Investigation on the characteristics of a two gap capillary discharge based on surface flash over ignition in atmosphere

Abstract

In this paper, a two gap capillary (TGC) structure is presented and the corresponding driving circuit based on surface flashover ignition is designed to achieve reliable and repetitive discharge in atmosphere. The characteristics of the two gap capillary (TGC) discharge in low energy are investigated, of which the discharge energy is from 27 J to 432 J. With the rise of charging voltage, the delay of the weak capillary discharge and the main discharge both decrease. Meanwhile, the current flowing through the main gap and the plasma jet ejection are enhanced. The main gap resistance is about several hundreds of milliohms in the main discharge and rises gradually with the decay of the current. The long tail extinction is witnessed at the relatively low charging voltage of 0.5 kV and 1.0 kV, by which the pulse width of the discharge is extended. However, the discharge during the long tail extinction contributes little to the plasma jet ejection with negligible plasma jet velocity and low degree of the plasma ionization. The effective energy deposition efficiency on the main gap increases gradually with the charging voltage and reaches approximately 2 times higher than that of the traditional structure at the charging voltage of 2.0 kV. The series inductor in the circuit can restrain the development of the long tail extinction and increase the effective energy deposition efficiency. Thus, the discharge characteristics and the plasma ejection of TGC under the relatively low charging voltage are optimized.