Stand-alone solid nitrogen cooled "permanent" high-temperature superconducting magnet system

This paper describes a stand-alone solid nitrogen cooled "permanent" high-temperature superconducting magnet system and presents its performance data. The system's cold body includes the magnet, shunted with a superconducting switch and comprised of six double pancakes, each wound with BSCCO-2223/Ag composite tape, and a volume of solid nitrogen and operates within a cyclic temperature range between 20 K and 40 K. At an operating current of 50 A the coil generates a central field of 0.5 T in a 12-mm diameter room temperature bore; the system's 2 liters of solid nitrogen is intended to give a cyclic operating period, from 20 K to 40 K, of about 70 hours. Included also in the paper is a preliminary design code that includes magnetic and thermal requirements of the system.