Abstract: An inductor device having a superconducting coil winding capable of maintaining a relatively large current flowing therethrough, and a normal conducting shield winding surrounding the superconducting coil. The superconducting coil and the shield are electrically connected in parallel with the shield functioning to maintain the current and the magnetic field in the superconducting coil substantially constant. The superconducting inductor device can be used to store energy and to return the stored energy to an energy consuming load over a relatively short period without incurring large losses in the superconducting material. This result is obtained by making the self inductance of the shield substantially equal to the mutual inductance between the shield and the superconducting coil, or by inserting a controlled compensating voltage source in series with the shield, so that pulse currents are conducted by the shield.