초록 ▼

In a "permanent" magnet system based on high-temperature superconductors, a superconducting magnet is cooled to a temperature below its critical temperature with a cooler. The magnet is coupled to a cold body of solid nitrogen which is insulated to minimize heat input to the system. The superconduct

In a "permanent" magnet system based on high-temperature superconductors, a superconducting magnet is cooled to a temperature below its critical temperature with a cooler. The magnet is coupled to a cold body of solid nitrogen which is insulated to minimize heat input to the system. The superconducting magnet is energized to generate a magnetic field and the cooler is removed. Unlike conventional superconducting magnets in which the magnet operating temperature is maintained at a fixed point, in the system of the present invention the operating temperature is allowed to rise from an initial value of approximately 20 K to as high as 63 K (the melting point of nitrogen), enabling operation over an extended period without the aid of direct cooling. The superconducting magnet is recooled periodically to lower its temperature to approximately 20 K. The magnetic field is maintained and the system is fully operable during the recooling process. For large systems, the time period between recooling cycles can exceed one year. This cryocoolerless lightweight "permanent" magnet system is particularly effective in on-board or portable applications which would benefit from the absence of a cumbersome cryocooler.

대표청구항 ▼

[ We claim:] [1.] An apparatus for generating a magnetic field comprising:a superconducting magnet in thermal contact with a cold body, the magnet operating in a persistent state at a temperature below its critical temperature T.sub.c, for generating a magnetic field;insulation surrounding the cold

[ We claim:] [1.] An apparatus for generating a magnetic field comprising:a superconducting magnet in thermal contact with a cold body, the magnet operating in a persistent state at a temperature below its critical temperature T.sub.c, for generating a magnetic field;insulation surrounding the cold body for minimizing heat input to the magnet; anda cooling device adapted to be placed in thermal contact with the cold body for cooling the magnet upon the magnet temperature rising to a first temperature T.sub.1, T.sub.1 being less than T.sub.c, the cooling device thereby cooling the magnet until the magnet temperature lowers to a second temperature T.sub.2, such that the superconducting magnet continues to generate a magnetic field over an extended period of time and over a range of temperatures between T.sub.2 and T.sub.1 before recooling is required.