First demonstration of Super-X divertor exhaust control for transient heat load management in compact fusion reactors

Nuclear fusion could offer clean, abundant energy. However, managing the power exhausted from the core fusion plasma towards the reactor wall remains a major challenge, compounded in emerging compact reactor designs promising more cost-effective pathways towards commercial fusion energy. Alternative Divertor Configurations (ADCs) are a potential solution. In this work, ADC exhaust control is demonstrated for the first time, employing a novel method to diagnose the neutral gas buffer which shields the target. Our work on MAST-U shows that ADCs tackle key risks and uncertainties for fusion energy: 1) their highly reduced sensitivity to perturbations enables active exhaust control in otherwise unfeasible situations and facilitates 2) passive absorption of transients which would otherwise damage the divertor; furthermore, 3) isolating each divertor from other reactor regions enables near-independent control of the divertors and core plasma. Our work showcases the real-world benefits of ADCs for effective heat load management in reactors.