Concerning microsecond megaampere-current plasma opening switches

The operation mechanism of a microsecond megaampere-current plasma opening switch is considered. The magnetic field penetrates into the plasma via nea r-electrode diffusion. The increase in the degree of plasma magnetization d ue to electron heating results in an increase in plasma resistivity and cur rent break. The problem of calculating a plasma opening switch is mathemati cally formulated. The problem reduces to simultaneously solving one-fluid t wo-temperature MHD equations with allowance for the Hall current and two-di mensional electric circuit equations. To analyze the solution obtained, one -dimensional equations are derived based on the assumption that the size of the electrode region in which the plasma is strongly magnetized is much sm aller that the plasma column length. In this approximation, the operating m odes of a plasma opening switch are studied numerically. On long time scale s (greater than or equal to2-3 mus), the operation is limited by plasma eje ction from the interelectrode gap. On short time scales (less than or equal to1 mus), the dominant process is the penetration of the magnetic field wi th the current velocity. The results of the calculations are compared with the available experimental data. The developed concept and numerical proced ure are used to optimize the scheme for an explosion experiment on breaking megaampere currents under conditions similar to those in the EMIR complex. (C) 2001 MAIK "Nauka/Interperiodica".