High-field warm-bore HTS conduction cooled magnet

A 7.25 T laboratory magnet utilizing Bi 2223 conductor has been designed, built, and installed at the Naval Research Laboratory. Operating at 21 K at full field, the coil provides field homogeneity of /spl plusmn/1% in a 2-inch warm-bore. The system is conduction cooled with a pair of Leybold single stage cryocoolers that allow cooldown in less than 36 hours and allow extended fast ramp operation. Operation at a total refrigerator input power of 6 kW is facilitated by the use of ASC Cryosaver/sup TM/ HTS current leads. The fully integrated system consists of the magnet, cryogenic system, control and protection system and power supply. This paper presents information on the magnet design, construction and subsequent testing.