Design of a 12 K Superconducting Magnet System, Cooled Via Thermal Conduction by Cryocoolers

The operation of superconducting magnets is usually involved with the handling of cryogenic liquids and the associated aspects of availability and safety. In order to improve this a magnet system is developed which is cooled by small cryocoolers in the absence of liquids. The dry magnet having Nb3Sn windings is mounted in a vacuum vessel with only one intermediate thermal shield. Three small model coils were fabricated, one made with the react and wind technique, the other two were first wound and then reacted. case specific conduction cooled leads were designed and tested. Also a dummy coil at full scale was cooled down to 11 K for which the shield temperature had values between 41 K and 46 K.