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Overview of ASDEX Upgrade results

A Kallenbach, J Adamek, L Aho-Mantila, S Aekaeslompolo, C Angioni, CV Atanasiu, M Balden, K Behler, E Belonohy, A Bergmann, et al. (2011) NUCLEAR FUSION. 51(9).
abstract
The ASDEX Upgrade programme is directed towards physics input to critical elements of the ITER design and the preparation of ITER operation, as well as addressing physics issues for a future DEMO design. After the finalization of the tungsten coating of the plasma facing components, the re-availability of all flywheel-generators allowed high-power operation with up to 20 MW heating power at I(p) up to 1.2 MA. Implementation of alternative ECRH schemes (140 GHz O2- and X3-mode) facilitated central heating above n(e) = 1.2 x 10(20) m(-3) and low q(95) operation at B(t) = 1.8 T. Central O2-mode heating was successfully used in high P/R discharges with 20 MW total heating power and divertor load control with nitrogen seeding. Improved energy confinement is obtained with nitrogen seeding both for type-I and type-III ELMy conditions. The main contributor is increased plasma temperature, no significant changes in the density profile have been observed. This behaviour may be explained by higher pedestal temperatures caused by ion dilution in combination with a pressure limited pedestal and hollow nitrogen profiles. Core particle transport simulations with gyrokinetic calculations have been benchmarked by dedicated discharges using variations of the ECRH deposition location. The reaction of normalized electron density gradients to variations of temperature gradients and the T(e)/T(i) ratio could be well reproduced. Doppler reflectometry studies at the L-H transition allowed the disentanglement of the interplay between the oscillatory geodesic acoustic modes, turbulent fluctuations and the mean equilibrium E x B flow in the edge negative E(r) well region just inside the separatrix. Improved pedestal diagnostics revealed also a refined picture of the pedestal transport in the fully developed H-mode type-I ELM cycle. Impurity ion transport turned out to be neoclassical in between ELMs. Electron and energy transport remain anomalous, but exhibit different recovery time scales after an ELM. After recovery of the pre-ELM profiles, strong fluctuations develop in the gradients of n(e) and T(e). The occurrence of the next ELM cannot be explained by the local current diffusion time scale, since this turns out to be too short. Fast ion losses induced by shear Alfven eigenmodes have been investigated by time-resolved energy and pitch angle measurements. This allowed the separation of the convective and diffusive loss mechanisms.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (original)
publication status
published
subject
keyword
REFLECTOMETRY, TOKAMAK, PHYSICS
journal title
NUCLEAR FUSION
Nucl. Fusion
volume
51
issue
9
article number
094012
Web of Science type
Article
Web of Science id
000294731600013
JCR category
PHYSICS, FLUIDS & PLASMAS
JCR impact factor
4.09 (2011)
JCR rank
2/31 (2011)
JCR quartile
1 (2011)
ISSN
0029-5515
DOI
10.1088/0029-5515/51/9/094012
language
English
UGent publication?
no
classification
A1
copyright statement
I have transferred the copyright for this publication to the publisher
id
2947553
handle
http://hdl.handle.net/1854/LU-2947553
date created
2012-06-29 16:03:02
date last changed
2016-12-21 15:42:17
@article{2947553,
  abstract     = {The ASDEX Upgrade programme is directed towards physics input to critical elements of the ITER design and the preparation of ITER operation, as well as addressing physics issues for a future DEMO design. After the finalization of the tungsten coating of the plasma facing components, the re-availability of all flywheel-generators allowed high-power operation with up to 20 MW heating power at I(p) up to 1.2 MA. Implementation of alternative ECRH schemes (140 GHz O2- and X3-mode) facilitated central heating above n(e) = 1.2 x 10(20) m(-3) and low q(95) operation at B(t) = 1.8 T. Central O2-mode heating was successfully used in high P/R discharges with 20 MW total heating power and divertor load control with nitrogen seeding. Improved energy confinement is obtained with nitrogen seeding both for type-I and type-III ELMy conditions. The main contributor is increased plasma temperature, no significant changes in the density profile have been observed. This behaviour may be explained by higher pedestal temperatures caused by ion dilution in combination with a pressure limited pedestal and hollow nitrogen profiles. Core particle transport simulations with gyrokinetic calculations have been benchmarked by dedicated discharges using variations of the ECRH deposition location. The reaction of normalized electron density gradients to variations of temperature gradients and the T(e)/T(i) ratio could be well reproduced. Doppler reflectometry