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 electrostatic fluid model where the principal waves are assumed to propagate along the magnetic field lines. Numerical results using a spectral method with periodic boundary conditions demonstrate "quasi-collapsing" solutions for localized initial conditions with sufficiently high amplitude. For smaller initial amplitudes quasi-recurrent variations are found, which have not been treated previously. The emphasis of the study is placed on an investigation of the acceleration of electrons by the high-frequency waves. This problem is analyzed using the numerically obtained wave-field 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 significant.