Progress on Tests on Splices Between Nb3Sn Rutherford Cables for Graded High-Field Accelerator Magnets

Future high-field accelerator magnets foresee the extensive use of Nb3Sn, more expensive than the Nb-Ti of LHC. For projects involving the series production of magnets, conductor grading is mandatory in order to reduce the cost. To allow grading, a splice between higher and lower grade cables must be implemented. The internal splice option, i.e., embedded in the winding pack, is the one considered in this manuscript. The magnet technology is Wind & React (W & R). The target resistance is 1 n at a background field of B & approx;10 T and ratio between operational and critical current IIc& approx;13, the one at which such Nb3Sn dipoles are expected to work. This manuscript reports progress on ultrasonically welded, soldered and diffusion-bonded splices. The feasibility studies on ultrasonic welding between Nb3Sn Rutherford cables and strands is presented. The potential corrosive effect of fluxing agents of impregnated soldered samples is examined. In the end, the design and test in SULTAN of bent diffusion-bonded splices is reported.