Effect of the Plasma Density on the Generation Efficiency and Changes in the Spectrum of a Plasma Relativistic Microwave Generator

The features of the experimental operation of the Sinus 550-80 plasma relativistic microwave generator (PRG) at different plasma densities are considered. Two plasma density values are considered, at which the central frequencies of the PRG output microwave radiation are 5.1 and 11.5 GHz. Numerical simulation demonstrates a decrease in the plasma electron density as a result of the action of a relativistic electron beam (REB) charge during the Cherenkov interaction and the appearance of an “ion background” during the PRG pulse. At low plasma densities, this can lead to a change in microwave generation conditions accompanied by a change in the broadband radiation to the narrowband one and a decrease in the radiation power. At the same time, at high plasma densities, when the microwave radiation is generated at high frequencies, the average amplitude of the electric field of the wave almost does not change during the REB pulse, and the radiation remains broadband. The analysis of the experimental and numerical simulation results is supported by estimates of the linear theory, which proves that the PRG works more stably at higher plasma density values.