Speaker
Description
Eliminating quench training in superconducting accelerator magnets requires understanding the underlying mechanical transients, which include cracking of the impregnation material, interfacial debonding between the impregnation material and conductor, and slip-stick conductor motion; these events can release heat and lead to premature quenching and training. Earlier, we developed a system consisting of a cryogenic probe and tensile tester in order to apply mechanical stress to samples of copper wire embedded in commonly used impregnation materials [1]. The samples were monitored by a shear-piezo transducer and miniature temperature sensor to record acoustic emissions (AE) and local temperature variations. We have now also integrated a capacitive displacement sensor and pulsed spot heater to more accurately measure the sample displacement and thermally calibrate the system. We have tested a range of impregnation materials and reported the AE and temperature change of each to assess each material’s suitability for high-field magnet fabrication. A finite element thermomechanical model was developed to estimate the heat released during transient mechanical events based on the observed rise in temperature. We have calculated material-specific ratios of released AE energy to thermal energy to inform future AE-based diagnostics for different event types.
