Modeling of a Multi-Gigawatt Ka-Band Superradiant Source With a Slow Traveling Wave

Results of a numerical simulation of the generation of Ka-band Cherenkov superradiation (SR) with an instant (unaveraged) power of up to $\approx ~50$ GW performed using a particle-in-cell method are presented. The model included a high-current electron beam (1.1 MeV, 12.5 kA) which excites a TM01 slow wave co-propagating in a corrugated waveguide. Application of a fast-rising voltage to the cathode and kinematic sharpening of the beam current enhance the seed signal and reduce the number of slow electrons at the beam front. This provides excitation of SR peak containing about four oscillations with an instant power a factor of 3.6 greater than the beam power and $\approx ~35$ % of the beam energy converted to SR. Approaches to the formation of beams with required properties and elimination of the harmful effect of breakdowns in the slow-wave system are discussed.