Speaker
Mr
Thomas Pütterich
(Germany)
Description
For the ITER-like wall at JET, the screening of the divertor W source is investigated along with possibilities to influence the central metal transport. From visible spectroscopy the erosion fluxes of W are determined at the outer strike line, which intersects the horizontal, solid tungsten target tile. The W-fluxes as determined by visible spectroscopy are related to the W-content in the main plasma, which is derived from VUV spectroscopy, in order to obtain an effective W confinement time tau_W. The investigations have been performed in low- and high-triangularity H-mode discharges at 2.0MA and 2.5MA, while a deuterium fuelling gas puff has been varied from shot to shot. Both the W-erosion in the divertor and the W-screening behave beneficial for increasing gas puff, i.e. the erosion decreases and tau_W decreases. Thus, an increasing gas puff leads to a strong reduction of the W-content in all investigated H-mode plasmas. Important players for this behaviour are the divertor electron temperature, the SOL and plasma edge transport and the ELM frequency. While the absolute numbers for the W-concentrations are very low (a few 1E-6), impurity accumulation is observed for cases without any gas puff. This behaviour is discussed also considering the influence of other metal impurities. Independent of the radiating species, it is explored to what extent central wave heating (ICRH and LH) and impurity avoidance strategies, i.e. gas puffing and ELM-pace-making, help to avoid impurity accumulation.
Country or International Organization of Primary Author
Germany
Collaboration (if applicable, e.g., International Tokamak Physics Activities)
JET-EFDA
Primary author
Mr
Thomas Pütterich
(Germany)
Co-authors
Dr
Agata Czernecka
(EURATOM Assoc., Inst Plasma Phys & Laser Microfus)
Dr
Andrew Meigs
(CULHAM CENTRE FOR FUSION ENERGY)
Dr
Elena de la Luna
(EURATOM CIEMAT Assoc.)
Dr
Emmanuel Joffrin
(Institut de Recherche sur la Fusion par confinement Magnétique Association Euratom-CEA)
Dr
Fernanda Rimini
(CULHAM CENTRE FOR FUSION ENERGY)
Dr
Gerard van Rooij
(FOM Institute Differ)
Dr
Ivor Coffey
(Queen's University Belfast)
Dr
Jan Willem Coenen
(INSTITUTE OF ENERGY AND CLIMATE RESEARCH, FORSCHUNGSZENTRUM JÜLICH)
Dr
Jerome Bucalossi
(Institut de Recherche sur la Fusion par confinement Magnétique Association Euratom-CEA)
Dr
Joelle Mailloux
(CULHAM CENTRE FOR FUSION ENERGY)
Dr
Kerry Lawson
(CULHAM CENTRE FOR FUSION ENERGY)
Dr
Marc Beurskens
(CULHAM CENTRE FOR FUSION ENERGY)
Dr
Marco Sertoli
(MAX-PLANCK-INSTITUT FÜR PLASMAPHYSIK)
Dr
Marie-Line Mayoral
(CULHAM CENTRE FOR FUSION ENERGY)
Dr
Michael Lehnen
(INSTITUTE OF ENERGY AND CLIMATE RESEARCH, FORSCHUNGSZENTRUM JÜLICH)
Dr
Michael Stamp
(CULHAM CENTRE FOR FUSION ENERGY)
Dr
Ralph Dux
(Max-Planck-Institut für Plasmaphysik)
Dr
Rudolf Neu
(MAX-PLANCK-INSTITUT FÜR PLASMAPHYSIK)
Dr
Sebastijan Brezinsek
(INSTITUTE OF ENERGY AND CLIMATE RESEARCH, FORSCHUNGSZENTRUM JÜLICH)
Dr
Stefan Marsen
(MAX-PLANCK-INSTITUT FÜR PLASMAPHYSIK)
Dr
Sven Wiesen
(INSTITUTE OF ENERGY AND CLIMATE RESEARCH, FORSCHUNGSZENTRUM JÜLICH)
Dr
Volodymir Bobkov
(Max-Planck-Institut für Plasmaphysik)
