Operation limits of the EURATOM LCT coil at He II temperature

摘要

Within the framework of the IEA 'Large Coil Task' (LCT), on behalf of the European Union the Forschungszentrum Karlsruhe (FZK) constructed a D-shaped toroidal field coil using a forced flow cooled NbTi conductor. The excellent performance and additional mechanical support structure promised to achieve the outermost boundary operation limit for a large forced flow cooled magnet (20 kA at about 11 T). The TOSKA facility was modified for operation of forced flow He II. After a cool down time of about 290 h, the coil was operated at 3.6 K first to compare the results with those obtained in ISMTF at ORNL. The coil showed a spontaneous quench of the high field pancake at 16.4 kA in full agreement with the critical current data measured at short sample strands. After cooldown to 1.8 K, the coil was ramped up with its current sharing region clearly visible on the resistive voltage. The quench started in the high field pancake as expected, the inlet temperature was 1.89 K, the current 19.45 kA, corresponding to a maximum magnetic field of 10.77 T. Comparison with single strand data extrapolated from 4.2 K measurements showed no degradation. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 9]