studies at the L-H transition allowed the disentanglement of the interplay between the oscillatory geodesic acoustic modes, turbulent fluctuations and the mean equilibrium E x B flow in the edge negative E(r) well region just inside the separatrix. Improved pedestal diagnostics revealed also a refined picture of the pedestal transport in the fully developed H-mode type-I ELM cycle. Impurity ion transport turned out to be neoclassical in between ELMs. Electron and energy transport remain anomalous, but exhibit different recovery time scales after an ELM. After recovery of the pre-ELM profiles, strong fluctuations develop in the gradients of n(e) and T(e). The occurrence of the next ELM cannot be explained by the local current diffusion time scale, since this turns out to be too short. Fast ion losses induced by shear Alfven eigenmodes have been investigated by time-resolved energy and pitch angle measurements. This allowed the separation of the convective and diffusive loss mechanisms.},
  articleno    = {094012},
  author       = {Kallenbach, A and Adamek, J and Aho-Mantila, L and Aekaeslompolo, S and Angioni, C and Atanasiu, CV and Balden, M and Behler, K and Belonohy, E and Bergmann, A and Bernert, M and Bilato, R and Bobkov, V and Boom, J and Bottino, A and Braun, F and Bruedgam, M and Buhler, A and Burckhart, A and Chankin, A and Classen, IGJ and Conway, GD and Coster, DP and de Marne, P and D'Inca, R and Drube, R and Dux, R and Eich, T and Endstrasser, N and Engelhardt, K and Esposito, B and Fable, E and Fahrbach, HU and Fattorini, L and Fischer, R and Flaws, A and Fuenfgelder, H and Fuchs, JC and Gal, K and Garcia Munoz, M and Geiger, B and Adamov, M Gemisic and Giannone, L and Giroud, C and Goerler, T and da Graca, S and Greuner, H and Gruber, O and Gude, A and Guenter, S and Haas, G and Hakola, AH and Hangan, D and Happel, T and Hauff, T and Heinemann, B and Herrmann, A and Hicks, N and Hobirk, J and Hoehnle, H and Hoelzl, M and Hopf, C and Horton, L and Huart, M and Igochine, V and Ionita, C and Janzer, A and Jenko, F and Kaesemann, CP and Kalvin, S and Kardaun, O and Kaufmann, M and Kirk, A. and Klingshirn, HJ and Kocan, M and Kocsis, G and Kollotzek, H and Konz, C and Koslowski, R and Krieger, K and Kurki-Suonio, T and Kurzan, B and Lackner, K and Lang, PT and Lauber, P and Laux, M and Leipold, F and Leuterer, F and Lohs, A and Luhmann, NC and Lunt, T and Lyssoivan, A and Maier, H and Maggi, C and Mank, K and Manso, ME and Maraschek, M and Martin, P and Mayer, M and McCarthy, PJ and McDermott, R and Meister, H and Menchero, L and Meo, F and Merkel, P and Merkel, R and Mertens, V and Merz, F and Mlynek, A and Monaco, F and Mueller, HW and Muenich, M and Murmann, H and Neu, G and Neu, R and Nold, B and Noterdaeme, Jean-Marie and Park, HK and Pautasso, G and Pereverzev, G and Podoba, Y and Pompon, F and Poli, E and Polochiy, K and Potzel, S and Prechtl, M and Pueschel, MJ and Puetterich, T and Rathgeber, SK and Raupp, G and Reich, M and Reiter, B and Ribeiro, T and Riedl, R and Rohde, V and Roth, J and Rott, M and Ryter, F and Sandmann, W and Santos, J and Sassenberg, K and Sauter, P and Scarabosio, A. and Schall, G and Schmid, K and Schneider, PA and Schneider, W and Schramm, G and Schrittwieser, R and Schweinzer, J and Scott, B and Sempf, M and Serra, F and Sertoli, M and Siccinio, M and Sigalov, A and Silva, A and Sips, ACC and Sommer, F and Staebler, A and Stober, J and Streibl, B and Strumberger, E and Sugiyama, K and Suttrop, W and Szepesi, T and Tardini, G and Tichmann, C and Told, D and Treutterer, W and Urso, L and Varela, P and Vincente, J and Vianello, N and Vierle, T and Viezzer, E and Vorpahl, C and Wagner, D and Weller, A and Wenninger, R and Wieland, B and Wigger, C and Willensdorfer, M. and Wischmeier, M and Wolfrum, E and Wuersching, E and Yadikin, D and Yu, Q and Zammuto, I and Zasche, D and Zehetbauer, T and Zhang, Y and Zilker, M and Zohm, H},
  issn         = {0029-5515},
  journal      = {NUCLEAR FUSION},
  keyword      = {REFLECTOMETRY,TOKAMAK,PHYSICS},
  language     = {eng},
  number       = {9},
  title        = {Overview of ASDEX Upgrade results},
  url          = {http://dx.doi.org/10.1088/0029-5515/51/9/094012},
  volume       = {51},
  year         = {2011},
}

Chicago
Kallenbach, A, J Adamek, L Aho-Mantila, S Aekaeslompolo, C Angioni, CV Atanasiu, M Balden, et al. 2011. “Overview of ASDEX Upgrade Results.” Nuclear Fusion 51 (9).
APA
Kallenbach, A, Adamek, J., Aho-Mantila, L., Aekaeslompolo, S., Angioni, C., Atanasiu, C., Balden, M., et al. (2011). Overview of ASDEX Upgrade results. NUCLEAR FUSION, 51(9).
Vancouver
1.
Kallenbach A, Adamek J, Aho-Mantila L, Aekaeslompolo S, Angioni C, Atanasiu C, et al. Overview of ASDEX Upgrade results. NUCLEAR FUSION. 2011;51(9).
MLA
Kallenbach, A, J Adamek, L Aho-Mantila, et al. “Overview of ASDEX Upgrade Results.” NUCLEAR FUSION 51.9 (2011): n. pag. Print.