A method for overcoming the velocity space filamentation problem in collisionless plasma model solutions

Abstract

A method is introduced for overcoming the velocity space filamentation problem which occurs in solutions of the Vlasov-Maxwell system of equations. This method is shown to introduce no error in the evolution of the Vlasov-Maxwell solutions, to leave the field portion of the solutions unmodified, and to yield velocity-filtered distribution functions which do not carry filamentation in the velocity variable. It is conjectured that the filtered distributions do not develop spatial filamentation as well. It is shown that the method can be applied to the most general three-dimensional, electromagnetic Vlasov-Maxwell model. Several examples are presented in which comparisons between filtered and unfiltered solutions are made. These are numerical solutions of a Fourier-Fourier transformed one-dimensional electron plasma model. In the comparisons, which are favorable, reductions in run time by factors of approximately ten and in necessary machine memory by factors of twenty to thirty are demonstrated. © 1987.