The impact of non-local fluid models on 1D impurity driven detachment in an ITER-like SOL

Abstract Understanding parallel thermal transport in the scrape-off layer (SOL) is crucial for designing future high-powered tokamak exhaust systems. Fluid models, whilst computationally efficient, cannot accurately predict heat flux in conditions with large temperature gradients or low upstream collisionality. Here the electron mean free path becomes large and so the heat transport is non-local. The impact of non-local electron thermal transport on key detachment processes is often overlooked. The Hermes-3 multi-fluid SOL code is applied to a medium collisionality ( S || /λ e ≈ 25 upstream) ITER-like scenario in 1D, comparing non-local (SNB), to classical Spitzer-H¨arm (SH) as well as flux-limited (FL) electron conduction models. A neon fixed-fraction impurity seeding model is applied at increasing percentage until detachment is observed. Competing behaviour between FL and impurity seeding on target temperatures is observed, whilst the SNB model agrees qualitatively with SH, showing earlier detachment onset compared to FL (at∼ 1% lower neon fraction). This motivates the inclusion of non-local thermal conduction models (such as the SNB model) in fluid detachment modelling of SOL plasmas.