Predicting Ion Charge State Distributions of Vacuum Arc Plasmas

TitlePredicting Ion Charge State Distributions of Vacuum Arc Plasmas
Publication TypeJournal
Year of Publication1996
AuthorsAndré Anders, T. Schulke
Abstract

Multiply charged ions are present in vacuumarc plasmas. The ions are produced at cathode spots,and their charge state distributions (CSDs) depend onthe cathode material but only little on the arc currentor other parameters as long as the current is relativelylow and the anode is not actively involved in theplasma production. There are experimental data ofion CSDs available in the literature for 50 differentcathode materials. The CSDs can be calculated basedon the assumption that thermodynamic equilibrium isvalid in the vicinity of the cathode spot, and theequilibrium CSDs "freeze" at a certain distance fromthe cathode spot (transition to a non-equilibriumplasma). Plasma temperatures and densities at the"freezing points" have been calculated, and, based onthe existence of characteristic groups of elements inthe Periodic Table, predictions of CSDs can be madefor metallic elements which have not yet been used ascatqode materials.

LBNL Report Number

LBL-37921