火花放电喷射等离子体触发气体开关导通特性及工作模式分析

Discharge Characteristics and Working Modes of a Gas Switch Ignited by Spark-discharge Ejected Plasma

为理解喷射等离子体触发气体开关的导通过程和触发机理,利用高速分幅相机拍摄火花放电喷射等离子体触发气体开关的导通过程,结合开关导通时延测量,研究了该开关在10%~90%工作系数下的触发导通特性,分析了开关在高、低工作系数下的导通过程和工作模式。结果表明,火花放电喷射等离子体触发气体开关在10%~90%的极宽工作系数范围内能可靠触发导通,导通时延随工作系数提高而逐步从数十μs减小至数百ns。低工作系数时气体开关为慢导通模式,导通过程可分为喷射等离子体形成阶段、喷射等离子体快速发展阶段、喷射等离子体发展饱和阶段和主间隙放电4个阶段,其导通延时受工作系数和触发脉冲幅值的影响,为数μs至数十μs。随着开关工作系数提高,开关由慢导通模式逐步过渡到快导通模式,导通过程只包括喷射等离子体形成阶段和主间隙放电两个阶段,放电发展过程较为迅速,导通时延约为数百ns。

For further understanding the working progress and mechanism of gas switches ignited by spark-discharge ejected plasma （SIGS）, we studied the discharge characteristics ofa SIGS under the switching coefficient of 10%-90% by utilizing a high speed framed camera to record the breakdown process and measuring the delay time simultaneously. The breakdown processes and working modes corresponding to high and low switching coefficients are also discussed in comparison. The results indicate that the SIGS can be triggered reliably under extremely wide switching coefficient of 10%-90%, and the delay time significantly reduces from dozens of microseconds to hundreds of nanoseconds with the increase of switching coefficient. The switch operates in slow mode under low switching coefficient and the delay time is several microseconds to dozens of microseconds. The breakdown process of the switch in slow mode can be divided into four stages, namely the formative stage of ejected plasma, the rapid development stage of ejected plasma, the saturated development of ejected plasma and the discharge of the main gap. With the increasing switching coefficient, the working mode of the switch transforms gradually from the slow mode into the fast mode. The breakdown process of the switch in fast mode only includes two stages, which are respectively the formative stage of ejected plasma and the discharge of the main gap. Therefore, the development of the discharge is relatively fast and the delay time is about hundreds of nanoseconds.