Experimental Setup for Studying Induced Backward Scattering of Microwaves by a Subnanosecond High-Current Electron Beam

This paper presents the results of an experiment in which the effect of generation of picosecond superradiation pulses was first observed during the induced backward scattering of a high-power pump microwave by a short high-density relativistic electron beam. These investigations became feasible due to an experimental setup built around two high-current electron accelerators of the Radan series that were set to operate synchronously to within ~300 ps. The pump wave was generated by a relativistic Ka-band backward-wave oscillator with a power of ~100 MW. To direct this wave into the scattering region, a quasioptical system was used. The scattered radiation detected in the experiment was a short (~200 ps) pulse with a spectrum-integrated power of up to 1 MW. Due to the relativistic Doppler shift, the scattered radiation spectrum covered frequencies up to 150 GHz