N_2微空心阴极放电特性及其阴极溅射的PIC/MC模拟

Simulation of N_2 microhollow cathode discharge and cathode sputtering by using a PIC/MC model

采用两维PIC/MCC模型模拟了氮气微空心阴极放电以及轰击离子(N+2,N+)的钛阴极溅射.主要计算了氮气微空心阴极放电离子(N+2,N+)及溅射原子Ti的行为分布,并研究了溅射Ti原子的热化过程.结果表明:在模拟条件下,空心阴极效应是负辉区叠加的电子震荡;在对应条件下,微空心较传统空心放电两种离子(N+2,N+)密度均大两个量级,两种离子的平均能量的分布及大小几乎相同;在放电空间N+的密度约为N+2的1/6,最大能量约大2倍;在不同参数(P,T,V)下,轰击阴极内表面的氮离子(N+2,N+)的密度近似均匀,其平均能量几乎相等;从阴极溅射出的Ti原子的初始平均能量约6.8eV,离开阴极约0.15mm处几乎完全被热化.模拟结果为N2微空心阴极放电等离子体特性的认识提供了参考依据.

The nitrogen microhollow cathode discharge and Ti cathode sputtering, bombarded by ions （N2＋, N＋）, have been studied using a two-dimensional PIC/MCC model. The behavior of ions （N2＋, N＋） and sputtered atom （Ti）, and the thermalization process of the sputtered atoms in a nitrogen microhollow cathode discharge are simulated. The results show that hollow cathode effect is due to electron oscillations in the overlapping negative glow under our simulation condition. The densities of ions （N2＋, N＋） in the microhollow cathode discharge are two orders in magnitude greater than that in the conventional hollow cathode discharge; but the distributions and sizes of the mean energy of the ions （N2＋, N＋） are almost the same. The density of N2＋ is fivefold as much as that of N＋ in the microdischarge space; however, the maximum of mean energy of the latter is twice larger than the former. For various parameters （P, T, V）, the densities of ions（N2＋, N＋） bombarding the cathode internal surface are almost uniformly distributed, and their mean energy are almost the same. When these atoms are 0.15 mm away from the cathode. The sputtered atoms are almost thermalized completely.