New approach to stability of superconducting magnet related with ramp-rate limitation

Abstract

This thesis describes stability related with RRL (Ramp-Rate Limitation) in CICC (Cable-In-Conduit Conductor) superconducting magnets. To precisely investigate the basic process of RRL, numerical analysis and RRL experiment are performed for a simple sample conductor, which consists of an insulated two-strand cable. Moreover, the simplified current diffusion model and the advanced transient heat transfer model are suggested to explain RRL behavior of practical CICC magnets. The analysis results are verified with the previous experimental results of other investigations. A parametric study is also carried out with the modified analysis model to investigate the effects of the operation and strand parameters. Summarizing the numerical analysis, the stability evaluation method is suggested, which can give a design criterion and guarantee the stable operation regime of superconducting magnets related with RRL. The new evaluation method, which is called ‘RRL quench recovery map’, is applied to the previous experimental results and this map shows that it can be used as a design criterion for practical superconducting magnets.