENT BEGIN:VEVENT SUMMARY:Study of response of negative ion beam to bias voltage in phase sp ace DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1958@indico.inp.nsk.su DESCRIPTION:Speakers: Masashi Kisaki (National Institute for Fusion Scienc e)\n----------\n\n\nMechanism of the meniscus formation in negative ion so urces for fusion has not been clarified yet since negative charges in the plasmas consist of multiple components\, electron and negative ion\, and a magnetic field in the vicinity of extraction holes has 3D complicated top ology. In our previous study\, correlation between the negative ion beam o ptics and plasma parameters was examined by varying a bias voltage\, where the beam width was measured by means of beamlet monitor consisting of CFC tiles and an IR camera. It was observed that the beam width changes along the same curve with respect to the negative ion density for different bia s voltages while the negative ion-to-electron density ratio and the plasma potential significantly changed depending on the bias voltage[1]. This im plies that the meniscus shape in the negative ion extraction could be cont rolled by just a perveance matching as usually adopted in the positive ion extraction. On the other hand\, a specific feature in the negative ion be amlet was observed in the phase space. The phase space of negative ion bea mlet is occupied by multi-Gaussian components[2]\, and this feature has no t been reported for the positive ion beamlet. Then\, in this study the bea m measurement in the phase space was conducted at different bias voltages (3 V and -10 V) with the same negative ion density in order to clarify the impact of the bias voltage on the meniscus formation in more detail. As a result\, it was observed that a beamlet is composed of three Gaussian com ponents in both cases\, and that the phase space structure does not depend s on the bias voltage. This suggests that the electron is not involved wit h the meniscus formation at least in caesiated plasmas. In addition\, the effect of an electric field estimated from the difference between the bias voltage and plasma potential on the meniscus shape was not clearly identi fied in this study.\n\n \n\n 1. M. Kisaki et. al.\, Rev. Sci. Instrum. 91. 023503 (2020).\n 2. Y. Haba et. al.\, New J. Phys. 22 (2020) 023017.\n\nh ttps://indico.inp.nsk.su/event/28/contributions/1958/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1958/ END:VEVENT BEGIN:VEVENT SUMMARY:Probe for in situ measurement of work function and cesium dynamics DTSTART;VALUE=DATE-TIME:20200902T082000Z DTEND;VALUE=DATE-TIME:20200902T084000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1922@indico.inp.nsk.su DESCRIPTION:Speakers: Pranjal Singh (Institute for Plasma Research\, Gandh inagar)\nNegative ion production in the hydrogen plasma of a fusion grade negative ion source relies on the surface production mechanism. Surface pr oduction is associated with the resonance electron capture (REC) by neutra l hydrogen atoms and ions impinging on a low work function surface. In ord er to reduce the surface work function\, a Cesium (Cs) layer is deposited in situ primarily on the first grid of the negative ion extraction system called\, plasma grid (PG). For that Cs vapour is injected into the ion sou rce volume\, kept under vacuum to avoid reactions of Cs with atmospheric g ases and moisture. Too much presence of Cs inside the source possesses a serious maintenance issue because of its deposition on the actively cooled surfaces\, mainly in the extractor system and leads to high voltage break down among the grids kept at different voltage levels. Therefore\, optimiz ation of Cs injection to maintain low surface work function is the need to achieve an efficient negative ion source performance. There is no vacuum compatible probe suitable for ion source application\, available which can measure three Cs relevant parameters: (a) Cs flux on a surface\, (b) Cs c overage on the surface and (c) correspondingly the work function of the su rface in situ and can establish a correlation among all these three parame ters.\n\nThe present work deals with the development of a vacuum compatibl e probe for in situ measurement (PRISM) of work function and Cs dynamics\, including Cs flux and Cs coverage on a surface.\n\nhttps://indico.inp.nsk .su/event/28/contributions/1922/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1922/ END:VEVENT BEGIN:VEVENT SUMMARY:Estimation of inter conductor stray capacitance for HV dc transmis sion line of negative neutral beam injector DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1979@indico.inp.nsk.su DESCRIPTION:Speakers: Vishnudev M N (ITER India\, Institute for Plasma Res earch)\nNeutral beam injectors inject multi megawatt neutral beams\, sever al tens of amperes and energies from few 100 kV to MV\, into the tokamak f or heating and diagnostic purposes. The neutral beams are produced through the route of neutralisation of ion beams. The ion beams of machines like ITER shall use large area RF based negative ion sources\, for plasma produ ction\, coupled to multi grid (3-7)\, extractor and accelerator systems. D epending on the energy requirements and the beam optics the gaps between t he extractor and accelerator stages can range between a few mm to few tens of mm. The multi aperture multi grid extractor accelerator systems also p rovide the route for the gas being fed in the ion source for the plasma pr oduction to escape to the surrounding. As a result the gas density in the gaps is high and can lead to breakdowns often referred to as Paschen break downs. Another source of stored energy could be the inter conductor stray capacitance of the high voltage transmission line. These breakdowns could lead to damage of the grid segments and thereby considerable down time of the injector. One of the possible route to reduce the stored energy could be to reduce the inter conductor stray capacitance by increasing the dista nce between the conductor and the outer ground cover. This will result in complex geometry of transmission line and direct estimation of inter condu ctor stray capacitance of such complex geometry is not possible. Hence a t echnique is proposed to estimate the inter conductor stray capacitance of complex geometry transmission line.\n\nA study has been carried out to est imate the inter conductor stray capacitance for various configurations of the transmission line using the method of stored energy in COMSOL platform . The estimates for one such configuration have been validated experimenta lly from measured values of capacitances for a 1 m long prototype element. The results of these studies and the experimental observations shall be p resented and discussed.\n\nhttps://indico.inp.nsk.su/event/28/contribution s/1979/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1979/ END:VEVENT BEGIN:VEVENT SUMMARY:Design of FPGA based Triggering and Synchronization System (TSS) f or Laser Photo Detachment diagnostic in ROBIN DTSTART;VALUE=DATE-TIME:20200909T042000Z DTEND;VALUE=DATE-TIME:20200909T044000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1965@indico.inp.nsk.su DESCRIPTION:Speakers: Himanshu Tyagi (ITER-India\, Inst. for Plasma Resear ch)\nROBIN [1] is a single RF driver based negative ion test bed currently in operation at IPR\, Gandhinagar\, India. To understand and have deeper insights of physical phenomenon\, several diagnostics have been interfaced with ROBIN system.\nTo quantify the negative ion density in ROBIN source\ , laser photo detachment (LPD) diagnostic is configured. LPD at ROBIN is b ased on single high power Nd:YAG laser which has a pulse width of 3 ns and repetition rate of 20 Hz. Successful integration of LPD needs control on laser energy\, precise triggering and detection of weak signals. Precise triggering has two aspects. One is to control laser energy via delay betwe en Flash lamp and Q switch pulses and second is to trigger it in phase wit h 1 MHz RF signal. This required a triggering system which can work with a ccuracy of few nano seconds.