Cryogenic System Architecture

REBCO magnets run cold; a refrigeration plant, cold box, current leads, and distribution keep the cold mass at operating temperature.

Keeping the magnet cold

The breeder's REBCO magnets operate at cryogenic temperature to keep critical-current margin. That requires a cryogenic plant: warm compressors, a cold box that produces the cold working fluid, distribution to the magnet cold mass, and current leads that carry power in from room temperature. The system runs continuously whenever the magnets are energized.

The pieces

• Warm compressors that drive the refrigeration cycle.
• A cold box that produces cold helium for the magnet.
• HTS current leads that minimize heat carried in with the current.
• Distribution and return that manage heat loads along the way.

Why HTS raises the temperature option

REBCO's higher-temperature capability means the magnet can, in principle, run warmer than a low-temperature superconductor, easing the refrigeration burden. In practice the operating temperature is set by critical-current margin against the 16.84 T peak field: colder buys margin but costs refrigeration. The architecture is sized to that balance.

A supporting system that constrains the core

Cryogenics is a balance-of-plant system, but it feeds back into the magnet: nuclear heating from the shield, resistive heat from joints and leads, and the chosen operating temperature all set the plant's size. It is designed together with the magnet and shield, not bolted on afterward.

Redundancy and turndown

The plant is designed with redundancy so a single compressor or cold-box fault need not force a magnet warm-up, and with turndown so it can match load as operation varies. Warm-up and cooldown of a large cold mass are slow, so keeping the magnet cold through minor faults protects both schedule and the magnet itself.

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.