Plasma opening switch with extrinsic magnetic field

Abstract

Summary form only given, as follows. We have demonstrated in series of experiments that plasma opening switch (POS) switching voltage (UPOS) is defined by energy density (w) deposited in the POS plasma. If we then consider a plasma erosion mainly responsible for the effect of POS switching (the erosion effect could be described by Hall or Child-Langmuir models) the energy density (w) could be measured as a function of a system macro-parameter such as the initial charging voltage of the capacity storage system (the Marx pulsed voltage generator) UMarx. The POS voltage in this case could be given by UPOSaw=aUMarx4/7, where a is a constant. This report demonstrates that for the high-impedance POS which has limited charge density transferred through the POS plasma a2.5 (MV3/7) with no external magnetic field applied. The use of the extrinsic magnetic field allows to increase a up to 3.6 (MV3/7) and to achieve higher voltages at the opening phase - UPOS=3.6UMarx4/7. To verify this approach set of experimental tests has been assigned at RS-20 megavolt-range POS generator. The generator was modified so that the Marx generator could provide output voltage from 160 to 860 kV (with a maximum drive current near 350 kA level). A pulsed magnetic field coil generating the extrinsic magnetic field to enhance POS magnetic insulation has been also introduced. The magnetic field amplitude was near 15 kGs. The maximum POS voltage achieved was 3.5 MV and started from 0.86 MV at the Marx generator.