Niobium-titanium (Nb-Ti) is an alloy of niobium and titanium, used industrially as a type II superconductor wire for superconducting magnets, normally as Nb-Ti fibres in an aluminium or copper matrix.
In 1962, at Atomics International, T. G. Berlincourt and R. R. Hake, discovered the superior high-critical-magnetic-field, high-critical-supercurrent-density properties of Nb-Ti that, together with affordability and easy workability, distinguish Nb-Ti alloys from thousands of other superconductors and justify their status as the most widely utilized (workhorse) superconductors.
With a maximal critical magnetic field of about 15 teslas, Nb-Ti alloys are suitable for fabricating supermagnets generating magnetic fields up to about 10 teslas. For higher magnetic fields, higher-performance, but more expensive and less easily fabricated superconductors, such as niobium-tin, are commonly employed.
The part of global economic activity for which superconductivity is indispensable amounted to about five billion euros in 2014. MRI (Magnet Resonance Imaging) systems, most of which employ niobium-titanium, accounted for about 80% of that total.
About 1000 NbTi SC magnets were used in the 4-mile-long main ring of the Tevatron accelerator at Fermilab. The magnets were wound with 50 tons of copper cables containing 17 tons of NbTi filaments. They operate at 4.5 K generating fields up to 4.5 tesla.
In the Large Hadron Collider particle accelerator the magnets (containing 1200 tonnes of NbTi cable of which 470 tonnes are Nb-Ti and the rest copper) are cooled to 1.9 K to allow safe operation at fields of up to 8.3 T.
Niobium-titanium superconducting magnet coils (liquid helium cooled) were built to be used in the Alpha Magnetic Spectrometer mission to be flown on the international space station. They were later replaced by non-superconducting magnets.
The Wendelstein 7-X stellarator uses NbTi for its magnets.
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The test coil achieves stable operation at 52 kA and 6.4 Tesla.