Conduction Cooled High Temperature Superconducting Dipole Magnet for Accelerator Applications

A 3T proof-of-principle dipole magnet for accelerator applications, based on 2nd generation high temperature superconducting tape was designed, built, and tested by a consortium under the lead of Danfysik. The magnet was designed to have a straight, circular bore with a good field region of radius r = 25 mm, and a magnetic length of 250 mm. A total length of 2.5 km YBCO-based copper stabilized conductor supplied by SuperPower Inc., NY, USA, was isolated with 0.025 mm of epoxy and subsequently wound into 14 saddle coils and 4 racetrack coils with a cosine theta like configuration. The coils were impregnated with epoxy and mounted between a support of stainless steel and a collar made from aluminum. The cold mass consisting of the coil assembly and a laminated steel yoke is cooled by two cryocoolers from via copper bars to below 20 K. Current leads were made from the same batch of HTS tape. Cryogen-liquid free operation of an HTS accelerator magnet was demonstrated. The cold mass support design permits magnet orientation under arbitrary angles. Careful choice of materials in terms of magnetic, heat conducting and mechanical properties resulted in a robust and compact solution which opens up for accelerator applications in many fields, in particular where cryogenic liquid cooling is not an option.