Current chopping space charge layers in a low pressure arc plasma

Chopping of the electric discharge current occurs in the positive column of low pressure mercury arcs, accompanied by a rapid increase of the tube resistance. The high tube voltage drops occurring when the current is stabilized by the external circuit are found to be concentrated to a single space charge layer, which forms across the column. Simultaneously, microwave emission and fast electrons can be detected. For currents close to the instability threshold, small amplitude voltage pulses are found to propagate along the column with the ion sound speed. (Auth.)