Numerical study on ion filtering of titanium hydride cathodic vacuum arc plasma through a double-layer extraction grid

A novel method of filtering titanium hydride cathodic vacuum arc ions through a double-layer extraction grid is proposed in this paper. Two grids with different transmission rates are placed very closely, and apertures of the two grids are staggered. Due to the differences of ions in the charge state and kinetic energy, H⁺ can easily go through the second grid after passing the first grid and then be extracted, while most Tiⁱ⁺ (i = 1 3) are blocked and absorbed by the second grid. Using a 2D electrostatic particle-in-cell simulation, the effectiveness of the double-layer extraction grid on ion filtering is verified. The results show that the fraction of H⁺ can be increased from 39% to 80% by the double-layer grid and the fraction of metal ions decreases significantly. The fraction of H⁺ depends on the distance and the overlap length of the two grids. Besides, in a wide range of extraction voltage, the double-layer grid is effective in increasing the fraction of H⁺.