Investigation of collisional effects in the plasma erosion opening switch

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Abstract
During the conduction phase of the plasma erosion opening switch (PEOS), magnetic field has been observed experimentally to penetrate completely through plasmas up to 30 cm long. Current channels in the main body of the plasma have been observed that are more than 10 cm (or more than about 60 collisionless skin depths) wide. In addition, the maximum current carried by the switch before opening (the conduction current) seems to scale roughly linearly with plasma density n and switch length l. Collisionless pic code simulations of the plasma switch show current conducted in skin‐depth‐like channels, with the conduction current scaling close to l 2/5 and n1/4. In this paper, the effect of collisions on the behavior of the PEOS is investigated and is shown to bring the pic simulations and experimental results in closer agreement. In collisional simulations, current channels as wide as those in experiments are observed, and the conduction current scales linearly with l and as n1/2 in the anode‐dominated case. In the cathode‐dominated case, linear scaling with both length and density can be inferred from the cathode penetration distance versus time.