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在考虑粒子碰撞的情况下,利用二流体模型研究了等离子体与器壁之间的相互作用。首先,应用类似于分析势阱中粒子运动的方法研究了德拜 (Debye) 鞘层判据和边界条件,结果表明,原来用于推导鞘层判据 (Bohm’scriterion) 的方法在有些情况下是不适用的,而且求得鞘层判据的新的表示式,其中包含碰撞的影响。此外分析了磁预鞘层 (magnetic presheath) 边界的离子流和预鞘层宽度之间的关系,发现在一定的碰撞频率下,沿磁力线方向的离子速度随预鞘层宽度的增加而减小,其规律类似于指数下降,因此可以用离子速度的e-倍衰减长度 (e-foldlength) 定义预鞘层宽度,基于这一定义计算了边界离子流与碰撞之间的函数关系。
Under the condition of particle collision, the interaction between the plasma and the vessel wall is studied by using a two-fluid model. First, the Debye sheath criterion and boundary conditions were studied using a method similar to analyzing the particle motion in a potential well. The results show that the original method used to derive the shell criterion (Bohm’scriterion) Is not applicable, and a new representation of the sheath criterion is obtained, which contains the impact of the collision. In addition, the relationship between the ion pres- sure and the width of the pre-sheath is analyzed. It is found that the ion velocity decreases along with the increase of the pre-sheath width at a certain collision frequency, The law resembles that of exponential decline, so the e-fold length of the ion velocity can be used to define the width of the pre-sheath. Based on this definition, the functional relationship between the boundary ion flux and the collision is calculated.