Three-dimensional Particle-In-Cell simulation of ion characteristics in anode layer ion source

Abstract

Ion characteristics in cylindrical anode layer ion source (ALIS) with an outlet diameter of 80 mm (D80) are experimentally investigated. The ion beam current in the high-current and low-voltage mode is higher than that in the low-current and high-voltage mode and divergence half angle of ion beam is up to 42°. Numerical simulation by three-dimensional Particle-In-Cell with Monte Carlo collisions method (PIC-MCC) is performed to demonstrate the ion characteristics in different operational conditions. The simulation results reveal that ion density distribution and ion energy and ion divergence half-angle is mainly affected by discharge voltage which induce the formation and movement of ions. About 52% ions have divergence half-angle range from 30°to 45°, meanwhile this kind of ion source has a wide range of ion energy distribution which is helpful for application. Therefore, according to specific process, keeping the balance of a relatively large ion divergence angle and a concentrated ion energy distribution and choosing a proper working gas pressure is the key to improve the processing effect.