Training Curves of Nb₃Sn Rutherford Cables With a Wide Range of Impregnation Materials Measured in the BOX Facility

Abstract

Training of accelerator magnets is a costly and time consuming process. The number of training quenches must therefore be reduced to a minimum. We investigate training of impregnated Nb3Sn Rutherford cable in a small-scale experiment named BOX (BOnding Experiment). The test involves a Rutherford cable impregnated in a meandering channel simulating the environment of a canted-cosine-theta (CCT) coil. The sample is powered using a transformer and the Lorentz force is generated by an externally applied magnetic field. The low material and helium consumption enable the test of a larger number of samples. In this article, we present training of samples impregnated with alumina-filled epoxy resins, a modified resin with paraffin-like mechanical properties, and a new tough resin in development at ETH Zürich. These new data are compared with previous results published earlier. Compared to samples with unfilled epoxy resin, those with alumina-filled epoxy show favorable training properties with higher initial quench currents and fewer training quenches before reaching 80% of the critical current.

Training-free performance of the wax-impregnated SuShi septum magnet

“…Although a 2.4-Tesla non-impregnated NbTi CCT magnet performed well without impregnation [31], conductor-ingroove type magnets (such as CCTs) are typically impregnated. Non-impregnated Nb 3 Sn samples showed a significantly reduced performance with respect to impregnated samples [32]. As illustrated above with the example of the LHC dipoles, some other magnet types do not require impregnation but other technologies.…”