Simulation of Laser Ion Loading into ECR Source

Abstract

A new version of computer codes based on balance equations for all ionic charge states and theory of electron and ion confinement in the open magnetic trap of an ECR ion source was developed and tested for the numerical simulation of ion injection into the ECR plasma. The presented numerical simulations of pulsed ion injection into the ECR source have shown some advantages of the combination of ECRIS and laser ion or neutral sources. The pulse loading of heavy elements in the ECR source could give a high current output of highly charged ions due to a narrow charge state distribution of ions in the source. The extraction current of every charge state has a pulse structure with a duration of a few milliseconds. Different charge states have different build-up times. It is possible to select the extraction of a charge state by changing the time length of the RF pulse after the time of ion or neutral beam injection. There are only few charge states at every moment of time in the source and the charge state distribution of the extracted current is very narrow in comparison with ordinary ion loading. This effect should be strongly enhanced in the afterglow mode of operation and results of simulations promise to produce ion pulses of Pb27+ of about 1 mA in the afterglow mode (0.3 ms duration) in the SERSE (INFN-LNS, Catania) type ion source. The presented simulations are in qualitative agreement with existing experimental data of neutral flow injection from laser ablation plasma.