Quench Tests and FEM Analysis of ${\rm Nb}_{3}{\rm Al}$ Rutherford Cables and Small Racetrack Magnets

In collaboration between NIMS and Fermilab, we have made copper stabilized Nb₃Al Rutherford cables, using Nb-matrixed and Ta-matrixed strands. First these cables were investigated at high current in low self field using a flux pump. Using these Rutherford cables, we built and tested small racetrack magnets. The magnet made with the Nb-matrixed strand showed the flux jump instability in low field. The small racetrack magnet wound with the Ta-matrixed Nb₃Al Rutherford cable was very stable at 4.5 K operation without any instability, as well as at 2.2 K operation. With the successful operation of the small racetrack magnet up to its short sample data, the feasibility of the Nb₃Al strand and its Rutherford cable for their application to high field magnets is established. The characteristics of Nb₃Al Rutherford cable is compared with that of the Nb₃Sn Rutherford cable and the advantages of Nb₃Al Rutherford cable are discussed.