Improved Divertor Performance in Strongly Baffled, Alternative Divertors on MAST Upgrade

Managing power exhaust from fusion core plasma is crucial for advancing fusion energy. The MAST Upgrade tokamak distinctively integrates strong neutral baffling - to segregate the exhaust area (divertor) from the fusion core - with advanced divertor shaping, enabling long-legged divertors and high total flux expansion (F_R = B_xpt/B_t up to 2.3). This study provides compelling experimental evidence that such configurations markedly reduce target heat and particle loads, representing a significant step forward in addressing the fusion power exhaust challenge. Our comparative analysis of various divertor shapes demonstrates that even modest adjustments can significantly enhance exhaust performance while preserving core plasma performance. Through novel analysis, we attribute the reductions in particle and power loads to the expanded plasma-neutral interaction volume within long-legged divertors. Importantly, the neutral buffer formed in front of the target is highly resistant to variations of the plasma state in strongly baffled, long-legged divertors with F_R > 1.6. Our results underscore the critical role of strategic divertor shaping in enhancing exhaust performance, stability and core-edge integration, aligning with reduced models and simulation forecasts. This study not only paves new avenues for optimising power exhaust systems but also signifies an essential advancement towards sustainable fusion energy.