POS experiments on Hawk using an inverse pinch, gas plasma source

We report results from the first series of POS experiments using an “Inverse Pinch” gas plasma source on the Hawk generator with a short circuit load. Our results showed that under certain conditions a hydrogen plasma filled switch resulted in significantly higher POS voltages and faster load current rise times than other types of IP produced plasmas, or cable guns. This situation existed only for the case where the initial plasma density was radially uniform. For Ar plasmas, the conducted current scaled with the injected mass according to MHD theory if the average charge state was +2, while for the H plasmas M/Z=6 was needed to reach agreement with theory. The H result can be reconciled if, the additional electrons that we detected during the conduction phase, originated from secondary plasma with M/Z=12.5. We also found with the IP source that, during opening, the electron density in a large radial region (⩾1 cm) was below the sensitivity limit of the interferometer