HTS Current Leads and Feeders

Current leads carry power from room temperature into the cold magnet; HTS leads cut the heat they drag along with the current.

The unavoidable heat highway

To energize the magnet, current must travel from room-temperature power supplies into the cold mass. Any conductor that spans that temperature range carries heat as well as current, straight into the coldest, most expensive part of the system. Current leads are engineered to carry the required current while leaking the least possible heat.

Why HTS leads help

A high-temperature-superconductor section in the cold part of the lead carries current without generating resistive heat and conducts relatively little heat, cutting the load compared with an all-metal lead. The warm end still uses a gas-cooled metallic section. HTS leads are a direct application of the same superconductor family used in the magnet, turned to the heat-leak problem.

• Leads carry current and, unavoidably, heat into the cold mass.
• An HTS section reduces both resistive heat and conduction.
• The warm end is gas-cooled metallic conductor.
• Lead heat load is a sizeable share of the refrigeration budget.

A system trade

Lead design trades current capacity, heat leak, and quench safety. Bigger leads carry more current but leak more heat; smaller leads leak less but limit ramp and margin. The breeder sizes leads as part of the cryogenic-load budget alongside nuclear heating and cryostat performance, because they all draw on the same refrigeration capacity.

Failure modes

A current lead that loses cooling can overheat quickly, so leads are protected and monitored: loss of coolant flow or an HTS-section quench must be detected and the current safely reduced. Because the lead bridges warm and cold, its failure is both a heat-load and a magnet-protection event, tying it to the quench-protection system.

This page documents a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. Figures are computed, reproducible targets, not measurements.