Abstract: A superconducting switching device having no moving components for reversing current flow through a load. This load typically is a superconducting magnet and, in this application, the present invention also selectively serves as a persistent switch. The invention includes a pair of switching units connected between the load (magnet) and a current source. These switching units each have a pair of superconductor members and a mechanism for selectively producing in the switching units either a substantial electrical resistance or no resistance. Through the use of a control logic, the level of resistance of the switching units can be changed to effect the direction of current flow. In the case of the superconductor magnet, both switch units can be simultaneously made to have substantially zero resistance, and their interconnection forms the persistent switch for the superconducting magnet.

Abstract: A low current superconducting magnet, and a method of fabrication, having improved protection against quench damage. The magnet utilizes the technique of forming a twisted cable of a plurality of substantially parallel superconductor wires and then winding this cable in turns to form the desired magnet configuration. A curable potting material such as an epoxy is applied during winding so as to substantially fill all interstices between the wires. After winding the ends of the wires are connected so as to put each wire in a series array. The intermixing of the wires throughout the magnet winding, together with the heat transfer characteristics of the potting material, provides for many parallel paths for heat conduction to a cryogenic fluid to reduce potential thermal damage. Furthermore, a voltage limiting device, such as a diode pair, is connected across the adjacent ends of each wire.

Abstract: An automatic current lead retraction system for superconducting magnet installations. An automatic current lead retraction system utilizes an operator wherein either hydraulic or pneumatic cylinders bring about electrical contact of the current leads or the separation thereof as well as a safety shorting switch for the system. By using the pneumatic or hydraulic cylinders and all non-magnetic materials, there is no influence upon the magnetic field created by the superconducting magnet. Provision is made to monitor the condition of the magnet to be certain that it is in a persistent mode before the current leads are retracted. Furthermore, safety signals are generated to assure that no current is flowing at the time of retraction, that the resistance across the contacts is sufficiently low when engaged and that all electrical, air/hydraulic fluid systems are functioning properly before operation of the retracting system. Overall control is achieved using a microprocessor.