Speaker
Description
In previous ST40 experimental campaigns, distinct wide and narrow scrape-off layer (SOL) profile widths have been observed [Zhang et al., Nuclear Materials and Energy 41 (2024)]. The “wide” profiles follow traditional scalings built on a multi-device empirical database [T. Eich et al., 2013 Nucl. Fusion 53 093031], while the “narrow” profiles have been found to be an order of magnitude narrower. A comparison between divertor Langmuir probe and infrared (IR) thermography measurements of parallel heat flux yield good agreement for both cases with parallel heat fluxes reaching up to 150 MW/m2 in the narrow case. Upgrades to the ST40 tokamak related to divertor diagnostics by the addition of more Langmuir probes and another IR camera system viewing the lower divertor are also presented.