Simulation of ion confinement in an ECR ion source under electron injection

A new model for the simulation of some physical processes in ECR ion sources is presented. It considers two electron components in the plasma and an additional injection of electrons to increase the electron density. Thereby the electron density is determined from balance equations for cold and hot electrons. The model includes the appearance of electrons due to ionisation of neutral atoms and ions by electron impact, the transition of cold into hot electrons due to microwave heating, the electron losses from the magnetic trap of the source and the additional electrons due to injection. The dependence of the total electron density in the plasma and the ion charge distribution at the exit of the source on the injected electron current was analyzed. It is shown that an additional electron injection in the ECR source leads to an increasing electron density in the source and therefore to an increasing output of highly charged ions, particularly at a sufficiently low pressure in the source. ((orig.))