Fast electrons generation by RF and random fields near the antenna I. One dimensional model and regular fields

Abstract

Test particle motion and acceleration has been explored in strong radio frequency (RF) fields, for which quasilinear ponderomotive force approximation is not valid. By nonlinear acceleration in spatially varying wave amplitude of RF travelling wave, electrons may be accelerated to time averaged velocities significantly larger than the RF wave phase velocity, and than the boundary plasma thermal velocity, in RF fields of several Volts per centimeter at wave frequency of 7 MHz. It is also demonstrated that even weak spatial gradients, much weaker than those expected in experiments, of the RF wave field amplitude, have significant consequences for the particle motion. Estimates are presented of the total energy transferred from the near antenna RF field to the plasma due to the nonlinear electron acceleration effects.