Energy Content and Spectral Composition of a Submillimeter Radiation Flux Generated by a High-Current Electron Beam in a Plasma Column With Density Gradients

This article presents the results of experimental studies on radiation flux generation in the submillimeter wavelength range due to a strong beam–plasma interaction. A relativistic electron beam (REB) with parameters 0.5 MeV/12 kA/ $6 \mu \text{s}$ pumps plasma waves in a plasma column with a length of ~2 m at a plasma density of $\sim 10^{15} {\mathrm{ cm}}^{-3}$ in a magnetic field of ~4 T. In the presence of density gradients in the plasma column, direct measurements of the energy content of the radiation flux 18 cm in diameter leaving the plasma column into the atmosphere showed that its value reaches 5–7 J. The pulse duration of the flux at half of its amplitude was about $0.5 \mu \text{s}$ , and therefore, the pulse power was at the level of ~10 MW. In this series of experiments, the spectral composition of the radiation flux in the frequency range of 0.1–0.5 THz and the energy distribution function of the beam electrons passed through the plasma have been measured.