Speaker
Description
Handling plasma exhaust without compromising core performance remains one of the central challenges for fusion energy. Research on alternative divertor configurations (ADCs) has progressed rapidly in recent years, moving beyond exploratory studies [1,2] toward demonstrations of substantial benefits [3–5]. Reported advantages include order-of-magnitude reductions in target heat flux, extended operational windows for detachment, improved active feedback control, and enhanced resilience of the detached state to transients such as ELMs - all while preserving good core conditions. Particularly strong exhaust performance has been achieved with the X-Point Target Divertor [3] and the Super-X Divertor [4,5], supporting their prospective implementation in SPARC/ARC and STEP, respectively. Additional key benefits have further been projected for tightly-baffled, long-legged divertor configurations, which improve neutral confinement and detachment stability while remaining compatible with both conventional and alternative magnetic geometries [6–9]. Extrapolation capabilities of these concepts have been strengthened through higher-power experiments and advances in modelling, with state-of-the-art transport simulations now routinely covering arbitrary geometries, including multiple divertor X-points, and incorporating drift effects. In parallel, the need for ADCs in next-step devices has become increasingly clear: they are essential for compact, high-field designs such as SPARC/ARC and STEP, while recent findings that even modest, strategic divertor modifications can yield significant benefits make ADC research equally relevant and timely for divertor optimization in more conventional approaches such as DEMO and CFEDR. Beyond specific designs, ADC research also improves the general understanding of power exhaust, providing validation of models and operational insights directly relevant to ITER. This talk will review the rapid progress in both experimental demonstrations and theoretical understanding of ADCs, highlighting the emerging physics basis for optimized divertor solutions that balance exhaust performance with engineering complexity.
[1] C. Theiler et al., Nucl. Fusion 2017
[2] V. Soukhanovskii, Plasma Phys. Control. Fusion 2017
[3] K. Lee et al., Phys. Rev. Lett. 2025
[4] K. Verhaegh et al., Nature Comm. Phys. 2025
[5] B. Kool et al., Nature Energy 2025
[6] M. Umansky et al., Phys. Plasmas 2017
[7] M. Wigram et al., Nucl. Fusion 2023
[8] G. Sun et al., Nucl. Fusion 2023
[9] J. Yu et al., Nucl. Mater. Energy 2024