On the Performance of Triggered Closing Switches Deployed in High Explosive Pulsed Power Experiments

Reported in this paper are the results of efforts to improve the performance of a triggered closing switch system used in a 450 kilojoule capacitor bank, which is used as a seed current source for magnetic flux compression generator experiments. The capacitor bank switch utilizes two different high power closing switches: a commercial-off-the-shelf pressurized spark gap and a custom designed solid dielectric puncture switch. Discussion of the spark gap will focus on the results of an investigation aimed at determining the pre-fire rates, self-break voltage distributions, function times and jitter characteristics of two different switches. A campaign aimed at improving the function time and jitter of a Mylar^® solid dielectric puncture switch resulted in almost a two-fold decrease in switching characteristics after reducing the thickness of the solid dielectric.

I. Introduction

For greater than a decade, Lawrence Livermore National Laboratory has been performing equation-of-state studies of materials via isentropic compression, utilizing high explosive pulsed power sources [1]–[4]. In these experiments, staged magnetic flux compression generators (FCGs) are used to create high magnetic fields which dynamically load the material samples. As described in [5], there are several subsystems that must work in a precise sequence in order to successfully conduct a test. Thus, triggered closing switches are used extensively throughout these subsystems. Since high explosive pulsed power experiments are inherently single-shot events, a high degree of confidence is needed in the performance of these switches. Repeatability and reliability are key considerations in assessing closing switch performance for these applications.