吸附对电子输运特性的影响  

Effect of Attachment on Electron Transport Properties

作　　者：蔡新景[1] 王新新[2] 邹晓兵[2] 鲁志伟[1] 

机构地区：[1]东北电力大学电气工程学院,吉林省吉林市132012 [2]电力系统及发电设备控制与仿真国家实验室(清华大学电机系),北京市海淀区100084

出　　处：《中国电机工程学报》2016年第11期3126-3132,共7页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51207019)~~

摘　　要：电力工程上常见气体如SF6和空气等均是电负性气体,吸附是其流注放电过程中一个非常重要的碰撞过程。为了研究吸附对电子输运特性的影响,该文采用多项近似法解玻尔兹曼方程计算了模型电负性气体和真实电负性气体SF_6的电子输运特性。首先采用O_2简化模型分析了自由参数v_(max)、lmax和Tb对计算结果收敛性的影响,发现:当Tb取值为T_b(opt)时,电子速度分布函数展开所需的拉盖尔多项式阶数v_(max)最小;一般地,在l_(max)增加到3时,所有输运系数能达到4位数字精度。接着利用改进的Dujko电子吸附模型计算了不同吸附频率下的电子输运系数,结果表明:随着吸附截面的增大,吸附系数逐渐增大,体漂移速度、体扩散系数和平均能量逐渐减小;电子在低能区吸附频率越高,电子平均能量和体漂移速度越小。最后对真实气体SF_6的电子输运特性进行计算,得到了电子通量漂移速度、体漂移速度、电子平均能量、反应速度、通量扩散系数和体扩散系数,并与实验结果比较,验证了多项近似法解玻尔兹曼方程计算电负性气体输运系数的合理性,指出了在约化场强较小时实验测量电负性气体输运系数的不足。The gases commonly used in electrical engineering applications such as SF_6 and air et al are electronegative, so attachment is a key collision process in their streamer discharges. In order to investigate the effects of attachment on electron transport characteristics, electron transport coefficients of model and real electronegative gases were calculated based on multi-term solution of Boltzmann equation. Firstly the effects of the free parameters such as vmax, lmax and Tb on the convergence of the transport coefficients were analyzed. It can be seen that the order vmax of the Laguerre polynomials which is needed to expand the electron velocity distribution function is smallest when T_b is equal to T_b（opt）, and in general all transport coefficients can achieve four-digit accuracy when lmax is increased to 3. Then the modified attachment model of Dujko was considered to investigate the effects of different attachment frequency on the electron transport characteristics. It is shown that the attachment coefficient tends to increase as attachment cross section increases, however the bulk drift velocity, bulk diffusion coefficient and mean electron energy tend to decrease as attachment cross section increases. If the attachment frequency in low-energy region is higher, the bulk drift velocity and mean electron energy are smaller. In the end the transport coefficients of the real gas SF_6 were considered. The flux and bulk drift velocities, mean electron energy, reaction coefficient, flux and bulk diffusion coefficients were obtained. The validity of multi-term solution of Boltzmann equation to obtain the transport coefficients of electronegative gases was demonstrated and the deficiency of experimental method was pointed out when the reduced electric field is small.

关 键 词：玻尔兹曼方程 多级近似 吸附 电离 碰撞算子 电负性 电子输运系数 

分 类 号：TM85[电气工程—高电压与绝缘技术]