Solid state switches for high frequency operation as thyratron replacements

Thyratrons and spark gap switches continue to be the predominant technologies used for high current, high voltage pulsed power applications. The offerings from thyratron manufacturers have been diminishing and prices have increased as vacuum tube manufacturing continues its decline. In addition, the maintenance requirements for thyratrons make them unsuitable for many potential main stream applications for pulsed power. High voltage IGBT based switches have become common, but current limitations have prevented them from being an attractive alternative for many thyratron replacement applications. Thyristors have the advantage of high current capacity but their pulsed power usage has typically been limited to lower frequency applications. This paper will describe high frequency, compact, high current, high voltage solid state switches for thyratron replacements, based on thyristor technology. The switches are based on series connected fast thyristors with 3cm2 die in a 20cm2 package which can achieve 40 kA/usec peak di/dt. These switches operate at 500 pps, 28kV or higher, 800A or higher maximum fault current and greater than 1011 pulse lifetime. Thyratron replacement switches based on thyristor technology are currently in use at CERN, Argonne National Lab and SLAC National Accelerator Laboratory. They offer advantages over thyratron switches for cost, lifetime, size, weight and maintenance requirements.