Experimental and numerical study of a wire-explosion POS plasma dynamics

Abstract

We study possibility to design fast current switch using wire explosion. It was carried out series of experiments on explosion of single wire connecting two coaxial cylindrical electrodes. Current with the amplitude value of 80 kA and rise time of 7 μs flow through the 4-μm tungsten wire. The outer magnetic field (up to 30 kG) was directed along the electrodes. Setup design allow to us to change the amplitude of current flowing between the electrodes and to measure the total resistance of interelectrode space. So we can study POS plasma dynamics with different currents (current amplitude is changed in range of 10-80 kA, current rise rate is changed in range of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> -10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> A/s) and magnetic field. We compare experimental data with results of simulations carried out by means of the 3D radiative magnetohydro dynamic code MARPLE 3D (KIAM RAS). We simulate (i) a stage of a wire explosion and plasma stirring in the inter-electrode gap, and (ii) a stage of a plasma switch performance. Numerical simulations allow to estimate a time we need to fill the volume between the coaxial electrodes with the plasma generated from the wire and switch inhomogeneity, and to study the switch dynamics dependence on the hydromagnetic instability as well as the Hall effect. The calculated switch evolution correlates with experimental data.