中文摘要：

采用Pockels电光效应原理，对大气条件交流电压下聚合物绝缘材料的表面电荷分布进行了研究。实验以聚苯二甲酸乙二醇酯（polyetllyleneterephthalate，PET）和聚偏氟乙烯（polyvinylidenefluoride，PVDF）为样品，在针板电极上施加幅值5kV、频率20Hz的正弦交流电压，施加电压分别从正半波开始和从负半波开始，采用高速CCD摄像机纪录1个周期内2种聚合物材料在沿面放电过程中表面电荷分布的变化。实验结果表明，材料表面电荷分布的极性效应非常明显，负电荷分布半径要小于正电荷分布。材料特性也显著影响电荷分布，随着施加电压的升高，PET表面正流注通道逐步延伸，呈弯曲状分支分布，而PVDF表面正流注通道的形成明显要快，并呈现规则的轮辐状分布。分析认为，这与不同材料的禁带宽度、表面层电离能、介电常数和厚度等的差异都有很大关系。

英文摘要：

Based on the Pockels electro-optic effect, the surface charge distribution of polymeric insulating materials were studied under HVAC in atmospheric air. Different polymer materials such as polyethylene terephthalate （PET） and polyvinylidene fluoride （PVDF） were employed as experimental samples. One cycle of 5 kV and 20 Hz sinusoidal HVAC was applied to a needle-plate electrode-sample configuration and the applied voltage starts from the positive or negative half-cycle. During the development process of surface discharge across different materials, the dynamic observation on the surface charge distribution in a cycle was recorded by a high speed CCD camera. Experimental results showed that there is significant voltage polarity effect observed, and the radius of negative charge distribution is smaller than that of positive charges. Moreover, PET and PVDF samples indicate different surface charge distribution. With the increase of applied voltage, positive streamer channels on PET are gradually growing with a snake-like pattern. However, positive streamers on PVDF develop instantaneously and exhibit a regular spoke-like pattern. It is considered that, many factors are closely related to the phenomena observed, e.g., the energy band gap, ionization energy of surface layer, dielectric constant and thickness of different material samples.