Gross dynamics of a high pressure helium discharge

The spectroscopic and plasma characteristics of a brief (200 nsec) repetitive discharge in 50 torr of helium are approximately determined. Time resolved spectroscopic analysis of the divers atomic and molecular species is employed over the entire discharge period from 100 nsec prior to breakdown to 115 μsec afterwards. Discussion of the discharge is focused on three distinct periods: the arc period, comprising the first 200 nsec after initiation of the excitation pulse; the plasma or cool period, 200–1100 nsec; and the afterglow, 1100 nsec and beyond. Coupled differential equations representing the time dependent concentration of each species are solved approximately and are found to be in general agreement with the spectral data. The energy storage modes for the several periods are obtained. Particular comments on the 600 Å bands of the helium molecule are made.