Turbulence intermittency linked to the weakly coherent mode in ASDEX Upgrade I-mode plasmas. (24th May 2016)

• Record Type: Journal Article
• Authors: Happel, T.; Manz, P.; Ryter, F.; Hennequin, P.; Hetzenecker, A.; Conway, G.D.; Guimarais, L.; Honoré, C.; Stroth, U.; Viezzer, E.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 56:Number 6(2016:Jun.)
• Publication Date: 2016-05-24
• Subjects: plasma turbulence -- tokamaks -- microwave measurements -- I-mode -- intermittency -- weakly coherent mode; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/0029-5515/56/6/064004
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: This letter shows for the first time a pronounced increase of extremely intermittent edge density turbulence behavior inside the confinement region related to the I-mode confinement regime in the ASDEX Upgrade tokamak. With improving confinement, the perpendicular propagation velocity of density fluctuations in the plasma edge increases together with the intermittency of the observed density bursts. Furthermore, it is shown that the weakly coherent mode, a fluctuation feature generally observed in I-mode plasmas, is connected to the observed bursts. It is suggested that the large amplitude density bursts could be generated by a non-linearity similar to that in the Korteweg–de-Vries equation which includes the radial temperature gradient.