This article emphasizes a confinement model for electrons and ions in an ECR source for multicharged ions, on the basis of specific measurements performed on the 16.6 GHz MINIMAFIOS and 10 GHz CAPRICE facilities. The conclusions partially support the above model.

The principles, construction, and performance of the MINIMAFIOS electron cyclotron resonance ion source (ECRIS) are reviewed. The source can operate either pulsed, with pulse width of > 50 ms, or cw, with 10 1 \ fully stripped light ions per second and much higher amounts oflower charge state ions. The source has excellent reliability and reproducibility. It has acceptable emittance and energy dispersion. The manner of operation and adjustment of the source is very simple since it depends only on the two parameters: gas feed and rfpower injected. In addition, metallic ions can be produced directly. ECRIS is well suited for injection into heavy ion accelerators and for atomic physics. Its high ion fluxes in a quasicontinuous regime are useful for numerous other applications and open new fields for scientific research with multiply charged ions. Thus, more and better sources are desired. New ideas have been proposed and new sources have been built or are under construction. We present the latest performance data of MINIMAFIOS for gaseous elements as a reference for evaluating the performance of new ECRIS in various laboratories. For metallic ions we need more experimental results in order to establish basic data references.

The 1.2 T–14.5 GHz ECR Caprice source is an upgrade version of previous Caprice sources where the three main ingredients of an ECR ion source of multicharged ions have been optimized: (i) the magnetic configuration has higher axial fields (1.4–1.45 T at the mirror throats) and radial field (1.05 T at the wall inside the plasma chamber) as well as higher mirror ratios, (ii) the 14.5 GHz rf frequency is convenient to higher magnetic fields, and (iii) more efficient electron sources allow the electron density to reach higher values, and thus high extracted ion currents (both first stage and wall coating). Emphasis is given to the metallic elements, the source is able to produce 10 eμA of Ca14+, 3 eμA of Fe17+ and Ni20+, 1 eμA of U37+, while being able to deliver 1130 eμA of O6+, 190 eμA of O7+, and 100 eμA of Ar12+.

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