Nonlinear evolution of drift instabilities in the presence of collisions

Federici, John F.; Lee, W. W.; Tang, W. M.

doi:10.1063/1.866393

Cited by 20 publications

(20 citation statements)

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“…These simulations have revealed unexpected coherent nonlinear phenomena and unexpected parameter dependences of the particle flux (in the direction opposite to that of the mean density gradient) and the saturation levels. 3,2 Furthermore, similar phenomena are seen in simulations of the rj\ mode, 7 which has been invoked to explain ion thermal transport in tokamaks. 8 Thus, the understanding of these simulations may provide important insight into the behavior of more realistic cases.…”

Section: Introductionsupporting

confidence: 52%

“…Both the saturation levels and the particle flux increase with electron collisionality. 2 This was unexpected since the collisions are too weak to affect the linear growth rates significantly. The difficulty in understanding this dependence of the saturation levels and especially the particle fluxes on the collisionality motivated the present work.…”

Section: Introductionmentioning

confidence: 99%

“…Finally, the density distributions that result from and are advected by the E X B drift to produce the E X B diffusion and the regions of enhanced density require modes of quite high wave number for their adequate representation. The mode-coupling systems studied by Lee et al 3 and Federici et al 2 do not resolve the gyrocenter densities accurately enough to contain the effects of the E X B motion that con trol the particle fluxes which, in turn, affect the nonlinear dynamics of the particle simulations.…”

Section: Introductionmentioning

confidence: 99%

“…They arise because of the balance between the near-adiabatic electron response 6n/n 2; e4>/T c and the ion density perturbations due to the E X B advection of ions from an ion density distri bution with a nonzero density gradient, and are driven unstable by the combination of inverse electron Landau damping and finite ion-gyroradius or polarization-drift effects. The main results of the linear theory have been summarized by Federici, Lee, and Tang, 2 and will be repeated in Sec. III.…”

Section: Introductionmentioning

confidence: 99%

“…Some of the phenomena have been reported before. 2 In Sec. IV we derive the useful test-gyrocenter Hamiltonians for the cases of interest here as well as for nonzero shear.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear mechanisms for drift wave saturation and induced particle transport

Dimits

Lee

1991

Physics of Fluids B: Plasma Physics

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A detailed theoretical study of the nonlinear dynamics of gyrokinetic particle simulations of electrostatic collisionless and weakly collisionai drift waves is pre sented. In previous studies it was shown that, in the nonlinearly saturated phase of the evolution, the saturation levels and especially the particle fluxes have an unexpected dependence on collisionality. In this paper, the explanations for these collisionality dependences are found to be as follows: The saturation level is deter mined by a balance between the electron and ion fluxes. The ion flux is small for levels of the potential below an E X B-trapping threshold and increases sharply once this threshold is crossed. Due to the presence of resonant electrons, the elec tron flux has a much smoother dependence on the potential. In the 2 ^-dimensional ("pseudo-3D") geometry, the electrons are accelerated away from the resonance as they diffuse spatially, resulting in an inhibition of their diffusion. Collisions and three-dimensional effects can repopulate the resonance thereby increasing the value of the particle flux. DISCLAIMERThis report was prepared is an account of -work sponsored by an agency of ihe Uniiiai Slates Government. Neither Ihe United Stales Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsi bility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents thai its use would not infringe privately owned rights Refer ence herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise docs not necessarily constitute or imply its endorsement, recom mendation, or favoring by the United States Government or any agency thereof The views and opinions or authors expressed herein do not necessarily Hale or reflect those of Ihe United States Government or any agency thereof MASTER tp n jt/tl-J' •-

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Section: Introductionsupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Some of the phenomena have been reported before. 2 In Sec. IV we derive the useful test-gyrocenter Hamiltonians for the cases of interest here as well as for nonzero shear.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear mechanisms for drift wave saturation and induced particle transport

Dimits

Lee

1991

Physics of Fluids B: Plasma Physics

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Nonlinear evolution of the temperature gradient instability in the midlatitude ionosphere

