Modeling of Strong Discharges in Water

Abstract

The aim of the work is to analyze and model strong discharges in water.1 In these measurements a cylindrical strongly coupled plasma is created by vaporizing a copper wire embedded in water with a burst of current. The resulting plasma column expands radially, compressing the surrounding water and causing a cylindrical shockwave to move radially outwards in the water. The plasma is observed to remain quite stable during this expansion.Both the current and voltage across the channel were measured, and reactive contributions to the voltage were accounted for. The column diameter was observed photographically and calculated using the SESAME code, and the conductivity values were deduced.The new set of data, 1 obtained for the conditions different from those reported earlier, 2 implies that, at longer times for some shots the scaling time dependence is valid for the column radius:In this sense the experiments resemble those reported in [3] for longer timescales.Current was supplied by a capacitor bank of charged to V = 15kV. The bank inductance was about 212nH, to which the load (wire) inductance of typically 20 to 30nH must be added. Some shots were terminated by short currents, and we will focus on four shots with the discharge current across the plasma channel measured over a relatively long time interval of up to 10 with up to three current zeros observed.The circuit current oscillation equation in this case reads:Here being the circuit net inductance,The wire length was 26.5mm. We presume the plasma column conductivity to be constant on the timescale when the column cross-section S(t) can be approximated as Strongly Coupled Coulomb Systems