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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。
The generation of higher concentrations of low temperature plasma through gas discharges requires high repetition fast pulses with nanosecond rising edges and nanosecond pulse widths that are not being met by widely used MOSFETs and IGBTs and bipolar junction Transistor (BJT) collector and emitter between the avalanche breakdown process has the advantages of fast turn-on, fast recovery, high stability, suitable as a small Marx generator self-breakdown switch. In this paper, we compared the breakdown characteristics of BJTs with different types of BJTs and found that the avalanche breakdown voltage can be adjusted by changing the parallel resistance of the BJT’s gate and emitter to achieve a certain range of operating voltage. Avalanche breakdown recovery characteristics experiments show that when the breakdown current decay below the maintenance current, BJT will begin to restore the insulation and shut down, by changing the parameters of the circuit to control the breakdown current changes can be controlled BJT avalanche Wear on-time (ie on-pulse width). Applying these conclusions to practical circuits, we can get nanosecond fast pulses with rising edge of 5ns, pulse width of 10ns, amplitude of 2kV and repetition rate of up to 100kHz, which can be used to excite high concentration low temperature plasma.