\nA triggering and synchronization system (TSS ) based on a custom FPGA (Field Programmable Gate Array) is designed and i ntegrated in order to assure reliable and synchronized operation of the la ser. Precise delay between laser pulses is necessary to obtain appropriate laser energy and to prevent the active medium\, the Nd:YAG rod from therm al damage. In order to synchronize laser operation with 1 MHz RF\, Rogowsk ii coil based peak detection is used and interfaced with TSS. The LPD setu p is HV referenced\; hence the interfaces were designed with optical isola tion.\nAnother challenge is to detect weak signal from LPD probe. For this a custom low noise pre amplifier circuit is designed to measure signal in range of 1-2 mA in presence of large RF noise. The engineering solution d esigned for LPD interface contains mix of analog and digital systems. The TSS is based on low cost FPGA platform with custom analog based interfaces . The unit has been integrated without using any specific commercial syste m for the desired goal.\nThis paper presents the details regarding the des ign of interfacing electronics of LPD with some test results. In addition\ , the FPGA firmware\, the control software and signal acquisition process are presented.\nReferences:\n[1] K Pandya et. al.\, “First results from negative ion beam extraction in ROBIN in surface mode”\, AIP Conference proceedings 1869 (2017)\, p. 030009\n[2] J. Soni\, et al.\, ” Conceptual design\, implementation and commissioning of data acquisition and control system for negative ion source at IPR”AIP Conference Proceedings\, 1390 (2011)\, pp. 624-633\n\nhttps://indico.inp.nsk.su/event/28/contributions/ 1965/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1965/ END:VEVENT BEGIN:VEVENT SUMMARY:Study of the multi-driver decoupling model of RF negative ion sour ces DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1968@indico.inp.nsk.su DESCRIPTION:Speakers: Na Wang (a) Institute of Plasma Physics\, Hefei Inst itutes of Physical Science\, Chinese Academy of Sciences\, Hefei 230031\, China\; b) University of Science and Technology of China\, Hefei 230026\ , China)\, Zhimin Liu (a) Institute of Plasma Physics\, Hefei Institutes o f Physical Science\, Chinese Academy of Sciences\, Hefei 230031\, China\; b) University of Science and Technology of China\, Hefei 230026\, China)\ , Yahong Xie (a) Institute of Plasma Physics\, Hefei Institutes of Physica l Science\, Chinese Academy of Sciences\, Hefei 230031\, China\; b) Univ ersity of Science and Technology of China\, Hefei 230026\, China)\nAccordi ng to the latest physics design of the China Fusion Engineering Test React or (CFETR)\, radio-frequency(RF) driven negative ion sources are selected as the preferred ion source for CFETR neutral beam injector (NBI).To solve the key problems of the CFETR\, the engineering design\, development\, an d construction of the Comprehensive Research Facility for Fusion Technolog y (CRAFT) has begun. Since the RF driven negative ion sources of CRAFT are Large-area high-current extraction beam sources\, according to the NBI be am line extraction surface requirements\, the RF negative ion sources will adopt the working mode of multi-driver distributed driving. When multiple RF drivers of the same type work at the same time\, there may be mutual c oupling and interference between them\, which results in an asymmetric dis tribution of the RF magnetic field in the driver\, thereby affects the ext raction of ion current of the RF negative ion sources. This study analyzes the multi-driver decoupling model of the RF ion negative sources by simul ating the mutual coupling of drivers in different distribution modes and o btains the distribution mode with the least mutual coupling and interferen ce between the driver. In this mode\, through simulating decoupling effect s of adding metal shielding on the periphery of the driver\, adding decoup ling circuit in the driver circuit\, replacing multiple drivers with large r drivers and so on\, the best method of eliminating the coupling interfe rence between the RF negative ion sources drivers is obtained\, which prov ides theoretical support for CRAFT's RF negative ion sources to achieve st able operation of the extracted ion current.\n\nhttps://indico.inp.nsk.su/ event/28/contributions/1968/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1968/ END:VEVENT BEGIN:VEVENT SUMMARY:Research activities of RF based negative ion source in the ASIPP DTSTART;VALUE=DATE-TIME:20200902T072000Z DTEND;VALUE=DATE-TIME:20200902T074000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1947@indico.inp.nsk.su DESCRIPTION:Speakers: Yahong Xie (Institute of plasma physics\, Chinese ac ademy of sciences)\, Yuanlai Xie (ASIPP)\nThe Comprehensive Research Facil ity for Fusion Technology (CRAFT) is a large scientific device that is pre ferentially deployed for the construction of major national science and te chnology infrastructures. A negative beam source based neutral beam inject or (NNBI) with beam energy of 400 keV\, beam power of 2 MW and beam durati on of 100 s is one of the device. A radio frequency (RF) based negative be am source was designed for the CRAFT NNBI system. In order to understand t he physics and pre-study the engineering problems for RF negative beam sou rce\, a prototype source with single driver was developed. Recently\, this beam source was tested on the RF source test facility with RF plasma gene ration\, negative ion production and extraction. The long pulse of 105 sec onds negative ion beam was extracted successfully from a three electrons a ccelerator. The extracted ion current is 153 A/m2 with Cs injection and th e ratio of electron and negative ion is around 0.3. It lays good foundatio n for the R&D of negative ion source for CRAFT NNBI system. The details of design and experimental results of beam source was shown in this paper.\n \nhttps://indico.inp.nsk.su/event/28/contributions/1947/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1947/ END:VEVENT BEGIN:VEVENT SUMMARY:Measurements of work function and negative Ion spectra from C12A7 electride immersed in a hydrogen plasma. DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1991@indico.inp.nsk.su DESCRIPTION:Speakers: Mamiko SASAO (Doshisha University)\nRecently the C12 A7 electride attracts much attention as one of the possible plasma electro de material of Cs-free negative hydrogen isotope (H⁻/D⁻/T⁻) ion sour ces[1-2]. \n In this work\, H-/D⁻ spectra from a C12A7 electride target immersed in an ICP plasma was measured in the apparatus\, Phisis[3] . The target was biased negatively against the electrically grounded chamber. Th e temperature of the target was controllable up to 800 C. Negative ions we re energy analyzed by a Hiden EQP300 mass spectrometer. By rotating the ta rget\, it can be irradiated by an energy-tunable photon beam\, Omni Lamda 300i[4]\, when the plasma off\, and the photo-electric current was measure d. The work function of the sample can be obtained from the threshold phot on energy. The lowest value of the work function observed was ~2.5 eV. Thi s value was confirmed by UPS measurement with the similar conditioning pro cedure.\nChange of the negative ion yield due to the work function was mea sured. \n\n[1] Y. Toda\, et al.\, Advanced Materials 19\, 3564 (2007).\n [2] M. Sasao\, et al.\, Applied Physics Express 11\, 066201 (2018).\n[3] G . Cartry\, et al.\, A\, New Journal of Physics 19 025010 (2017).\n[4] L. T ahari\, et al.\, presented at JSI 2020 - Journées Surfaces & Interfaces( Sorbonne Université\, 22-24 janvier 2020).