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22-27 October 2018
Mahatma Mandir Conference Centre
Asia/Kolkata timezone
CONFERENCE MATERIAL NOW AVAILABLE!

Core Density Peaking Experiments in JET, DIII-D and C-Mod in Various Operational Scenarios - Driven by Fuelling or Transport

24 Oct 2018, 18:20
20m
Mahatma Mandir Conference Centre

Mahatma Mandir Conference Centre

Gandhinagar (nearest Airport: Ahmedabad), India
Oral EXC - Magnetic Confinement Experiments: Confinement EX/4-TH/2 H-Mode & Pedestal

Speaker

Dr Tuomas Tala (VTT)

Description

Core density profile peaking has been extensively studied by performing several dimensionally matched collisionality scans in various plasma operation scenarios on JET as well as by executing a 3-point collisionality scan on DIII-D and a 2-point collisionality scan in I-mode on C-Mod. In L-mode, D and V are large in all cases even if the NBI power is much smaller than in the H-mode cases. However in H-mode, D and V are both small, and therefore, NBI fueling plays an important role in contributing to density peaking. These small D and V here represent electron particle transport, but there is evidence now from JET that the ion particle Di and Vi can be an order of magnitude larger. Gyro-kinetic GENE simulations were performed to infer the peaking factor of background ions. Peaked density profiles are obtained only for L-mode while H-modes discharges show flat or hollow density profiles at ρ=0.6. TGLF and QuaLiKiz transport simulations confirm the dominant role of NBI fueling in producing peaked ne profiles in JET H-mode plasmas. A similar 3-point collisionality scan to JET was performed on DIII-D. Density peaking increased with collisionality very similarly to JET. The perturbative analysis from the gas puff modulation data confirms the significant role of NBI fueling in each case. The dependence of density peaking on collisionality was studied in I-mode and L-mode on C-Mod by applying gas puff modulation. The steady-state ne data indicates no dependence on collisionality in neither I- nor L-mode, consistent with JET but in contrast to H-mode data in C-Mod. The results from the scans on various tokamaks and modelling all indicate that in H-mode the NBI fueling is a significant contributor to density peaking. The consequences of this on ITER fueling will be discussed. Acknowledgement: This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. This material is based upon work supported by the Department of Energy under Award Number DE-FC02-04ER54698. Supported by U.S. Department of Energy awards DE-FC02-99ER54512, DE-SC0007880 using Alcator C-Mod, a DOE Office of Science User Facility.
Country or International Organization Finland
Paper Number EX/4-4

Primary author

Dr Tuomas Tala (VTT)

Co-authors

Dr Adrianus Sips (EFDA-JET) Dr Amanda Hubbard (Massachusetts Institute of Technology, Plasma Science and Fusion Center) Dr Anders Skyman (Chalmers University of Technology) Dr Antti Salmi (VTT) Dr Carine Giroud (CCFE) Dr Costanza Maggi (CCFE) Dr Czarnecka Agatha (IPPLM) Dr Daniel Tegnered (Chalmers University of Technology) Dr Elisabeth Tolman (MIT) Dr Hans Nordman (Chamers University of Technology) Mr Henri Weisen (JET EFDA) Jerry Hughes (MIT PSFC) Dr Jon Hillesheim (Culham Centre for Fusion Energy) Dr Jonathan Citrin (FOM DIFFER - Dutch Institute for Fundamental Energy Research) Dr Luis Meneses (Instituto de Plasmas e Fusão Nuclear) Dr Maximos Tsalas (ITER) Dr Michel Oberparleiter (Chalmers University of Technology) Dr Mikhail Maslov (UKAEA) Dr Paola Mantica (Istituto Di Fisica Del Plasma, Consiglio Nazionale delle Ricerche (CNR), 20125 Milan, Italy) Prof. Saskia Mordijck (The College of William and Mary) Dr Sheena Menmuir (UKAEA) Dr Volker Naulin (DTU) Mrs clarisse bourdelle (CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France.)

Presentation Materials

Paper