大口径倒腔式等离子体开关

大口径倒腔式等离子体开关是神光Ⅱ升级装置倒腔式多程放大方案的关键单元,该方案要求等离子体开关能够在极短的时间内完成工作状态的转换。采用正负开关脉冲驱动的等离子体开关响应时间较长,无法满足装置的使用要求。基于Blumlein脉冲形成线结构的高压低阻抗开关脉冲发生器能够实现倍压输出,使单一脉冲驱动等离子体开关成为可能,从而大幅减小开关响应时间。单一脉冲驱动的350mm×350mm口径倒腔式等离子体开关理论充电时间约为54ns,其开关响应时间可做到小于90ns。实验测得的等离子体开关全口径开关效率大于99.7%,静态消光比大于381,时间窗口顶宽大于160ns,底宽小于400ns,上述指标均满足神光II升级装置的使用要求。

Large Aperture Plasma Electrode Pockels Cell for Multi-Pass Amplified Scheme

Large aperture plasma electrode Pockels cell (PEPC) is the key unit of the multi-pass amplified scheme of SGⅡ upgrading laser. The PEPC in this scheme should achieve the status switching between on and off in a very short time. The response time of the PEPC driven by positive-negative switching pulses is not as short as the demand of the multi-pass amplified scheme. In the single-pulse process, the low-impedance high voltage generator based on Blumlein pulse-forming line is used to drive the PEPC, and the response time can be reduced greatly. The theoretical charge time of the plasma switch with 350 mm×350 mm aperture is about 54 ns, and the response time can be less than 90 ns in single-pulse process. The experimental results of the switching efficiency of full aperture are higher than 99.7%. The extinction rate exceeds 381. The top width of the time window is larger than 160 ns, and the bottom width is less than 400 ns. All these experimental results can meet the specification of SGⅡ upgrading laser.