Turbulence characteristics of the I-mode confinement regime in ASDEX Upgrade

The ASDEX Upgrade Team; P. Manz; T. Happel; F. Ryter; M. Bernert; G. Birkenmeier; G. D. Conway; M. Dunne; L. Guimarais; P. Hennequin; A. Hetzenecker; C. Honoré; P. Lauber; M. Maraschek; V. E. Nikolaeva; D. Prisiazhniuk; U. Stroth; E. Viezzer

doi:10.1088/1741-4326/aa7476

Turbulence characteristics of the I-mode confinement regime in ASDEX Upgrade

The ASDEX Upgrade Team, P. Manz, T. Happel, F. Ryter, M. Bernert, G. Birkenmeier, G. D. Conway, M. Dunne, L. Guimarais, P. Hennequin, A. Hetzenecker, C. Honoré, P. Lauber, M. Maraschek, V. E. Nikolaeva, D. Prisiazhniuk, U. Stroth, E. Viezzer

Chair of Plasmarand- und Divertorphysik

Research output: Contribution to journal › Article › peer-review

16 Scopus citations

Abstract

Besides strong geodesic acoustic mode (GAM) activity, turbulence in the I-mode confinement regime of ASDEX Upgrade exhibits two prominent features, the weakly coherent mode (WCM) and strongly intermittent solitary density perturbations. The nonlinear interaction between these structures is studied in detail by means of a conditional averaged wavelet-bicoherence analysis. The wavelet analysis reveals that these density perturbations are at the WCM frequency. The GAM is coupled to all frequency scales of the velocity fluctuations via a modulational instability. The WCM shows coupling to higher frequencies prior to the bursts, indicating a process resembling wave-steepening. A possible mechanism for the generation of such solitary density perturbations by a Korteweg-de Vries-like nonlinearity is discussed.

Original language	English
Article number	086022
Journal	Nuclear Fusion
Volume	57
Issue number	8
DOIs	https://doi.org/10.1088/1741-4326/aa7476
State	Published - 29 Jun 2017

Keywords

GAM
I-mode
intermittency
wavelets

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10.1088/1741-4326/aa7476

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ASDEX Upgrade Team, T., Manz, P., Happel, T., Ryter, F., Bernert, M., Birkenmeier, G., Conway, G. D., Dunne, M., Guimarais, L., Hennequin, P., Hetzenecker, A., Honoré, C., Lauber, P., Maraschek, M., Nikolaeva, V. E., Prisiazhniuk, D., Stroth, U., & Viezzer, E. (2017). Turbulence characteristics of the I-mode confinement regime in ASDEX Upgrade. Nuclear Fusion, 57(8), Article 086022. https://doi.org/10.1088/1741-4326/aa7476

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title = "Turbulence characteristics of the I-mode confinement regime in ASDEX Upgrade",

abstract = "Besides strong geodesic acoustic mode (GAM) activity, turbulence in the I-mode confinement regime of ASDEX Upgrade exhibits two prominent features, the weakly coherent mode (WCM) and strongly intermittent solitary density perturbations. The nonlinear interaction between these structures is studied in detail by means of a conditional averaged wavelet-bicoherence analysis. The wavelet analysis reveals that these density perturbations are at the WCM frequency. The GAM is coupled to all frequency scales of the velocity fluctuations via a modulational instability. The WCM shows coupling to higher frequencies prior to the bursts, indicating a process resembling wave-steepening. A possible mechanism for the generation of such solitary density perturbations by a Korteweg-de Vries-like nonlinearity is discussed.",

keywords = "GAM, I-mode, intermittency, wavelets",

author = "{ASDEX Upgrade Team}, The and P. Manz and T. Happel and F. Ryter and M. Bernert and G. Birkenmeier and Conway, {G. D.} and M. Dunne and L. Guimarais and P. Hennequin and A. Hetzenecker and C. Honor{\'e} and P. Lauber and M. Maraschek and Nikolaeva, {V. E.} and D. Prisiazhniuk and U. Stroth and E. Viezzer",

note = "Publisher Copyright: {\textcopyright} Max-Planck-Institut fuer Plasmaphysik.",

year = "2017",

month = jun,

day = "29",

doi = "10.1088/1741-4326/aa7476",

language = "English",

volume = "57",

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ASDEX Upgrade Team, T, Manz, P, Happel, T, Ryter, F, Bernert, M, Birkenmeier, G, Conway, GD, Dunne, M, Guimarais, L, Hennequin, P, Hetzenecker, A, Honoré, C, Lauber, P, Maraschek, M, Nikolaeva, VE, Prisiazhniuk, D, Stroth, U & Viezzer, E 2017, 'Turbulence characteristics of the I-mode confinement regime in ASDEX Upgrade', Nuclear Fusion, vol. 57, no. 8, 086022. https://doi.org/10.1088/1741-4326/aa7476

TY - JOUR

T1 - Turbulence characteristics of the I-mode confinement regime in ASDEX Upgrade

AU - ASDEX Upgrade Team, The

AU - Manz, P.

AU - Happel, T.

AU - Ryter, F.

AU - Bernert, M.

AU - Birkenmeier, G.

AU - Conway, G. D.

AU - Dunne, M.

AU - Guimarais, L.

AU - Hennequin, P.

AU - Hetzenecker, A.

AU - Honoré, C.

AU - Lauber, P.

AU - Maraschek, M.

AU - Nikolaeva, V. E.

AU - Prisiazhniuk, D.

AU - Stroth, U.

AU - Viezzer, E.

PY - 2017/6/29

Y1 - 2017/6/29

N2 - Besides strong geodesic acoustic mode (GAM) activity, turbulence in the I-mode confinement regime of ASDEX Upgrade exhibits two prominent features, the weakly coherent mode (WCM) and strongly intermittent solitary density perturbations. The nonlinear interaction between these structures is studied in detail by means of a conditional averaged wavelet-bicoherence analysis. The wavelet analysis reveals that these density perturbations are at the WCM frequency. The GAM is coupled to all frequency scales of the velocity fluctuations via a modulational instability. The WCM shows coupling to higher frequencies prior to the bursts, indicating a process resembling wave-steepening. A possible mechanism for the generation of such solitary density perturbations by a Korteweg-de Vries-like nonlinearity is discussed.

AB - Besides strong geodesic acoustic mode (GAM) activity, turbulence in the I-mode confinement regime of ASDEX Upgrade exhibits two prominent features, the weakly coherent mode (WCM) and strongly intermittent solitary density perturbations. The nonlinear interaction between these structures is studied in detail by means of a conditional averaged wavelet-bicoherence analysis. The wavelet analysis reveals that these density perturbations are at the WCM frequency. The GAM is coupled to all frequency scales of the velocity fluctuations via a modulational instability. The WCM shows coupling to higher frequencies prior to the bursts, indicating a process resembling wave-steepening. A possible mechanism for the generation of such solitary density perturbations by a Korteweg-de Vries-like nonlinearity is discussed.

KW - GAM

KW - I-mode

KW - intermittency

KW - wavelets

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U2 - 10.1088/1741-4326/aa7476

DO - 10.1088/1741-4326/aa7476

M3 - Article

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SN - 0029-5515

VL - 57

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 8

M1 - 086022

ER -

Turbulence characteristics of the I-mode confinement regime in ASDEX Upgrade

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Keywords

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