Generation of ultrashort microwave pulses based on cyclotron superradiance

We have theoretically and experimentally investigated the superradiance from a bunch of electrons rotating in a homogeneous magnetic field. A RADAN-303B modulator equipped with a subnanosecond pulse slicer has been used to generate high current subnanosecond electron bunches (250 kV, 0.1-1 kA, 0.3-0.5 ns). Transverse momentum was imparted to the electrons by a kicker. It is shown that for the experimental observation of cyclotron superradiance from high current electron bunches the optimum conditions are the conditions of group synchronism, when the translational velocity of the bunch coincides with the group velocity of the radiation propagating in the waveguide. In the 35 GHz range microwave pulses with record short duration, down to 0.4 ns, with a peak power level up to 200 kW, have been obtained.