REBCO Magnet Technology

High-temperature superconducting tape is what lets the burner reach a 26.49 T plug field — impossible for the low-temperature superconductors used before.

The enabling conductor

REBCO — rare-earth barium copper oxide — is a high-temperature superconductor made as a coated tape. It carries very high current density at very high magnetic field, well past where low-temperature superconductors like Nb3Sn quench (around 23 T). The burner's 26.49 T plug and 17 T throat are only reachable because REBCO exists as an engineering material.

Properties that matter

• Superconducts at high field where LTS conductors fail
• Large temperature headroom — tolerant of local heating before quench
• Manufactured as long tape, wound or stacked into high-field coils
• Shared technology with the breeder's high-field magnets

The engineering trade

High field means large forces. Lorentz stress scales with the square of the field, so a 26.49 T coil experiences enormous outward pressure and must be caged in strong structure. REBCO tape is also anisotropic and sensitive to strain, so the winding and support must keep it within tight mechanical limits. Managing quench and screening currents in stacked tape is an active area of the design.

REBCO is commercially available and improving, and both Kronos machines are designed around it. In the burner design study the plug and throat coils are modeled against measured REBCO conductor performance, so the field values rest on real material data rather than on assumed future improvements.

That the same conductor serves both the breeder's high-field magnets and the burner's plugs concentrates the program's magnet development on one technology, so advances in winding, joints, and quench handling accrue to both machines at once.