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

The paper presents the results of experimental studies on the radiation flux generation in the sub-millimeter wavelength range due to a strong beam-plasma interaction. A relativistic electron beam (REB) with parameters 0.5 MeV / 12 kA / 6 us pumps plasma waves in a plasma column with a length of ~2 m at a plasma density of ~10^15cm-3 in a magnetic field of B~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 of 0.5 us, 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 0.1-0.5 THz as well as the energy distribution function of the beam electrons passed through the plasma have been measured.