Simulations of vacuum electron flow in inductive-energy-store pulsed-power systems

The current understanding of the opening process of a long-conduction-time (>300 ns) plasma opening switch (POS) involves the formation of a fairly small (2–4 mm) vacuum gap. As the switch opens, electrons which are magnetically insulated in the switch gap flow into the downstream magnetically insulated transmission line (MITL). Since the vacuum electron flow can be a large fraction of the net current, it is important to understand the nature of this flow. In this paper the vacuum electron flow into an MITL as the POS opens is studied with the particle-in-cell method Simulation results are presented for both the Decade Proto-type Module-1 (DPM1) at Physics International and the HAWK inductive energy store accelerator at NRL. The simulations show vacuum electron flow primarily near the anode as the POS opens. The HAWK simulations suggest that a low density plasma (∼10¹² cm⁻³) can significantly alter the electron flow in the MITL.