Design, manufacturing and testing of a high-field 2 + 3 T MgB2 dry magnet demonstrator

This paper presents the design, manufacturing and testing result of a 2 + 3 T high field MgB $_2$ conduction-cooled solenoid magnet demonstrator. The prototype almost reached 2 T at 10 K inside a homogeneous background field of 3 T produced by a NbTimagnet. The demonstrator was wound with 1.6 km of Columbus ex-situ React and Wind (R&W) conductor. The mechanical design of the prototype is presented including the homogenization of the mechanical properties of the composite conductor. The Von Mises equivalent strain calculated after both cooling and energizing conditions is below the conductor strain criteria of 0.4%. In order to obtain the required magnetic field, three length of wires were linked together by two resistive junctions of approximately 150 n $\Omega$ each. The heat generated by the junctions was extracted by several heat sink apparatus. The different apparatus designed for the thermalization of both the junctions and the magnet are presented. Prior to the testing of the demonstrator, the conductor used for the prototype was tested. The results of these tests are compared to the current measurement of the demonstrator and no current degradation of the conductor wound is evidenced, proving the good handling of the wire during all the manufacturing steps and testing phase.