Evaluation of the Bindings between the Superconductor and Matrix by Ultrasonic Spectrum of AE when S-N Transition

摘要

In the practical use of superconducting magnet, combination of the superconductor and high conductive normal metal is now indispensable. And this binding property is one of the key points whether superconductive characteristics is fully attained or its current is failed prematurely in the practical magnet.. But these binding evaluations are not so easy, because even in the mechanically well-jointed conductor, it often appears poor in electric and magnetic joint in cryogenic temperature. Here we report new technique for evaluating these bindings by observing ultrasonic spectra when a normal transition is propagated along the superconductor. We have discovered a fact that good contacting conductor has an emission of this sound with sharp resonating frequency peak or peaks at around highest spectrum area; from 0.5 to 1.0MHz.