High-field warm-bore HTS conduction cooled magnet

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