A composite POS: first proof-of-principle results from GIT-12

Experiments with the microsecond plasma opening switch were carried out on the GIT-12 installation at the conduction current level of 3 MA. In this series an attempt to increase both the critical charge responsible for the conduction phase and the POS voltage was undertaken. The necessity of such improvement is conditioned by the difficulties of application of existing POS technology for construction of a new, multi-MA class IES driver. The experiments were inspired by several phenomenological ideas and theoretical results described as the main background philosophy of this work. Possible improvement of the POS operation is predicted if using the following technique: 1) optimization of the plasma injection length in order to increase the critical charge by keeping the initial plasma density at minimum possible level; 2) use of the initial plasma density gradient in the direction from the load to the generator in order to decouple the plasma densities responsible for the conduction and opening times; 3) use of the controlled plasma motion during the conduction phase for abrupt enhancement of the magnetic field prior to the opening phase. A composite POS satisfying these conditions and consisting of initially prepared MHD and Hall parts was applied. The first, mainly proof-of-principle results from C-POS operation on GIT-12 are reported.