The upgrading of the multiply charged heavy-ion source Minimafios

The basic principles and performance of the Minimafios 10 GHz electron cyclotron resonance ion source (ECRIS) are reviewed. The source can operate either pulsed, with a pulse width of > 50 ms, or cw, with 1011 fully stripped light ions per second and much higher amounts of lower charge state ions. The source has excellent reliability and reproducibility. It has good emittance and energy dispersion. The way of operation and adjustment of the source is very simple since it depends only on two parameters: gas feed and rf power injected. ECRIS is well suited for injection into heavy ion accelerators and for atomic physics. Thus more and better sources are desired. But the upgrading is not simple. In this paper, we show the experimental results when the electron cyclotron resonance is shifted from 10 to 16.6 GHz. This new source mainly aimed to small duty cycle acceleration (theta<0.15) exhibits remarkable improvements in beam intensities and even more interesting results in the production of higher charged ions. A comparative study of the performances at 10 and 16.6 GHz is given. (orig.)