\n\nhttps://indico.inp.nsk.su/ event/28/contributions/1991/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1991/ END:VEVENT BEGIN:VEVENT SUMMARY:Recent progress in the RF Hydrogen Negative Ion Source in NFRI DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1982@indico.inp.nsk.su DESCRIPTION:Speakers: Byungkeun Na (National Fusion Research Institute)\nA prototype radio frequency (RF) negative hydrogen ion source is under deve loping in the national fusion research institute (NFRI) in pursuing of the negative ion beam extraction of 200 keV\, 0.5 A. The machine has extracte d negative hydrogen ion beam since 2018\, and recently two major upgrades have been implemented. The first upgrade is in the inductively coupled pla sma (ICP) source. The ICP antenna is modified to supply a maximized RF cur rent at the LC resonance frequency by installing additional capacitors. Th e RF power supply delivers 50 kW of RF power by active control of the RF f requency. A tungsten filament provides seed electrons just before the RF p ower is applied\, and the plasma is generated by the RF power supply withi n 200 us. The second upgrade is in the series of the stackable high voltag e power supplies. The output of the power supply is 20 kV / 1 A\, and each power supply is floated and powered by batteries. So far\, stacking is su ccessfully applied to two modules\, and will be extended. In this presenta tion\, the details of the above upgrades and beam extraction result will b e shown. In the near future\, more upgrades will be followed: the plasma g rid heater using hot oil circulation system will be used for Cs conditioni ng\, and diagnostics using triple probe\, CR based OES\, and laser photo-d etachment will be prepared.\n\nhttps://indico.inp.nsk.su/event/28/contribu tions/1982/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1982/ END:VEVENT BEGIN:VEVENT SUMMARY:BTR code Recent Modifications for Multi-Run Operation DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1967@indico.inp.nsk.su DESCRIPTION:Speakers: Eugenia Dlougach (RRC "Kurchatov Institute")\nBTR co de has been used for many years in the design and performance optimization of ITER HNB/DNB components and other NBI systems based on negative or pos itive ion sources. BTR beam formation and transmission along the beam line is simulated by a simple and comprehensive 6D beam model\, which accounts for beam transport losses and power deposition on the injector surfaces. Beam particles tracks are followed in deterministic manner (no random valu es) with electromagnetic fields deflection\, with transforming on gas and plasma targets (neutralization\, ionization in gas/plasma). In BTR power f lux and power deposition at the injector components are calculated along t he entire beam track. Each single BTR run in “conventional” BTR sessio n is started by the input manual tuning procedure for a specific scenario\ , which is next followed by the code restart. This input routine required the User's extensive efforts and time to get the final result for multiple operation scenarios. Recent modifications in BTR-5 code engine and I/O ha ve made it possible to run automatically multi-parametric scans of differe nt scenarios by a single click\, with a preset list of scenarios input rec ords. This reduces much of the User’s handwork\, and makes the total des ign routine shorter and more efficient (including the post-processing effo rts). NBI geometry input has become more flexible\, allowing the User to c hoose between the “standard” NBI geometry (PDP - compatible) and free- surfaces input. Memory optimization in BTR-5 allows independent tracking o f each sort of particles - to obtain the optimum statistics for maps calcu lation\, without restrictions (in earlier versions the maximum was ~10000 particles per beamlet). BTR-5 multi-run version has been used for parametr ic scans of DLM power loading\, which resulted in the DL “worst case” scenario definition\, and maximum power load for each DL surface across al l the range of scenarios. Power maps resolution in BTR-5 (unsmoothed 2D pr ofiles) on average is higher than in BTR-4\, due to the increased number o f model particles of each sort\, the standard cell for each surface is v aried between 1mm and 1cm depending on the specific surface dimensions.\n\ nhttps://indico.inp.nsk.su/event/28/contributions/1967/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1967/ END:VEVENT BEGIN:VEVENT SUMMARY:Extraction of Negative Hydrogen Ions through a Plasma Electrode Co vered by a Ta or Ti Foil DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1984@indico.inp.nsk.su DESCRIPTION:Speakers: Kenta Maeshiro (Graduate School of Science and Engin eering\, Doshisha University)\nWe have discussed in the previous meetings on the possible improvements for the negative ion to electron current rati o by depositing fresh coating of tantalum (Ta) on the plasma grid surface of a negative hydrogen (H-) ion source [1]. A fresh Ta evaporation by bur ning a thin Ta filament increased H- ion current by 12 % [2]. However\, t he enhanced H- production lasted only about one hour after burning off the Ta filament in a discharge maintained by the electron emission from a hot tungsten filament. To find out the mechanism responsible for improving H - ion to electron current ratio\, a thin (0.1 mm thick) foil of Ta was att ached to the area of the extraction hole opened at the center of the plasm a grid. The attached Ta foil did not show enhancement as large as that ob served by evaporation\, while the dependence of H- ion current upon the pl asma grid bias [3] showed a change in local plasma potential by putting th e foil on the surface of a stainless-steel plasma electrode. When the pla sma grid surface facing the hydrogen plasma was covered by a titanium foil \, the H- to electron current ratio increased like the case of Ta\, while the absolute amount of H- ion current decreased. Correlations among the H - ion to electron current ratio\, plasma parameters and the local H- ion d ensity measured by the photodetachment method have been observed.\n\n\n[1] M. Bacal and M. Wada\, AIP Conf. Proc. 1869\, 030025 (2017).\n[2] K. Maes hiro\, M. Wada\, S. Masaki\, Proc. 34th Int. Conf. Phys. Ionized Gases\, P O16PM-027.\n[3] M. Bacal et al.\, Rev. Sci. Instrum. 87\, 02B132 (2016).\n \nhttps://indico.inp.nsk.su/event/28/contributions/1984/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1984/ END:VEVENT BEGIN:VEVENT SUMMARY:Ion time-of-flight signals from nanosecond laser ablation plasmas excited in constricted cavities DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1987@indico.inp.nsk.su DESCRIPTION:Speakers: James Edward Hernandez (Doshisha University)\nNegati ve ions as well as singly and multiply charged positive ions are generated in a laser produced plasma. During laser vaporization of the target\, var ious atomic processes related to negative ion production take place involv ing radiative capture\, dielectronic recombination\, and ternary collision s\, where the last is found to be most probable in the case of a laser pla sma due to its high electron density [1]. During ternary collisions\, elec trons collide with neutral atoms to form negative ions. When the plasma pl ume is geometrically confined\, plasma density is further increased\, whic h also increases the probability of ions and electrons in colliding with n eutrals [2]. In this work\, laser vaporized plasma is confined by forming a cavity on the target by multiple pulse ablation\, wherein the inner wall of the cavity constricts the plasma plume. The ion species and velocity d istribution are characterized by time-of-flight (TOF) spectroscopy.\n\nThe setup consists of a laser ion source and a TOF spectrometer. The ion sour ce consists of a Q-switched Nd:YAG laser (pulse width = 5 ns\, wavelength = 1064 nm\, repetition rate 10 Hz) which is focused on the 10 mm diameter graphite target at 12$^\\circ$ incidence\, with 0.7 mm spot diameter. The laser is incident on the same spot of the target surface while being rotat ed along its axis\, deepening the hole as the number of subsequent pulses increases. Ions passing through an extraction aperture are accelerated tow ards the TOF spectrometer which consists of a 50-Ω resistor terminated Fa raday cup (FC) array positioned 0.6 m from the target axis. Flight times o f the ions are recorded by a 250 MHz oscilloscope triggered by a high-spee d photodiode. The system is operated inside a stainless steel vacuum chamb er with an ambient pressure of 10$^{-6}$ Pa.