A classical model of ion confinement and losses in ECR ion sources

A model of the ion confinement and losses in the open magnetic trap of an electron cyclotron resonance ion source (ECRIS) is proposed in this article. This model is based on the processes connected with the elastic and inelastic collisions of the charged particles in the ECR plasma and the classical particle losses from the open magnetic trap. In the ECRIS the ions are confined in the negative potential well. The ions with higher charge states have longer lifetimes and less probability of leaving the source. Therefore the mean ion charged state in the trap is higher than that in the output ion flow. General methods to increase multiply charged ion extraction from the ECRIS are determined. The use of the ion cooling mode to increase the ion charge states in the plasma is shown and the large output pulse of multiply charged ions in the RF pulse mode is explained. A numerical simulation of the ion cooling and radio frequency (RF) pulse processes for a MINIMAFIOS type ECRIS has been carried out. The simultaneous application of the ion cooling and pulse regimes is proposed for pulse injection of highly charged ions in the heavy-ion accelerators and storage rings.