Cyclotron superradiance of a high-current electron bunch under group synchronism conditions

We have theoretically and experimentally investigated the process of induced coherent emission (superradiance) in an electron bunch rotating in a homogeneous magnetic field. We have shown that this process makes it possible to generate ultrashort microwave pulses. In this case, the optimum conditions are found under group synchronism conditions, when the translational velocity of the bunch matches the group velocity of the radiation propagating in the waveguide circuit. For experimental investigation of the superradiance, we used a RADAN accelerator with subnanosecond electron pulse sharpener. In the 35 GHz range, we obtained microwave pulses with record short duration, down to 0.4 nsec for a peak power level up to 200 kW. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 89–97, December, 1996.