物理学报2017，Vol.66Issue(19)：184-194,11.DOI:10.7498/aps.66.195101
流注放电低温等离子体中电子输运系数计算的蒙特卡罗模型
Monte Carlo simulations of electron transportcoefficients in low temperature streamerdischarge plasmas
摘要
Abstract
Streamer is usually present at the initial stage of atmospheric pressure air discharge, which occurs in nature as a precursor to lightning, transient luminous events in upper atmosphere and has much potential applications in industry, such as the treatment of polluted gases/liquids, assisted combustion, plasma enhanced deposition etc. Streamer is a multi-scale problem both in time and in space, which brings much difficulty to the conventional diagnostic approaches. In past decades, fluid or particle-fluid hybrid models have been frequently used for understanding the mechanisms of streamer discharges because of their high efficiencies of calculations. Accuracies of the electron transport coefficients (including drift/diffusion coefficient, ionization/attachment coefficient, electron mean energy and extra) play a key role in ensuring the correctness of the fluid or hybrid simulations. As far as we know, BOLSIG+ and MAGBOLTZ are two typical tools for obtaining the electron transport coefficients and have been widely utilized in previous models. BOLSIG+uses"two-term"approximation which is not sufficient for some molecular gases, MAGBOLTZ cannot calculate the bulk transport coefficients: these data are required for some models. METHES is an additional tool for computing electron transport coefficients, however, specific platform is required which is not very user-friendly. As sorts of drawbacks exist in currently available calculating tools, in the paper, a Monte Carlo model is developed for computing the electron transport coefficients in gases, the model is flexible to choose any type of gas mixture and its accuracy has been validated by comparing with BOLSIG+and METHES. Furthermore, the influences of N2-O2 mixture and three-body attachment process in high gas pressures on the transport coefficient are investigated. It is worth mentioning that three-body attachment process can significantly change the electron transport properties at a relatively low reduced electric field. Thus, specific attention must be paid to the transport coefficients if simulation is performed at a high pressure. In addition, differences between the bulk and flux coefficients are analyzed which are not distinguished in some previous models. Finally, we further validate the present Monte Carlo model by performing simulation of streamer discharge in atmospheric N2, which shows that the improved electron transport coefficient from our Monte Carlo model can improve the simulated plasma properties, in particular at the interior of the streamer channel. The existence of divergence at the tip of the streamer channel might be due to our local field approximation; if a density gradient term is included in the impact ionization term and local electron energy approximation of the electron transport coefficients is used, the accuracy of the fluid can be improved further.关键词
流注/低温等离子体/电子输运系数/蒙特卡罗模型Key words
streamer/low temperature plasma/electron transport coefficient/Monte Carlo model引用本文复制引用
孙安邦,李晗蔚,许鹏,张冠军..流注放电低温等离子体中电子输运系数计算的蒙特卡罗模型[J].物理学报,2017,66(19):184-194,11.基金项目
国家自然科学基金(批准号: 51777164)、西安交通大学"青年拔尖人才支持计划" (批准号: DQ1J008)、电力设备电气绝缘国家重点实验室(批准号: EIPE17311)和中央高校基本科研业务费专项资金(批准号: 1191329723) 资助的课题.Project supported by the National Natural Science Foundation of China (Grant No. 51777164), the "Young Talent Plan"of Xi'an Jiaotong University, China (Grant No. DQ1J008), State Key Laboratory of Electrical Insulation and Power Equipment, China (Grant No. EIPE17311), and the Fundamental Research Funds for the Central Universities, China (Grant No. 1191329723). （批准号: 51777164）
