Superconducting Magnets for Fusion

The magnet is the machine. Everything about a compact fusion device follows from how much field its coils can hold.

Fusion needs strong magnetic fields to confine a hot plasma; the stronger the field, the smaller and cheaper the machine can be for the same performance. High-temperature superconductors — chiefly REBCO — carry enormous currents at high field with no resistive loss, enabling fields that copper coils could never sustain continuously.