Presentation Abstract

Presentation Number: 2LX-05
Title: A 22T compact superconducting magnet system at 4.2K with integrated Bi-2212 solenoid insert coils
Presentation Time: Tuesday, Aug 03, 2010, 2:45 PM - 3:00 PM
Authors: S. P. G. Chappell1, Z. Melhem1, C. Friend1, A. Twin1, Y. B. Huang1, H. P. Miao1, E. A. Young2, Y. Yang2;
1Oxford Instruments, 2University of Southampton.
Keyword: ++L1.1 Very High Magnetic Field Magnets (LTS and/or HTS)
Abstract: We have previously demonstrated fields of 22.5T at 4.2K using a 100mm high, 14 layer wind-and-react Bi2212 HTS insert solenoid operating in a wide-bore LTS magnet background field of 20T. As a significant step towards realization of commercial high field magnets we now report on development of a compact superconducting magnet system with improved Bi2212 insert coils and focus on high field quench stability and system integration.
For optimal heat treatment, mechanical support and protection flexibility, two 6-layer concentric 300mm long Bi2212 HTS solenoids were combined and integrated into a 20T LTS system. Systematic tests were performed at different LTS fields (15, 18, 20T) and HTS currents up to 50-90% Ic. Repeated controlled quenches of the HTS coils were induced by localised heat pulses and the interplay of HTS and LTS systems was studied.
The HTS coils were demonstrated to be safely protected by a shunt system despite slow propagation of the normal zone. Upon these forced quenches of the HTS coils, the LTS coils withstood rapid field change (up to 2T/s) without developing a single quench event. A protection-control procedure was tested successfully to prevent the quench of the LTS system at a higher field change rate (>10T/s). It was also found that the quench of HTS coil induced by the quench of the LTS system could be safely managed with the shunt protection.