NUMERICAL-SIMULATION OF NONSTATIONARY PROCESSES IN INTENSE HELICAL ELECTRON-BEAMS OF GYROTRONS

Experiments with helical electron beams (HEB) of powerful gyrotrons di splayed the existence of intense nonstationary processes in HEB. A ver sion of numerical simulation of HEB's is proposed, which is based on t he method of large particles. Some results of the analysis are given w ith account of the electrons reflected from the magnetic mirror and lo cked in the adiabatic trap. One of the effects detected is intense bom bardment of the cathode by the trapped electrons. Besides, formation o f quasi-stationary states whose parameters (velocity spread, pitch-fac tor) differ significantly from those given by the static theory was ob served. In the absence of the reflected particles, the solution acquir es a stable state. The HEB parameters in this case are almost the same as the static parameters.