Abstract: An object of the present invention is to provide a method for protecting a superconducting coil, which method prevents damage to the superconducting coil caused by a quench or the like, in a new way, without using a voltage (a change in voltage) generated in the superconducting coil. Provided is the method for protecting a superconducting coil made by winding tape-like superconducting wire having a superconducting layer. Power from a power supply is shut off based on the magnitude of a screening field, which is a difference between a measured magnetic field B in a direction of a thickness of the superconducting wire at a predetermined position, and a magnetic field Bcal in the direction of the thickness of the superconducting wire calculated disregarding an effect of screening current.

Abstract: An object of the present invention is to provide a method for protecting a superconducting coil, which method prevents damage to the superconducting coil caused by a quench or the like, in a new way, without using a voltage (a change in voltage) generated in the superconducting coil. Provided is the method for protecting a superconducting coil made by winding tape-like superconducting wire having a superconducting layer. Power from a power supply is shut off based on the magnitude of a screening field, which is a difference between a measured magnetic field B in a direction of a thickness of the superconducting wire at a predetermined position, and a magnetic field Bcal in the direction of the thickness of the superconducting wire calculated disregarding an effect of screening current.

Abstract: A superconductive element containing Nb3Sn, in particular a multifilament wire, comprising at least one superconductive filament (8) which is obtained by a solid state diffusion reaction from a preliminary filament structure (1), said preliminary filament structure (1) containing an elongated hollow pipe (2) having an inner surface (3) and an outer surface (4), wherein said hollow pipe (2) consists of Nb or an Nb alloy, in particular NbTa, wherein the outer surface (4) is in close contact with a surrounding bronze matrix (5) containing Cu and Sn, and wherein the inner surface (3) is in close contact with an inner bronze matrix (5) also containing Cu and Sn, is characterized in that the inner bronze matrix (5) of the preliminary filament structure (1) encloses in its central region an elongated core (6) consisting of a metallic material, said metallic material having at room temperature (=RT) a thermal expansion coefficient ?core<17*10?6K?1, preferably ?core?8*10?6 K?1, said metallic material having at RT a