Development of the third generation ECR ion source

The LBNL third generation electron cyclotron resonance (ECR) ion source has progressed from a concept to the fabrication of a full scale prototype superconducting magnet structure. This new ECR ion source will combine the recent ECR ion source techniques that significantly enhance the production of high charge state ions. The design includes a plasma chamber made from aluminum to provide additional cold electrons, three separate microwave feeds to allow multiple-frequency plasma heating (at 10, 14, and 18 GHz or at 6, 10, and 14 GHz) and very high magnetic mirror fields. The design calls for mirror fields of 4 T at injection and 3 T at extraction and for a radial field strength at the wall of 2.4 T. The prototype superconducting magnet structure which consists of three solenoid coils and six race track coils with iron poles forming the sextupole has been tested in a vertical Dewar. After training, the sextupole magnet reached 105% of its design current with the solenoids off. With the solenoids operating at approximately 70% of their full design field, the sextupole coils operated at 95% of the design value which corresponds to a sextupole field strength at the plasma wall of more than 2.1 T. copyright 1998 American Institute of Physics