Speaker
Prof.
Nikolai Peskov
(Institute of Applied Physics RAS)
Description
Up to now free-electron lasers are much powerful generators in THz-band able to operate at multi-megawatt power level. Such devices are driven by relativistic electron beams (REBs) of ~ 5 - 10 MeV oscillating in magnetostatic undulators and, thus, are rather bulky and costly. At the same time, generation of powerful THz radiation can be realized when using moderately-relativistic (0.5 - 1.5 MeV) high-current (1 - 3 kA) electron beams together with intense mm wave to pump transverse oscillations of the electrons (so-called RF-undulator), which could possesses much shorter period (wavelength) in comparison with “traditional” magnetostatic undulators (with additional twice higher Doppler up-conversion in counter scattering scheme). In FEL of such type (FEL-scattron) it is attractive to exploit an inter-cavity scattering regimes when pumping wave is generated by the same or parallel electron beam and, thus, no additional powerful microwave sources is needed.
Original project of multi-MW long-pulse two-stage FEL-oscillator based on two parallel sheet REBs is under development at the high-current accelerator ELMI in collaboration between BINP RAS (Novosibirsk) and IAP RAS (N.Novgorod). The basis for this project is 75 GHz planar FEM with two-dimensional distributed feedback, which was elaborated currently with a record-level output power (~ 50 MW) and narrow-band spectrum. In the two-stage scheme, this 75 GHz FEM module is used as a driver (i.e. the first stage of the oscillator). This 75 GHz radiation is transported by special waveguide (set of the Bragg deflectors) to the second channel and used as a pumping wave. At the second stage this wave undergoes stimulated scattering at the supplementary REB to produce THz radiation.
According to simulation, proposed scheme allows THz radiation pulses of ~ 10 - 20 kW power to be obtained in the so-called SASE-regime. Installation in the FEL-scattron section of advanced Bragg resonator to provide feedback loop for THz radiation, would result in increase of the output power of the THz channel up to a multi-megawatt level. As a result, energy content of up to 1 - 10 J in the THz-band pulses of hundreds nanoseconds to microsecond pulse duration can be achieved.
Key components of the electrodynamical system for two-stage FEM were manufactured and good coincidence of their “cold” tests with results of simulations was demonstrated. Experimental studies of this FEM scheme is in progress currently.
Primary authors
Dr
Alexander Sergeev
(IAP RAS)
Prof.
Andrey Arzhannikov
(BINP RAS)
Prof.
Naum Ginzburg
(IAP RAS)
Prof.
Nikolai Peskov
(Institute of Applied Physics RAS)
Dr
Petr Kalinin
(BINP RAS)
Dr
Sergey Kuznetsov
(BINP RAS)
Prof.
Stanislav Sinitsky
(BINP RAS)
Dr
Vasily Stepanov
(BINP RAS)
Dr
Vladislav Zaslavsky
(IAP RAS)