\n\nPreliminary experiments fo r initial target ablation of a fresh target surface at 2 GW/cm$^2$ laser p ower density and -2 kV extraction voltage resulted in an initial burst of fast electrons followed by positive ions. Collected ion current was observ ed to be highest along the target axis. Experiments are underway to correl ate the laser fluence and hole depth with the resulting ion spectra.\n\nRe ferences\n[1] S.S. Alimpiev\, M. E. Belov\, V.V.Mlinsky.\, S.M. Nikiforov\ , and V.I. Romanjuk\, Appl. Phys. A 58 67 (1994).\n[2] Y. Qiu\, C. Yao\, C . Yao\,1\,2 J. Gan\, W. Zhang\, N. Xu\, J. Sun.\, and J. Wu\, AIP Advances 9\, 095021 (2019).\n\nhttps://indico.inp.nsk.su/event/28/contributions/19 87/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1987/ END:VEVENT BEGIN:VEVENT SUMMARY:Some technical verification on infra-red temperature measurement DTSTART;VALUE=DATE-TIME:20200908T020000Z DTEND;VALUE=DATE-TIME:20200908T040000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1993@indico.inp.nsk.su DESCRIPTION:Speakers: Chao Shi (Science Island Branch\, Graduate School of University of Science and Technology of China)\nRadiation temperature mea surement is acquired widely to be based on the famous Planck's law of blac kbody radiation\, which indicate that any object with a temperature higher than absolute zero is constantly radiating infrared rays outward. Accordi ng to the law\, the radiation emission at a given temperature is constant in object and varies among materials which ruled by its emission rate.\nJu st as other emission model\, the received energy of a given radiation sour ce is dominated by its spatial placement and the emission rule of the give source. So\, my work here is to verify the radiation rule of the blackbod y and the spatially variation rule of the received emission.\nFor a typica l monochromatic radiation temperature measurement\, the measured voltage o f the transferred emission follows this equation:\n$V_{num} = \\rho M \\cd ot \\frac{\\Delta A_B}{\\pi l^2_B} \\times D_{decay} \\times S_{sensor} \\ times T_{trans} \\times A_{amp}$\nAmong them\, $\\rho$ represent the emiss ion rate of the source\, $\\Delta A_B$ is light collection area and $l_B$ shows its distance\, $D_{decay}$ give a sum to the optical attenuation\, $ T_{trans}$ gives us the conversion factor from radiation to electric signa l\, $A_{amp}$ is the amplifier magnification\, M is the blackbody spectral radiance\, which follows Planck blackbody radiation formula:\n$M=\\int_{\ \lambda_{1}}^{\\lambda_{2} } \\cdot \\frac{2 \\pi h c^{2}}{\\lambda^{5}} \ \cdot \\frac{d \\lambda}{e^{h c / k_{B} \\lambda T}-1}$\nAmong them\, is Planck's constant equals 6.626e-34 J · s\, c is the speed of light equals 2.997925e8 m / s\, T is the temperature of the source\, is spectral wave length\, and is Boltzmann's constant equals 1.38054e-23 J / K.\nTo verify the emission rule\, we keep the spatial placement fixed and change the te mperature of the source to collect the data. Under such situation\, the ou tput voltage $V_{num}$ is proportional to Planck blackbody spectral radian ce M. But considering the zero drift\, the presented $M-V_{num}$ relations hip is a linear function theoretically. So we did the verification:\n![en ter image description here][1]\nUsing the above $M-V_{num}$ data\, we did a linear fit and get a COD of 0.99969\, So $M-V_{num}$ have a typical line ar relationship.\nTo verify the spatially variation rule\, we keep the sou rce temperature and the spatial phase fixed and change the observing dista nce to record the vary of the output voltage $V_{num}$. The distance shoul d be inversely proportional to the output voltage $V_{num}$. And due to th e zero drift $b_0$ and the initial distance of the blackbody source $l_0$\ , the actual relationship follows equation:\n$V_{num}=\\frac{k}{(l_B+l_0)^ 2}+b_0$\nWe used two different temperature sets\, each has a zero drift of 0.5V\, since $l_0$ is a constant number we use one data set to fitting th e k\, $l_0$ data with $b_0=0.5V$\, another one using the $l_0$ data and fi tting the k\,$b_0$ to see whether $b_0$ fitted to 0.5V. The result shows t hat $b_0=0.53V$\, so the fitting result meets the expected data and the sp atial relationship is verified.\n![enter image description here][2]\nThose two rules are the bases for a more accurate infra-red measurement way of NBI process monitoring\, as for infra-red measurement results changes with different arrangement which should be verified beforehand.\n\n [1]: http s://tva1.sinaimg.cn/large/007S8ZIlly1ghaigbyxhoj30yo0dedhb.jpg\n [2]: htt ps://tva1.sinaimg.cn/large/007S8ZIlly1ghaij4bkyej30wy0cewgq.jpg\n\nhttps:/ /indico.inp.nsk.su/event/28/contributions/1993/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1993/ END:VEVENT BEGIN:VEVENT SUMMARY:Are resonance phenomena creating instabilities in the magnetic fil ter region in a low-temperature plasma? DTSTART;VALUE=DATE-TIME:20200903T080000Z DTEND;VALUE=DATE-TIME:20200903T082000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1971@indico.inp.nsk.su DESCRIPTION:Speakers: Miral Shah (DA-IICT\, Gandhinagar)\nLow pressure\, l ow-temperature plasma (LTP) with a spatially varying transverse magnetic f ilter field configuration has a wide range of applications. In such device s\, the magnetic field value is low enough that it magnetizes only the ele ctrons and not the ions and works as an electron cooler by limiting the f lux of hot electrons [1]. Due to the gradient of the transverse magnetic f ilter field\, the electron cyclotron frequencies are also changing with lo cation and in some places it comes close to different collision frequencie s. A parallel 2D-3V Particle-in-Cell Monte Carlo Collision (PIC MCC) kinet ic model is developed [2\, 3] to study plasma transport in a negative ion source where spatially varying transverse magnetic filter field is conside red in a source geometry similar to that of ROBIN (RF Operated Beam source in India) [4]. Various collision dependent physical phenomena\, having di fferent time scales and length scales are studied. It is observed that th e magnetic filter increases electron-ion and electron-electron collisions a couple of times than those in the absence of the magnetic filter. In t his article\, we summarize with observations based on the collision freque ncies and try to understand if there are any resonant phenomena happening in the magnetic filter region which may lead to any instability and influe nce the cross-field transport.\nReferences:\n[1] Boeuf\, J. P. et al. (20 12)\, Physics of a magnetic filter for negative ion sources. I. Collisiona l transport across the filter in an ideal\, 1D filter. Physics of Plasmas\ , 19(11). \n[2] Chaudhury\, B. et al. (2018). Hybrid Parallelization of P article in Cell Monte Carlo Collision (PIC-MCC) Algorithm for Simulation o f Low Temperature Plasmas. In Communications in Computer and Information S cience book series (pp. 32–53). Springer\, Singapore.\n[3] Shah\, M (20 20). Computational characteristics of plasma transport across magnetic fil ter in ROBIN using PIC-MCC simulation. Fusion Engineering and Design\, 151 \, 111402. \n[4] Bansal\, G. et al. (2013). Negative ion beam extraction in ROBIN. Fusion Engineering and Design\, 88(6–8)\, 778–782.