纳秒级脉冲电压作用下聚丙烯膜反极性充电现象的研究

采用针-板电极系统，对无纺聚丙烯过滤膜纳秒级脉冲电压作用下电介质膜空间电荷形成过程进行研究。发现了聚丙烯膜积累的空间电荷与所加脉冲电压极性相反的聚合物膜反极性充电现象。正极性脉冲峰值越高越容易引起聚合物膜反极性充电。峰值足够高且脉宽足够窄的负极性脉冲也导致反极性充电。脉宽大于200ns的负极性脉冲作用下，聚合物膜充电过程为同极性充电，并且电荷积累量与脉冲峰值无关，随着脉宽的增大均趋于同一个稳定值。据此，文中提出了基于强场注入和反向注入两种充电过程并存的新理论模型，强调了针-板空气间隙固有放电特性对聚合物膜充电过程的影响。

POLARITY REVERSAL DISCHARGE ON POLYPROPYLENE SURFACE BY NANOSECOND PULSE DISCHARGE

A needle-plane electrode system and non-woven polypropylene filters were used to study the space charge formation on the surface of dielectrics by nanosecond pulse discharge. A novel discovery of polarity reversal discharge was found that the accumulated space charges on the surface of polymers show a different polarity against the applied pulse. It was found that a higher positive pulse peak leads to easier polarity reversal charge accumulation in polymers. It was also found that a negative pulse causes a positive charge accumulation when the peak is sufficient high and the pulse width is sufficient small. In addition, a negative pulse will produce the same polarity of charges on the surface of polymers when the width of pulse is larger than 200 ns. More important, the charge accumulation is independent of the pulse peak, it decreases to a particular value as the pulse width increases. According to these, a novel mechanism of two charging processes of high field injection and return stroke injection has been put forward here to fit the polarity reversal charging phenomena. We emphasized the inherent discharge characteristic in needle-plane electrode system can affect the charging process of polymer films.