The simulation of a plasma confined in an electrostatically plugged spindle cusp

Abstract

A particle simulation code is used to study the dynamic evolution and the confinement of a non-neutral plasma in an electrostatically plugged magnetic spindle cusp configuration. The code assumes axial symmetry and functions in the electrostatic limit. The walls and electrodes of the actual experimental device are included. The electrons are found to be extremely well confined. The excess electron charge creates a potential well, which, after initial fluctuations, is found to be stable. At later times ions are found to leak out slowly through the point cusps, in contrast with the beginning where most ion losses are through the line cusp. This is due to electron shielding of the electrode potential, as predicted by an earlier theoretical model.