High-Voltage Spark Spectra: Utility as a Function of Temporal and Spatial Resolution

Abstract

The utility of the high-voltage spark discharge as an analytical emission source is considered. Temporal and spatial windowing was used to reiterate well-documented characteristics of heterogeneities of the spark plasma in both time and space. Cathodes of pure magnesium and aluminum 2024 alloy were used as samples. It was shown that by using a unidirectional current waveform, and by selecting a spatial position off of the interelectrode axis, at times late in the plasma lifetime, one can obtain relatively clean emission spectra (high signal-to-background ratio). This is in contrast to recent literature reports which suggest that the high-voltage spark exclusively produces spectra which are complex and which demonstrate poor background characteristics. The dynamic range of the spark is also demonstrated to be somewhat larger than the cited work suggests. The implications of various methods of presenting experimental results for such data are discussed.