Optical observation of localized plasma after pulsed discharges in liquid helium

Summary form only given, as follows. Transient localized high-density plasma, in liquid helium (LHe) has been studied. Stark broadening of a He spectral line reveals the spatial and temporal evolution in the decaying plasma with density above 10/sup 16/ cm/sup -3/ produced by pulsed discharge between a pair of W needle electrodes in gaseous bubble surrounded by LHe. When one of the electrodes is replaced by Mg rod, strong spectral lines of Mg atoms are observed. Measurements axe made for two cases that the common axis of the electrodes is horizontal and vertical. In these cases, the density distribution in the directions, respectively, along and across the common axis can be measured.