Transient thermal analysis and quench detection characteristics of the ITER TF and CS coils

The toroidal field (TF) and the central solenoid (CS) coils of ITER experience a variety of transient heating loads. During normal operation, the conductor in the TF coil experiences nuclear heating, whose magnitude is a function of the plasma operating conditions. In addition, the TF coils experience minor heating due to AC losses and the friction between the support plates. The heating in the CS coil is mainly due to AC losses which is significant during plasma start-up and shut-down. Due to the pulsed operation, and because of the long length of the flow paths (/spl sim/800 meters), steady state conditions are not established during a single pulse. In order to determine the operating margins, time dependent analyses of both the TF and the CS coils are performed under various heating conditions and over many cycles. Quench detection methods based on flow measurements at the inlet and outlet of the flow paths have to distinguish between "normal" and quench related flows. Extensive analyses of the flow signals under different operating and quench conditions show that, with the proper differencing the signal due to quench can be extracted.<>