Conceptual Design of Quench Detection System for the CS HTS Magnets

The maximum magnetic field designed for the Central Solenoid (CS) of China's next-generation fusion reactor is more than 19 T, for which hybrid magnets of High Temperature Superconductivity (HTS) and Low Temperature Superconductivity (LTS) have been used for the CS. The CS HTS magnets quench detection system has been almost completed and will be described in this paper. The simulation results show that the maximum induced voltage during HTS magnets operation is greater than one kilovolt. The small quench resistance voltage has to be distinguished from the high induced voltage. We plan to use a two-stage induced voltage suppression system to detect the quench of the HTS magnets. The primary induced voltage suppression system uses Co-wound Wire (CWW), Co-wound Tape (CWT), and Balance bridge to suppress the induced voltage within ± 30 V, and the secondary induced voltage suppression system uses Inductive Noise Real-time Calculation (MIK) to suppress the induced voltage below 1 mV. The quench detection system design of the CS HTS magnets has been validated by simulation of the Normal Scenario (NS) and the Vertical Displacement Event (VDE). It has been proven to satisfy the design requirements. The new quench detection method of distributed optical fiber will be applied appropriately according to our following development on it as a backup detection method. The detection system we designed will be steadily upgraded according to the planned HTS quench detection experiments.