Fabrication and Test of 90-mm $\hbox {Nb}_{3}\hbox {Sn}$ Quadrupole Coil Impregnated With MATRIMID—Bismaleimide Based Material

The traditional fabrication process used for Nb₃Sn accelerator magnets involves reaction of the coils at high temperature and impregnation with epoxy to restore the electrical and mechanical properties of the insulation. The traditional epoxy offers adequate structural and electrical properties, but has low radiation strength, limiting the lifetime of magnets operating in severe radiation environments. This paper presents the results of a study in which the traditional epoxy was replaced with Matrimid 5292 as a coil impregnation material. Test stacks of cable were fabricated and impregnated with epoxy and Matrimid. Electrical, structural and thermal properties were measured and compared. A 90-mm-bore, 1-meter-long Nb₃Sn quadrupole coil made of RRP 54/61 strand was fabricated, reacted, impregnated with Matrimid, and tested in a single coil test structure (quadrupole magnetic mirror). Test results are compared with the results for similar coils impregnated with epoxy.