Ultrahigh-Speed Camera Study of a Plasma Source for a Repetitive and Miniature POS

The plasma opening switch (POS) is the fastest opening switch available for use in high-power pulsed systems. The present study reported in this paper arose during the development of a compact and repetitive radiation generator, in which a POS is to be used to produce very fast rising high-voltage multi gigawatt pulses. Since the present POS requires a relatively low opening current, which is about 50 kA with a rise time of about 50 ns, a careful study was required to ensure that the proper plasma conditions (such as density and velocity) were generated by the simultaneous operation of a number of plasma guns. Initially, a Faraday cup-based technique established accurately most of the plasma parameters produced by a single gun (density:10¹³ cm^-3 ; velocity: 2.2 cm/mus ). However, an optical study, which is mainly based on picture frames taken by an ultrahigh-speed camera, was also necessary to obtain the overall dynamics of the plasma generated by a set of four guns. Principle results are presented.