Experiment and Numerical Simulation on Quench Characteristics of ReBCO-Impregnated Coil

Abstract

The SuperKEKB project underway at KEK will increase the KEKB luminosity by 40 times using nanobeam interaction-region focusing optics. The chromaticity correction of the collision beams is crucial to achieve the high luminosity. Sixteen special sextupole magnets, which can simultaneously produce normal and skew sextupole fields, are required in the 100-m-long straight sections around the interaction point for the chromaticity correction. As a candidate for the sextupoles, a cryocooled high-temperature superconducting (HTS) magnet was proposed and the development has started. In HTS magnets, quench protection is a major concern. Especially for accelerator magnets, reliable quench detection and protection systems are essential. In this study, we have performed heat-induced quench tests and numerical simulations on the ReBCO-impregnated double pancake coils at operating temperatures of 30, 40, and 50 K. Two test coils with different thickness of the copper stabilizer were prepared for the tests to compare the quench characteristics. The hot spot temperature was discussed with the operating conditions and quench detection criteria. The copper stabilizer thickness of the sextupole ReBCO coils was designed by using the validated numerical model.