Laser injection into ECRIS: Theoretical considerations and first experimental results

Some of experimental results of ion production using Al and Cd neutral flows of laser ablation plasma in the electron cyclotron resonance (ECR) ion source at RIKEN (Japan) and Frankfurt University are presented, analyzed and simulated. Computer codes based on balance equations for all ionic charge states and theory of electron and ion confinement in the open magnetic trap of ECR ion source was used for the numerical simulation of ion or neutral injection into the ECR plasma. The presented numerical simulation of pulsed neutral injection into the ECR source a good coincidence with experimental data. Different regimes on pulsed neutral injection into ECR source are studied and analyzed in a series of numerical simulations. The existed experiments and these simulations have shown some evident advantages of the combination of ECRIS and laser source: there are only a few charge states at every moment of time and the CSD of extraction current is narrow; pulsed loading of heavy elements gives a high current output of highly charged ions in comparison with CW mode loading; extraction current of every charge state has a pulse structure with duration of few ms; different charged states have different buildup times; pulsed laser injection can be used for the CW mode of highly charged ion production if the repetition rate of laser pulses is high enough; The presented considerations and simulations of laser pulsed ion loading into a 18 GHz type ECR source have shown that an ion pulse of Au35+ about 0.5 mA and of 0.5 ms duration could be produced in the afterglow operation mode. Future ECR sources of next generation promise to enhance this output up to a few of mA.