Effect of collisions on the two-stream instability in a finite length plasma
Effect of collisions on the two-stream instability in a finite length plasma
复制标题
碰撞对有限长度等离子体中两流不稳定性的影响
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
I. Kaganovich
中科院分区：
文献类型：
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作者：
P. Ventzek;D. Sydorenko;I. Kaganovich
在接地壁之间限制的一维等离子体中单能电子束的不稳定性在分析和数值上都被考虑[1,2]。电子和中性子之间的碰撞仅考虑等离子体电子[2]。色散方程的解表明，不稳定性的时间增长率是碰撞频率的递减线性函数，当碰撞频率是无碰撞增长率的两倍时，该函数变为零。该结果通过流体模拟得到证实。给出了用于估计阈值束电流的实用公式，该阈值束电流是在给定系统长度、中性气体压力、等离子体密度和束能量下产生两流不稳定性所需的。使用不同的中性密度和束流进行的颗粒内细胞（PIC）模拟表明，生长速率和阈值束流与流体理论预测具有良好的一致性。
The instability of a monoenergetic electron beam in a one-dimensional plasma bounded between grounded walls is considered both analytically and numerically [1,2]. Collisions between electrons and neutrals are accounted for the plasma electrons only [2]. Solution of a dispersion equation shows that the temporal growth rate of the instability is a decreasing linear function of the collision frequency which becomes zero when the collision frequency is two times the collisionless growth rate. This result is confirmed by fluid simulations. Practical formulas are given for the estimate of the threshold beam current which is required for the two-stream instability to develop for a given system length, neutral gas pressure, plasma density, and beam energy. Particle-in-cell (PIC) simulations carried out with different neutral densities and beam currents demonstrate good agreement with the fluid theory predictions for both the growth rate and the threshold beam current.