Oil-Switched Planar Blumlein Pulse Generators for Dielectric Wall Accelerators

We are developing oil-switched, planar-Blumlein pulse-generators for use in high-gradient dielectric-wall accelerators (DWA). This technology is applicable to a variety of applications including both proton and electron accelerators. In our designs, simple spark-gap switches are very tightly integrated to the ends of solid-insulated planar-Blumlein pulse -forming lines. We can operate the switches with either pressurized gas or liquid (oil). By using oil as the switching medium, we have eliminated the requirement for a pressure interface around the switch. We immerse the entire assembly including the switch region in oil. In gas switches, switch-gap and pressure are the free parameters to set the operating voltage. With oil switches, the adjustment parameters are gap and charging time. We have built a single-stage prototype with Mylar/oil insulation that generates a 5-ns pulse with<1-ns risetime. To date, we have achieved an operating gradient of 38 MV/m with a goal of 50 MV/m into a matched load using 50 ns pulse-charge time. We operate the switch in self-break mode. For multi-stage versions, we plan on adding triggers to the switches. We present our experimental design and most recent results