The Interelectrode Plasma

Abstract

After plasma production at non-stationary cathode spots, the plasma expands into the interelectrode space. Plasma properties such as local density, temperature, streaming velocity, and ion charge state distribution are described for the expanding plasma. We are interested in the subject because it is one way to look back at cathode process and learn about plasma generation. Knowledge about the interelectrode plasma is also relevant to the application. Much of the information on arc plasmas is based on averaging over extended periods of time (DC arcs) or many pulses (pulsed arcs). In doing so, correlations between the solid-state cathode properties and the plasma properties can be established, which allowed us to formulate empirical rules. One section is dedicated to discuss the sources and effects of neutrals in the interelectrode plasma.