Generation of 150 MW/0.7 ns W-Band Superradiant Pulses in a Strongly Oversized 2D Periodical Surface-Wave Structure

We present the results of experiments on generation of sub-nanosecond 90-GHz superradiant (SR) pulses with a record peak power of ~150 MW. Such pulses are produced based on excitation of a surface wave in an oversized waveguide with 2D (double-periodical) corrugation. In such a structure, azimuthally propagating wave fluxes synchronize radiation from different azimuthal segments of a tubular electron bunch with a diameter greatly exceeding the wavelength. The implemented approach opens up the prospect of a radical increase in the total electron current and the peak power of SR pulses while maintaining azimuthal coherence of radiation. The results of experiments are in line with the theoretical predictions within the frame of the quasi-optical model and direct PIC simulations.