Acoustic emission monitoring results from a fermi dipole

Abstract Acoustic emission (AE) techniques have been used to monitor a Fermi dipole magnet during quench current experiments. The dipole data show that conductor motion is the principal source of AE and the primary cause of quenches, as is the case for most high-performance superconducting magnets. The middle of the dipole was found to be more susceptible to quenches with motion than either end. This result is consistent with the field distribution along the magnet. There is good correlation between quench current and AE history. The experimental data can be satisfactorily explained by a model relating AE energy and frictional motion. Acoustic emission was used in conjunction with voltage data to quantify the average frictional dissipation in the windings, estimated to be ≈ 10 μW cm −3 .