Planar laser-induced fluorescence (PLIF) measurements of a pulsed electrothermal plasma jet

Abstract

The characteristics of a pulsed plasma jet originating from an electrothermal capillary discharge have been investigated using laser-induced fluorescence (LIF) measurement. Previous emission spectroscopic measurements of a 3.1 kJ plasma jet show that upstream of the Mach disk the temperature and electron number density are about 14,000 K and 1017 cm−3, while downstream of the Mach disk the values are about 25,000 K and 1018 cm−3, respectively. However, these values are based on line-of-sight integrated measurements that may be misleading. Hence, LIF is being used to provide both spatially and temporally resolved measurements. Our recent work has been directed at using planar laser-induced fluorescence (PLIF) imaging of atomic copper in the plasma jet flow field. Copper is a good candidate for PLIF studies because it is present throughout the plasma and has electronic transitions that provide an excellent pump-detect strategy. Our PLIF results to date show that emission measurements may give a misleading picture of the flow Field, as there appears to be a large amount of relatively low temperature copper outside the barrel shock, which may lead to errors in temperature inferred from emission spectroscopy. In this paper, the copper LIF image is presented and at the moment, relative density of atomic copper, which is distributed in the upstream of the pulsed plasma jet, is discussed qualitatively.