We report the results of a particle-in-cell Monte-Carlo collision simulation of an axially symmetric DC magnetron discharge with a 5cm diameter flat cathode in argon at pressures from 1 to 10mTorr at a constant discharge current of about 0.5A. Calculations show that the cathode region, where almost the entire discharge voltage drops, consists of a cathode sheath 0.1–0.2mm wide and a presheath about 2cm wide, where most of the ionizations occur, separated by a region 0.25–0.35mm wide, where the plasma potential remains almost unchanged and the plasma density reaches its maximum value. Most of the discharge voltage drops in the presheath at low gas pressure, and in cathode sheath at high pressure. The ratio of sheath to presheath voltages increases linearly with pressure. The distribution of the ionization rate has two maxima: near the cathode sheath and in the presheath. The fraction of ionizations near the cathode sheath increases with pressure. The electron energy distribution function (EEDF) is generally a two-temperature function. At low pressures at a distance of less than 1cm from the cathode, the EEDF becomes one-temperature. A high-energy tail is observed on the EEDF near the cathode; the fraction of electrons in the tail (in the order of tenths of a percent at 10mTorr) and their energy, determined by the sheath voltage, increase with pressure. The electron temperature decreases with pressure due to a decrease of the electric field in the presheath, which leads to a decrease of energetically accessible regions of collisionless electron motion and to a corresponding decrease in the energy that electrons can obtain in these regions. The dependence of the discharge voltage on the gas pressure has a minimum at about 3mTorr, which occurs due to the competition of two processes on pressure increase: a decrease in the electron temperature and a decrease in the fraction of electrons returning back to the cathode. Plasma density waves are observed in the presheath region at pressures of 1–3mTorr.

我们报告了在 1 至 10mTorr 的压力下，在约 0.5A 的恒定放电电流下，在氩气中使用直径为 5cm 的扁平阴极进行轴对称直流磁控管放电的电池内粒子蒙特卡罗碰撞模拟的结果。计算表明，几乎整个放电电压下降的阴极区域由 0.1-0.2 毫米宽的阴极护套和大约 2 厘米宽的预护套组成，大部分电离发生在那里，由 0.25-0.35 毫米宽的区域隔开，其中等离子体电位几乎保持不变，等离子体密度达到最大值。大多数放电电压在低气压下的预护套中和高压下的阴极护套中下降。护套电压与预护套电压之比随压力线性增加。电离率的分布有两个最大值：靠近阴极护套和预护套中。阴极鞘附近的电离部分随压力增加。电子能量分布函数（EEDF）一般是二温函数。在距离阴极不到 1 厘米的低压下，EEDF 变成一个温度。在阴极附近的 EEDF 上观察到高能尾；尾部电子的比例（在 10mTorr 时大约为 0.0%）及其能量（由鞘层电压决定）随着压力增加。由于预鞘中电场的减小，电子温度随着压力而降低，这导致无碰撞电子运动的能量可及区域减少，并且电子在这些区域可以获得的能量相应减少。放电电压对气压的依赖性在约 3mTorr 处具有最小值，这是由于两个过程对压力增加的竞争而发生的：电子温度降低和返回阴极的电子比例减少。在 1-3mTorr 的压力下在预鞘区观察到等离子体密度波。