New Magnet Technology for High-Field Collider Dipoles and Uber-Toroids for Detectors

• Peter McIntyre [p-mcintyre@tamu.edu] (Texas A & M University)

The Accelerator Research Lab at Texas A&M is developing several technologies of potential benefit for developing high-field collider dipoles. An 18 T series-connected hybrid dipole is being developed, in which the insert winding utilizes a conformal winding of tape-stack REBCO cable and the outsert utilizes a Nb3Sn structured cable-in-conduit. The dipole is designed so that the 20 kA sub-windings can be fabricated separately and then assembled onto the core and preloaded. The tape-stack REBCO cable achieves optimized current-sharing among the tapes of each cable, stress management at the cable level, small bending radius for flared ends. The conformal winding orients the REBCO cable so that it is everywhere parallel to the local magnetic field, providing twice the operating current/tape compared with other designs and natural suppression of persistent-current multipoles and AC losses. The SuperCIC cable provides full transposition, stress management at the cable level, small bending radius for flared ends, and direct contact of liquid helium with all wires for stabilization against microquenches. In a separate development, a Blocks-in-Conduit cable provides benefits for use in the immense windings required for an Uber-Toroid for a collider detector. Four square blocks of REBCO tape-stack cable are cabled with twist pitch around a perforated hollow core in a stack of copper forming washers to make a round cable capable of ~20 kA at 20 T. The cable is then co-wound with a 2-piece armor core directly onto the desired winding geometry. This approach yields full transposition and stress management at the cable level, and compatibility with winding adaptively for the windings of a solenoid or toroid.