Quench Characteristics of a Superconducting Compensation Solenoid for SuperKEKB

The construction of a final focusing superconducting magnet system for SuperKEKB has been completed. The superconducting magnet system consists of eight quadrupole magnets, four superconducting compensation solenoids, and 43 corrector coils. These magnets are installed in two cryostats, QCS-L and QCS-R. The QCS-L and QCS-R are inserted into the particle detector, Belle-II, which has a superconducting solenoid of 1.5 T. In order to eliminate the influence of the Belle-II solenoid field on the collision beam and to achieve the required high luminosity, four superconducting compensation solenoids are excited to produce a magnetic field in the opposite direction of the Belle-II solenoid field. One of the longest superconducting compensation solenoids, named ESR1, is installed in QCS-R. The ESR1 consists of 15 coils. The coil design and excitation test of the ESR1 are presented in this paper. The experimental and analysis results of the quench characteristic are also discussed.