Acoustic emission induced from alternating current superconducting coils resulting from vibration of windings

Acoustic emission (AE) induced from alternating current (ac) superconductin g coils was studied in terms of the vibration of the superconducting windin gs caused by the interaction between self-magnetic fields and operating cur rents. The AE signals were analyzed regarding two types of epoxy-impregnate d NbTi coils having different tension at their winding ends. The AE pulses from vibrations appear at the time of zero-crossings of the operating curre nts as well as at the time of peaks of the currents, where the former AE si gnals resulted from the electromagnetic farce in the axial direction combin ed with that in the radial direction. The waveforms of AE envelopes that de pended on the tension and the amplitude of operating current were also desc ribed. Those data are considered to contribute to understanding of AE signa ls, for example, for detecting vibration that suddenly appears during opera tion or for discriminating between the vibration-induced AE components and other components.