Fusion Reactor Magnet Issue Debunked: Path Cleared for Advanced Designs

MIT researchers have dispelled concerns about the instantaneous impact of neutron irradiation on superconducting magnets in fusion power plants. Early tests suggested that neutron irradiation might suppress the critical current, the ability to carry current without resistance, potentially reducing fusion power output. However, experiments have demonstrated that the beam on effect, the instantaneous impact of neutron bombardment, poses no issue during reactor operation. The team, led by MIT graduate student Alexis Devitre and professors Michael Short, Dennis Whyte, and Zachary Hartwig, reported their findings in *Superconducting Science and Technology*. Initially, tests on REBCO tapes, considered for the ARC fusion system, showed a 30% drop in critical current under radiation conditions. Further investigation revealed that temperature changes caused by the proton beam, not the irradiation itself, were responsible for the decrease. These findings alleviate concerns for companies like Commonwealth Fusion Systems and others developing fusion plants. The results also benefit other applications of REBCO magnets, such as satellite thrusters and particle accelerators. While long-term degradation of REBCO remains under investigation, this discovery removes a significant obstacle in fusion reactor design.