直流场畸变开关中混合气体击穿特性

Reverse avalanche breakdown characteristics of collector junctions in bipolar junction transistors

通过气体放电产生更高浓度的低温等离子体要求具有纳秒上升沿和纳秒脉宽的高重频快脉冲,而目前被广泛使用的MOSFET和IGBT都无法满足这些参数要求,而双极结型晶体管（BJT）的集电极与发射极之间的雪崩击穿过程具有快导通、快恢复、高稳定性等优点,适合作为小型Marx发生器的自击穿开关。文中对用多种型号的BJT进行击穿特性比较测试实验,发现可以通过改变BJT的门极和发射极的并联电阻来调节其雪崩击穿电压,实现一定范围的工作电压。雪崩击穿恢复特性实验表明,当击穿电流衰减到低于维持电流时,BJT就会开始恢复绝缘而关断,通过改变电路中的参数以控制击穿电流的变化就可以控制BJT的雪崩击穿导通时间（即导通脉宽）。将这些结论应用到实际电路中,可获得上升沿5ns、脉宽为10ns、幅值2kV、重复频率高达100kHz的纳秒快脉冲,可用于激发高浓度低温等离子体。

Generating low-temperature plasma with high density requires fast pulses with high repetitive frequency, nanosecond rise time and nanosecond pulse width, which is very difficult for the widely used MOSFET and IGBT. Studies show that the bipolar junction transistor＇s avalanche breakdown process has the characteristics of fast conduction, fast recovery and high stability, which is suitable for the self-breakdown switches in compact solid-state Marx generators. In this paper, it is found that the avalanche breakdown voltage can be adjusted by changing the resistance between BJT＇s gate and emitter. The experiments of avalanche breakdown and recovery show that BJT will turn off when the breakdown current attenuates below the maintain current, so the BJT avalanche breakdown＇s conduction time can be controlled by adjusting the parameters to change the attenuation of the discharging current in the circuit. Applying these conclusions to the actual circuit, fast pulses, with rise time of 5 ns, pulse width of 10 ns and amplitude of 2 kV and frequency of 100 kHz, are obtained.