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Title: Quench propagation in conduction cooled HTS pancake coils
Author: Johnstone, Adam Paul
ISNI:       0000 0001 3591 6690
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2005
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The formation and propagation of normal zones in a conduction cooled (BiPb)2223 Ag alloy sheathed pancake coil has been investigated both experimentally and through simulation. To provide stable operating conditions for the coils a conduction cooling system, incorporating a single stage cryocooler, and current leads were designed and manufactured. The apparatus was tested up to a maximum operating current of 300A at which only a 0.7K drift in the coldhead temperature was observed. A minimum operating temperature at the coil boundaries of 35K was achieved. Highly instrumented pancake coils were wound with a (BiPb)2223 tape conductor. The current-voltage characteristics were measured and the response to a steady overcurrent observed. The quench energy was measured as a function of operating temperature by applying transient disturbances of varying sizes to the coil. A similar dependence of the quench energy on operating temperature was obtained from a simplified finite element model. A method of determining the temperature profile of a minimum propagating zone was proposed. The size and shape of the MPZ was measured as a function of operating temperature. It was observed that the shape of the temperature profiles was significantly affected by the operating temperature. The normal zone propagation velocity was determined as a function of operating temperature by examining the propagating temperature profiles. The results obtained will be of use to the magnet designer when determining the stability of coils at various operating temperature and when designing protection systems for HTS magnets.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available