Multi-filament PCSS modules to replace high current pulsed power switches

Summary form only given. Methods of producing multiple current-sharing filaments (MCSF) in GaAs photoconductive semiconductor switches (PCSSs) have produced as many as 30 filaments per switch with a spacing of 330 μm. As the approaches to triggering and isolating MCSF mature, the replacement of high current, conventional pulsed power switches with banks of MCSF PCSSs capable of switching tens of kiloamps become feasible and economical. Multiple banks of MCSF PCSS can eventually produce optically controlled pulsed power systems with faster rise-times, shorter pulses, and higher peak powers using more economical switches with device lifetimes of over one million pulses.This paper will report results from three types of MCSF approaches: (1) line-of-sight optics focused with cylindrical micro-lens arrays into bright narrow lines of light on the surface of the PCSS; (2) high-reflectivity dielectric optical masks which produce shadows of bright narrow lines of light on the surface of the PCSS; and (3) etched-steps in the surface of the PCSS to divide up the illuminating light and isolate the filaments. These approaches are being tested to switch 2-3 kA with three 1cm square GaAs PCSS. Switching parameters, approximate device lifetimes, and current-sharing capability are being measured and evaluated for each of these triggering techniques. Many other approaches have been considered previously, and their potential for other specific applications will be discussed. Increasing PCSS current density through the development of longer-lived PCSS with higher currents per filament is research that has continued in parallel with the multi-filament triggering work. This however is primarily an interface issue where the contact metal meets the GaAs. We will discuss new electrical contact geometries capable of reducing current crowding. Thereby lowering the peak current density to enable higher total filament current. Theoretical bases for improving contacts will also be discu- sed.