ECR ion source development for super-stripped positive ions in accelerator and atomic physics applications

Abstract

The present generation of electron cyclotron resonance ion sources (ECRIS), operating in the frequency range of 6–18 GHz, can produce fully stripped ions up to Z = 20 and extending to 30–35 + ions for Z = 50–90 [1]. To obtain even higher charges, the next generation of ECR sources may employ superconducting magnets for resonance heating at 28 GHz. This frequency matches gyrotron microwave sources developed for ECR heating in plasma fusion experiments. Higher frequency operation permits, in principle, operation at higher plasma densities, by raising the cutoff limit and there is now evidence that both the peak and average charges extracted from ECR sources scale with the plasma density [2]. In order to further study these issues, a superconducting magnet structure for a variable frequency ECR, the SC-ECR at NSCL, is now under construction [3–5]. In this paper, the background for this line of source development will be reviewed and the design and present status of the SC-ECR will be presented.