基于毛细管放电的大气压等离子体射流喷射装置放电特性

Discharge Characteristics of Atmospheric Plasma Flow Ejector Based on Capillary Discharge

为满足更长间隙距离、更高电压等级气体开关在较低工作系数下的可靠触发,设计了一种基于毛细管放电的大气压等离子体射流喷射装置,即两间隙毛细管等离子体喷射装置(two gap capillary,TGC)。通过引入中间电极将毛细管通道分为触发通道和主通道,借助触发通道在放电初始时的弱毛细管放电引燃主通道的放电,实现了重复放电。等离子体射流在触发后的169μs时达到了11 cm左右。主通道电弧电阻呈现"U型"分布,电阻值开始时随主通道电弧电流的增长快速减小,最低时不到200 m?,而后随着电流的跌落快速增加。同时,主通道电弧电阻值在电流增长时要高于电流跌落时,这一差异在流过主通道电弧电流较小时十分明显,而后随着电流幅值的增加逐渐减小。由于没有传统放电结构金属丝电爆的过程,电容器所储能量主要释放于喷射装置主通道,主通道电弧能量沉积效率几乎是传统放电结构的2倍,达到了62.7%。喷射装置寿命大概在300次左右,使用扫描电子显微镜(SEM)拍摄触发通道表面,发现喷射装置TGC中间电极的烧蚀和触发通道的碳化是影响TGC寿命的关键因素,对TGC的寿命优化设计还需做进一步的努力。

In order to meet the reliable ignition of the gas switch with longer distance working in higher working voltage, an atmospheric plasma, ejector based on capillary discharge is presented, which is named as TGC （Two Gap Capillary）. By introducing the middle electrode, the capillary is divided into the trigger gap and the main gap. At the beginning of the discharge, the trigger gap is flashed under the high-voltage pulse and the soft capillary discharge begins. Thus, repetitive discharge is achieved. The length of the plasma flow is close to 11 cm after 169 μs of the triggering. The waveform of the main gap resistance during the discharge seems to be U-shape, of which the minimum value is less than 200 mΩ The main gap resistance decreases rapidly in the preliminary stage of the discharge and rises with the shrink of the current. In addition, the resistance is considerably higher as the current increases than decreases, which is particularly markable when the current is not high enough and disappears gradually with the growth of the current. Without the process of the wire explosion, there is about 62.7% of the energy stored in the capacitor consumed on the main gap and the energy deposition efficiency on main gap, is approximately 2 times higher than that of the traditional structure. The mean life of the TGC is about 300 times. With the aid of the SEM, it is found the erosion of the middle electrode and trigger gap carbonization are the key factors that limit the life performance of the TGC, which still needs further research.