In fusion reactor designs, superconductors (which suffer no resistive power loss) are used to generate the magnetic fields that confine the 100 million degree C plasma. While increasing magnetic field strength offers potential ways to improve reactor performance, conventional low-temperature superconductors suffer dramatic drops in current carrying ability at high magnetic fields. Now, the emergence of high-temperature superconductors that can also operate at high magnetic fields opens a new, lower-cost path to fusion energy.
Ref: 57th Annual Meeting of the APS Division of Plasma Physics. Considerations of the high magnetic field tokamak path on the approach to fusion energy