Generation of a Directed Flux of Megawatt THz Radiation as a Result of Strong REB-Plasma Interaction in a Plasma Column

Experiments at the multimirror open trap as plasma emitter of THz radiation (GOL-PET) facility have shown that the injection of a relativistic electron beam (REB) with a kiloampere current into a magnetized plasma column is accompanied by the generation of a THz radiation flux. Our experiments have revealed three-generation mechanisms. The first mechanism is the scattering of upper hybrid waves on plasma density gradients, the second is the direct pumping of electromagnetic waves by an electron beam, and the last one is the merging of two upper hybrid waves into an electromagnetic one. Both theoretical and experimental studies have shown the possibility to achieve a megawatt power of the flux at the upper hybrid frequency in the presence of significant plasma density gradients. Resent experiments have shown that a strong density decrease at the end of the plasma column is necessary for high-efficiency emission of the generated flux along its axis. This THz radiation flux is emitted from the column into a vacuum chamber and then through an output window to the atmosphere. The measurement results of the spatial and angular properties of such a megawatt flux are described in our article.