60-GHz ECR Ion Sources

Electron Cyclotron Resonance Ion Sources (ECRIS) deliver high intensities of multicharged heavy ions to accelerators; nowadays the evolution of science requires extremely intense ion beams. Since 1987, semi empirical scaling laws state that the ECR plasma density, in a minimum- B magnetic field configuration, varies like the square of the electromagnetic waves (EM) frequency or of the resonant magnetic induction. The present most performing ECRIS are operated at 28 GHz. In order to significantly increase the ion beam intensities, the use of EM with frequencies of the order of 60 GHz is evaluated worldwide. Conceptual studies based on superconductors are performed and different magnetic configurations accepting such a high ECR frequency are proposed by several groups. Since 2009, LPSC collaborates with IAPRAS (Russia) and LNCMI (CNRS) and has built the first ECRIS with a topologically closed 60 GHz ECR resonance zone, using radially cooled polyhelices. Unique ion beam intensities have been extracted from this prototype, like 1.1 mA of O3+ through a 1mm hole representing a current density of 140 mA/cm2. The worldwide high frequency ECRIS research status is presented along with a focus on the present LPSC-IAP-LNCMI strategy.