\n\nhttps: //indico.inp.nsk.su/event/28/contributions/1971/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1971/ END:VEVENT BEGIN:VEVENT SUMMARY:Validation of the Distribution of Stripping Loss Neutrals in the A ccelerator of the Negative Ion Source DTSTART;VALUE=DATE-TIME:20200902T052000Z DTEND;VALUE=DATE-TIME:20200902T054000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1920@indico.inp.nsk.su DESCRIPTION:Speakers: Katsunori Ikeda (National Institute for Fusion Scien ce)\nNegative-ion based neutral beam injectors (N-NBI) are utilized for pl asma heating and current drive in the Large Helical Device (LHD). In the p revious operation\, we achieved 2.9 MW deuterium beam injection using the negative ion source optimized hydrogen operation. The deuterium negative i on current was reduced to 55.4 A and the average current density was 223 A /m$^3$ which is 0.65 times lower than the nominal hydrogen negative ion cu rrent [1]. On the other hand\, it is necessary to consider how the strippi ng loss due to the neutralization reaction in the accelerator affects the deuterium operation. The difference of the stripping loss between hydrogen and deuterium is examined using two different approaches. The first is th e measurement of the optical beam emission. An optical line-of-sight (LOS) is set to the angle of 33$^\\circ$ to the negative ion beam emitted from the ion source. The wavelength of beam emission spectrum reflects the ener gy distribution of beam particles by the Doppler effect. The low-energy pe aks are distributed in the energy band corresponding to the extraction vol tage\, and also the flat energy tail is observed in the lower energy regio n. Secondly\, the pressure distribution inside the accelerator is estimate d from the accelerator structure and vacuum pressures in the beam line. Si nce the neutralization cross section is large at the low energy\, the loss of negative ions at the extraction section is larger than that in the acc eleration section. Particularly inside of the extraction grid\, a lot of n egative ions are lost and neutral particles with the same energy are produ ced. These neutrals are the cause of the low-energy peaks in the energy di stribution. The beam emission spectrum is estimated from the energy distri bution and the cross section of the Balmer alpha emission. It is confirmed that the peak spectrum is asymmetric with a flat tail on the low energy s ide. The fraction of particles lost inside the accelerator increases from 0.16 for hydrogen to 0.24 for deuterium. Assuming that the negative ion ex traction efficiency is followed by the Child-Langmuir law\, the value of t he negative ion extraction efficiency is 0.84 for hydrogen and 0.53 for de uterium. Therefore\, the current ratio of $I_{D^-}/I_{H^-}$ should be 0.63 \, which is considered to be the cause of the degradation of the injected beam power in deuterium operation.\n\n[1] K. Ikeda\, et. al.\, Nucl. Fusio n **59** (2019) 076009.\n\nhttps://indico.inp.nsk.su/event/28/contribution s/1920/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1920/ END:VEVENT BEGIN:VEVENT SUMMARY:Experiments on Photo-Assisted O$^-$ and Al$^-$ Production with a C esium Sputter Ion Source DTSTART;VALUE=DATE-TIME:20200903T114000Z DTEND;VALUE=DATE-TIME:20200903T120000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1948@indico.inp.nsk.su DESCRIPTION:Speakers: Olli Tarvainen (STFC Rutherford Appleton Laboratory) \nIt has been recently proposed that the production of negative ions with cesium sputter ion sources could be enhanced by laser-assisted resonant io n pair production [1]. We have tested this hypothesis by measuring the eff ect of pulsed diode lasers at various wavelengths on the O$^-$ beam curren t produced from Al$_2$O$_3$ cathode of a cesium sputter ion source [2]. He re we summarize the previously reported experimental results demonstrating enhancement of the extracted beam current owing to the laser exposure and amend them with data on photo-assisted Al$^-$ production. The experimenta l results provide evidence for the existence of a wavelength-dependent pho to-assisted enhancement of negative ion currents but cast doubt on its all eged resonant nature as the effect is observed for both O$^-$ and Al$^-$ i ons at laser energies above a certain threshold. The beam current transien ts observed during the laser pulses suggest that the magnitude and longevi ty of the beam current enhancement depends on the cesium balance on the ca thode surface. It is shown that the ions produced by the laser exposure or iginate from slightly different potential than the surface produced ions\, which allows us to constrain the underlying physical mechanisms. It is co ncluded that the photo-assisted negative ion production could be of practi cal importance as it can more than double the extracted beam current under certain operational settings of the cesium sputter ion source. We describ e experiments designed to unambiguously confirm or dispute the relevance o f the ion pair production for negative ion production. Finally\, the possi bility of ion pair production explaining the beneficial effect of xenon ad mixture on the negative ion yield of an RF-driven H$^-$ ion source [3] is discussed. \n\n[1] J. S. Vogel\, Nucl. Instrum. Methods Phys. Res. B 438\, (2019)\, pp 89-95.\n[2] O. Tarvainen et al.\, submitted to J. App. Phys. (2020)\; arXiv:2007.00521\n[3] T. Kalvas\, S.K. Hahto\, J.H. Vainionpää\ , K.N. Leung\, S.B. Wilde and P. Mandrillon\, AIP Conf. Proc. 925\, 136 (2 007).\n\nhttps://indico.inp.nsk.su/event/28/contributions/1948/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1948/ END:VEVENT BEGIN:VEVENT SUMMARY:H- Ion Source Research and Development at the Oak Ridge National L aboratory DTSTART;VALUE=DATE-TIME:20200904T150000Z DTEND;VALUE=DATE-TIME:20200904T152000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1954@indico.inp.nsk.su DESCRIPTION:Speakers: Robert Welton (Oak Ridge National Laboratory)\nThe U .S. Spallation Neutron Source (SNS) is a state-of-the-art neutron scatteri ng facility delivering the world’s most intense pulsed neutron beams to a wide array of instruments which are used to conduct investigations in ma ny fields of science and engineering. Neutrons are produced by spallation of liquid Hg by bombardment of short (~1s)\, intense (~40A) pulses of protons delivered at 60 Hz by a storage ring which is fed by a high-intens ity\, 1 GeV H- LINAC. This facility has operated almost continuously sinc e 2006\, with ion source performance increasing steadily over those years\ , and now currently providing 50-60 mA of H- ions for maintenance-free run s of ~100 days with near 100% availability. Ion source research and devel opment at ORNL has played a key role in enabling and supporting these achi evements\, and this report provides a snapshot of our current efforts incl uding infrastructure upgrades to the SNS front end systems as well as R&D related to improving the external and internal antenna ion sources. In pa rticular\, we have recently simplified and improved the reliability of the plasma ignition system for the external antenna ion source which is discu ssed in detail. Overall\, experimental ion source R&D is conducted on a 6 5 keV test stand\, 2.5 MeV beam test facility\, the SNS accelerator during beam study periods\, and on a plasma gun test bench. Finally\, future di rections and collaborations with other laboratories are discussed.\n\nhttp s://indico.inp.nsk.su/event/28/contributions/1954/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1954/ END:VEVENT BEGIN:VEVENT SUMMARY:Interface Boundary Conditions for Global Models of Multi-Chamber N egative Hydrogen Ion Sources* DTSTART;VALUE=DATE-TIME:20200904T154000Z DTEND;VALUE=DATE-TIME:20200904T160000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1966@indico.inp.nsk.su DESCRIPTION:Speakers: Sergey Averkin (Tech-X Corp)\nGlobal models of plasm a discharges are a standard tool in plasma fluid simulations incorporating complicated chemistry. These models use global balances of energy and con servation of species number in order to estimate volume averaged number de nsities and temperatures of plasma components. Simple semi-analytic estima tes of species density profiles valid in a wide range of parameters are us ed in order to include wall fluxes. Due to the nature of wall flux estimat ion\, the global models are limited to single chamber designs.