Speaker
Prof.
Yousuke Nakashima
(Plasma Research Center, University of Tsukuba)
Description
In this paper an overview of the recent progress and the near future plan of GAMMA 10/PDX project is described. The GAMMA 10/PDX tandem mirror has open magnetic field configuration and improvement of plasma confinement has been demonstrated by using potential formation [1].
By making best use of the open magnetic field, divertor simulation experiments have been started at the end-cell. One of the most distinctive merits of using large tandem mirror is to be capable of achieving ion flux with high temperature ($\it T_{i}$ = 100 $\sim$ 400 eV) which is comparable to SOL plasma parameters [2]. Additional ICRF antennas have been installed in the anchor and plug/barrier cells to increase both particle and heat fluxes. A remarkable increase of the particle flux $ \it\Gamma_{ion} $ of 3.3×10$^{23}$ particles/s$\cdot$m$^2$ is observed when ICRF waves are applied in both east and west anchor cells together with the ECH at east plug/barrier-cell. Experiments aiming characterization of detached plasmas in the divertor simulation experimental module (D-module) have been performed [3]. Remarkable reductions of electron temperature ($\it T_e$), heat and particle fluxes (${\it P_{Heat}}$, $\it\Gamma_{ion}$) are observed according to the increase of the gas throughput into D-module. Comparison in applied radiator gases (Xe, Ar, Ne and $N_2$) showed that Xe is most effective in reduction of $\it T_e $, $\it P_{Heat}$, $\it\Gamma_{ion}$. Recycling studies in the end-cell is also investigated by using high-speed camera under the condition with heated tungsten target.
Development of high power gyrotrons and their application to divertor simulation experiments are another important subject in the GAMMA 10/PDX project [4-5]. Gyrotrons with wide range of frequencies from 14 to 300 GHz have been developed in collaboration with JAEA, NIFS and TETD. Superimposing a short ECH pulse of $\sim$ 400 kW into ICRF-produced plasma attained the peak heat-flux value of more than 15 MW/m$^2$ at the west end-cell. A 28 GHz 1 MW gyrotron developed for GAMMA 10/PDX achieved an output power of 1.38 MW. The design study of a new 28/35 GHz dual-frequency gyrotron (2 MW 3 s and 0.4 MW CW) also has been completed together with the development of double-disk sapphire window.
Recently development of Thomson scattering (TS) system [7] was progressed. This system enables multi-pass TS scattering signal from first to eighth passing, which improves reliability of measurement and time resolution.$\\$
[1] T. Imai, et al., Trans. Fusion Sci. Technol. **63** No.1T (2013) 8. $\\$
[2] Y. Nakashima, et al., Fusion Eng. Design volume **85** issue 6 (2010) 956. $\\$
[3] Y. Nakashima, et al., Fusion Sci. Technol. **68** No.1 (2015) 28. $\\$
[4] R. Minami, et al., Fusion Sci. Technol. **68** No.1 (2015) 142. $\\$
[5] T. Kariya, et al., Nucl. Fusion **55** (2015) 093009. $\\$
[6] M. Yoshikawa, et al., Fusion Sci. Technol. **68** No.1 (2015) 99.
Primary author
Prof.
Yousuke Nakashima
(Plasma Research Center, University of Tsukuba)
Co-authors
Group GAMMA 10/PDX
(Plasma Research Center, University of Tsukuba)
Dr
Isao Katanuma
(Plasma Research Center, University of Tsukuba)
Dr
Junko Kohagura
(Plasma Research Center, University of Tsukuba)
Dr
Kazuya Ichimura
(Plasma Research Center, University of Tsukuba)
Dr
Mafumi Hirata
(Plasma Research Center, University of Tsukuba)
Dr
Masayuki Yoshikawa
(University of Tsukuba)
Prof.
Mizuki Sakamoto
(Plasma Research Center, University of Tsukuba)
Dr
Naomichi Ezumi
(Plasma Research Center, University of Tsukuba)
Dr
Ryutaro Minami
(Plasma Research Center, University of Tsukuba)
Dr
Ryuya Ikezoe
(Plasma Research Center, University of Tsukuba)
Dr
Tomoharu Numakura
(Plasma Research Center, University of Tsukuba)
Prof.
Tsuyoshi Imai
(Plasma Research Center, University of Tsukuba)
Dr
Tsuyoshi Kariya
(Plasma Research Center, University of Tsukuba)
Dr
Xiaolong Wang
(Plasma Research Center, University of Tsukuba)
