EFDA-JET-PR(11)03

Scrape Off Layer Heat Transport and Divertor Power Deposition of Pellet Induced ELMs

Results on key aspects of Scrape Off Layer (SOL) heat transport and divertor power load associated with pellet induced ELMs in comparison to spontaneous ELMs are presented. We focus on the 3D structure of the SOL heat transport by revealing the footprints of power load on the divertor target. Additionally, the time scales of ELM loss and consecutive energy transport in the SOL towards the divertor target of pellet induced ELMs are discussed. By employing a toroidal magnetic field (BT) scan we achieve evidence that a toroidally asymmetric divertor power deposition structure is extending to positions exceptional far off the strike line and exceeding toroidaly localized the power flux density at the strike line. Field lines tracing is used to predict correctly for the full BT scan the position of the divertor power footprint of an ELM filament through the pellet injection trajectory. Consistently the divertor heat flux modelled with the non-linear MHD-code JOREK features in addition to the toroidally symmetric component peaking at the strike line a spiral like structure joining this symmetric component from higher radii. For the investigated JET discharges we conclude that the divertor heat loads due to pellet induced ELM consist out of two components. First, the toroidaly symmetric peak heat load at the strike line is comparable to the one of spontaneous ELMs. Secondly, the toroidal asymmetric component is found to be higher by ~30% at a toroidal position defined by the SOL field line pitch.
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EFDP11003 2.00 Mb