Quench Detection Design for CFETR CSMC

The Central Solenoid Model Coils (CSMC) project (2014 to 2018), a part of the National Magnetic Confinement Fusion Science Program, is being developed by China independently under one of the largest research and development activities of the China Fusion Engineering Test Reactor (CFETR), demonstrating and validating the engineering design criteria of the CFETR central solenoid (CS) coil. The expected achievement is to charge the coil up to the operation current of 47.3 kA and the maximum magnetic field to 12 T with a swift rump rate of 1.5 T/s without quench. The quench detection shall be fast enough to dump out the magnetic energy and avoid irreversible damage to the systems. It is expected to provide the validation of design and analysis tools and the demonstration of quench analysis methods in the quench detection of the CFETR CS and the poloidal field (PF) magnet system.

Quench detection by voltage measurements is likely to be the fastest available technical solution, but the voltage detection is a real challenge due to large noise induced by the power supply in alternating current operation. Specific solutions have been proposed for the voltage compensation to effectively reduce the large inductive components from the measured voltage to a certain level. In 2016, the conception design was completed and adopted after the domestic and foreign experts review. This technical note gives an overall view of the quench detection design applied to the CSMC and its numerical results developed, including the classical hot-spot criterion, the quench propagation study, the quench detection parameter settings using the commercial code Supermagnet, and the estimation of the inductive disturbances.