Dynamics of the current front in a current-carrying plasma bridge

At the RRC Kurchatov Institute, high-impedance plasma opening switches have recently been developed that enable efficient pulse sharpening and are capable of operating in a repetitive mode. This paper presents the results of studying the conduction phase preceding the current break. In this stage, the magnetic-field and current waves propagate in the plasma from the switch to the load. The magnetic-field and current detectors placed along the plasma axis are used to measure the velocity and acceleration of the current front near the cathode and anode. At the end of the conduction phase, the characteristic velocities near the cathode and anode attain 100 and 50 cm/mus, respectively. During the current front propagation, the width of the front nearly triples. The acceleration and widening of the front are reasonably explained within electron magnetohydrodynamics. It is shown that the voltage during the current break depends on the length of the coaxial cathode of the switch. When the cathode length is shorter than the distance covered by the current front, the generated voltage decreases substantially. (C) 2001 MAIK "Nauka/Interperodica".