Effect of the relative shift between the electron density and temperature pedestal position on the pedestal stability in JET-ILW and comparison with JET-C
García Muñoz, Manuel
|Department||Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear|
|Abstract||The electron temperature and density pedestals tend to vary in their relative radial positions,
as observed in DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) and ASDEX Upgrade
(Dunne et al 2017 Plasma Phys. Control. ...
The electron temperature and density pedestals tend to vary in their relative radial positions, as observed in DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) and ASDEX Upgrade (Dunne et al 2017 Plasma Phys. Control. Fusion 59 14017). This so-called relative shift has an impact on the pedestal magnetohydrodynamic (MHD) stability and hence on the pedestal height (Osborne et al 2015 Nucl. Fusion 55 063018). The present work studies the effect of the relative shift on pedestal stability of JET ITER-like wall (JET-ILW) baseline low triangularity (δ) unseeded plasmas, and similar JET-C discharges. As shown in this paper, the increase of the pedestal relative shift is correlated with the reduction of the normalized pressure gradient, therefore playing a strong role in pedestal stability. Furthermore, JET-ILW tends to have a larger relative shift compared to JET carbon wall (JET-C), suggesting a possible role of the plasma facing materials in affecting the density profile location. Experimental results are then compared with stability analysis performed in terms of the peeling-ballooning model and with pedestal predictive model EUROPED (Saarelma et al 2017 Plasma Phys. Control. Fusion). Stability analysis is consistent with the experimental findings, showing an improvement of the pedestal stability, when the relative shift is reduced. This has been ascribed mainly to the increase of the edge bootstrap current, and to minor effects related to the increase of the pedestal pressure gradient and narrowing of the pedestal pressure width. Pedestal predictive model EUROPED shows a qualitative agreement with experiment, especially for low values of the relative shift.
|Citation||Stefanikova, E., Frassinetti, L., Saarelma, S., Loarte, A., Nunes, I., Jet Contributors, y García Muñoz, M. (2018). Effect of the relative shift between the electron density and temperature pedestal position on the pedestal stability in JET-ILW and comparison with JET-C. Nuclear Fusion, 58 (5), 1-12.|
Except where otherwise noted, this item's license is described as: Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Showing items related by title, author, creator and subject.
Maggi, C.F.; Frassinetti, L.; Horvath, L.; Lunniss, A.; Saarelma, S.; Jet Contributors; García Muñoz, Manuel (IOP Publishing, 2017-11)
The pedestal structure of type I ELMy H-modes has been analysed for JET with the ITERlike Wall (JET-ILW). The electron ...
Global and pedestal confinement and pedestal structure in dimensionless collisionality scans of low-triangularity H-mode plasmas in JET-ILW Frassinetti, L.; Beurskens, M.; Saarelma, S.; Boom, J. E.; Delabie, E.; Jet Contributors; García Muñoz, Manuel (IOP Publishing, 2017-01)
Abstract A dimensionless collisionality scan in low-triangularity plasmas in the Joint European Torus with the ITER-like ...
Silvagni, D.; Eich, T.; Happel, T.; Harrer, G. F.; Griener, M.; Dunne, M. G.; Cavedon, M.; Faitsch, M.; Viezzer, Eleonora (IOP Publishing, 2020)
The I-mode confinement regime can feature small edge temperature drops that can lead to an increase in the energy deposited ...