Conductor on Round Core (CORC®) cables produced by Advanced Conductor Technologies (ACT) using REBCO tapes. The company can tailor the cable dimensions and current-carrying capability to meet magnet design needs.

The HEP community has identified several opportunities for experiments that reach new physics and require advanced high-field solenoids. Prime examples include a muon collider and various axion search experiments. Significant advances in high-field solenoids over the last decade have been led by the National High Magnetic Field Laboratory, motivated primarily by the need to provide >30 T magnets for their users, culminating in the all-superconducting hybrid LTS/REBCO 32 T magnet. The 2023 P5 report, coupled with the 2024 National Academies report, motivates a strong partnership between MDP and the NHMFL to advance further high-field solenoid technology tailored to the needs of HEP. This is a new area within the USMDP, and the goal is to leverage synergies with the NHMFL and fusion applications to rapidly develop solenoid technologies tailored to HEP needs.

Berkeley Lab staff scientist Diego Arbelaez (left) discusses the first MDP hybrid CCT magnet assembly with technician Chet Spencer (middle) and graduate student Marika D’Addazio (LBNL and Turin Polytechnic)

A unique characteristic of HEP solenoids is the diversity of scale. Muon colliders need solenoids ranging from a few unique, very-large-bore, high-field solenoids for the muon production area to a kilometer-scale suite of high-field, smaller-bore solenoids for the muon-cooling section of the collide. For axion searches, a range of field strength and bore sizes are of interest, but generally the search sensitivity scales linearly with field volume and quadratically with field strength, motivating large-bore, high-field solenoids.

The unique characteristics of HEP solenoid needs, and in particular the likely use of scalable conductor architectures, motivate review and adaptation of solenoid magnet design for high-field solenoid designs characteristically needed by high-field users, e.g., in condensed matter science. Managing the large hoop, radial, and axial stresses reliably and cost-effectively, and designing magnet protection methodologies compatible with the scale of field and volume envisioned, are significant challenges that require in-depth design and analysis.