Magnetic method for AC losses measurement of coil wound CICCs in pulsed regimes

摘要

AC losses measurements have been performed on a coil wound NbTi CICC magnet in pulsed regimes by the pick-up magnetic method. Owing to the complex set of mutually inducting coils and to the very high field variation rates which are needed to simulate plasma disruption conditions, the simple compensation by two concentric pick-up coils normally adopted for solenoid magnetization measurements cannot be used. In fact, appreciable eddy currents are induced in the metallic parts of the system and a huge 'empty coil effect' is observed. Thus, an extra-compensation procedure is applied by subtracting from the compensated pick-up signal the corresponding one measured in 'warm' conditions, i.e., at a temperature slightly over the superconductor T_c. Experimental evidence is presented for the effectiveness of the adopted procedure for data elaboration.