A superconducting magnetic energy storage device that can maintain a large ratio of the stored energy to the static energy loss, and has the ability to by-pass the current through a fast, high-voltage superconducting switch. More particularly, this invention relates to the design and application of novel high-voltage superconducting switch provided with a direct heating of the active superconducting layer through a metal substrate either by transport or by inductive current, and the protection of the superconducting layer by cryogenically-cooled metal-oxide-semiconductor field-effect transistors.
STATEMENT OF GOVERNMENT LICENSE RIGHTS
 The present invention was made was made with Government support under contract number DE-ACO2-98CH10886 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.