Source Parameters and Excitation in a Spark Discharge

Abstract

Experiments are reported for two key lines of aluminum, sparked in nitrogen against graphite for a variety of discharge current waveforms, that suggest that changes in spark source parameters do not fundamentally change the excitation processes in the spark. A straightforward, “either-or” excitation condition is imposed on a simple mass transport model, calculated from measured velocities of electrode vapor in the spark, to predict the time dependence of a primary feature of radiation emitted in the Al II spectrum. The data combine to suggest that parameter-dependent excitation indices require re-examination in terms of the manner in which radiation emitted from the discharge is viewed by the spectrometer.