Vapor density and electron density determination during high-current anode phenomena in vacuum arcs

This paper presents time and space resolved results of spectroscopic measurements in a vacuum circuit breaker experiment during high-current anode modes, i.e., anode spot type 1, anode spot type 2, and anode plume. Excited state densities for Cu I, Cu II, and Cu III transitions are determined during anode spot type 1 and type 2 as well as for the anode plume. Temporal evolution of excited state densities and Cu neutral gas densities are also determined during anode spot type 1 and type 2, which show that the Cu density in front of the anode during anode spot type 2 is about 6 times higher compared to anode spot type 1. Electron densities are also determined during both types of anode spot using Stark broadening. The electron densities during anode spot type 2 are remarkably higher than during anode spot type 1.