Numerical Evaluation of Heat Flux and Surface Temperature on a Misaligned JET Divertor W Lamella during ELMs

A series of experiments have been performed on JET to investigate the dynamics of transient melting due to Edge Localized Modes (ELMs). The experiment employs a deliberately misaligned lamella in one module of the JET bulk tungsten outer divertor, allowing the combination of stationary power flux and ELMs to transiently melt the misaligned edge. During the design of the experiment a number of calculations have been performed using 2D particle-in-cell (PIC) simulations and a heat transfer code to investigate the influence on the deposited power flux of finite Larmor radius effects associated with the energetic ELM ions. This has been done by parameter scans inside a range of pedestal temperatures and densities to scope different ELM energies corresponding to what was expected to be found in the experiment. On one hand, we observe optimistic results with the smoothing of the heat flux due to the Larmor gyration on the protruding side of the lamella that sees the direct parallel flux. Indeed, the deposited power tends to be lower than the nominal one on a distance smaller than 2 Larmor radii, which is always valid during ELMs for such a geometry. On the other hand, the fraction of the flux that does not reach the directly wetted side is transfered and spread to the top surface of the lamella. The hottest point of the lamella (corner side/top) does not always benefit from the gain from the larmor smoothing effect because of an enhanced power deposition from the second contribution.
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