Progress in the Design of the ASTERICS 28 GHz ECR Ion Source Superconducting Magnet for the NEWGAIN Project at GANIL

In the framework of the NEWGAIN project (NEW GAnil INjector), a new injector is under development to supply the SPIRAL2 LINAC at GANIL with heavy ion of a mass to charge-state ratio up to A/q = 7. In order to produce this heavy ion beam, a superconducting 28 GHz ECR Ion Source called ASTERICS is under development and its superconducting magnet used for plasma confinement is designed at CEA in collaboration with LPSC and GANIL. The magnetic design of the ion source is based on the well-proved sextupole-in-solenoids configuration used in different laboratories worldwide. The superconducting coils will be in Nb-Ti placed in a He bath cooled by 6 in-situ cryocoolers. A magnetic and protection optimization has been done to meet the NEWGAIN requirements which calls for a bigger plasma chamber than the existing superconducting ECR ion sources while maintaining the same temperature margin in the coils. This paper focuses on the magnetic analysis, the protection studies and the choice of the superconducting conductor for the sextupole and the solenoids. To validate the coil fabrication steps and the assumptions made in the magnetic design, some winding trials have been done. Both simulations and mock-up results are presented here.