Metal ion filtering of vacuum arc ion source through an inclined-aperture extraction grid

• Published in: Plasma sources science & technology Vol. 28; no. 7; pp. 75008 - 75014
• Main Authors: Lan, Chaohui, Long, Jidong, Zheng, Le, Dong, Pan, Li, Jie, He, Jialong
• Format: Journal Article
• Language: English
• Published: IOP Publishing 25.07.2019
• Subjects: ion filtering; metal hydride; particle-in-cell; vacuum arc plasma
• ISSN: 0963-0252; 1361-6595; 1361-6595
• DOI: 10.1088/1361-6595/ab1a90

The paper reports a novel method of increasing the fraction of H+ ions produced by vacuum arc ion sources with metal hydride cathodes, which applies the ionic selectivity of an inclined-aperture extraction grid to separate and filter heavy metal ions. A simple theoretical model is built to describe the filtering mechanism. Since H+ ions and Tin+ (n = 1 ∼ 3) ions produced by vacuum arc discharge have a great difference in the ratio of charge state and kinetic energy, H+ ions are easy to pass through the inclined-aperture grid, while most of the Ti ions are blocked and absorbed by the grid wall. Using a 2D particle-in-cell simulation, the ionic selectivity of an inclined-aperture extraction grid is demonstrated. The numerical simulation results show that after ion filtering through the extraction grid, the fraction of H+ ions is increased from 39% to more than 80%. The increased amplitude of H+ ion fraction depends on the thickness of the grid and the angle of grid apertures. In addition, an extraction grid with different aperture angles for the extraction of divergent vacuum arc plasma is proposed.