Liquid Helium

Helium cooled below its boiling point (4.2 K at atmospheric pressure), used as a cryogenic coolant for superconducting magnets. Superconducting magnets in fusion devices (including HTSHTSLiquid helium and LTS systems) require cryogenic temperatures to maintain zero electrical resistance. Liquid helium logistics — production, transport, and storage — are a significant operational cost for fusion facilities.