Time-resolved spectroscopy of high pressure rare gases excited by an energetic flash X-ray source
Résumé
Fluorescence from high pressure (0.1-30 bar) rare gas plasmas has been excited using an intense flash X-ray source specially developed and optimized for this experiment. Spectral analysis of the so-called “third continuum” of rare gases is presented. Time-resolved spectroscopy, absorption measurements and pressure dependence studies have provided an extended database on this longer wavelength continuum of rare gases. These data allow us to understand some of the previously contradictory results reported in the literature. They strongly support a multi-component spectral aspect of the previously called “third continuum”. In fact, the observed fluorescence result from the superposition of several continua whose relative intensities are strongly dependent upon pressure. This suggests that different species are at its origin. The name of “third continuum” does not seem anymore appropriate when speaking of the whole fluorescence emitted in the longer wavelength continuum by high pressure rare gas plasmas. Generally speaking, the flash X-ray device was proven to be a very convenient and powerful tool for the study of high pressure plasmas resulting in UV-VUV fluorescence.