Dynamics of micropinches in exploding wire and vacuum spark plasmas

Abstract

Summary form only given, as follows. We report work done on two experiments that have similar physics because both have micropinches in their plasma column. An experimental investigation of the dynamical behavior of micropinches was carried out in exploding wire and in vacuum arc discharges. Fast pulses from a 1.5 kJ generator were applied to a set of electrodes first in high vacuum and then to the same set bridged by a thin metallic wire. The diagnostics employed included time-resolved soft X-ray detection and streak photography. We observed short pulses of X-rays coincident in time with sharp changes in the current signal and with plasma channel contractions. The energy of the X-radiation measured was in the 3-9 keV range. On the subject of vacuum sparks there is still controversy concerning which electrode provides the metallic vapor on which the discharge propagates. In order to contribute to the understanding of the origin of this vapor a series of experiments were carried out using dissimilar electrodes and the exchange of their polarity. We found that the vapor in which the discharge propagates is provided preferently by one of the electrodes, be it the anode or the cathode.