Abstract
A testing method which makes it possible to measure 10 kArms class AC quench current (Iq) and AC losses in AC magnetic field (50-60 Hz), has been investigated. A testing apparatus was developed and the specification was determined in consideration of the testing method for 10 kArms class Nb-Ti stranded cables, expected conductor size, permissible bending strain and so on. The AC superconducting magnet generating the maximum magnetic field of 1 Tpeak in the bore of 150mm and a 10 kArms class power supply were manufactured. For the Iq measurement, the AC current is directly applied to the specimen in the field of 0.5 Tpeak (50-60 Hz). As regards the AC losses measurement, the magnetization method using pick-up coils was adopted and its sensitivity has been improved by reducing unnecessary output signal. By some trial tests, it was confirmed that the apparatus using the testing method can be adopted to estimations of basic AC characteristics. Moreover, improvements of conductor structure based on measurement results brought about low AC losses 10 kArms class Nb-Ti cables and 5 kArms class Nb3Sn cables.
