AE spectra during super-to-normal transition in a superconducting rotor

Abstract We discovered new quantitative relations regarding AE spectra and super-to-normal transition in a rotating superconducting machine. Hence, we have reported mainly qualitative evaluation of AE from the rotating superconducting machine, such as AE and super-to-normal transition, AE and normal propagation, AE and quench magnitude, AE versus heat and changes in magnetic flux, and a prediction of the area to a certain point [H. Nomura et al. Ultrasonics 34 (1996) 307–309]. By repeating the experiments, interesting quantitative relations were found in the AE spectrum's main frequency which shifts, according to changes in the magnetic field, the rotational speed and the transport current. Furthermore, these shifts can be explained using simple arithmetic. These discoveries will be useful for both evaluating and monitoring the superconducting rotor.