Magnetohydrodynamic Simulation of a Coaxial High-Density Plasma Opening Switch

The plasma dynamics and the magnetic-field penetration in a coaxial plasma opening switch (POS) are studied self-consistently based on the two-dimensional magnetohydrodynamic (MHD) equation conjunction with the generalized Ohm's law. The energy transfers between the plasma and the magnetic field are considered during the penetration of the magnetic field, in which both the Ohmic heating and the heat transfer are included in the energy-balance equation. The profiles of magnetic field, plasma density, and plasma temperature are simulated with the initial plasma density
$n_0 = 10^16 hboxcm^-3$
. For the high-density plasma, it is shown that the convection effect dominates the magnetic-field penetration; the plasma near the cathode is rapidly compressed by the magnetic pressure, and the temperature of the plasma in the shock region increases noticeably because of the compression effect. Furthermore, the increase of temperature in the shock region enhances the magnetic-field penetration near the cathode. The energy analysis shows that more than half of the input energy is stored as magnetic-field energy, and a significant amount of the input energy goes into the plasma thermal energy. The scaling relation between the maximal conduction current and the initial plasma density is also studied, and the simulation results agree with the theoretical law and experimental data well.