Speaker
Description
Nb$_3$Sn magnet conductors will continue to be the workhorse material for accelerator magnets over the coming decade because they can deliver significantly higher magnetic fields than Nb-Ti at significantly lower cost than higher performance HTS conductors. While R&D enhancements for advanced Nb$_3$Sn could improve performance by 30% or more in the 15-16 T field range envisioned for future dipoles, pushing the limits of the present restacked rod process (RRP®) conductors provides a competitive baseline to emulate. Developments in cabled REBCO tape HTS conductors and Bi-2212 round-wire strand are creating opportunities for hybrid Nb$_3$Sn-HTS dipole magnets approaching 20 T and solenoid magnets pushing toward 50 T. Bi-2212 conductors must confront a still nascent supply chain with small production batches and high cost due to factors not related to materials or production, where help will come from efforts to commercialize new ultra-high field laboratory magnets. REBCO cables are under study from multiple agendas, but testing activities at NHMFL and elsewhere reveal that run-to-run and along-run property variations are still rather wide. Conductors are not yet interchangeable across manufacturers for cables in the accelerator sector and for winding solenoids. The present billion-dollar investment in REBCO-based fusion could spur a new era of helium-free magnet development, creating potential challenges for the accelerator sector to find synergy between helium and helium-free technology development ecosystems. Actions are proposed to extend the benefits of private investments to the accelerator sector.
