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Snyder, P. B.*; Aiba, Nobuyuki; Beurskens, M.*; Groebner, R. J.*; Horton, L. D.*; Hubbard, A. E.*; Hughes, J. W.*; Huysmans, G. T. A.*; Kamada, Yutaka; Kirk, A.*; et al.
Nuclear Fusion, 49(8), p.085035_1 - 085035_8, 2009/08
Times Cited Count：170 Percentile：98.64(Physics, Fluids & Plasmas)The pressure at the top of the edge transport barrier impacts fusion performance, while large ELMs can constrain material lifetimes. Investigation of intermediate wavelength MHD mode has led to improved understanding of the pedestal height and the mechanism for ELMs. The combination of high resolution diagnostics and a suite of stability codes has made edge stability analysis routine, and contribute both to understanding, and to experimental planning and performance optimization. Here we present extensive comparisons of observations to predicted edge stability boundaries on several tokamaks, both for the standard (Type I) ELM regime, and for small ELM and ELM-free regimes. We further discuss a new predictive model for the pedestal height and width (EPED1), developed by self-consistently combining a simple width model with peeling-ballooning stability calculations. This model is tested against experimental measurements, and used in initial predictions of the pedestal height for ITER.
Snyder, P. B.*; Aiba, Nobuyuki; Beurskens, M.*; Groebner, R. J.*; Horton, L. D.*; Hubbard, A. E.*; Hughes, J. W.*; Huysmans, G. T. A.*; Kamada, Yutaka; Kirk, A.*; et al.
Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10
Investigation of intermediate wavelength MHD modes has led to improved understanding of important constraints on the pedestal height and the mechanism for ELMs. The combination of high resolution pedestal diagnostics and a suite of highly efficient stability codes, has made edge stability analysis routine on several major tokamaks, contributing both to understanding, and to experimental planning and performance optimization. Here we present extensive comparisons of observations to predicted edge stability boundaries on several tokamaks, both for the standard ELM regime, and for small ELM and ELM-free regimes. We further use the stability constraint on pedestal height to test models of the pedestal width, and self-consistently combine a simple width model with MHD stability calculations to develop a new predictive model (EPED1) for the pedestal height and width. This model is tested against experimental measurements, and used in initial predictions of the pedestal height for ITER.
Chankin, A. V.*; Coster, D. P.*; Asakura, Nobuyuki; Bonnin, X.*; Conway, G. D.*; Corrigan, G.*; Erents, S. K.*; Fundamenski, W.*; Horacek, J.*; Kallenbach, A.*; et al.
Nuclear Fusion, 47(5), p.479 - 489, 2007/05
Times Cited Count：34 Percentile：73.71(Physics, Fluids & Plasmas)Radial electric field in known to be one of the drivers for the parallel ion flow in the SOL. It contributes to the ion Pfirsch-Schluter flow and determines the return parallel flow compensating poloidal ExB drift. It was established recently that 2D fluid codes EDGE2D and SOLPS underestimate the predicted Er in the SOL compared to experimentally measured values. The present work demonstrates that this underestimate can be responsible for the large discrepancy between measured and simulated parallel ion flows in the SOL. Provided radial electric field was modelled correctly by the codes, an increase in the predicted Mach number of the parallel ion flow by up to a factor 3 for the JET could be expected. This would entirely eliminate the difference between the experimentally determined part of the ion flow that depends on the toroidal field direction, and the modelled ion flow attributed to drifts. Discrepancy between measured and simulated flows in ASDEX-Upgrade was also reduced.
