PIC simulations of EMH and MHD effects in the plasma opening switch

Summary form only given, as follows. Plasma opening switches (POS) are the key components of inductive energy store (IES) pulsed power systems. In the closed phase an IES system stores magnetic energy in the inductance of a vacuum transmission line. As the POS opens the stored magnetic energy flows past the POS and into a load (for example an electron or ion diode). To achieve power multiplication the opening time should be much shorter than the conduction time. There are three proposed mechanisms that control the conduction phase of the POS: 1) sheath effects at the electrodes, 2) rapid penetration of magnetic field into the body of the plasma due to EMH effects, and 3) displacement and distortion of the plasma. due to J/spl times/B (MHD) forces. In this paper, the PIC code, MAGIC, is used to study EMH and MHD effects in a POS. These simulations were performed in negative polarity with a strong radial density gradient. In regimes where EMH is expected to be dominant, the simulations show rapid axial penetration of magnetic field into the plasma in a narrow radial channel along the positive density gradient. No field penetration is observed along the negative portion of the density gradient. In positive polarity, field penetration occurs along the negative gradient and no field penetration is observed along the positive density gradient. This agrees with EMH theory of shock penetration of magnetic field. However, the speed of penetration is somewhat slower than predicted by fluid treatments. The PIC simulations also show the formation of vortices in the electron flow behind the EMH shock front.