Technology · Specialized
Helium keeps powerful magnets cold
At CERN, a circulating helium system holds superconducting magnet coils at temperatures where they can carry very large electric currents.
THE MATERIAL THAT DOES THE WORK
Chemical form
The Large Hadron Collider uses liquid helium in a closed cooling circuit. At its 1.9 kelvin operating temperature, helium is superfluid. The magnet conductors themselves use niobium-titanium; helium provides their thermal environment.
- 01
Prepare the cold circuit
Helium and the refrigeration equipment are integrated with magnet cryostats, piping, and components designed to accommodate thermal contraction.
- 02
Cool in stages
The magnet system passes through successive temperature levels, with checks before reaching its final superfluid-helium operating condition.
- 03
Circulate and recover
Helium circulates during operation and is recovered for storage and reuse when the accelerator warms for maintenance.
Cryogenics: Low temperatures, high performanceFor the first time the LHC reaches temperatures colder than outer spaceLarge Hadron Collider (LHC) magnet interconnection
Why it works
coils can carry current without electrical resistance only within suitable operating conditions. Helium remains liquid at extremely low temperatures, and its superfluid state transfers heat exceptionally effectively, helping stabilize the cold magnet system.
How it is made & used
CERN cools the system in stages, using refrigeration and heat exchangers before reaching the final operating temperature. Lowering pressure in the refrigeration process supports the last stage of cooling. This is a large engineered installation rather than a single container of coolant.
For the first time the LHC reaches temperatures colder than outer space
Inside the application
An accelerator needs magnetic fields to guide and focus its beams. Superconducting conductors carry large currents within compact magnets. Helium links those conductors to the refrigeration system, maintaining the cold conditions that make their operation possible.
For the first time the LHC reaches temperatures colder than outer space
Limits & alternatives
Cooling contracts pipes, cables, and connections, which must accommodate movement. Local heating can end superconductivity. Commissioning checks the installation before operation; the quoted temperature is specific to the LHC.
For the first time the LHC reaches temperatures colder than outer spaceLarge Hadron Collider (LHC) magnet interconnection
Part of a larger system
The same assembly brings together distinct elemental jobs: niobium and titanium form the superconducting wire, while helium moves heat. CERN recovers helium during warm-up for maintenance so it can be stored and reused.
Cryogenics: Low temperatures, high performanceLarge Hadron Collider (LHC) magnet interconnection
Sources & further reading
- Cryogenics: Low temperatures, high performance ↗CERNReference explanation · Source checked
- For the first time the LHC reaches temperatures colder than outer space ↗CERNReference explanation · Source checked
- Large Hadron Collider (LHC) magnet interconnection ↗CERNTechnical documentation · Source checked
Sources and further reading. What the review labels mean