等离子体扩散流中金属平板上下游的鞘层结构  

Upstream and downstream sheath structures near a metal plate in the flow of a diffusive plasma

作　　者：郑尧邦[1,2] 马锦秀[1] 李毅人[1] 李卫[1] 

机构地区：[1]中国科学技术大学近代物理系,中国科学院基础等离子体物理重点实验室和磁约束等离子体理论中心,合肥230026 [2]中国空气动力研究与发展中心,绵阳621000

出　　处：《核聚变与等离子体物理》2012年第1期21-26,共6页Nuclear Fusion and Plasma Physics

基　　金：国家自然科学基金资助课题(10875121,40831062);中国科学院知识创新工程资助课题(kjcx2-yw-n28);国家重点基础研究项目资助课题(2009GB105001,2008CB717800)

摘　　要：利用发射探针诊断了处于扩散等离子体流场中平板两侧的鞘层电势分布并给出鞘层厚度及边界电场。结合Child-Langmuir(CL)定律并利用一维流体模型,分析对比了鞘厚及边界电场。结果显示,上下游的鞘层呈现不对称结构,下游比上游厚,边界电场下游比上游弱,并且下游的预鞘还呈现类似虚阳极的结构。上下游CL鞘的厚度满足线性比例关系,比例系数约为1.2,且实验值与理论值非常接近。上下游CL鞘的边界电场与模型Te/(eλD)比较接近,上游Bohm鞘边界电场的实验结果与过渡区模型e/(3D/5i2/5)T e较符合,但下游Bohm鞘的边界电场与现有模型有较大差异。The potential distributions in the sheath and presheath in the upstream and downstream sides of a metal plate immersed in the flow of diffusive plasma were measured using a fine structured emissive probe, Combining the Child-Langmuir（CL） law and one-dimensional fluid model, the sheath thicknesses and edge electric fields were analyzed. It is shown that the sheath in the downstream side is thicker than that in the upstream side, while the measured edge electric field of the upstream sheath is stronger than that of the downstream sheath. Both experimental and numerical results show that the thicknesses of the CL sheath in the two sides of the plate satisfy a linear relation, with a fitting proportionality of 1.2 between the down- and upstream thickness. The electric field at the CL sheath edge in both up-and downstream sides is consistent with the value given by Te Te（eλD）, while the measured electric field at the Bohm sheath edge in the upstream side is close to Te/（eλd^[3/5]λ1^[2/5]＇）. However, the Bohm sheath edge electric field in the downstream side shows a significant deviation from available models.

关 键 词：等离子体鞘层 上下游 边界电场 

分 类 号：O590[理学—应用物理]