Generation and amplification of powerful ultrashort microwave pulses

Experimental results of the observation of superradiance from intense, subnanosecond electron bunches moving through a periodic waveguide and interacting with a backward propagating TM01 wave are presented. At 38 GHz 60 MW 300 ps pulses were generated by 200 keV, 1.2 kA, 1 ns electron bunch. The SR pulse power increased up to 150 MW when electron energy and current were increase up to 300 keV and 2 kA. The initial observation of 75 GHz 10–15 MW radiation pulses with duration less than 150 ps, and of 150 GHz microwave spikes with a risetime of 75 ps are also reported. The ultra-short microwave pulses in Ka, W, and G band were generated with repetition frequencies of up to 25 Hz. It is demonstrated the possibility of further amplification and shortening of SR pulses during propagation of these pulses over quasi continues electron beam.