Study Of High-Power High-Repetition-Rate GaAs Photoconductive Semiconductor Switch

Pulsed power technology has been used extensively in the fields of scientific experiments, national defense, biomedicine and environmental protection etc. As one of the crucial components, a high-energy switch with high pulse repetition rate, high voltage, high current and long life-time is greatly expected to meet the rapid development of pulsed power system. In this paper, the central task of research is to design high-power high-frequency switching devices, and study its performance through testing.In this paper, the characteristics and research present condition of the pulsed power technology are described; the important role of switch used in pulsed power system is analyzed and several of the pulsed power switches are studied in detail. Photoconductive semiconductor switches are considered to be an excellent switching device. From the characteristics of the work, it is well suited to be used as a pulsed power switch. The study of the high power high-repeated-frequency characteristic of photoconductive semiconductor switch is seldom reported at domestic and international.Through checking the papers of photoconductive semiconductor switches in domestic and international, the systematic and detailed analysis of photoconductive semiconductor switches on the structural characteristics, the working principle in the linear and nonlinear finite mode is made. On the basis of theoretical analysis, photoconductive semiconductor switches is designed by the use of semi-insulating GaAs materials. In the linear and nonlinear model of working models, experimental results: (1) There are higher darkness breakdown voltage and efficient voltage transmission efficiency for the switches. The darkness breakdown strength achieves 35kV/cm, voltage transmission efficiency is 93%. (2) In the linear model, the switches can work at 82MHz repetition rate in normal. (3) In the non-linear model, the power of GaAs photoconductive switch’s output electromagnetic pulse is very high, but repeat performance is not very stable. Due to limited experimental conditions, the experiment of triggering switches with the high repetition rate light pulse at the same time with high power isn’t taken.Currently, gas spark switch is one of the switches generally applied in pulsed power system and can bear the bigger current, but, its repetition rate is relatively low. Through analyzing the discharge of gas spark switch, the idea has been improved to design a new structure switch by adding a gas discharge gap in the GaAs photoconductive switch. Theoretically, the new structure switch can bear the bigger current and work well at high repetition rate. In the experiments, the output pulse power reaches MW level. When triggered 1250 times by ns laser, the switches show a good temporary response, the waveforms output with high reproducibility are very good. It shows that the composite switch has good properties in insulating, power transmission, current transport and high repetition response, and can be used for high-power high-repetition-rate switching devices.This research was supported by the National Natural Science Foundation of P. R. China No: 50477011.