介绍了应用于介质壁加速器的小间隙异面电极结构的光导开关。所用光导开关为异面结构的砷化镓(GaAs)光导开关, 电极间隙5 mm, 偏置电压为15~22 kV脉冲高压, 工作在非线性(高增益)模式, 由半导体激光器产生的脉冲激光触发。脉冲激光的中心波长为905 nm, 脉冲宽度(FWHM)约20 ns, 前沿约3.1 ns, 抖动小于200 ps, 峰值功率约90 W。实验结果表明: 光导开关的偏置电压较低时, 开关寿命较长, 导通性能较差; 偏置电压较高、驱动脉冲激光功率较大时, 开关导通性能较好, 寿命较短。

A kind of narrow-gap opposed-contact photoconductive semiconductor switch(PCSS) is described in this paper, and it will be used in the dielectric wall accelerator(DWA) in a near future. The switch we used in the experiment is an opposed contact GaAs PCSS whose electrode gap is 5 mm. When the bias pulsed voltage is between 15 kV and 22 kV, it works in the nonlinear mode. The pulsed laser, triggering the PCSS, is from the laser diode, and it has the wavelength, FWHM, rise-time, and peak power of about 905 nm, 20 ns, 3.1 ns and 90 W, respectively. As a result, when the PCSS works at a low voltage, it has a long lifetime but poor performance; while, when the PCSS works at a high voltage and is triggered by a high peak power pulsed laser, it works well but has a shorter lifetime.