First steps towards modeling of ion-driven turbulence in Wendelstein 7-X

F. Warmer, P. Xanthopoulos, J.H.E. Proll, C.D. Beidler, Y. Turkin, R.C. Wolf

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

Uittreksel

Due to foreseen improvement of neoclassical confinement in optimised stellarators - like the newly commissioned Wendelstein 7-X (W7-X) experiment in Greifswald, Germany - it is expected that turbulence will significantly contribute to the heat and particle transport, thus posing a limit to the performance of such devices. In order to develop discharge scenarios, it is thus necessary to develop a model which could reliably capture the basic characteristics of turbulence and try to predict the levels thereof. The outcome will not only be affordable, using only a fraction of the computational cost which is normally required for repetitive direct turbulence simulations, but would also highlight important physics. In this model, we seek to describe the ion heat flux caused by ion temperature gradient (ITG) micro-turbulence, which, in certain heating scenarios, can be a strong source of free energy. With the aid of a relatively small number of state-of-the-art nonlinear gyrokinetic simulations, an initial critical gradient model (CGM) is devised, with the aim to replace an empirical model, stemming from observations in prior stellarator experiments. The novel CGM, in its present form, encapsulates all available knowledge about ion-driven 3D turbulence to date, also allowing for further important extensions, towards an accurate interpretation and prediction of the 'anomalous' transport. The CGM depends on the stiffness of the ITG turbulence scaling in W7-X, and implicitly includes the nonlinear zonal flow response. It is shown that the CGM is suitable for a 1D framework turbulence modeling.

TaalEngels
Artikelnummer016017
TijdschriftNuclear Fusion
Volume58
Nummer van het tijdschrift1
DOI's
StatusGepubliceerd - 1 jan 2018

Vingerafdruk

turbulence
ions
gradients
stellarators
ion temperature
temperature gradients
Germany
heat flux
stiffness
simulation
free energy
costs
scaling
heat
physics
heating
predictions

Trefwoorden

    Citeer dit

    Warmer, F., Xanthopoulos, P., Proll, J. H. E., Beidler, C. D., Turkin, Y., & Wolf, R. C. (2018). First steps towards modeling of ion-driven turbulence in Wendelstein 7-X. Nuclear Fusion, 58(1), [016017]. DOI: 10.1088/1741-4326/aa9290
    Warmer, F. ; Xanthopoulos, P. ; Proll, J.H.E. ; Beidler, C.D. ; Turkin, Y. ; Wolf, R.C./ First steps towards modeling of ion-driven turbulence in Wendelstein 7-X. In: Nuclear Fusion. 2018 ; Vol. 58, Nr. 1.
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    title = "First steps towards modeling of ion-driven turbulence in Wendelstein 7-X",
    abstract = "Due to foreseen improvement of neoclassical confinement in optimised stellarators - like the newly commissioned Wendelstein 7-X (W7-X) experiment in Greifswald, Germany - it is expected that turbulence will significantly contribute to the heat and particle transport, thus posing a limit to the performance of such devices. In order to develop discharge scenarios, it is thus necessary to develop a model which could reliably capture the basic characteristics of turbulence and try to predict the levels thereof. The outcome will not only be affordable, using only a fraction of the computational cost which is normally required for repetitive direct turbulence simulations, but would also highlight important physics. In this model, we seek to describe the ion heat flux caused by ion temperature gradient (ITG) micro-turbulence, which, in certain heating scenarios, can be a strong source of free energy. With the aid of a relatively small number of state-of-the-art nonlinear gyrokinetic simulations, an initial critical gradient model (CGM) is devised, with the aim to replace an empirical model, stemming from observations in prior stellarator experiments. The novel CGM, in its present form, encapsulates all available knowledge about ion-driven 3D turbulence to date, also allowing for further important extensions, towards an accurate interpretation and prediction of the 'anomalous' transport. The CGM depends on the stiffness of the ITG turbulence scaling in W7-X, and implicitly includes the nonlinear zonal flow response. It is shown that the CGM is suitable for a 1D framework turbulence modeling.",
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    Warmer, F, Xanthopoulos, P, Proll, JHE, Beidler, CD, Turkin, Y & Wolf, RC 2018, 'First steps towards modeling of ion-driven turbulence in Wendelstein 7-X' Nuclear Fusion, vol. 58, nr. 1, 016017. DOI: 10.1088/1741-4326/aa9290

    First steps towards modeling of ion-driven turbulence in Wendelstein 7-X. / Warmer, F.; Xanthopoulos, P.; Proll, J.H.E.; Beidler, C.D.; Turkin, Y.; Wolf, R.C.

    In: Nuclear Fusion, Vol. 58, Nr. 1, 016017, 01.01.2018.

    Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

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    AU - Xanthopoulos,P.

    AU - Proll,J.H.E.

    AU - Beidler,C.D.

    AU - Turkin,Y.

    AU - Wolf,R.C.

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    KW - Gyrokinetic simulations

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    KW - ion-temperature-gradient turbulence

    KW - stellarators

    KW - transport modeling

    KW - Wendelstein 7-X

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    Warmer F, Xanthopoulos P, Proll JHE, Beidler CD, Turkin Y, Wolf RC. First steps towards modeling of ion-driven turbulence in Wendelstein 7-X. Nuclear Fusion. 2018 jan 1;58(1). 016017. Beschikbaar vanaf, DOI: 10.1088/1741-4326/aa9290