\n\nIn this paper we present the development of interface boundary conditions that all ows the use of conventional global models for separate chambers. Additiona l source terms corresponding to interface boundary conditions provide clos ure for simulations of multi-chamber ion sources. We use an extension of t he Global Enhanced Vibrational Kinetic Model (GEVKM) [1] with updated hydr ogen plasma chemistry [2] to model multi-chamber negative hydrogen sources . We compare newly developed interface boundary conditions based on the fl uid approximation with the thermal flux approximation [3]. We present prel iminary results of simulations using different interface boundary conditio ns for the negative hydrogen ion source at IPP Garching. We compare our ne w two-chamber model results to previous fluid simulation results and exper imental measurements.\n\n[1] Averkin S.N. et al\, “A Global Enhanced Vib rational Kinetic Model for High Pressure Hydrogen RF Discharges”\, IEEE Trans. Plasma Sci.\, Vol. 43\, N. 6\, pp. 1926-1943\, 2015.\n[2] Yang W. e t al\, “Benchmarking and Validation of Global Model Code for Negative Hy drogen Ion Sources”\, Phys. Plasmas\, 25\, 113509\, 2018.\n[3] Averkin S .N. and S. A. Veitzer\, “Global Model of Multi-Chamber Negative Hydrogen Ion Sources with Updated Hydrogen Plasma Chemistry”\, 10th Int. Partile Accelerator Conf.(IPAC'19)\, Melbourne\, Australia\, 19-24 May 2019. \n\n \n----------\n*This work was performed under the auspices of the Departmen t of Energy\, Office of Basic Energy Sciences Award #DE-SC0009585\n\nhttps ://indico.inp.nsk.su/event/28/contributions/1966/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1966/ END:VEVENT BEGIN:VEVENT SUMMARY:IMPROVING OF THE CONVERTER SURFACE PLASMA SOURCES. DTSTART;VALUE=DATE-TIME:20200904T160000Z DTEND;VALUE=DATE-TIME:20200904T162000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1974@indico.inp.nsk.su DESCRIPTION:Speakers: Vadim Dudnikov (Muons\, Inc)\nA Large Volume Surface Plasma Source with a converter for the Los Alamos linear accelerator was developed. A large gas-discharge chamber with a multipole magnetic wall an d 2 heated cathodes can support a discharge generating a plasma. A cooled converter with a diameter of 5 cm and a potential of up to -300 V emits ne gative ions\, accelerates them and focuses in an emission aperture with a diameter of 6.4 mm. From this SPS\, up to 18 mA of H- ions are extracted a t a duty cycle of up to 10%. \nFor dependence of an extracted H- beam curr ent on the discharge current is typical a strong saturation through H- des truction in thick layer of discharge plasma. The H- beam intensity and H- generation efficiency can be increased by decrease of plasma layer thickne ss between converter surface and emission aperture. It is possible to impr ove beam characteristics by small modification of this converted SPS. It i s proposed to used a thin Penning discharge in front of the converter. Mag netic field for Penning discharge is created by permanent magnets. Decreas e of plasma end gas between converter and emission aperture can decrease H - beam loss and increase an extracted beam intensity up to 2 times.\n\nhtt ps://indico.inp.nsk.su/event/28/contributions/1974/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1974/ END:VEVENT BEGIN:VEVENT SUMMARY:Negative Ion Beam Acceleration and Transport in the HV injector pr ototype DTSTART;VALUE=DATE-TIME:20200909T032000Z DTEND;VALUE=DATE-TIME:20200909T034000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1983@indico.inp.nsk.su DESCRIPTION:Speakers: Oleg Sotnikov (Budker Institute of Nuclear Physic s)\nA high-voltage negative ion based neutral beam injector is under const ruction at the Budker Institute of Nuclear Physics [1]. It consists of the negative ion source\, of the low-energy beam transport section (LEBT) to purify the beam before the acceleration\, of the multi-electrode single-ap erture beam accelerator and of the plasma neutralizer and beam magnetic se parator with beam energy recuperators. The test stand for study of the ma in injector components\, consisting of ion source and LEBT\, installed at the HV platform and of accelerator section with HEBT was physically launch ed in 2019. A negative ion beam production and transport through LEBT to t he input of the accelerator tube was studied before [2]. In the first hal f of 2020 the initial beam acceleration to energy up to 180 keV and the ac celerated beam transport through the HEBT section with the quadrupole lens es were tested. The parameters of the transported beam were measured by th e secondary emission detectors\, installed at different points of the beam line and by the beam calorimeter\, installed at the beam line exit in 10 m from the source. The power load to the acceleration tube electrodes was measures. The efficiency of the beam transport vs various source and LEBT parameters will be presented and discussed.\n[1]. A.A. Ivanov\, G. Abdrash itov\, V. Anashin\, et.al.\, Rev. Sci. Instrum.\, 85\, 02B102 (2014)\;\n[2 ]. A. A. Ivanov\, Yu. Belchenko\, P. Deichuli\, A. Sanin\, and O. Sotnikov . AIP Conf. Proc.\, 1771\, 030012 (2016).\n\nhttps://indico.inp.nsk.su/eve nt/28/contributions/1983/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1983/ END:VEVENT BEGIN:VEVENT SUMMARY:Steady-state charge-exchange ion source of 10 mA H- beam DTSTART;VALUE=DATE-TIME:20200909T022000Z DTEND;VALUE=DATE-TIME:20200909T024000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1960@indico.inp.nsk.su DESCRIPTION:Speakers: Igor Shikhovtsev (Budker Institute of Nuclear Physic s of Siberian Branch Russian Academy of Sciences)\nFor injection into a ta ndem accelerator of the BNCT device at Budker INP\, Novosibirsk\, a steady -state charge-exchange negative ion source with a current of ~ 10 mA is b eing developed. The primary beam of hydrogen ions with a current of 1–2 A and an energy of 30 keV is formed by a an RF ion source using a multi-ap erture four-electrode ion-optical system with ballistic focusing. The RF p lasma source operated at low hydrogen supply produces a plasma with a high content of molecular ions H2+. The formed beam of hydrogen ions passes th rough a charge-exchange target. Fast molecular ions H2+ in the charge-exch ange target dissociate into two half-energy protons and are partially conv erted into negative ions. The resulting negative beam with half energy is deflected by 90 degrees by a focusing bending magnet and then accelerated by a single-aperture ion-optical system to an energy of 100 keV. Residua l fast atoms and protons formed in the charge-exchange target are dumped. To reduce the stripping of the negative ion beam\, high vacuum is to be p rovided in the transport region using differential pumping by turbopumps. In the paper\, we discuss a design of the primary molecular ion source and that of beam line. At present\, the source design has been completed and its parts are being manufactured. Power supply and control systems of the ion source are already prepared.\n\nhttps://indico.inp.nsk.su/event/28/con tributions/1960/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1960/ END:VEVENT BEGIN:VEVENT SUMMARY:Damage to N-NBI systems due to positive ion back-streaming DTSTART;VALUE=DATE-TIME:20200902T064000Z DTEND;VALUE=DATE-TIME:20200902T070000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1931@indico.inp.nsk.su DESCRIPTION:Speakers: Motoi Wada (Doshisha University)\nLong term stabilit y of a plasma heating system is indispensable for realizing a DEMO nuclear fusion reactor. One possible cause for deteriorating the accelerator/ion source system of negative ion based neutral beam injection (N-NBI) heatin g is the damage due to energetic positive ions back-streaming from the bea m produced plasma. The positive ions strike the surfaces of downstream si des of the extraction/acceleration electrodes and they can acquire the ful l acceleration energy to bombard the back end-plate of the ion source. Th e heat flux should be comparable or even greater than that to divertor as the beam energy and the current density reach ITER design goals. The robu stness against the damage due to back-streaming ions should now be evaluat ed by taking the reactor operation life into account.