Burning voltage dynamics of cathodic arcs : theory and experiment

Abstract

The burning voltage of cathodic arcs is a key indicator of plasma-cathode interactions, yet its dependence on material, gas environment, and transient surface processes remains is not fully understood and well described. In this work, we investigated the burning voltage dynamics of cathodic arcs on titanium, aluminum, copper, and graphite cathodes in vacuum, argon, oxygen, and nitrogen atmospheres. We addressed how the burning voltage dynamics can be analyzed through the dynamics in the burning voltage amplitude and the power spectrum. We proposed the use of the Poisson point process to interpret burning voltage power spectrum dynamics. Argon reduces burning voltage through gas-enhanced ion bombardment nearby the operating spot, while reactive gases promote dielectric-covered surfaces that increase the prevalence short-lived type 1 spots. The presence of short-lived type 1 spots is reflected in the increasing decay rate γmax of the Poisson point process model. In aluminum-oxygen discharges, a disappearing anode effect drives voltage drift to higher values, whereas graphite shows distinct spectral behavior due to its thermal and emission properties. The use of the Poisson point process model provides a framework linking burning voltage amplitude and spectra to the established cathodic arcs physics.