Experimental study of the system parameters for the operation of a liquid dielectric Marx generator

Investigation of the alternative concept of a Marx generator with liquid dielectric switches was carried forward recently. A special, two-stage Marx generator was set up in order to identify and to experimentally analyze the critical system parameters for a reliable, synchronized breakdown of the Marx stages. Degassing and filtration of the chosen liquid Galden HT270, a perfluoropolyether fluid, and the extremely precise adjustment of the electrode gap distances proved to be imperative basic requirements for a successful generator operation. Pressurization and circulation of the liquid through the spark gaps improve the chance of the correct voltage multiplication inside the generator. A better than 95% success rate for the operation of the two-stage Marx generator with liquid dielectric switches at an operative pressure of p_G = 1350 kPa and a liquid flow of I_V = 50 ml/s for repetition rates up to 4 Hz was demonstrated for the first time. Analysis of the delay time to breakdown by Laue diagrams conveyed indication of the existence of two modes with different values for the statistical ¹ and formative part of the delay time to breakdown. This likely depends on the spatial position of the micro bubbles between the electrodes in the discharge initiation stage and leads as a result to the development of either a supersonic or subsonic streamer in the discharge channel propagation stage. Design considerations of a future multi-stage, modular liquid dielectric Marx generator will be discussed.