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 ex perience a variety of transient heating loads. During normal operation , the conductor in the TF coil experiences nuclear heating, whose magn itude is a function of the plasma operating conditions. In addition, t he 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 f low paths (similar to 800 meters), steady state conditions are not est ablished during a single pulse. In order to determine the operating ma rgins, time dependent analyses of both the TF and the CS coils are per formed under various heating conditions and over many cycles. Quench d etection methods based on flow measurements at the inlet and outlet of the flow paths have to distinguish between ''normal'' and quench rela ted flows. Extensive analyses of the flow signals under different oper ating and quench conditions show that, with the proper differencing th e signal due to quench can be extracted.