Novel Methods for Measuring the Inductance of Superconducting Coils and Material Resistivity

Abstract

With the in-depth study of the interaction behavior between a magnet and a superconducting coil, we have developed a new method to determine the inductance of a superconducting coil. With the same apparatus, the resistivity of a normal conductor can also be evaluated. The principle of the new methods is based on the measurement of proper physical quantities during the interaction between a permanent magnet and a superconducting coil or between a permanent magnet and a normal conducting ring. Unlike conventional inductance and resistance measurement, the proposed methods do not require any power supply or voltmeter. We use a simple force measuring apparatus to perform the measurements. The resistivity of the sample is obtained by comparison with a pure copper sample of the same geometry and dimensions. In the case of a superconducting coil, its inductance can be obtained from the measured interacting force and induced current curves as it interacts with a permanent magnet. This article introduces the principle, the procedure, and validity of the proposed methods. The uncertainties of the proposed methods are discussed and compared with the existing methods of measuring inductance and resistivity. These methods may serve as alternatives in measuring the inductance of a superconducting coil or in measuring the resistivity of a normal conductor, especially when the conditions of the conventional methods for such measurements cannot be satisfied.