High-efficient particle-in-cell/Monte Carlo model for complex solution domain andsimulation of anode layer ion source

Abstract

Plasma simulation is important in studying the plasma discharge systematically, especially the anode layer ion source which has the complex geometrical characteristics of the discharge structure. However, owing to the complex solution domain formed by the geometric profile of the anode and cathode, the traditional simulation models show extremely small computational efficiency and poor convergence. This work presents a separate simulation for the ion source structure and the plasma discharge, separately, where the cathode geometric parameters (including the size, the shape and the relative position of the inner and outer cathodes) are simplified into two magnetic mirror parameters (the magnetic mirror ratio <i>R</i>_m and the magnetic induction intensity in the center of the magnetic mirror <i> <b>B</b> </i>₀), and then a high-efficient particle-in-cell/Monte Carlo collision (PIC/MCC) model is established to improve the computational efficiency and stability of the plasma simulation later. As a result, the convergence time of the plasma simulation is shortened significantly from 1.00 μs to 0.45 μs, and by which the influences of the geometrical characteristics of the discharge structure on the plasma properties are systematically studied. The simulation results reveal that magnetic mirror with <i>R</i>_m = 2.50 and <i> <b>B</b> </i>₀ = 36 mT can best confine the plasma in the central area between the inner cathode and outer cathode. When the discharge center of the plasmacoincides with the magnetic mirror center, the anode layer ion source presents both high density output of ion beam current and significantly reduced cathode etching, suggesting that the best balance is obtained between the output and cathode etching.