High field CORC solenoids

Hybrid solenoid magnets that would generate a magnetic field of 40 T by combining a low- temperature superconducting (LTS) outsert with a high-temperature superconducting (HTS) insert are required for the future muon collider. No proven magnet technology exists for developing the low-inductance HTS inserts needed for practical and reliable magnet operation. The proposed program aims to develop low-inductance, 40 T solenoids by combining series- connected, high-current coils wound from HTS Conductor on Round Core (CORC®) cables that may be operated in a hybrid configuration within an LTS outsert thatĺs powered separately from the HTS insert. Stand-alone HTS CORC® solenoids, in which the LTS outsert is replaced by a CORC® coil, allowing operation at 20 K without need for liquid helium, will also be designed. During Phase I, we will perform the initial design of CORC® insert solenoid, based on the 320 mm bore of the 12 T LTS outsert magnets. The CORC® insert will most likely contain 3 different coils, connected in series. Each coil requires a different level of bending flexibility of the CORC® conductor, while also exposing it to magnetic fields of different magnitudes. Different approaches to connect the CORC® coils in series will be explored. Subscale prototypes of each of the three coils will be manufactured. The outer coil of the insert will contain a CORC® cable with two insulated, or metal-insulated current paths that will be connected in series. Its performance will be measured at different current ramp rates and during a heater-induced quench to understand the operational benefits, but also potential limitations of this approach. The middle coil will be wound from a single CORC® cable and will be connected in series to the inner coil in which three CORC® wires are wound in parallel. The initial design of an HTS-only CORC® solenoid that would generate 40 T at 4 K and 20 ľ 30 T at 20 K will be performed at the end of the Phase I program. High-current, low-inductance HTS insert solenoids will enable the next generation of high-energy physics magnets operating at 40 T, magnets for scientific research and compact fusion magnets for power generation. These magnets will also benefit superconducting magnetic energy storage systems for use in the power grid and within the Department of Defense.