Tungsten transport and sources control in JET ITER-like wall H-mode plasmas

A set of discharges performed with the JET ITER-like wall is investigated with respect to control capabilities on tungsten sources and transport. In attached divertor regimes, increasing fueling by gas puff results in higher divertor recycling ion flux, lower divertor tungsten source, higher ELM fre...

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Bibliographic Details
Published in:Journal of nuclear materials 2015-08, Vol.463, p.85-90
Main Authors: Fedorczak, N., Monier-Garbet, P., Pütterich, T., Brezinsek, S., Devynck, P., Dumont, R., Goniche, M., Joffrin, E., Lerche, E., Lipschultz, B., de la Luna, E., Maddison, G., Maggi, C., Matthews, G., Nunes, I., Rimini, F., Solano, E.R., Tamain, P., Tsalas, M., de Vries, P.
Format: Article
Language:English
Subjects:
Cyclotrons
Elm
Flushing
Plasma radiation
Plasmas
Transport
Tungsten
Walls
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Summary:A set of discharges performed with the JET ITER-like wall is investigated with respect to control capabilities on tungsten sources and transport. In attached divertor regimes, increasing fueling by gas puff results in higher divertor recycling ion flux, lower divertor tungsten source, higher ELM frequency and lower core plasma radiation, dominated by tungsten ions. Both pedestal flushing by ELMs and divertor screening (including redeposition) are possibly responsible. For specific scenarios, kicks in plasma vertical position can be employed to increase the ELM frequency, which results in slightly lower core radiation. The application of ion cyclotron radio frequency heating at the very center of the plasma is efficient to increase the core electron temperature gradient and flatten electron density profile, resulting in a significantly lower central tungsten peaking. Beryllium evaporation in the main chamber did not reduce the local divertor tungsten source whereas core radiation was reduced by approximately 50%.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2014.12.044