Marx Generators Based on MOS-Gated Switches With Magnetic Assist for Accelerator Applications

In the field of pulsed power, gas switches have been widely used due to their high operating voltages and currents. One example of these gas switches is the thyratron, which is in use for some particle accelerators even today. At the Extreme Energy-Density Research Institute, the Nagaoka University of Technology, Nagaoka, Japan, such devices are in use. In recent times, semiconductor switches have been considered as possible replacements due to their ease of maintenance and control. In general, it is difficult to achieve the same ratings for maximum switching current and voltage of a gas switch with a single semiconductor device, so connecting many in series, parallel, or a different scheme is often applied. We propose a study to evaluate a Marx topology using MOS-gated thyristors capable of high current output. The attractive factors of these semiconductors are the low gate current required for turning ON, a low resistance during the ON-state, a four-stage prototype was built, and it achieved a peak output of 1 kV and 1 kA with a 2 μs pulsewidth. To improve the output voltage and current, a ferrite core was implemented as a magnetic switch on every stage; this method has been used before to improve the efficiency of thyristors, however, not combined with circuit topologies like a Marx generator. Adding these magnetic switches increased the efficiency to 89% (from 70%) and allowed an output of 2.2 kV and 2.2 kA without changing the shape of the pulse or the rise time.