平板电极型激光触发真空开关的导通特性研究

强激光触发方式的真空开关由于触发精度高、可靠性好、并能有效避免触发装置的电磁干扰,在快速关合开关、电磁发射、串联补偿电容保护等领域具有非常广阔的应用前景。设计了一种平板电极型激光触发真空开关。为了提高其触发寿命,针对触发电极进行优化。触发电极耐烧蚀,靶材选取TiH_2,其能为开关导通提供丰富的初始等离子体,开关的触发性能得到加强,开关的最短时延可达650 ns。详细讨论激光参数、聚焦镜位置、主电压值等对开关的触发阈值、最低工作电压和时延特性的影响,提出触发阈值理论和电弧形成机制,为此类开关的性能优化提供理论依据。实验表明:开关稳定的触发阈值达4.5×10~7W/cm~2,最低工作电压为30 V;采用正常聚焦模式能大幅度降低开关的时延;电弧电流的开始阶段存在强烈振荡过程,电流值大于5 A后,如果外加电压足够高,振荡现象消失,真空电弧稳定燃烧。

Research on Conduction Characteristics of Plate Electrode Type Laser Triggered Vacuum Switch

High power laser triggered vacuum switch,due to its accuracy,reliability and anti-electromagnetic interference,has a very broad application prospects in many field,such as fast closing switch,electromagnetic emissions,series compensation capacitor protection.A flat electrode type laser triggered vacuum switch is presented.In order to improve its trigger life,the design of the trigger electrode is optimized.The designed trigger electrode can be effectively ablative resistant.TiH2 is used as target material,which can provide extensive initial plasma for the switch.The trigger performance of switch is improved,and the shortest delay is up to 650 ns.The relationship among the laser parameters,focus lens positions,applied voltages and the trigger characteristics which mainly contain the trigger threshold,minimum operating voltage and the delay time is analyzed in detail.Trigger threshold theory and arc ignition mechanism are proposed to explain the switch conduction,which can provide the theory basis of the design of the LTVS.Is the experiment can concluded that the stable trigger threshold can reach 4.5×107 W/cm2,and the minimum operating voltage observed is 30 V.Time delay under the normal focus mode can be effectively reduced.Furthermore,it is found that the process of laser-stimulated arc initiation is of a random nature.A short transition phase of strongly fluctuating exists.When the arc current value is beyond 5 A and the external voltage is high enough,the oscillation phenomenon disappears and the vacuum arc is ignited stably.