High density ECR plasmas for the production of intense highly charged ion beams

An average increase of about one order of magnitude per decade in the performance of ECR ion sources was obtained since the time of pioneering experiment of R. Geller at CEA Grenoble and this trend is not deemed to get the saturation at least in the next decade, according to the increased availability of powerful magnets and microwave generators. Otherwise a further step forward is needed to fulfil the requirements of many projects of accelerators recently proposed or in the construction phase. Electron density above 1013 cm−3 can be obtained by 28 GHz microwave heating, but only an adequate plasma trap may allow to exploit that plasma for heavy elements ionization. A study about the optimization of the magnetic field and of the other different parameters affecting the ECRIS plasma is presented, with a special emphasis on the coupling of microwaves to plasma. The simulations confirm that higher frequencies are viable, which will permit to get in future either mA beams of 20+ to 30+ heavy ions or μA beams of 50+ to 60+ ions, through the change of a few parameters.