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

Abstract

In this paper, the magnetic heating effect of the superconducting quarter-wave resonator (QWR) cavities is investigated, and the Q slopes of the superconducting cavities are measured with an increasing accelerating field. Bardeen–Cooper–Schrieffer (BCS) resistance is calculated for the zero-temperature limit. The vertical test is shown for the performance test of the QWR cavities. The parameters for the 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 degrade the quality factor. From the magnetic degradation, we determine the magnetic moments of the superconducting cavities. All quarter-wave resonator (QWR) cryomodules are installed in the tunnel, and beam commissioning is performed successfully.