Identification of high order closure terms from fully kinetic simulations using machine learning

Laperre, Brecht; Amaya, Jorge; Jamal, Sara; Lapenta, Giovanni

doi:10.1063/5.0066397

Cited by 5 publications

(4 citation statements)

References 45 publications

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“…To take only a few recent examples, one can pinpoint the onset of the formation of strong current structures, from a fully kinetic formulation to that of MHD, as for the KH instability, using wavelets 135 . One can also identify closure terms in a hierarchy of moment equations from numerical simulations by performing a nonlocal closure for the electron heat flux, learning from 3D kinetic simulation data in the case of reconnection in a so-called double-Harris sheet using a particle in cell code, the input being the large-scale fields and their gradients as well as density and pressure ratio 136 (see 137 for another example).…”

Section: Discussionmentioning

confidence: 99%

The role of field correlations on turbulent dissipation

Pouquet¹

2023

Preprint

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Nonlinear phenomena and turbulence are central to our understanding and modeling the dynamics of fluids and plasmas, and yet they still resist analytical resolutions in many instances. However, progress has been made recently, displaying a richness of phenomena which was somewhat unexpected a few years back, such as the double constant-flux cascades of a same invariant to both the large and to the small scales, or the presence of non-Gaussian wings in the large-scale fields, for fluids and plasmas. Here, I will concentrate on the direct measurement of the magnitude of dissipation and an evaluation of intermittency in a turbulent plasma using exact laws stemming from invariance principles and involving cross-correlation tensors with both the velocity and the magnetic fields. I will illustrate these points through scaling laws, together with data analysis from existing experiments, observations and numerical simulations. Finally, I will also briefly explore the possible implications for validity and use of several modeling strategies. To appear, Plasma Physics & Controlled Fusion, 2023.

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Section: Discussionmentioning

confidence: 99%

The role of field correlations on turbulent dissipation

Pouquet¹

2023

Preprint

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“…Taking only a few recent examples, one can pinpoint the onset of the formation of strong current structures, from a fully kinetic formulation to that of MHD, as for the KH instability, using wavelets [135]. One can also identify closure terms in a hierarchy of moment equations from numerical simulations by performing a nonlocal closure for the electron heat flux, learning from 3D kinetic simulation data in the case of reconnection in a so-called double-Harris sheet using a particle in cell code, the input being the large-scale fields and their gradients as well as density and pressure ratio [136] (see [137] for another example).…”

Section: Discussionmentioning

confidence: 99%

The role of field correlations on turbulent dissipation

Pouquet

2023

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

Nonlinear phenomena and turbulence are central to our under- standing and modeling the dynamics of fluids and plasmas, and yet they still resist analytical resolutions in many instances. However, progress has been made recently, displaying a richness of phenomena which was somewhat unex- pected a few years back, such as the double constant-flux cascades of a same invariant to both the large and to the small scales, or the presence of non- Gaussian wings in the large-scale fields, for fluids and plasmas. Here, I will concentrate on the direct measurement of the magnitude of dissipation and an evaluation of intermittency in a turbulent plasma using exact laws stemming from invariance principles and involving cross-correlation tensors with both the velocity and the magnetic fields. I will illustrate these points through scal- ing laws, together with data analysis from existing experiments, observations and numerical simulations. Finally, I will also briefly explore the possible im- plications for validity and use of several modeling strategies.

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“…Finally, it should be noted that, the focus of this work is on the fundamental properties and scaling of the dispersion relation and the development of anomalous transport without additional collisions. The work performed here may be extended in the future to use the ten-moment model, and possibly even higherorder moment fluid models, with improved plasma closure relations based on physical constraints [2,4,5,25,42,44,58] or data-driven approaches [12,59,60].…”

Section: Discussionmentioning

confidence: 99%

Electron cyclotron drift instability and anomalous transport: two-fluid moment theory and modeling

Wang¹,

Hakim²,

Srinivasan³

et al. 2022

Plasma Sources Sci. Technol.

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In a cross-field (E×B) setup, electron EB flow relative to unmagnetized ions can cause Electron Cyclotron Drift Instability (ECDI) due to ion-acoustic mode and electron cyclotron harmonics resonances. This occurs, for example, in collisionless space shocks and EB discharge devices such as Hall thrusters. The rise of an electron flow parallel to the background E field at speeds far exceeding predictions by classical collision theory is a prominent feature of ECDI. The development of ECDI and anomalous transport is often thought to necessitate a fully kinetic treatment. However, in this paper, we show that a reduced variant of this instability, as well as the associated anomalous transport, can be produced self-consistently in a collisionless two-fluid framework with no adjustable collision parameter. By treating both electron and ion species on an equal footing, the free energy due to the inter-species velocity shear allows the growth of an anomalous electron flow parallel to the background E field. We will first present linear analyses of the instability in the two-fluid five- and ten-moment models, and compare them against the fully-kinetic theory. At lower temperatures, the two-fluid models predict the fastest-growing mode comparable to the kinetic result. Also, by including more moments, secondary (and possibly higher) unstable branches can be recovered. The dependence of the instability on ion-to-electron mass ratio, plasma temperature, and background field strength is also thoroughly explored. We then carry out five-moment simulations of the cross-field setup to verify the development of the instability and the anomalous transport. A comparison against Vlasov-Poisson simulation using experimental parameters is also presented. This work casts new insights into the nature of ECDI and the associated anomalous transport, and demonstrates the potential of the two-fluid moment model in efficient modeling of E×B plasmas at lower temperatures.

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Identification of high order closure terms from fully kinetic simulations using machine learning

Cited by 5 publications

References 45 publications

The role of field correlations on turbulent dissipation

The role of field correlations on turbulent dissipation

The role of field correlations on turbulent dissipation

Electron cyclotron drift instability and anomalous transport: two-fluid moment theory and modeling

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