Solid-State Nanosecond Pulse Generator Using Photoconductive Semiconductor Switch and Helical Pulse Forming Line

Abstract

A solid-state pulse generator module using two helical pulse forming lines (HPFLs) and a photoconductive semiconductor switch (PCSS) is presented. Two solid-state HPFLs are stacked as one stage Blumlein line. The HPFL is made of Al2O3 ceramic, which can hold-off voltages larger than 40 kV at microseconds-charging-time range. To achieve the goal of the synchronization for future power combining, the GaAs PCSS is adopted in the module. The GaAs PCSS is operated in the high-gain mode with a compact laser diode triggering, aiming to take advantage of the low-jitter and compactness. In tests, sub-ns jitter characteristic of GaAs PCSS has been obtained under different electrical conditions, and GaAs PCSS in the high-gain mode shows an attractive synchronous characteristic. By changing the angle between the two HPFLs of the module, we prove that the electromagnetic coupling effect is quite weak between the two lines. Based on the low-jitter characteristics of the GaAs PCSS, the jitter of delay time between command signal (3 V) and output pulse of the module is 612 ps among 30 times consecutive group tests. The module can deliver a high power pulse with 50-ns pulse duration and 18.5-kV peak voltage value on the matching resistive load ( $67~\Omega )$ .