Three-dimensional simulations of ion dynamics in the plasma of an Electron Cyclotron Resonance Ion Source

TL;DR

This paper presents a 3D particle-in-cell Monte Carlo collision simulation of ion dynamics in an Electron Cyclotron Resonance Ion Source, successfully reproducing experimental plasma features and exploring isotope effects and wall interactions.

Contribution

It introduces a detailed 3D simulation approach for ECRIS plasma, capturing charge distributions and isotope anomalies, with implications for understanding ion confinement and wall effects.

Findings

Reproduces charge-state distributions of extracted ions.

Observes isotope anomaly in neon mixture.

Discusses wall-coating effects and fast atom parameters.

Abstract

The ion production in an ECRIS is modelled using a particle-in-cell Monte-Carlo collision code in a three-dimensional geometry. Only the heavy particles (ions and atoms) are tracked, with the electron density determined from the requirement of quasi-neutrality, and the electron temperature is a free parameter. The electric fields in the plasma are assumed to be negligibly small, and the ion confinement due to a "potential dip" is neglected. It is found that experimentally observed features of ECRIS plasma are closely reproduced by the code, including the charge-state-distributions of extracted ion beams and sputtering patterns inside the source. The isotope anomaly is observed for the mixture of 20Ne + 22Ne isotopes, and some explanation for the effect is given. Possible connection between the wall-coating effect and parameters of the fast atoms created in collisions of the ions with the walls is discussed.