Influence of ion species on extraction characteristics of mixed ion beams

The spatial distributions of different kinds of ions are usually not completely the same in the process of extracting. In order to study the reason for the different characteristics of ion extraction, a simplified simulation model of Cu⁺ and Cr⁺ ions extraction process was established by 2D3V (two-dimensional in space and three-dimensional in velocity space) particle-in-cell (PIC) method. The effects of different extraction voltages from 0 V to 500 V on the density distribution of Cu⁺ and Cr⁺ ions and the change of plasma emission surface were analyzed. On the basis of this model, the ion density distribution characteristics of Cu⁺ ions mixed with Li⁺, Mg⁺, K⁺, Fe⁺, Y⁺, Ag⁺, Xe⁺, Au⁺, and Pb⁺ ions respectively under 200-V extraction voltage are further simulated, and it is revealed that the atomic mass of the ions is the key reason for different ion density distributions when different kinds of ions are mixed and extracted, which provides support for further understanding of ion extraction characteristics.