• D. Leitner, S. Caspi, P. Ferracin, C.M. Lyneis, S. Prestemon, G.L. Sabbi, D. Todd, F. Trillaud
  LBNL, Berkeley

Funding: This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Nuclear Physics Division of the U.S. Department of Energy under Contract DE AC03-76SF00098.

The de­vel­op­ment of the su­per­con­duct­ing 28 GHz ECR ion source VENUS at the Lawrence Berke­ley Na­tion­al Lab­o­ra­to­ry (LBNL) has pi­o­neered high field su­per­con­duct­ing ECR ion sources and opened a path to a new gen­er­a­tion of heavy ion ac­cel­er­a­tors. Be­cause of the suc­cess of the VENUS ECR ion source, su­per­con­duct­ing 28 GHz ECR ion sources are now key com­po­nents for pro­posed ra­dioac­tive ion beam fa­cil­i­ties. This paper will re­view the re­cent ion source de­vel­op­ment pro­gram for the VENUS source with a par­tic­u­lar focus on the pro­duc­tion of high in­ten­si­ty ura­ni­um beams. In ad­di­tion, the paper will dis­cuss a new R&D pro­gram start­ed at LBNL to de­vel­op ECR ion sources uti­liz­ing fre­quen­cies high­er than 28 GHz. This pro­gram ad­dress­es the de­mand for fur­ther in­creas­es of ion beam in­ten­si­ties for fu­ture ra­dioac­tive ion beam fa­cil­i­ties. The most crit­i­cal tech­ni­cal de­vel­op­ment re­quired for this new gen­er­a­tion of sources is the high-field su­per­con­duct­ing mag­net sys­tem. For in­stance, the mag­net­ic field strengths nec­es­sary for 56 GHz op­er­a­tion pro­duce a peak field in the mag­net coils of 12-14 T, re­quir­ing new su­per­con­duc­tor ma­te­ri­al such as Nb₃Sn. LBNL has re­cent­ly con­clud­ed a con­cep­tu­al, com­par­a­tive de­sign anal­y­sis of dif­fer­ent coil con­fig­u­ra­tions in terms of mag­net­ic per­for­mance and has de­vel­oped a struc­tural sup­port con­cept com­pat­i­ble with the pre­ferred mag­net­ic de­sign so­lu­tion. This de­sign ef­fort con­cludes that a sex­tupole-in-solenoid ECR mag­net struc­ture (VENUS type) is fea­si­ble with pre­sent Nb₃Sn tech­nol­o­gy, but that an in­vert­ed ge­om­e­try (solenoid-in sex­tupole) ex­ceeds the ca­pa­bil­i­ty of Nb₃Sn su­per­con­duc­tors and can be ruled out as can­di­date for a 56 GHz ECR ion source.

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