High Voltage Conduction and Breakdown Phenomena in Dielectrics

这项工作试图了解高场应力气体、液体和固体介质中的传导、老化、退化和击穿机制，使用新的现代光学、电子和计算机仪器来观察材料内部的电荷传输效应，这是以前没有见过的。在电力设备中使用的绝缘介质，如变压器和电缆，以及脉冲功率技术中使用的绝缘介质，如马克斯发生器和脉冲形成线，都会受到注入空间电荷的影响。空间电荷扭曲了电场分布，并将电极间的电荷迁移时间作为一个附加的时间常数引入到通常的介电松弛和流体传输时间之上。通过克尔电光场和电荷映射测量，测量了高压应力电极的电荷注入。此类光学测量已用于高纯水、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。在高纯水中，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强烈地依赖于电极材料组合和电压极性。具体任务包括：(1)克尔效应测量，包括介质的低压预应力；(2)电子束对固体的辐照；(3)电击穿树的分形数学建模；(4)行波高压电动泵浦。

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.