FAST ELECTRONS GENERATION BY RF AND RANDOM-FIELDS NEAR THE ANTENNA .1. ONE-DIMENSIONAL MODEL AND REGULAR FIELDS

Test particle motion and acceleration has been explored in strong radi o frequency (RF) fields, for which quasilinear ponderomotive force app roximation is not valid. By nonlinear acceleration in spatially varyin g wave amplitude of RF travelling wave, electrons may be accelerated t o 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 als o demonstrated that even weak spatial gradients, much weaker than thos e expected in experiments, of the RF wave field amplitude, have signif icant consequences for the particle motion. Estimates are presented of the total energy transferred from the near antenna RF field to the pl asma due to the nonlinear electron acceleration effects.