陡化开关动作特性及其对纳秒脉冲源输出的影响

Firing Performance of Peaking Switch and Its Influenceon Output of Nanosecond Pulse Voltage Source

脉冲变压器型高压脉冲源广泛应用于高电压试验等领域,但脉冲前沿较缓,陡化开关和峰化电容对其有重要影响。为优化脉冲源输出特性,研制了用于纳秒脉冲源输出脉冲陡化的两电极气体开关,电极为球-球、球孔-球孔(球头中心圆形孔)及尖-球3种结构,开关间隙距离3~20 mm可调,工作气压范围为1.5~8.5 atm(1 atm=1.01×10^(5)Pa)。当开关的间隙距离一定时,通过调节气压,使其在峰值处击穿,研究了电极形状、间隙距离及气压对陡化开关自击穿电压分散性和脉冲源输出参数的影响。实验结果表明:当间隙距离为5 mm时,尖(阴极)-球电极的开关动作电压较高且击穿稳定性较好。在尖(阴极)-球电极布置形式下,间隙距离为7 mm,工作气压为5.4 atm时,陡化开关动作电压最高,击穿稳定性最好,输出脉冲前沿更快。因此,增强阴极局部电场强度和使开关工作在短间隙高气压条件下更有利于陡化开关在峰值附近击穿,且利于提高击穿稳定性。优化陡化开关配置后,脉冲源输出脉冲电压幅值约为120 kV,幅值相对偏差约为2.3%,前沿约为17 ns。

The transformer-type high voltage pulse source is widely used in the field of high voltage testing,but the pulse front is relatively slow,and the peaking switch and sharpening capacitor have a significant impact on it.To optimize the output characteristics of the pulse source,a two electrode gas peaking switch is developed for sharpening the output pulse of the nanosecond pulse source.The electrodes have three configurations,such as sphere-sphere electrode,sphere hole-sphere hole electrode(spherical hole in the center of the ball electrode),and needle-sphere electrode.The switching gap distance is tunable from 3 mm to 20 mm with a working pressure range from 1.5 atm(1 atm=1.01×10^(5) Pa)to 8.5 atm.When the gap distance of the switch is constant,the influences of electrode shape,gap distance,and gas pressure on self-breakdown voltage dispersion and pulse output parameters of the peaking switch are studied by adjusting the gas pressure to breakdown at its peak.The experimental results show that when the gap distance is 5 mm,the switching firing voltage of the needle-sphere cathode electrode is high and the breakdown stability is good.When the gap distance is 7 mm and the working pressure is 5.4 atm,the breakdown voltage is higher,the stability is better,and the output pulse front is faster.Therefore,increasing the local electric field strength of the cathode and operating the switch with short gap distance under high pressure conditions are more conducive to the breakdown of the peaking switch near the peak value and improving the breakdown stability.After optimizing the configuration of the peaking switch,the output voltage amplitude of the pulse generator is about 120 kV,with a relative amplitude deviation of about 2.3%and a leading edge rise time of about 17 ns.