Operation of optically activated GaAs switches in striplines of low impedance at voltages up to 30 kV

摘要

Optically activated GaAs-switches have some significant advantages for the generation of steep voltage pulses, duration of some 10 ns, in extended stripline-systems: the parallel operation of a number of switching elements makes a proper impedance matching between stripline and load possible. In addition the high voltage stress can be controlled. The activation in the linear photoconducting mode allows a fast switch closure with low jitter. In order to keep the light energy small it is possible to transfer the GaAs-switch into the nonlinear photoconducting mode. This paper reports on investigations using CCD- camera systems to study the development and the formation-process of current filaments characterizing the nonlinear photoconducting mode. Furthermore results of experiments are given obtained from an extended Blumlein-system with an impedance of 2.5 approximately ega respectively 0.1 approximately ega operated at voltages up to 30 kV. The switch design, the conditions how the parallel operation of switching elements is influenced by the voltage applied across the switch, the wavelength and the intensity of the light are discussed.