Artículo
Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade
Autor/es | Laggner, F. M.
Keerl, S. Gnilsen, J. Wolfrum, E. Bernert, M. Carralero, D. Guimarais, L. Nikolaeva, V. Potzel, S. Cavedon, M. Mink, F. Dunne, M. G. Birkenmeier, G. Fischer, R. Viezzer, Eleonora Willensdorfer, M. Wischmeier, M. Aumayr, F. |
Departamento | Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear |
Fecha de publicación | 2018 |
Fecha de depósito | 2018-08-07 |
Publicado en |
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Resumen | In addition to the relaxation of the pedestal, edge localised modes (ELMs) introduce changes to
the divertor and scrape-off layer (SOL) conditions. Their impact on the inter-ELM pedestal
recovery is investigated, with ... In addition to the relaxation of the pedestal, edge localised modes (ELMs) introduce changes to the divertor and scrape-off layer (SOL) conditions. Their impact on the inter-ELM pedestal recovery is investigated, with emphasis on the electron density (ne) evolution. The typical ELM cycle occurring in an exemplary ASDEX Upgrade discharge interval at moderate applied gas puff and heating power is characterised, utilising several divertor, SOL and pedestal diagnostics. In the studied discharge interval the inner divertor target is detached before the ELM crash, while the outer target is attached. The particles and power expelled by the ELM crash lead to a reattachment of the inner target plasma. After the ELM crash, the outer divertor target moves into a high recycling regime with large ne in front of the plate, which is accompanied by high main chamber neutral fluxes. On similar timescales, the inner target fully detaches and the high field side high density region (HFSHD) is formed reaching up to the high field side midplane. This state evolves again to the pre-ELM state, when the main chamber neutral fluxes are reduced later in the ELM cycle. Neither the timescale of the appearance of the HFSHD nor the increase of the main chamber neutral fluxes fit the timescale of the ne pedestal, which is faster. It is found that during the ne pedestal recovery, the magnetic activity at the low field side midplane is strongly reduced indicating a lower level of fluctuations. A rough estimation of the particle flux across the pedestal suggests that the particle flux is reduced in this period. In conclusion, the evolution of the ne pedestal is determined by a combination of neutral fluxes, HFSHD and reduced particle flux across the pedestal. A reduced particle flux explains the fast, experimentally observed reestablishment of the ne pedestal best, whereas neutrals and HFSHD impact on the evolution of the SOL and separatrix conditions. |
Agencias financiadoras | European Commission (EC) |
Identificador del proyecto | EUROfusion 633053 |
Cita | Laggner, F.M., Keerl, S., Gnilsen, J., Wolfrum, E., Bernert, M., Carralero, D.,...,Aumayr, F. (2018). Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade. Plasma Physics and Controlled Fusion, 60, 025002. |
Ficheros | Tamaño | Formato | Ver | Descripción |
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Plasma2018_025002.pdf | 6.264Mb | [PDF] | Ver/ | |