Dielectric properties of water and water/ethylene glycol mixtures for use in pulsed power system design
Dielectric properties of water and water/ethylene glycol mixtures for use in pulsed power system design
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DOI：
10.1109/proc.1986.13611
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发表时间：
1986-09
影响因子：
20.6
通讯作者：
M. Zahn;Yoshimlchl Ohki;D. B. Fenneman;R. Gripshover;V. Gehman
中科院分区：
文献类型：
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作者：
M. Zahn;Yoshimlchl Ohki;D. B. Fenneman;R. Gripshover;V. Gehman
一类现代脉冲功率发生器使用去离子水作为能量存储、开关和传输电介质。选择水是因为其高介电常数和相对高的电阻率，这允许合理尺寸和有效的低阻抗高压脉冲线，其中脉冲持续时间小于100 µs。正在研究水/乙二醇混合物，以便旋转机械，而不是通常的马克思发电机，可以用作主要的能量储存。这些混合物在低温下的高电阻率和高介电常数允许在毫秒时间尺度上的低损耗操作。简单的设计标准链接的负载参数和充电电路特性的液体电介质的发展表明，介电常数，击穿强度，和弛豫时间是感兴趣的脉冲功率工程师的主要属性。在大于100 µs的时间尺度上，具有密度q和迁移率µ的空间电荷的注入会影响充电和放电电路特性，引入注入电荷在电极之间迁移的飞行时间的时间常数，并将有效欧姆电导率σ增加到σ + qµ。一个漂移主导的传导模型被用来描述测量的空间电荷效应。克尔电光场映射测量显示出强烈的空间电荷效应，在施加高电压后几百微秒的电场分布中具有显著的扭曲。注入的电荷大小和符号取决于电极材料。因此，通过适当地选择电极材料组合和电压极性，可以具有不带电的液体、单极带电的负或正或双极带电的液体。一个重要的情况是双极注入，它允许在没有击穿的情况下比没有电荷注入的情况下高出高达40%的施加电压，因此由于空间电荷屏蔽降低了两个电极处的电场强度，因此存储的能量加倍。尽管注入的空间电荷使存储的电能增加超过电容性无空间电荷能量（1/2）CV 2，但是在充电期间需要来自源的更多能量，并且由于电荷传导到电极时电容器中的内部耗散，传递到电阻性负载的能量减少。然而，如果空间电荷允许长充电时间或重复操作机器的更高电压操作，则由于注入电荷引起的这种额外耗散似乎可以小到可以忽略，并且非常值得。
One class of modern pulse power generators use deionized water as an energy storage, switching and transmission dielectric. Water is chosen for its high dielectric constant and relatively high resistivity, which allows reasonably sized and efficient low-impedance high-voltage pulse lines where pulse durations are less than 100 µs. Water/ethylene glycol mixtures are being researched, so that rotating machinery, rather than the usual Marx generator, can be used as the primary energy store. The high resistivity and high dielectric constant of these mixtures at low temperature permit low-loss operation on millisecond time scales. Simple design criteria linking load parameters and charging circuit characteristics to the liquid dielectric are developed which show that the dielectric constant, breakdown strength, and relaxation time are the primary properties of interest to the pulse power engineer. On time scales greater than 100 µs, injection of space charge, with density q and mobility µ, affects the charging and discharging circuit characteristics, introduces the time constant of the time of flight for injected charge to migrate between electrodes, and increases the effective ohmic conductivity σ to σ + qµ. A drift-dominated conduction model is used to describe measured space-charge effects. Kerr electrooptic field mapping measurements show strong space-charge effects with significant distortions in the electric field distribution a few hundred microseconds after high voltage is applied. The injected charge magnitude and sign depends on the electrode material. Thus by appropriate choice of electrode material combinations and voltage polarity, it is possible to have uncharged liquid, unipolar-charged negative or positive, or bipolar-charged liquid. An important case is that of bipolar injection, which has allowed up to a 40 percent higher applied voltage without breakdown than with no charge injection, and thus a doubling of stored energy due to the space-charge shielding which lowers the electric field strengths at both electrodes. Although injected space charge increases the stored electric energy over the capacitive space-charge-free energy, (1/2)CV2, more energy is required from a source during charging and the energy delivered to a resistive load is reduced because of internal dissipation in the capacitor as the charge is conducted to the electrodes. However, it appears that this extra dissipation due to injected charge can be made negligibly small and well worth the price if the space charge allows higher voltage operation for long charging time or repetitively operated machines.