Design of a Compact ECR Ion Source with Ku Band

The electron cyclotron resonance (ECR) ion sources are increasingly popular for producing highly charged ions. With worldwide proposals to build the Isotope Seperator OnLine (ISOL) facility being at hand, it becomes important to design a high efficiency ion source as a charge breeder for the secondary beam. A novel type of ECR ion source based on a flat magnetic field configuration has been proposed by Alton et al. [1, 2] This source provides a large, on-axis electron cyclotron resonance region, ”ECR-volume”. Due to a larger ECR zone, absorptivity of microwave power into plasma is much increased, thereby electron becomes so hot. And hot electron population of the plasma could result in higher charge states and higher beam intensity. Two sloenoids are used to produce axial mirror magnetic field. Twelve permanent magnets (NdFeB) are designed for confining the hot electrons in the radial direction. Moreover, specially designed iron yokes are added to create the flat central field region. The single injected microwave frequency is tunable in the range of 6.45 to 14 GHz covering the range of the Ku band. We shall present the design report concerning the field mapping obtained by POISSON and OPERA-3D together with and mechanical design.