H-mode pedestal scaling in DIII-D, ASDEX upgrade, and JET

M.N.A. Beurskens, T.H. Osborne, P.A. Schneider, E. Wolfrum, L. Frassinetti, R. Groebner, P. Lomas, I. Nunes, S. Saarelma, R. Scannell, P.B. Snyder, D. Zarzoso, I. Balboa, B. Bray, M. Brix, J. Flanagan, C. Giroud, E. Giovannozzi, M. Kempenaars, A. LoarteE. De La Luna, G. Maddison, C.F. Maggi, D. McDonald, R. Pasqualotto, G. Saibene, R. Sartori, E. Solano, M. Walsh, L. Zabeo

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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 Δ/a ρ*1/2to ρ* based on the radial extent of the pedestal being set by the point where the linear turbulence growth rate exceeds the E × B velocity. In the multidevice experiment where ρ* 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 ρ* 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 Δψ∝ βp1/2. All three devices show a scaling of the pedestal width in normalised poloidal flux as Δψ∝ βp1/2, 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. © 2011 American Institute of Physics.
Original languageEnglish
Article number056120
Pages (from-to)-
JournalPhysics of Plasmas
Volume18
Issue number5
DOIs
Publication statusPublished - May 2011
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

Cite this

Beurskens, M. N. A., Osborne, T. H., Schneider, P. A., Wolfrum, E., Frassinetti, L., Groebner, R., Lomas, P., Nunes, I., Saarelma, S., Scannell, R., Snyder, P. B., Zarzoso, D., Balboa, I., Bray, B., Brix, M., Flanagan, J., Giroud, C., Giovannozzi, E., Kempenaars, M., ... Zabeo, L. (2011). H-mode pedestal scaling in DIII-D, ASDEX upgrade, and JET. Physics of Plasmas, 18(5), -. [056120]. https://doi.org/10.1063/1.3593008