High Voltage Conduction and Breakdown Phenomena in Dielectrics

这项工作试图理解传导、老化、降解和击穿机制在高场应力气体、液体和固体介质中使用新的现代光学、电子和计算机仪器来观察以前无法看到的材料内部的电荷输运效应。在电力设备中，如变压器和电缆，在脉冲电源技术中，如马克思发生器和脉冲形成线，绝缘电介质的性能受到注入空间电荷的影响。空间电荷扭曲了电场分布，并在通常的介电弛豫和流体输运时间上引入了电极之间的电荷迁移时间作为附加时间常数。采用克尔电光场和电荷映射法测量高压应力电极的电荷注入。此类光学测量已用于高纯净水、水/乙二醇混合物、变压器油、硅油、液态和气态SF6、液氮以及高压应力和电子束辐照的聚甲基丙烯酸甲酯。在高度纯净水中，克尔电光测量、电压-电流终端测量和电击穿测试表明，注入电荷的大小和极性以及电击穿强度在很大程度上取决于电极材料组合和电压极性。具体任务是：(1)克尔效应测量，包括介质的低压预应力；(2)固体的电子束辐照；(3)电击穿树的分形数学建模；(4)利用行波高压进行电动泵送。

This work attempts to understand conduction, aging, degradation, and breakdown mechanisms in high field stressed gaseous, liquid, and solid dielectrics using new modern optical, electronic, and computer instrumentation to see charge transport effects inside materials that could not be seen before. Insulating dielectrics used in power apparatus, such as transformers and cables, and in pulse power technology, such as Marx generators and pulse forming lines, have their performance affected by injected space charge. The space charge distorts the electric field distribution and introduces the charge migration time between electrodes as an additional time constant over the usual dielectric relaxation and fluid transport times. Charge injection from high voltage stressed electrodes is measured by Kerr electro-optic field and charge mapping measurements. Such optical measurements have been performed for highly purified water, water/ethylene glycol mixtures, transformer oil, silicon oil, liquid and gaseous SF6, liquid nitrogen, and high voltage stressed and electron beam irradiated polymethylmethacrylate. In highly purified water, Kerr electro-optic measurements, voltage-current terminal measurements, and electrical breakdown tests have shown that the magnitude and polarity of injected charge and the electrical breakdown strength depend strongly on electrode material combinations and voltage polarity. Particular tasks are: (1) Kerr effect measurements including low-voltage prestressing of dielectrics; (2) electron beam irradiation of solids; (3) fractal mathematical modeling of electrical breakdown trees; and (4) electrokinetic pumping using traveling wave high voltages.