聚萘二甲酸丁二醇酯试样表面电荷迁移与消散机理

Charge Migration and Decay on Polybutylene Naphthalate Surface

采用静电探头对负直流高压下聚萘二甲酸丁二醇酯(PBN)表面电荷密度进行测量。结果表明,负电荷累积于介质表面,其主要来源于电极向介质的电荷注入,被表面态俘获后,形成表面电荷。随加压时间延长,电荷从高压电极侧向接地极迁移,表面平均电荷密度增大。电荷密度最大值出现在高压电极附近,最小值出现在接地极附近。在表面电荷消散初始阶段,电荷密度衰减速度快,随着消散时间延长,电荷密度衰减速度变慢。

Electrostatic charges can be accumulated on solid dielectric surface and are for a long time are observed. It has been found that the field is seriously enhanced and surface discharge is induced. Therefore, it＇s very important to investigate the behavior of surface charge. Previous works have shown that the charges are deposited on the region where normal component of electric field exists. However, knowledge of the behaviour of surface charge under the electric field with strong tangential but weak normal component is very limited. In this paper, polybutylene naphthalate （PBN） is employed as test sample. By applying a negative bias voltage between two aluminum electrodes on the surface, a field of strong tangential component is obtained. An electrostatic probe is designed to measure the charge density not only in the accumulating but also the decay processes. Obtained results show that a large amount of negative charges are deposited on the surface. The max charge density appears adjacent to the negative electrode and decreases towards the grounding electrode. Charge decay is observed including two processes, in which a fast decay initially occurs followed by a slow process. Furthermore, it is suggested that the presence of localized surface states should be account for the surface charging, the charge decay is ascribed to the recombination between de-trapped charges and positive ions which are in the air.