Optimization of a Dipole With Partially Keystoned Cable for the SIS 300

The last stage of the GSI Fast-Pulsed Synchrotron Project for FAIR (Facility for Antiproton and Ion Research) is the SIS 300 ring, which will use superconducting dipoles with 100mm aperture, 6 T magnetic field amplitude and 1 T/s field ramp rate. Stringent requirements on physical parameters and on the dependable service of the dipole necessitated using a cable with increased current carrying capability and low dynamic losses. A suitable geometry of the superconducting cable was found in that used for the outer layer of the Large Hadron Collider superconducting main dipole, supplemented by a stainless steel core for the reduction of the transverse contact resistance between the strands. The shape of the partially keystoned cable demands numerical methods for the optimization of the geometry in adaptation to the wide aperture dipole. The main characteristics of the optimized 2D and 3D geometry of the dipole are presented. Two grades of iron yoke steel were analyzed for use, in view of their resulting field quality. Thermal analysis of the dipole was carried out