Design of a 14 GHz minimum-B electron cyclotron resonance ion source for flexible operations

A 14 GHz minimum-B ECR ion source with movable extraction system and biased disk has been designed. This will be used as an ion source for heavy ion accelerator, for applications in atomic physics research, and for further physical understanding of electron cyclotron resonance (ECR) plasmas. To meet diversities in beam parameter and to optimize the system under the various conditions, the source is designed to be operated in flexible magnetic structures and extraction system. The designed magnetic field is minimum-B structure which is generated by two main yoked coils and 12 segmented permanent magnet. By using the central coil and by axially shifting the whole magnet system, the magnetic field structure can be changed to different profiles: therefore, the mirror ratio can be adjusted from 2.5 to 4, and the tuning of ion source can be facilitated under the various magnetic field geometries. The rectangular waveguide for RF injection is directly inserted to the source to make its radial position lie along the resonance surfaces so that it can ensure the maximum power coupling