Nonlocal Linear Theory of Neutral Driven Modes Near the Divertor

McCarthy, D. R.; Tucker, S. P.; Krasheninnikov, S. I.; Catto, Peter J.

doi:10.1002/ctpp.2150380130

Cited by 4 publications

(5 citation statements)

References 2 publications

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“…This instability is well known in experiments with weakly ionized plasmas 4,5 and was thought possibly to be relevant to divertor plasmas. [1][2][3] The main results of this study are as follows. First, it was shown that the ion-neutral interaction terms can be large for modest neutral pressures ( p 0d /p d Ӷ1) and densities (n 0d /n id Ͻ1); the neutral terms tend to be stabilizing for typical attached and detached divertor plasmas ͑see Table II and Fig.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…[1][2][3] Elastic collisions and charge exchange between the ion and neutral fluids introduce an effective frictional force fϭϪ(uϪu 0 )ϭϪ"p 0 /, where the latter form of f follows from the equilibrium pressure balance relation. Here, the subscript 0 denotes neutral quantities, is the frequency of ion-neutral ''collisions'' ͑typically dominated by charge exchange͒, (uϪu 0 ) denotes the relative speed of the ion and neutral fluids, is the plasma mass density, and p 0 is the neutral pressure.…”

Section: Introductionmentioning

confidence: 99%

“…Finally, a simulation of the nonlinear phase, again in slab geometry, concluded that the saturation levels of the mode could be substantial. 3 Two aspects of the problem require further treatment in order to draw conclusions about the relevance of this instability to realistic tokamak plasmas. First, the stability picture was shown to be extremely sensitive to the details of a model X-point geometry and to the assumed plasma and neutral profiles.…”

Section: Introductionmentioning

confidence: 99%

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Effect of neutrals on scrape-off-layer and divertor stability in tokamaks

D’Ippolito

Myra

1999

Physics of Plasmas

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The influence of ion-neutral interactions ͑charge exchange, elastic scattering͒ on scrape-off-layer ͑SOL͒ stability is studied in the eikonal limit for a single-null X-point geometry typical of tokamak divertors. Instability drives due to curvature and to the ion-neutral drag effect are included in the model. The ion-neutral interaction terms are highly localized near the divertor plates; these terms are stabilizing for typical parameters and large enough to affect the SOL ballooning-interchange stability in the absence of resistivity. It is shown that the growth rate of ideal curvature-driven modes is significantly reduced by the ion-neutral interaction terms; the growth rate of resistive ballooning modes is not affected much by the neutrals, because resistivity allows the mode to disconnect from the divertor region. In both cases, the X-point geometry significantly affects the stability. An ion-neutral drag instability localized near the plates is only found in a small region of parameter space. Conditions for the existence of this instability in X-point geometry are discussed.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of neutrals on scrape-off-layer and divertor stability in tokamaks

D’Ippolito

Myra

1999

Physics of Plasmas

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“…In order to get a better feel for the actual mode structure and dispersion relation of the instability ͑and ultimately test the accuracy of our code͒, we extend the local analysis of the previous section to a nonlocal analysis, 7 where the radial scale of the mode can be of the same order as the background density variation, i.e., k x L x ϳ1. We start by combining Eq.…”

Section: Nonlocal Linear Theorymentioning

confidence: 99%

Nonlinear saturation of the neutral driven interchange mode

et al. 1999

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The nonlinear behavior of a flutelike interchange mode driven by a background neutral pressure gradient in the collisionless regime has been studied both numerically and analytically. It is found that the mode saturates when the current produced by the friction force of the perturbed E×B drift against the neutrals balances the equilibrium ion current. Based upon this physical picture of the saturation mechanism, an analytical expression for the magnitude of the fluctuation levels as a function of the collisionality and magetization of the plasma is derived. An important result from these simulations is that the mode always grows to a state where kyLN∼1.

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“…It was shown that the interaction of neutrals with plasma through several effective collision processes such as elastic and chargeexchange collisions plays an important role in establishing a detached divertor regime [1] and the transitions between L and H modes [2][3][4][5]. It also demonstrated that the plasma-neutral interaction can largely affect the edge plasma instabilities and turbulent processes [6][7][8][9][10][11] and thus, accounting for such interaction in the study of anomalous edge plasma transport seems to be irrefutable.…”

Section: Introductionmentioning

confidence: 99%

Effect of neutrals on the anomalous edge plasma transport

Zhang

Krasheninnikov

2020

Plasma Phys. Control. Fusion

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The impact of neutrals on the anomalous edge plasma transport is examined in detail within the resistive drift wave (RDW) turbulence and zonal flow (ZF) system. It is shown that the neutral impact on the RDW turbulence itself is weak, but it can largely damp the ZF and thus lead to an enhancement of the anomalous transport. Such an impact is stronger for the system with a larger adiabatic parameter, where the ZF is more dominant in the absence of neutrals. It is shown that the enhancement of the anomalous transport is related to the detrapping of fluctuations from the vicinity of the extrema of ZF when the neutrals weaken the ZF effect.

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Nonlocal Linear Theory of Neutral Driven Modes Near the Divertor

Cited by 4 publications

References 2 publications

Effect of neutrals on scrape-off-layer and divertor stability in tokamaks

Effect of neutrals on scrape-off-layer and divertor stability in tokamaks

Nonlinear saturation of the neutral driven interchange mode

Effect of neutrals on the anomalous edge plasma transport

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