Speaker
Dr
Nicola Vianello
(Consorzio RFX, Padova, Italy)
Description
Addressing the role of Scrape Off Layer filamentary transport is a subject of intense studies in fusion science. Intermittent structures dominate transport in L-Mode and strongly contribute to particle and energy losses in H-mode. The role of convective radial losses has become even more important due to its contribution to the shoulder formation in L-Mode, describing the progressive flattening of the density scrape off layer profile at high density [1–3]. Investigation of this process revealed the strong relationship between divertor conditions and the upstream profiles, mediated by filaments dynamics which varies according to the downstream conditions. Preliminary investigations suggested that similar mechanisms occur in H-Mode [1] and that filaments contribute the SOL transport in H-mode density limit (HDL) as well [4]. The present contribution will report on results obtained on ASDEX-Upgrade and TCV tokamaks, to address the role of filamentary transport in high density regimes both in L- and H-Mode. The combined results enlarge the operational space, from a device with a closed divertor, metallic first wall and cryogenic pumping system to a carbon machine with a completely open divertor. The mechanism of shoulder formation and the role of filaments have been tested against variation of plasma current, magnetic configuration (single and double null plasmas), and divertor neutral densities, through modification of cryopump efficiency. At constant magnetic field the density decay length increases with filament-size independently of the plasma current for both machines in L-mode, consistently with the fact that upstream profiles and divertor neutral pressure exhibit the same trend with normalized greenwald fraction. In H-Mode fueling is insufficient to cause flattening of SOL profiles in the inter-ELM phases since large neutral pressure is needed. Consistently inter-ELM blob size in AUG are found larger whenever the cryopumps is switched off. The resulting picture suggests a complex relationship between divertor and upstream profiles, where filaments are modified by divertor conditions as well as by neutral particles interaction. [1] Carralero, D et al. Nucl. Fus. 57, 056044 (2017) [2] Militello, F et al. Nucl. Fus. 56, 016006 (2016). [3] Vianello, N. et al. Nucl. Fus. 57, 116014 (2017) [4] Bernert, M et al. Plasma Phys. Control. Fus. 57, 014038 (2014).
| Country or International Organization | Italy |
|---|---|
| Paper Number | EX/P8-13 |
Primary author
Dr
Nicola Vianello
(Consorzio RFX, Padova, Italy)
Co-authors
Dr
Alexander Karpushov
(Swiss Plasma Center (SPC), EPFL, Switzerland)
Dr
Antti Hakola
(VTT Technical Research Centre of Finland Ltd.)
Dr
BENOIT LABIT
(Swiss Plasma Center (SPC) EPFL SWITZERLAND)
Mr
Bernd Sebastian Schneider
(Institute for Ion Physics and Applied Physics, Innsbruck, Austria)
Dr
Cedric Kar-Wai Tsui
(UCSD)
Prof.
Christian Theiler
(Swiss Plasma Center (SPC) EPFL Switzerland)
Dr
Codrina Ionita
(Institute for Ion Physics and Applied Physics, Innsbruck, Austria)
Dr
Daniel Carralero
(CIEMAT)
Mr
Diogo Aguiam
(IPFN, IST, Lisbon)
Dr
Elisabeth Wolfrum
(Max Planck Institut fuer Plasmaphysik)
Dr
Fulvio Militello
(Culham Centre for Fusion Energy)
Mr
Gustavo Grenfell
(Consorzio RFX, Padova, Italy)
Dr
Heinz Isliker
(Aristotle University of Thessaloniki, Greece)
Dr
Holger Reimerdes
(Swiss Plasma Center (SPC) EPFL Switzerland)
Mr
Hugo De Oliveira
(Swiss Plasma Center (SPC) EPFL Switzerland)
Dr
Istvan Cziegler
(York Plasma Institute, University of York)
Prof.
Jens Juul Rasmussen
(DTU Technical University of Denmark)
Mr
Jeppe Miki Busk Olsen
(DTU Technical University of Denmark)
Dr
Jernej Kovacic
(Jozef Stefan Institute, Ljubljana)
Mr
Joaquin Galdon Quiroga
(University of Sevilla)
Dr
Jose Boedo
(UCSD)
Dr
Jose Vicente
(PFN, IST, Lisbon)
Dr
Ken Mc Klements
(Culham Centre for Fusion Energy)
Mr
Kevin Verhaegh
(York Plasma Institute, University of York)
Prof.
Lipschultz Bruce
(York Plasma Institute, University of York)
Dr
Matteo Agostini
(Consorzio RFX, Padova, Italy)
Dr
Matthias Bernert
(IPP Garching)
Dr
Monica Spolaore
(Consorzio RFX, Padova, Italy)
Dr
Nick Walkden
(Culham Centre for Fusion Energy)
Mr
Roberto Maurizio
(Swiss Plasma Center (SPC), EPFL, Switzerland)
Prof.
Roman Schrittwieser
(Institute for Ion Physics and Applied Physics, Innsbruck, Austria)
Dr
Scott Allan
(Culham Centre for Fusion Energy)
Mr
Stefan Costea
(Institute for Ion Physics and Applied Physics, Innsbruck, Austria)
Mr
Timo Ravensbergen
(DIFFER, The Netherlands)
Prof.
Volker Naulin
(DTU Technical University of Denmark)
Dr
Wei Zhang
(IPP Garching)
