粒子束对玻姆鞘层判据的影响

The influence of particle beams on the criterion of Bohm sheath

在一维平板鞘层中应用双流体模型在有无碰撞两种情况下分别研究了定向离子束和定向电子束的存在对玻姆鞘层判据的影响 .研究所涉及的碰撞主要有电荷交换碰撞、电离碰撞和总能量损失碰撞 .工作气体是氩气 ,气压是常压 .通过采用四阶龙格 -库塔法 ,得到了数值解 .结果表明定向离子束能减小漂移离子进入鞘层的最小速度 ,电荷交换碰撞也能减小这一速度 ;定向电子束使这一速度增加 。

A two-fluid model has been used to study the influence of the existence of the directive ions and directive electrons on the Bohm criterion of sheath. The main collisions included in this study consist of the charge exchange collision, ionization collision and total energy loss collision. The operated gas is argon with a gas pressure 101325 Pa. Numerical calculation results are obtained, which show that the minimal speed at which drift ions enter into the sheath for directive ions is decreased. This is also valid for the charge exchange collision. The directive electrons make this speed increase, but the ionization collision related to directive electrons makes the speed decrease obviously.