Magnetic Heating Effect for Quarter-Wave Resonator (QWR) Superconducting Cavities

Abstract

The magnetic heating effect for the superconducting quarter-wave resonator (QWR) cavities is investigated, and the Q slopes of the superconducting cavities are measured with an increasing accelerating field. Physical phenomena for zero-temperature limit are introduced. Bardeen–Cooper–Schrieffer (BCS) resistance and Casimir force are calculated for the zero-temperature limit. The vertical test is shown for the performance test of the quarter-wave resonator (QWR) cavities. The parameters for the quarter-wave resonator (QWR) cavity are presented. The Q slopes are measured as a function of an accelerating electric field at 4.2 K. The surface resistance of the superconducting cavity increases with an increasing peak magnetic field. The magnetic defects cause the degradation for the quality factor. From the magnetic degradation, we can find the magnetic moments of the superconducting cavities. All the quarter-wave resonator (QWR) cryomodules are installed in the tunnel, and beam commissioning is performed successfully.