Electron Acceleration by Nonlinear High Frequency Waves inWeakly Magnetized Plasmas

Abstract

The evolution of nonlinear electron plasma waves in weaklymagnetized plasmas is studied numerically. The analysis is based on anelectrostatic fluid model where the principal waves are assumed topropagate along the magnetic field lines. Numerical results using aspectral method with periodic boundary conditions demonstrate“quasi-collapsing” solutions for localizedinitial conditions with sufficiently high amplitude. For smallerinitial amplitudes quasi-recurrent variations are found, which havenot been treated previously. The emphasis of the study is placed on aninvestigation of the acceleration of electrons by the high-frequencywaves. This problem is analyzed using the numerically obtainedwave-field as an input for a code where particles are traced in spaceand time. It is found that electrons can gain significant energy inone part of the wave-packet and loose this energy again in anotherpart, without the net particle acceleration necessarily beingsignificant.