Generation of Superradiance Pulse Exceeding 100 GW Based on an Oversized Coaxial Cherenkov Generator with Profiled Slow Wave Structure and Coaxial Coupler

For several decades, considerable attention has been focused on the investigation of generating ultrashort electromagnetic pulses using the effect of superradiance (SR). In this paper, we propose an oversized coaxial Cherenkov generator to generate an extremely high peak power exceeding 100 GW. In the device, optimized profiled slow wave structure (SWS) with squarely increasing corrugation depth and uniform SWS with slightly larger corrugation period are used to provide better beam-wave interaction and accomplish energy accumulation of wave from the bunches exactly. Coaxial reflector and coaxial coupler are applied to realize single-pass output and reduce the power loss as it reenters the SWS. The operation mode in the coaxial SWS is quasi-TEM mode, which is almost completely reflected by the coaxial reflector and coupled into the coaxial coupler with TEM mode and coaxial TM
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mode. Particle-in-cell simulations show that as the diode voltage is 760 kV with a rise time of 4.1 ns and flattop duration of 3.2 ns, beam current is 78 kA, and the magnetic field is 3.4 T, a short pulse with peak power of 129 GW and pulse duration of 0.4 ns is generated. The corresponding conversion factor is up to 2.18. The maximum electric field in the device is about 4.1 MV/cm. However, it is believed that this high electric field will not lead to serious effect on the generation and transmission of the pulse in the experiment due to the ultrashort pulse duration and singlepass transmission. The corresponding experiment is in preparation.