Generation and Forming of Ultrashort High Voltage Pulses

Abstract

High voltage pulse forming techniques, utilizing spark gaps, is a mature field. However, problems associated with synchronizing spark gap switching, in the picosecond regime, limit its application. A new approach, developed over the past few years, is to use laser controlled photoconductive switches in generating ultrashort high voltage pulses.1 The use of photoconductive switches achieves picosecond synchronization and very long lifetimes. Furthermore such switches can be readily incorporated into various types of pulse generating and forming structures. We report here on an investigation of the performance of various types of high voltage generating structures with photoconductive switches. These include Blumleins (with multiple switches), Marx banks, stacked lines and L.C. generators in coaxial, microstrip and coplanar geometries. High voltage pulses with picosecond rise and fall times were generated and monitored using Pockels cells monolithically integrated with the pulse forming structures. Using dc charged voltage multiplication circuits, up to 5 kv was generated in nanosecond pulses. Also, 5 kv of peak to peak RF single cycle pulses were generated using a similar multiplication circuit. This type of RF pulses have important applications in high resolution radar systems.2