Inductive Noise Suppression in Quench Detection Circuits of ITER Central Solenoid

The ITER Central Solenoid (CS) is under fabrication by the US ITER organization and its subcontractors. US ITER will supply seven modules to ITER IO (International Organization), six of which will be assembled in a stack that forms the ITER Central Solenoid. In the ITER operational scenario the CS modules (CSM) experience very high voltages, especially during plasma initiation and plasma disruption. Also, there are a significant induced voltages in the CSM due to magnetic coupling with the PF coils and plasma current. During initiating of plasma current, the voltage on the CSM reaches up to 11 kV. We need to suppress the inductive signal to a much lower level, 60 mV or lower. Thus, the noise rejection ratio (NRR) required for a reliable quench detection (QD) is extremely high, not demonstrated on any of the superconducting magnet systems built so far. This article describes the QD principles, expectations, and test results obtained in some CSMs during testing. Preliminary analyses and methods for improvements of the NRR in QD are presented and discussed.