\n\nParticle retentio n directly affects the collision cascade of a high energy particle injecte d into solid materials and the resulting sputtering yields. Local tempera ture of the solid retaining injected particles determines the diffusion of the retained particles\, and thus can largely modify the overall erosion rate of the solid. The effects due to long term exposures to intense part icle injections of deuterium are studied with the computer simulation code ACAT (Atomic Collision in Amorphous Target) for molybdenum: the candidate material of the back end-plate for an ion sources of a DEMO reactor.\n\nh ttps://indico.inp.nsk.su/event/28/contributions/1931/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1931/ END:VEVENT BEGIN:VEVENT SUMMARY:Issues in the measured values of Langmuir and photo-detachment pro bes measuring Cs-seeded plasmas DTSTART;VALUE=DATE-TIME:20200909T020000Z DTEND;VALUE=DATE-TIME:20200909T022000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1934@indico.inp.nsk.su DESCRIPTION:Speakers: Katsuyoshi Tsumori (National Institute for Fusion Sc ience)\nDiagnostics at the region between magnetic filter to plasma grid o f negative ion sources are important to understand the mechanism of the pr ocess through production to extraction of negative ions in source plasmas seeded caesium (Cs). Millimeter microwave interferometry and cavity ringd own (CRD) measurement are reliable diagnostic methods to measure line-aver aged densities of electrons and negative ions\, respectively. \nThe plasm a close to the plasma grid\, however\, changes due to the vector field of magnetic field changing three dimensionally\, and a “local” measuremen t at any point is required in such cases. Langmuir probe and photo-detachm ent probe are suitable for the purpose\, while those methods have ambiguit ies caused by magnetic field and electrostatic field resulted from bias po tential at plasma grid to obtain accurate physics values. In addition\, i nfluence of photoelectrons to a Langmuir probe was observed at the measure ment of Cs-seeded plasma formed in the extraction region of LHD ion source .\nIn this presentation\, we report the problems to apply Langmuir and pho to-detachment probes and discuss the conditions to correct the magnetic fi eld and to reduce the influences of photoelectron to the measured values.\ n\nhttps://indico.inp.nsk.su/event/28/contributions/1934/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1934/ END:VEVENT BEGIN:VEVENT SUMMARY:Design of gas flow control of RF negative hydrogen ion source base d on ASIPP NBI test facility DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1969@indico.inp.nsk.su DESCRIPTION:Speakers: Jinxin Wang ()\nThe gas pressure during plasma disch arge affects the density and temperature of its electrons\, which is essen tial to realize the steady-state operation of the radio frequency negative hydrogen ion source used in the nuclear fusion auxiliary heating experime ntal device.In order to maintain the density and uniformity of the plasma and improve the operating efficiency of the ion source.It is necessary to keep the gas pressure during plasma excitation of the ion source and the g as pressure during beam extraction within a certain range.By simulating th e dynamic changes of vacuum in the ion source with different gas flow rate s\, gas intake times and pumping speeds\, hardware circuits are designed t o control solenoid valves and mass flow controllers (MFC) to achieve the p recise control of gas flow.The experimental results in the RF test facilit y of ASIPP NBI show that the precisely controlled gas flow strategy design ed has better repeatability and more stable density and uniformity of the plasma .At the same time\, gas flow is also an important reference for the calculation of the real-time pumping speed performance of cryopumps and t he analysis of the reasons for the failure of the beam extraction experime nt.\n\nhttps://indico.inp.nsk.su/event/28/contributions/1969/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1969/ END:VEVENT BEGIN:VEVENT SUMMARY:Analysis of plasma characteristics of high-power radio frequency n egative ion source based on Langmuir probe DTSTART;VALUE=DATE-TIME:20200910T080000Z DTEND;VALUE=DATE-TIME:20200910T100000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1977@indico.inp.nsk.su DESCRIPTION:Speakers: Yongjian Xu (Institute of Plasma Physics\, Chinese A cademy of Sciences)\nThe plasma parameters of the radio frequency (RF) neg ative ion source directly affect the density of negative ion and the unifo rmity of the plasma in the extraction zone. In order to understand the beh avioral characteristics of the plasma inside the RF negative ion source\, a set of Langmuir probe system (plate probe and cylindrical probe) was dev eloped and tested on the RF ion source test facility at the Institute of P lasma Physics\, Chinese Academy of Sciences (ASIPP). The Langmuir probe wa s used to measure the spatial distribution of the plasma parameters in the extraction zone and the axial distribution of the plasma parameters in th e expansion zone. In the experiment the relationship between the density p arameters and the RF power\, source pressures is explored. Experimental re sults show that the plasma parameters presents better uniformity and the e lectron temperature is maintained at a lower level (Te\n\nhttps://indico.i np.nsk.su/event/28/contributions/1977/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1977/ END:VEVENT BEGIN:VEVENT SUMMARY:BTR code for NBI Design and Optimization DTSTART;VALUE=DATE-TIME:20200903T090000Z DTEND;VALUE=DATE-TIME:20200903T092000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1944@indico.inp.nsk.su DESCRIPTION:Speakers: Eugenia Dlougach (NRC Kurchatov Institute Russia)\nB TR code is used for NBI beamlines design and studies since 2005. Initially tailored for beam re-ionized particles tracking in NBI Ducts\, BTR finall y became a universal tool for 3D geometry optimization and thermal loads e valuation in NB lines. BTR simulation includes all variety of neutral beam formation and transport conditions - after the ion beam extraction from t he Negative or Positive Ion Beam Source. From the very beginning BTR was c reated for public usage\, and it goes with interactive user-friendly inter face (Windows GUI). BTR code tracing model is straight-forward and determi nistic (with no random values used)\, thus it is replicable and easily cro ss-checked with other beam tracking codes\, including analytical models (P DP code). BTR standard beam is a 2D array of beamlets\, their spatial posi tions\, focusing and inner angular distributions can be reproduced with hi gh resolution (100-100000 macro-particles per each beamlet). The model 6D statistics leads to precise evaluations of beam direct losses and power de position profiles at beamline components (currently represented by 50 - 30 0 surfaces in total). BTR is parallel and able to trace up to 1e10 macro-p articles within few hours on average Windows machine\, with the best perfo rmance achieved on 4-8-processor systems. Today BTR is a lively and evolvi ng code\, and all the Users can have a free full-time/full-life support (3 FS). Basic applications of BTR code are presented – with a focus on conv entional BTR versions (Single-Run).