Eltrass

Scales

2014

JGR Space Physics

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The midlatitude Super Dual Auroral Radar Network radars frequently observe quiet time decameter‐scale irregularities in the nightside subauroral ionosphere. Since opposed temperature and density gradients are a persistent feature in the vicinity of the ionospheric projection of the plasmapause, the temperature gradient instability (TGI) is proposed to explain the observed irregularities. In this paper, modeling of the TGI is extended into the kinetic regime appropriate for HF radar frequencies and analyzed as the cause of these irregularities. The nonlinear evolution of the TGI is investigated utilizing gyrokinetic particle‐in‐cell simulation techniques with Monte Carlo collisions for the first time. The purpose of this investigation is to identify the mechanism responsible for the nonlinear saturation as well as the associated anomalous transport. It is found that the saturation amplitude level and the associated diffusion are greatly enhanced as a result of electron collisions. The simulation results indicate that the nonlinear E×Bconvection (trapping) of the electrons is the dominant TGI saturation mechanism. The spatial power spectra of the electrostatic potential and density fluctuations associated with the TGI are also computed, and the results show wave cascading of TGI from kilometer scales into the decameter‐scale regime of the radar observations. This implies that the E region may be responsible for shorting out the F region TGI electric fields before and around sunset. This also suggests that the observed midlatitude decameter‐scale ionospheric irregularities may be produced directly by the TGI or by turbulent cascade from primary longer‐wavelength irregularity structures produced from this instability.

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Investigation of the role of plasma wave cascading processes in the formation of midlatitude irregularities utilizing GPS and radar observations

et al. 2016

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Recent studies reveal that midlatitude ionospheric irregularities are less understood due to lack of models and observations that can explain the characteristics of the observed wave structures. In this paper, the cascading processes of both the temperature gradient instability (TGI) and the gradient drift instability (GDI) are investigated as the cause of these irregularities. Based on observations obtained during a coordinated experiment between the Millstone Hill incoherent scatter radar and the Blackstone Super Dual Auroral Radar Network radar, a time series for the growth rate of both TGI and GDI is calculated for observations in the subauroral ionosphere under both quiet and disturbed geomagnetic conditions. Recorded GPS scintillation data are analyzed to monitor the amplitude scintillations and to obtain the spectral characteristics of irregularities producing ionospheric scintillations. Spatial power spectra of the density fluctuations associated with the TGI from nonlinear plasma simulations are compared with both the GPS scintillation spectral characteristics and previous in situ satellite spectral measurements. The spectral comparisons suggest that initially, TGI or/and GDI irregularities are generated at large-scale size (kilometer scale), and the dissipation of the energy associated with these irregularities occurs by generating smaller and smaller (decameter scale) irregularities. The alignment between experimental, theoretical, and computational results of this study suggests that in spite of expectations from linear growth rate calculations, cascading processes involving TGI and GDI are likely responsible for the midlatitude ionospheric irregularities associated with GPS scintillations during disturbed times.Potential space weather applications have paid attention to the spatial temporal variability of the midlatitude subauroral ionosphere during magnetic storm periods [e.g., Mishin et al., 2003;Ledvina et al., 2002;Foster et al., 2002;Basu et al., 2001Basu et al., , 2008. During disturbed geomagnetic conditions, large regions hosting an ionospheric density gradient exist in the evening sector at subauroral latitudes in the ionosphere [e.g., Coster et al., 2005;Spiro et al., 1979;Evans et al., 1983;Anderson et al., 1991Anderson et al., , 1993. These density gradients are often associated with streams of enhanced plasma convection known as subauroral plasma streams (SAPS) [e.g., Foster and Burke, 2002] and with storm-enhanced densities [e.g., Erickson et al., 2002]. Satellite measurements reveal the existence of wave-like structures embedded within the SAPS [Mishin et al.(2016), Investigation of the role of plasma wave cascading processes in the formation of midlatitude irregularities utilizing GPS and radar observations, Radio Sci., 51, 836-851,

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Nonlinear evolution of drift instabilities in the presence of collisions

Cited by 20 publications

References 31 publications

Nonlinear mechanisms for drift wave saturation and induced particle transport

Nonlinear mechanisms for drift wave saturation and induced particle transport

Nonlinear evolution of the temperature gradient instability in the midlatitude ionosphere

Investigation of the role of plasma wave cascading processes in the formation of midlatitude irregularities utilizing GPS and radar observations

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