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Next generation ECR ion sources: First results of the superconducting 28 GHz ECRIS - VENUS

  • Author(s): Leitner, Matthaeus
  • et al.
Abstract

VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (Rare Isotope Accelerator) front end.The goal of the VENUS ECR ion source project as the RIA R&D injector is the production of 200 mu A of U30+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5e mu A of U48+, a low current, very high charge state beam. To achieve those ambitious goals, the VENUS ECR ion source has been designed for optimum operation at 28 GHz. The nominal design fields of the axial magnets are 4T at injection and 3T at extraction; the nominal radial design field strength at the plasma chamber wall is 2T, making VENUS currently the world most powerful ECR plasma confinement structure.Recently, the six year project has made significant progress. In June 2002, the first plasma was ignited at 18 GHz. During 2003, the VENUS ECR ion source was commissioned at 18 GHz, while preparations for 28 GHz operation were being conducted. In May 2004 28 GHz microwave power has been coupled into the VENUS ECR ion source for the first time. Preliminary performance-tests with oxygen, xenon and bismuth at 18 GHz and 28 GHz have shown promising results. Intensities close to or exceeding the RIA requirements have been produced for those few test beams.The paper will briefly describe the design of the VENUS source and its beam analyzing system. Results at 18 GHz and 28 GHz including first emittance measurements will be described.

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