The accuracy of collision cross sections in particle modeling on copper vacuum arcs

• Published in: Physics of plasmas Vol. 25; no. 6
• Main Authors: Yang, Wei, Zhou, Qianhong, Yang, Wenyuan, Dong, Ye, Dong, Zhiwei
• Format: Journal Article
• Language: English
• Published: 01.06.2018
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/1.5032276

Direct Simulation Monte Carlo and Particle-in-Cell (DSMC-PIC) method is a powerful tool in studying metal vapor vacuum arcs (VA). However, the collision cross sections (Xs) for metal atoms/ions are not evaluated yet, compared to the already developed databases for gas discharges. The Xs are subject to uncertainties which influence the accuracy and predictive ability of particle models. In this paper, the common electrode material copper (Cu) is taken as an example for survey of Xs. Various experimental data, theoretical calculation, and analytical fitting formula are reviewed. The electron-impact Cu elastic, excitation, and ionization Xs are found to have an overall uncertainty within 15%. The Cu-Cu+ resonant charge-exchange Xs are not as accurate as that of e-Cu collision. The Cu-Cu interaction Xs by variable hard sphere model requires further validation. Based on the evaluated Xs, the mean free path and collision frequency are derived in copper VA plasmas, and compared to the Debye length and plasma frequency, respectively. The influences of those spatial and time scales are discussed in developing DSMC-PIC codes for modeling of copper VA.