Investigation of the discharge structure in a noble gas alkali MHD generator plasma. I

The discharge structures in a noble gas alkali MHD generator were investigated under stationary conditions by means of image converter pictures and probe measurements. The current concentrations already known from short-time discharges and referred to as streamers were observed. The nature of these streamers was investigated by considering the relationship between the streamers and the ionization instabilities usually present in noble gas MHD generators. The measurements showed that the streamers are directed parallel to the mean current direction and constitute regions of elevated current density in which ionization instabilities can develop.