Quench detection using pick-up coils for the ITER Central Solenoid

Takahashi, Yoshikazu; Yoshida, Kiyoshi; Mitchell, N.*

The quench detection is important and necessary for the coil protection. The voltage tape method and the flow meter method are both considered for the ITER Central Solenoid (CS). The voltage tap method is primary due to its quick response. The CS consists of six pancake wound modules, which are operated with individual operating current patterns in ac mode. The induced voltage in the windings must be compensated to detect the voltage due to any normal transition during pulse operation. We have investigated the optimum configuration for pick-up coils (PC) for compensation. The results of simulations show that the compensated voltages are very low (70 mV) compared with the inductive voltage and adequate normal voltage sensitivity is obtained. The hot spot temperature in the CS during the operation was estimated from the simulation and the experimental data of the CSMC quench. The hot spot temperature estimated is about 144 K, lower than the ITER design criterion (150 K). It is shown that the detection system using the PCs could be designed with a high enough detection sensitivity.