Design, Manufacture, and Tests of a 1+3 Teslas MgB₂ Dry Magnet

As part of a program that aims at developing design tools and technologies for dry MgB₂ magnets, a react-and-wind MgB₂ solenoid operating at 10 K and medium field range (1 up to 4 T) has been developed at CEA/Saclay. The prototype coil is wound from approximately 2 km of a commercial MgB₂ wire and has a winding diameter of 200 mm, external diameter of 300 mm, and height of 200 mm. It has a nominal central magnetic field of 1 T and is placed in a 3 T background field generated by a classical NbTi magnet. The MgB₂ solenoid has been epoxy impregnated and then instrumented for low-temperature testing. The tests have been successfully performed with a nominal current of 100 A, an operating temperature of 10 K, and a background field of 3 T. Current sharing measurements have been carried out to compare the coil critical current to the bare tape critical current. In this paper, the magnet design, the manufacture, and the experimental results of the cryogenic tests are presented. (authors)