MEASUREMENTS OF THE PLASMA-DENSITY IN A FLOW ACROSS A MAGNETIC-FIELD

For the plasma flow generated in a discharge in the crossed magnetic a nd electric fields, the dynamics of the plasma density are studied by means of triple-mirror laser interferometry and a technique based on t he floating probe measurement of the Hall potential induced by the pro bing current. The obtained plasma-density profiles (directed across th e flow) are presented. It is shown that, under certain conditions, the jump in the plasma density (which, in the absence of a drift channel, is related to the decrease in the plasma drift velocity outside the d ischarge region) arises at the leading edge of the flow. The formation of a drift channel, which is caused by the polarization currents and the formation of plasma sheaths at the flow boundaries, is considered. It is shown that magnetosonic waves can be generated in the plasma re gion through which the polarization current flows.