Generation of Cherenkov superradiance pulses with a peak power exceeding the power of the driving short electron beam

Abstract

Theoretical investigation of a short electron beam (extended bunch) interaction with a backward wave propagating in a slow wave structure demonstrates the possibility of producing ultrashort superradiance pulses with a peak power which exceeds the power of the driving beam (conversion factor $K>$1). It is shown that a nonuniform slow wave structure with optimized profile is beneficial in order to increase the conversion factor. The results of theoretical analysis are confirmed by the experiments. At $X$ band using the SINUS-150 accelerator ($4\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$, $330\phantom{\rule{0.3em}{0ex}}\mathrm{kV}$, $2.6\phantom{\rule{0.3em}{0ex}}\mathrm{kA}$) 0.6--$0.8\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ superradiance pulses with a peak power of $1.2\phantom{\rule{0.3em}{0ex}}\mathrm{GW}$ and a conversion factor of 1.5 were obtained. Similar experiments at $\mathrm{Ka}$-band based on the RADAN-303 accelerator ($1\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$, $290\phantom{\rule{0.3em}{0ex}}\mathrm{kV}$, $2.5\phantom{\rule{0.3em}{0ex}}\mathrm{kA}$) demonstrated production of the superradiance (SR) pulse with duration $200\phantom{\rule{0.3em}{0ex}}\mathrm{ps}$ and peak power about $1\phantom{\rule{0.3em}{0ex}}\mathrm{GW}$ (conversion factor of 1.4).