气体放电空心阴极鞘层氩离子的蒙特-卡罗模拟研究

A SELF-CONSISTENT MONTE CARLO SIMULATION OF IONS IN HOLLOW-CATHODE SHEATH OF ARGON GAS DISCHARGES

建立了气体放电空心圆筒阴极鞘层离子的自洽蒙特-卡罗模拟模型,对鞘层区内离子的输运过程进行了研究。考虑了离子与中性原子的电荷交换碰撞和弹性散射,用到了精确依赖于离子能量的电荷交换和动量输运截面。模拟了氩离子在空心阴极鞘层中的运动,得到了不同放电条件下自洽电场分布,离子的能量分布,角分布以及电子密度分布和离子密度分布。计算结果表明:离子在由鞘层边界向阴极运动过程中,离子能量分布的高能部分逐渐增大,角分布向小角度部分压缩,鞘层中的强电场对离子起加速和聚焦作用;在鞘层内离子密度分布比较均匀,只是在鞘层边界附近变化急剧,电子密度在鞘层内几乎为零。在阴极鞘层内电场分布是非线性的。

In this paper, a self-consistent Monte Carlo simulation method including charge exchange and elastic scattering is developed, and the method is used to calculate the energy and angle distributions of ions, the density distributions of ions and electron in hollow-cathode sheath of a DC argon gas discharge for the different discharge conditions. Cross sections of the charge exchange and the momentum transfer that depend on the ion energy are taken into account precisely. It is found that, as the ions move towards the cathode, the high energy portions of ion energy distributions are enhanced gradually and the small angle portions of the angle distribution increase. A strong field accelerates the ions to higher speed and ensures more ions to move along the lines of force.