ELECTRON ACCELERATION BY NONLINEAR HIGH-FREQUENCY WAVES IN WEAKLY MAGNETIZED PLASMAS

The evolution of nonlinear electron plasma waves in weakly magnetized plasmas is studied numerically. The analysis is based on an electrosta tic fluid model where the principal waves are assumed to propagate alo ng the magnetic held lines. Numerical results using a spectral method with periodic boundary conditions demonstrate ''quasi-collapsing'' sol utions for localized initial conditions with sufficiently high amplitu de. For smaller initial amplitudes quasi-recurrent variations are foun d, which have not been treated previously. The emphasis of the study i s placed on an investigation of the acceleration of electrons by the h igh-frequency waves. This problem is analyzed using the numerically ob tained wave-held as an input for a code where particles are traced in space and time. It is found that electrons can gain significant energy in one part of the wave-packet and loose this energy again in another part, without the net particle acceleration necessarily being signifi cant.