Measurement of the spatial neutral deuterium temperature distribution in the HBTX1B reversed-field pinch by fluorescence scattering

The spatial neutral deuterium temperature distribution has been made in the HBTX1B reversed-field pinch plasma device by Balmer-beta fluorescence scattering. This measurement is based on tuning a dye laser to the n = 2--4 transition of deuterium and passing it through the deuterium plasma with sufficient power to saturate the selected transition. The technique, hitherto used to determine neutral densities and energies, has been extended by means of an optimized two-channel narrow-band interference-filter arrangement to analyze the scattered spectrum. Spatial resolution is achieved by a scanning Risley prism arrangement. Neutral temperatures in the range 20--150 eV have been measured and the spatial distribution is consistent with neutral particle analyzer results and an ion power balance model proposed for the reversed-field pinch