Presentation Abstract

Presentation Number: 4LA-06
Title: Quench characteristics of 2212 solenoid insert coils in background fields up to 20 Tesla
Presentation Time: Thursday, Aug 05, 2010, 9:15 AM - 9:30 AM
Authors: Y. Yang1, E. A. Young1, I. Falorio1, W. O. S. Bailey1, J. Simkin2, S. P. G. Chappell3;
1University of Southampton, 2Vector Fields, Cobham Technical Services, 3Oxford Instruments.
Keyword: ++L4.2 Stability, Magnet Protection and AC Losses (HTS)
Abstract: While Bi-2212 high field insert coils have been demonstrated to be a promising technology, their cryogenic stability and quench propagation are yet to be fully understood. The present work shows data from systematic quench measurements at 4.2K on two 6-layer 300mm high Bi-2212 solenoid coils at different currents I between 50% and 95% of Ic in background fields up to 20T. The quench was induced by localised heat pulses (20-100ms) and recorded with temporal-spatial resolved voltage taps and thermometers. By precise control of the power delivered in the heat pulse, the minimum quench energy MQE and the time constant for the quasi-stationary minimum propagation zone MPZ was obtained for each test condition. MQE was found to follow a scaling law of Ic2/I4. The MPZ was shown to be confined within the same layer where the quench started. The propagation was also predominantly along the winding layer with a relatively slow velocity less than 50cm/s. The corresponding radial propagation velocity of about 5mm/s. The interplay between the HTS coils and with the LTS magnets were also studied to aid the design of 20T+ high field magnets with integrated LTS and HTS coils. The results were analysed in the context of a wide current temperature range for current sharing in the Bi-2212 wire and the T3 dependence of cp at low temperatures. The quench data is also consistently with modelling results using quench module of OPERA.