Recently, the development of Nb3Al conductors has progressed rapidly with the aim apply them to fusion magnets. In general, the critical current density of Nb3Al is insensitive to strain (or stress) in comparison with that of Nb3Sn. This property is useful in the construction of high-field and large magnets; particularly, fusion magnets. The Nb3Al strands are copper-stabilized multifilamentary composites produced using a jelly-roll process. In this paper, the status of Nb3Al conductor development and the characteristics of the Nb3Al conductor are reported.
This paper presents a numerical analysis of quench propagation in an immersion-cooled, pancake-type superconducting coil. The influences of thermal and electromagnetic conditions on quench propagation are clarified for various values of the thickness of electric-insulation films and transport current. The numerical results presented are in good agreement with the optical observation of quench propagation, therefore proving the validity of this analysis.
This paper presents an experimental study of numerical analysis results for an immersion-cooled, pancake-type superconducting test coil. A thermal disturbance was applied to the test coil by the pulse-heating of film heaters wound in it. The experimental results were compared with calculated results regarding stability limit and quench propagation under various transport currents, durations and positions of thermal disturbance. The experimental values agreed well with the calculated results, thus confirming the reliability of the numerical analysis method.