Theory of drift-thermal instability-induced turbulence

Ware, A. S.; Diamond, P. H.; Carreras, B. A.; Leboeuf, J. N.; Lee, D. K.

doi:10.1063/1.860449

Cited by 36 publications

(20 citation statements)

References 23 publications

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“…[1][2][3][4][5] It is reasonable to inquire as to whether this phenomenon is widespread in plasmas or peculiar to some restricted set of physical processes, parameter regimes, and models. To provide a partial answer to this question, we survey here nine two-field fluid models for plasma turbulence, [8][9][10][11][12][13][14][15][16] representing a wide range of physical mechanisms for instability, turbulent mode coupling, and parameter regimes. The models describe trapped electron mode turbulence, 8 local Hasegawa-Wakatani turbulence, 9 two-dimensional turbulence driven by the Rayleigh-Taylor instability, 10 local electrostatic resistive g-mode turbulence, 11 ion temperature gradient turbulence, 12 microtearing mode turbulence, 13 a variant of microtearing turbulence with temperature fluctuations, 14 a thermally driven edge drift wave, 15 and an edge drift wave driven by ionization and charge exchange processes.…”

Section: Introductionmentioning

confidence: 99%

Damped eigenmode saturation in plasma fluid turbulence

et al. 2011

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A broad sample of fluid models for instability-driven plasma turbulence is surveyed to determine whether saturation involving damped eigenmodes requires special physics or is a common property of plasma turbulence driven by instability. Previous investigations have focused exclusively on turbulence in the core of tokamak discharges. The models surveyed here apply to a wide range of physical mechanisms for instability, turbulent mode coupling, and parameter regimes, with the common modeling feature that the physics has been reduced to a two-field fluid description. All the models have regimes in which damped eigenmodes saturate the instability by damping the fluctuation energy at a rate comparable to the injection rate by the unstable eigenmode. A test function derived from model parameters is found to predict when damped eigenmodes provide saturation. This confirms that a critical condition for saturation by damped eigenmodes is that the damping rate of the damped eigenmode does not greatly exceed the growth rate. For the quadratic dispersion relation of two-field models, this tends to hold in regimes of stronger instability and for regimes with strong gradients and strong diamagnetic frequency. Nonlinear coupling also matters. Strong coupling can overcome the effects of heavy damping, while weak coupling can prevent a damped eigenmode from saturating turbulence even though it is not heavily damped. This study indicates that damped eigenmodes represent a pervasive mechanism for the saturation of plasma instability in fluid descriptions, complementing recent works showing these effects in comprehensive gyrokinetic models.

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Section: Introductionmentioning

confidence: 99%

Damped eigenmode saturation in plasma fluid turbulence

et al. 2011

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“…For edge fluctuations, the understanding is at a more primitive level. Although numerous instabilities have been explored theoretically and tested experimentally, [3][4][5][6][7][8] none have yet been recovered both the universalit/ and the large amplitude of observations. (Some recent theories lO -12 are possible but not yet well-tested.)…”

Section: Introductionmentioning

confidence: 99%

Drift wave propagation as a source of plasma edge turbulence: Slab theory

Mattor

Diamond²

1994

Physics of Plasmas

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In a recent work [N. Mattor and P. H. Diamond, Phys. Rev. Lett. 62, 486 (1994)], it was suggested that large amplitude turbulence in edge plasmas [nlno-O( 1)] could originate from the core, reaching large amplitude when encountering regions of low density and temperature. Here the slab model of that theory is elaborated on and generalized to the case of nonadiabatic electron dynamics. It is shown that a drift wave launched with nlno<{l in a dense region can propagate into a sparse region and amplify. It is shown that such waves cannot propagate into regions with a large increase of velocity, suggesting a simple explanation of the observed correlation between edge shear flows and high confinement (HH" modes). It is shown that a wave launched in the adiabatic regime can become nonadiabatic when propagating into a low density and temperature edge region, suggesting a possible explanation for probe measurements.

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“…Most of these efforts have been performed in a simplified geometry, with a focus on the nonlinear regime. 12,13 In this paper, we consider the effects of atomic physics on the _]near stability of dissipative drift waves in toroidal geometry. It has been shown that in toroidal geometry, the coupling of adjacent poloidal harmonics readers magnetic shear induced damping ineffective.…”

Section: Introductionmentioning

confidence: 99%

Atomic physics effects on dissipative toroidal drift wave stability

Beer¹,

Hahm²

1992

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Theory of drift-thermal instability-induced turbulence

Cited by 36 publications

References 23 publications

Damped eigenmode saturation in plasma fluid turbulence

Damped eigenmode saturation in plasma fluid turbulence

Drift wave propagation as a source of plasma edge turbulence: Slab theory

Atomic physics effects on dissipative toroidal drift wave stability

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