电子非麦氏分布的二次电子发射磁化鞘层特性  

Characteristics of non-Maxwellian magnetized sheath with secondary electron emission

作　　者：陈龙 孙少娟 姜博瑞 段萍 安宇豪 杨叶慧 Chen Long;Sun Shao-Juan;Jiang Bo-Rui;Duan Ping;An Yu-Hao;Yang Ye-Hui(School of Science,Dalian Maritime University,Dalian 116026,China)

机构地区：[1]大连海事大学理学院,大连116026

出　　处：《物理学报》2021年第24期231-240,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11975062,11605021,11975088);中国博士后科学基金(2017M621120)资助的课题.

摘　　要：采用空间一维速度三维的磁流体模型研究了电子的非麦克斯韦分布对具有二次电子发射的磁化等离子体鞘层特性的影响.假设鞘层中电子速度服从非广延分布,离子在具有一定倾斜角度的磁场中被磁化.通过建立自洽的磁流体方程,研究了电子非广延分布参数q及磁场强度和角度对等离子体鞘层玻姆判据、壁面悬浮电势、鞘边二次电子数密度、鞘层厚度、离子速度等的影响.研究表明,当电子速度分布偏离麦克斯韦分布时,非广延参数q值越大,玻姆判据的值越小,壁面电势越高,鞘边二次电子数密度增大,鞘层厚度减小,鞘层区域离子、电子数密度下降加快,且壁面附近离子数密度较高,离子3个方向的速度均降低.此外,随着磁场强度增大,鞘层厚度减小,鞘层区域离子、电子数密度下降加快;磁场角度越大,参数q值对壁面电势、鞘层厚度的影响程度越显著,在超广延、亚广延分布情况下壁面附近离子x方向速度随磁场角度变化呈相反趋势.In this paper, the effects of non-Maxwellian distribution of electrons on the characteristics of magnetized plasma sheath with secondary electron emission are investigated by using a magnetic fluid model of onedimensional velocity and three-dimensional space. The velocity of electrons follows the non-extensive distribution, and the ions are magnetized in a magnetic field with a certain tilt angle relative to the wall. The effects of the non-extensive electron distribution parameter q and the magnetic field strength and angle on the Bohm criterion, the floating wall potential, the secondary electron number density at the sheath edge, the sheath thickness and the ion velocity are studied by establishing the self-consistent equations. When the electron velocity distribution deviates from the Maxwellian distribution, the results show that as the qparameter increases, the value of the Bohm criterion decreases, the floating wall potential increases, the number of secondary electrons at the sheath increases, the sheath thickness decreases, the number density of ions and electrons decline faster, the number density of ions near the wall is higher, and the velocities of the ions in the three directions are all reduced. In addition, as the magnetic field strength increases, the sheath thickness decreases, and the number density of ions and electrons in the sheath area decrease rapidly;the larger the magnetic field angle, the more significant the influences of the parameter q on the wall potential and the sheath thickness are, while the velocity component of the ion in the x-direction decreases with the increase of the magnetic field angle, but in the case of super-extensive distribution(q < 1), the velocity change near the wall presents an opposite trend, the increase of magnetic field angle causes wall velocity to increase;when it is close to Maxwellian distribution(q → 1), the velocity near the wall does not depend on the change of the magnetic field angle and basically tends to be identical;in the case of sub-extensiv

关 键 词：非广延分布 二次电子发射 磁化鞘层 玻姆判据 

分 类 号：O442[理学—电磁学]