JPS6425065A - Sensor - Google Patents

Abstract

PURPOSE:To make it possible to provide a sensor characterized by low energy loss, by providing a substrate comprising a superconductive material and a member comprising a normal conductive material having the different thermal expansion coefficient. CONSTITUTION:A member 2 comprising a normal conductive material is mounted on the surface of a substrate 1 comprising a superconductive material, and a sensor 3 is constituted. When the substrate 1 is in the superconductive state, the resistivity of the substrate 1 is low and a current does not flow through the member 2. When the substrate 1 is changed into the normal conductive state from the superconductive state, the substrate 1 has a finite resistance value. A current begins to flow through the member 2, which is provided on the surface of the substrate. The substrate 1 and the member 2 start thermal expansion owing to Joule heat yielded at this time. Since the thermal expansion coefficient of the member 2 is different from that of the substrate 1, shearing force is yielded in the direction of the thickness of the substrate 1. Since the substrate 1 is brittle and cannot withstand the shearing force, the substrate is broken. The current path is cut, and the generation of an excessive current and the like can be detected. When the current flowing through the substrate 1 is within a rated value, the substrate 1 is in the superconductive state. Since the resistance value is small, energy loss due to Joule heat becomes very few.