Speaker
Description
Nb3Sn accelerator magnets are poised to play a key role at improving the luminosity of the Large Hadron Collider (LHC) at CERN by a factor of 5-10, significantly improving its potential for exploring physics beyond the standard model of particle physics. Nb3Sn porotype magnets, based on cosine-theta design, consistently need 10-25 quenches to achieve their best performance whereas a new canted-cosine-theta design being explored at our group demonstrates a longer training but fundamentally a similar behavior. The training of Nb3Sn magnets is a critical issue to solve for future high energy proton-proton colliders that need thousands of such magnets. Fundamental to this issue is the epoxy impregnated superconducting winding technology for which helium doesn’t penetrate into the winding and only provides cooling at surfaces, and superconductors are vulnerable to quenches trigged by heat associated with failures of epoxy and insulation fibers and at their interfaces with metals. In 2018, we showed that several epoxies have a higher toughness and less tendency to crack at low temperatures than CTD-101K, the epoxy resin using which nearly all Nb3Sn accelerator magnets have been impregnated. Here we continue to explore the questions of to what degree quenching training is contributed by the failure of epoxy and their interfaces with other components (wedges and mandrels) of the superconducting coil winding, and how advanced epoxies (high toughness, high thermoconductivity, high specific heat, or epoxy with improved bonding with metal interfaces) can play a role in reducing quench training of Nb3Sn accelerator magnets, through a combination of magnet inspections and analysis, multiphysics modeling, and comprehensive materials testing that includes tensile, compressive, shear tests, and shear/compression tests with advanced instrumentations.
The work is supported by the U.S. Department of Energy (DOE), Office of Science, Office of High Energy Physics under the framework of the US Magnet Development Program. The NHMFL is funded by the National Science Foundation (Award No. DMR-1157490), the US DOE (Award No. 227011-520-032288), and by the State of Florida.
