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Title: H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET

Abstract

Multidevice pedestal scaling experiments in the DIII-D, ASDEX Upgrade (AUG), and JET tokamaks are presented in order to test two plasma physics pedestal width models. The first model proposes a scaling of the pedestal width {Delta}/a {proportional_to} {rho}*{sup 1/2} to {rho}* based on the radial extent of the pedestal being set by the point where the linear turbulence growth rate exceeds the ExB velocity. In the multidevice experiment where {rho}* at the pedestal top was varied by a factor of four while other dimensionless parameters where kept fixed, it has been observed that the temperature pedestal width in real space coordinates scales with machine size, and that therefore the gyroradius scaling suggested by the model is not supported by the experiments. The density pedestal width is not invariant with {rho}* which after comparison with a simple neutral fuelling model may be attributed to variations in the neutral fuelling patterns. The second model, EPED1, is based on kinetic ballooning modes setting the limit of the radial extent of the pedestal region and leads to {Delta}{sub {psi} {proportional_to}} {beta}{sub p}{sup 1/2}. All three devices show a scaling of the pedestal width in normalised poloidal flux as {Delta}{sub {psi} {proportional_to}} {beta}{sub p}{sup 1/2},more » as described by the kinetic ballooning model; however, on JET and AUG, this could not be distinguished from an interpretation where the pedestal is fixed in real space. Pedestal data from all three devices have been compared with the predictive pedestal model EPED1 and the model produces pedestal height values that match the experimental data well.« less

Authors:
; ; ; ; ; ; ; ; ; ;  [1]; ; ; ;  [2]; ; ;  [3];  [4];  [5]
  1. EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)
  2. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
  3. Association EURATOM-Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany)
  4. Association EURATOM-VR, Alfven Laboratory, School of Electrical Engineering, KTH, Stockholm (Sweden)
  5. Centro de Fusao Nuclear, Associacao EURATOM-IST, Lisboa (Portugal)
Publication Date:
OSTI Identifier:
21537883
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 18; Journal Issue: 5; Other Information: DOI: 10.1063/1.3593008; (c) 2011 American Institute of Physics; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ASDEX TOKAMAK; BALLOONING INSTABILITY; DOUBLET-3 DEVICE; H-MODE PLASMA CONFINEMENT; JET TOKAMAK; PLASMA DENSITY; SCALING; TURBULENCE; CLOSED PLASMA DEVICES; CONFINEMENT; INSTABILITY; MAGNETIC CONFINEMENT; PLASMA CONFINEMENT; PLASMA INSTABILITY; PLASMA MACROINSTABILITIES; THERMONUCLEAR DEVICES; TOKAMAK DEVICES

Citation Formats

Beurskens, M N. A., Lomas, P, Saarelma, S, Scannell, R, Balboa, I, Brix, M, Flanagan, J, Giroud, C, Kempenaars, M, Maddison, G, McDonald, D, Osborne, T H, Groebner, R, Snyder, P B, Bray, B, Schneider, P A, Wolfrum, E, Maggi, C F, Frassinetti, L, and Nunes, I. H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET. United States: N. p., 2011. Web. doi:10.1063/1.3593008.
Beurskens, M N. A., Lomas, P, Saarelma, S, Scannell, R, Balboa, I, Brix, M, Flanagan, J, Giroud, C, Kempenaars, M, Maddison, G, McDonald, D, Osborne, T H, Groebner, R, Snyder, P B, Bray, B, Schneider, P A, Wolfrum, E, Maggi, C F, Frassinetti, L, & Nunes, I. H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET. United States. https://doi.org/10.1063/1.3593008
Beurskens, M N. A., Lomas, P, Saarelma, S, Scannell, R, Balboa, I, Brix, M, Flanagan, J, Giroud, C, Kempenaars, M, Maddison, G, McDonald, D, Osborne, T H, Groebner, R, Snyder, P B, Bray, B, Schneider, P A, Wolfrum, E, Maggi, C F, Frassinetti, L, and Nunes, I. 2011. "H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET". United States. https://doi.org/10.1063/1.3593008.
@article{osti_21537883,
title = {H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET},
author = {Beurskens, M N. A. and Lomas, P and Saarelma, S and Scannell, R and Balboa, I and Brix, M and Flanagan, J and Giroud, C and Kempenaars, M and Maddison, G and McDonald, D and Osborne, T H and Groebner, R and Snyder, P B and Bray, B and Schneider, P A and Wolfrum, E and Maggi, C F and Frassinetti, L and Nunes, I},
abstractNote = {Multidevice pedestal scaling experiments in the DIII-D, ASDEX Upgrade (AUG), and JET tokamaks are presented in order to test two plasma physics pedestal width models. The first model proposes a scaling of the pedestal width {Delta}/a {proportional_to} {rho}*{sup 1/2} to {rho}* based on the radial extent of the pedestal being set by the point where the linear turbulence growth rate exceeds the ExB velocity. In the multidevice experiment where {rho}* at the pedestal top was varied by a factor of four while other dimensionless parameters where kept fixed, it has been observed that the temperature pedestal width in real space coordinates scales with machine size, and that therefore the gyroradius scaling suggested by the model is not supported by the experiments. The density pedestal width is not invariant with {rho}* which after comparison with a simple neutral fuelling model may be attributed to variations in the neutral fuelling patterns. The second model, EPED1, is based on kinetic ballooning modes setting the limit of the radial extent of the pedestal region and leads to {Delta}{sub {psi} {proportional_to}} {beta}{sub p}{sup 1/2}. All three devices show a scaling of the pedestal width in normalised poloidal flux as {Delta}{sub {psi} {proportional_to}} {beta}{sub p}{sup 1/2}, as described by the kinetic ballooning model; however, on JET and AUG, this could not be distinguished from an interpretation where the pedestal is fixed in real space. Pedestal data from all three devices have been compared with the predictive pedestal model EPED1 and the model produces pedestal height values that match the experimental data well.},
doi = {10.1063/1.3593008},
url = {https://www.osti.gov/biblio/21537883}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 5,
volume = 18,
place = {United States},
year = {Sun May 15 00:00:00 EDT 2011},
month = {Sun May 15 00:00:00 EDT 2011}
}