niobium-tin · wire
Nb₃Sn
A brittle intermetallic with roughly twice the transition temperature of NbTi, and a manufacturing process built entirely around the fact that it cannot be bent.
Nb₃Sn in numbers
- Transition temperature
- 18.3 K
- Made as
- wire
- Nitrogen line
- Below 77 K
What Nb₃Sn runs in today
ITER’s toroidal field coils; the HL-LHC 11 T dipoles; high-field NMR magnets.
Source: Textbook value; ITER magnet system documentation; CERN HL-LHC technical design report
Why engineers choose Nb₃Sn
Nb3Sn is where a magnet program goes when NbTi runs out of field, and what it costs is the freedom to treat the conductor as wire. The compound only forms after a long reaction heat treatment, and once formed it is ceramic-brittle, so the coil is wound from a ductile precursor and then the entire wound coil goes into a furnace. Everything downstream inherits that. The insulation has to survive the reaction. The support structure has to be in place before it. And the finished winding is strain-sensitive enough that the Lorentz force the magnet generates on itself degrades the conductor carrying it. A Nb3Sn magnet is a mechanical design problem with a superconductor inside it.
Where Nb₃Sn stops
The transition temperature is generous next to NbTi and low next to a brief written at twenty kelvin, which is where the fusion and high-field magnet work now sits. It is the conductor most often eliminated by the temperature line rather than by the field line.
Current under field
Tc 18.3 K, gone before the brief starts.
Fields built on Nb₃Sn
- Fusion magnetsTwenty tesla, and the reason a compact tokamak is credible at all.
- Particle therapyA superconducting gantry brought a heavy-ion treatment room from 600 tonnes down to about 300.
- NMR spectrometersThe magnet that resolves a protein structure runs at a few kelvin.
- Particle accelerators1,232 superconducting dipoles bend the beam around 27 km at CERN.
Nb₃Sn and the other wire conductors
Terms used on this page about Nb₃Sn
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