\n\nhttps://indico.inp.nsk.su/event/28/ contributions/1944/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1944/ END:VEVENT BEGIN:VEVENT SUMMARY:Transferring knowledge gained for pulsed extraction at the ELISE t est facility to ITER-relevant CW extraction DTSTART;VALUE=DATE-TIME:20200903T104000Z DTEND;VALUE=DATE-TIME:20200903T110000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1925@indico.inp.nsk.su DESCRIPTION:Speakers: Dirk Wünderlich (Max Planck-Institut für Plasmaphy sik)\nThe ELISE test facility with its half ITER-size ion source is an ess ential part of the European Roadmap towards the ITER NBI system. One aim o f ELISE is to demonstrate the ITER target values for the extracted current density\, the ratio of co-extracted electrons to extracted ions and the u niformity of the extracted beam during long pulses\, i.e. $1000\\\,\\mathr m{s}$ in hydrogen and $3600\\\,\\mathrm{s}$ in deuterium and at a filling pressure of $0.3\\\,\\mathrm{Pa}$.\nDue to limitations in the available HV power supply\, operation of ELISE is currently limited to pulsed extracti on\, i.e. short extraction phases\, so-called extraction blips\, of up to $10\\\,\\mathrm{s}$ each ${\\approx}150\\\,\\mathrm{s}$. During the past y ears\, a good insight in the physics of this operational mode was gained i n both hydrogen and deuterium operation. $1000\\\,\\mathrm{s}$ hydrogen pl asma pulses with repetitive extraction blips are possible with an extracte d current density of over $90\\\,\\%$ of the ITER target value\, while als o fulfilling the requirements for the electron-ion ratio and the beam homo geneity. In deuterium roughly 67 % of the ITER target for the extracted cu rrent density has been achieved for long pulses.\nDuring such pulses an ov erall increase of the co-extracted electron current is typically observed between one blip and the next\, even though the electron current is observ ed to actually decrease during each blip. These opposing effects are expla ined by different caesium dynamics during the source plasma phase when com pared to the beam phase and they were one motivation behind the currently ongoing upgrade of ELISE to a CW extraction system. Being able to achieve beam pulses of up to 1 hour will allow knowledge to be gained on the physi cs of caesium redistribution and conditioning over the long timescales nee ded for ITER operation.\nThis update consists of two main hardware changes : i) installation of a new CW high voltage power supply and ii) installati on of a CW beam calorimeter. Delivery and commissioning of the CW high vol tage power supply as well as first tests using a dummy load are planned fo r summer 2020. First operation of ELISE using the CW power supply will tak e place at the end of the year. A CW calorimeter design developed at IPP i s currently being tested at the BATMAN Upgrade test facility.\nThe present ation discusses the physics of pulsed beam extraction and the differences to CW extraction. Additionally\, the status of both systems\, the CW power supply and the CW calorimeter and first results of the CW calorimeter pro totype used at BATMAN Upgrade will be presented.\n\nhttps://indico.inp.nsk .su/event/28/contributions/1925/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1925/ END:VEVENT BEGIN:VEVENT SUMMARY:First operation of SPIDER and 1MV integrated power test in MITICA DTSTART;VALUE=DATE-TIME:20200903T110000Z DTEND;VALUE=DATE-TIME:20200903T112000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1929@indico.inp.nsk.su DESCRIPTION:Speakers: Diego Marcuzzi (Consorzio RFX)\nTo reach fusion cond itions and control the plasma configuration in ITER\, the next step in tok amak fusion research\, two neutral beam injectors (NBIs) will supply 17MW each\, by neutralizing accelerated negative hydrogen or deuterium ions. Th e requirements of ITER NBIs (40A/1MeV D- ions for ≤1h\, 46A/870keV H- io ns for ≤1000s) have never been simultaneously attained. So in the Neutra l Beam Test Facility (NBTF\, Consorzio RFX\, Italy) the operation of the f ull-scale ITER NBI prototype (MITICA) will be tested and optimised up to f ull performances\, focussing on accelerator (including voltage holding)\, beam optics\, neutralisation\, residual ion removal. The NBTF includes als o the full-scale prototype of the ITER NBI source with 100keV particle ene rgy (SPIDER)\, for early investigation of negative ion production and extr action\, source uniformity\, negative ion current density and beam optics. \nThis contribution will describe the main results of the first two years of SPIDER operation\, devoted to characterizing plasma and beam parameters . Investigation of the efficiency of RF coupling to the plasma in differen t configurations of the RF circuits and the temporary introduction of a ma sk reducing the number of beamlets (for a total number of ~100 out of 1280 ) allowed to extend the operation parameter range\, by maintaining the pre ssure profile within a controlled range to reduce disruptive occurrences. Magnetic filter field effectiveness in reducing the co-extracted electron current was verified\, however this field was found to affect the plasma n ecessitating a modification to the magnetic configuration. A major shutdow n\, planned for 2021\, to solve the issues identified during the operation and to carry out scheduled modifications\, will be outlined.\nThe install ation of each MITICA power supply and auxiliary system was completed\; mec hanical components are under procurement by F4E. Integration. Commissionin g and test of the power supplies (PS)\, procured by different Domestic Age ncies\, will be presented. In particular\, 1.0MV insulating tests were car ried out step-by-step and successfully completed. During 2020 PS integrate d tests on accelerator dummy load will be carried out\, including the resi lience to accelerator grid breakdowns using a short-circuit device in vacu um.\nThe overall programme of the NBTF\, aimed at validating the NBI desig n and at meeting the ITER schedule (requiring NBIs in operation in 2032)\, will be outlined.\n\nhttps://indico.inp.nsk.su/event/28/contributions/192 9/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1929/ END:VEVENT BEGIN:VEVENT SUMMARY:Correction algorithm for cavity ring down based anion density meas urement in a negative ion source having continuously fed cesium vapour DTSTART;VALUE=DATE-TIME:20200902T084000Z DTEND;VALUE=DATE-TIME:20200902T090000Z DTSTAMP;VALUE=DATE-TIME:20260819T045039Z UID:indico-contribution-28-1978@indico.inp.nsk.su DESCRIPTION:Speakers: Debrup Mukhopadhyay (Institute for plasma research)\ nNegative ion or anion density measurement is frequently done non-invasive ly by employing Cavity Ring-Down Spectroscopy (CRDS) diagnostic system. Th e optical cavity in the CRDS system is created by installing two highly re flecting concave mirrors on two collinear opposite ports of the ion source chamber\; so that the cavity encloses the plasma as an absorbing medium. In a continuously fed cesium seeded ion source the CRDS mirror is exposed to Cs vapour environment. As a result\, a finite probability of Cs deposit ion is possible on the mirror surface. In addition\, ion sputtering and th ermal distortion may degrade the mirror reflectivity and mirror alignment with time of ion source operation respectively. Distorted cavity alignment may affect the CRDS functionality. All the above issues increase themirro r loss which can be misinterpreted as absorption losses and lead to an ove r-estimation of negative ion density for a long ion source operational win dow.The CRDS sensitivity and accuracy depend on its mirror reflectivity or rather “effective reflectivity”.Due to continuous change in reflectiv ity of the CRDS mirrors because of continuous Cs deposition\, sputtering a nd distortion\, the CRDS sensitivity and accuracy are also function of tim e and a correction factor is needed to take care of the overestimation in negative ion density value\, if the time difference between the reference instance and measurement instance is significantly large.In this article\, an algorithm is presented to find the correction scheme.\n\nhttps://indic o.inp.nsk.su/event/28/contributions/1978/ LOCATION: URL:https://indico.inp.nsk.su/event/28/contributions/1978/ END:VEVENT END:VCALENDAR