Analytical model of the breakdown mechanism in a two-phase mixture
Analytical model of the breakdown mechanism in a two-phase mixture
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DOI：
10.1088/0022-3727/37/24/004
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发表时间：
2004-12
期刊：
影响因子：
--
通讯作者：
Ye Qizheng;Li Jin;Xie Zhihui
中科院分区：
文献类型：
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作者：
Ye Qizheng;Li Jin;Xie Zhihui
两相混合物（TPM）是气体和高浓度大颗粒的混合物。它在许多不同的领域，如大颗粒污染的绝缘系统，气液放电，尘埃等离子体和处理等离子体中都很有意义。基于Townsend的理论，提出了TPM失效机理的解析物理模型。该模型考虑了影响电子雪崩传播的两个因素：大粒子对电场的扭曲和电子的捕获。根据该击穿机理和计算TPM中最大局部场强的偶极子增强模型，提出了计算TPM击穿电压的修正Paschen定律。当两极板电极之间的系列宏观粒子数(m)很小时，如m = 1时，TPM的击穿电压始终低于气体的击穿电压。对于相同体积分数的大颗粒，随着m的增大或半径的减小，击穿电压有逐渐增大的趋势。当m > 1时，TPM的击穿电压可能比气体的击穿电压低或高，这取决于宏观粒子捕获的饱和电子数与阴极产生的电池初级电子数的比值。文中还讨论了微粒体积分数、介电失配、充电速率以及气体压力与气体长度的乘积等相关因素。
A two-phase mixture (TPM) is a mixture of gas and macroparticles of high concentration. It is of interest in many different areas, such as in macroparticle-contaminated insulated systems, gas–liquid discharges, dusty plasmas and processing plasmas. Based on Townsend's theory, a physical model in analytical form for the breakdown mechanism in TPM is presented. In this model, two factors that influence the electron avalanche propagation are considered: macroparticles distorting the electric field and capture of the electrons. According to this breakdown mechanism and the dipole-enhanced model for calculating the maximum local field strength in TPM, the modified Paschen' law for TPM is presented to calculate the breakdown voltage. When the number of series of macroparticles (m) between two plate electrodes is very small, such as when m = 1, the breakdown voltage of the TPM is always lower than that of gas. With an increase in m or a decrease in the radius of macroparticles, the breakdown voltage tends to increase gradually for the same volume fraction of macroparticles. When m ≫ 1, the breakdown voltage of TPM may be lower or higher than that of gas, depending on the ratio of the number of saturation electrons captured by a macroparticle to the cell primary electrons generated at the cathode. Some other relevant factors, such as the volume fraction of macroparticles, the dielectric mismatch, the charging rate and the product of gas pressure and the gas length, are also discussed.