Development of a High-Power Wideband Amplifier on the Basis of a Free-Electron Maser Having an Operating Frequency Near 30 GHz: Modeling and Results of the Initial Experiments

Abstract

We develop a high-power wideband amplifier based on a free-electron maser for particle acceleration, which will be operated in the 30 GHz frequency band, on the basis of the LIU-3000 linear induction accelerator forming an electron beam with an electron energy of 0.8 MeV, a current of 250 A, and a pulse duration of 200 ns. As the operating regime, we chose the regime of grazing of dispersion curves, since, according to the modeling performed, it allows one to ensure an instantaneous amplification band of about 5–7% in an undulator with regular winding for an output radiation power at a level of 20 MW and a gain of 30–35 dB. The results of the first experiments studying this FEM-based scheme are presented, in which the specified power level is achieved in the range around 30 GHz, and fast tuning of ±0.5 GHz in the band of variations in the frequency of the master magnetron is demonstrated. Modeling shows that the use of the non-resonance trapping/braking regime, which is realized in an undulator with profiled parameters, allows one to expect an increase in the radiation power of up to 35–40 MW with simultaneous widening of the amplification band up to 30% under the conditions of the LIU-3000 experiments.