Geodesic mode instability driven by electron and ion fluxes in tokamaks

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Geodesic mode instability driven by electron and ion fluxes in tokamaks

Popis výsledku v původním jazyce

Geodesic Acoustic Modes (GAM) are M=0, N=0 axisymmetric toroidal modes combined with M=1, 2 poloidal side-bands and driven by the electron and anisotropic ion pressure perturbations with the frequency omega_G^2 = (7T_i/2+2T_e)/R_0^2m_i. These modes may be important for plasma transport as it has been theoretically discussed [2] and observed in experiments [4-7]. Furthermore, they may be useful as a diagnostic tool to indicate L-H confinement transition in tokamaks [5]. Eigenmodes in the geodesic frequency range have been experimentally detected under a wide range of conditions in various tokamaks. Typically, GAM oscillations are observed during counter NB injection [7,8], but they may also appear in ohmic discharges [6,8]. The nature of the experimentally observed geodesic eigenmodes is still not clear and several different mechanisms might be responsible for their dispersion and manifest themselves in different conditions. Recently, it has been theoretically shown that GAMs may be driven by an electric current with velocity along the equilibrium magnetic field in combination with the diamagnetic drift [3]. The instability occurs only when the electron current velocity is higher than the GAM phase velocity of sidebands, V_{e0}>RqomeganHere, we extend previous studies [3] and investigate whether the parallel plasma flow can drive the GAMs via coupling with the ion drift dynamics or/and the parallel current. Finally, comparison with NB experiments in COMPASS tokamak is discussed.nnnn

Název v anglickém jazyce

Geodesic mode instability driven by electron and ion fluxes in tokamaks

Popis výsledku anglicky

Geodesic Acoustic Modes (GAM) are M=0, N=0 axisymmetric toroidal modes combined with M=1, 2 poloidal side-bands and driven by the electron and anisotropic ion pressure perturbations with the frequency omega_G^2 = (7T_i/2+2T_e)/R_0^2m_i. These modes may be important for plasma transport as it has been theoretically discussed [2] and observed in experiments [4-7]. Furthermore, they may be useful as a diagnostic tool to indicate L-H confinement transition in tokamaks [5]. Eigenmodes in the geodesic frequency range have been experimentally detected under a wide range of conditions in various tokamaks. Typically, GAM oscillations are observed during counter NB injection [7,8], but they may also appear in ohmic discharges [6,8]. The nature of the experimentally observed geodesic eigenmodes is still not clear and several different mechanisms might be responsible for their dispersion and manifest themselves in different conditions. Recently, it has been theoretically shown that GAMs may be driven by an electric current with velocity along the equilibrium magnetic field in combination with the diamagnetic drift [3]. The instability occurs only when the electron current velocity is higher than the GAM phase velocity of sidebands, V_{e0}>RqomeganHere, we extend previous studies [3] and investigate whether the parallel plasma flow can drive the GAMs via coupling with the ion drift dynamics or/and the parallel current. Finally, comparison with NB experiments in COMPASS tokamak is discussed.nnnn

Druh

D - Stať ve sborníku

CEP obor

BL - Fyzika plasmatu a výboje v plynech

OECD FORD obor

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Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

EPS 2016: 43rd European Physical Society Conference on Plasma Physics

ISBN

2-914771-99-1

ISSN

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e-ISSN

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Počet stran výsledku

4

Strana od-do

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Název nakladatele

European Physical Society

Místo vydání

Mulhouse

Místo konání akce

Leuven

Datum konání akce

4. 7. 2016

Typ akce podle státní příslušnosti

EUR - Evropská akce

Kód UT WoS článku

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