CERN Built the Large Hadron Collider's Next-Gen Magnets

CERN is preparing the Large Hadron Collider for a high-luminosity upgrade planned to support experiments after 2030. The upgraded collider aims to raise the number of particle collisions from about 60 to 140-200 per crossing, increasing the odds of detecting rare particles and phenomena. That requires compact, powerful magnets. Existing niobium-titanium coils reach 8.3 tesla, near their practical limit; new niobium-tin (Nb₃Sn) quadrupole magnets are designed to approach 12 tesla. A study of their development reports that CERN’s 7.2-meter magnets passed quality-control tests at 11.3 tesla.

Making the coils requires a different method because Nb₃Sn becomes brittle and cannot withstand winding once superconducting. Engineers first wind a 760-meter cable into its final coil shape, then heat it through a multiday process that peaks at about 650 °C, forming the superconducting material. They carefully handle the coils afterward, fill gaps with epoxy, and cure it into a rigid structure. The team produced 250 coils for the magnets; 25 failed because of human error or manufacturing problems. Even a tiny flaw, such as a suspected trapped metal particle, could disqualify a coil. After years of development and testing by an international team, CERN has confirmed the magnets work and is now making spares.