The effective anode-cathode gap in an ion diode operating in a bipolar-pulse regime

The effective anode-cathode gap (ACG) in a self-magnetically insulated ion diode operating in a double (bipolar) pulse regime has been studied. In this diode, the ACG is bounded by a plasma layer at the anode surface and by electrons drifting near the cathode surface. Analysis of the system operation showed that, during the first voltage pulse, the effective ACG decreases at a constant velocity of 1.5 $\pm$ 0.1 cm/$\mu$s from 9 to 1–2 mm (depending on the pulse duration) and is not completely bridged by plasma. After reversal of the voltage polarity, the effective gap width is restored for 10–20 ns on a nearly initial level. During the second pulse, electrons drift within a 1- to 1.5-mm-thick layer near the anode, while the thickness of a plasma layer on the anode surface does not exceed 0.5 mm.