Results 11 to 20 of about 158 (153)
Nonlinear gyrokinetic equations [PDF]
The Physics of Fluids, 1983 Nonlinear gyrokinetic equations are derived from a systematic Hamiltonian theory. The derivation employs Lie transforms and a noncanonical perturbation theory first used by Littlejohn for the simpler problem of asymptotically small gyroradius. For definiteness, we emphasize the limit of electrostatic fluctuations in slab geometry; however, there is a ...
Dubin, D. H. E. +3 more
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Long time gyrokinetic equations
Quarterly of Applied Mathematics, 2023 The aim of this text is to elucidate the oscillating patterns (see C. Cheverry [Res. Rep. Math. (2018)]) which are generated in a toroidal plasma by a strong external magnetic field and a nonzero electric field. It is also to justify and then study new modulation equations which are valid for longer times than before.
Cheverry, Christophe, Farhat, Shahnaz
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Energy Transfer and Electron Heating in Turbulent Flux Pileup Region
Geophysical Research Letters, Volume 49, Issue 24, 28 December 2022., 2022 Abstract We report observations of intense energy transfer developed within a flux pileup region (FPR) inside a plasma jet in the Earth's midtail. Strong electromagnetic turbulences, with ( and are wave numbers perpendicular and parallel to background magnetic field respectively), are observed together with intermittent sub‐ion‐scale structures ...
C. M. Liu +3 more
wiley +1 more source
Contributions to Plasma Physics, Volume 62, Issue 5-6, June‐July 2022., 2022 Abstract Gyrokinetic simulations are among the main tools to predict turbulent transport in the core of fusion devices. Unlike the core, the plasma edge and scrape‐off layer are characterized by lower temperature and higher collisionality. To allow for realistic gyrokinetic modelling of edge and scrape‐off layer turbulence, it is crucial to include ...
Philipp Ulbl +2 more
wiley +1 more source
Energetically consistent collisional gyrokinetics [PDF]
Physics of Plasmas, 2015 We present a formulation of collisional gyrokinetic theory with exact conservation laws for energy and canonical toroidal momentum. Collisions are accounted for by a nonlinear gyrokinetic Landau operator. Gyroaveraging and linearization do not destroy the operator's conservation properties.
J. W. Burby, A. J. Brizard, H. Qin
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Revisiting the improved core confinement simulations for FT‐2 tokamak
Contributions to Plasma Physics, Volume 62, Issue 5-6, June‐July 2022., 2022 Abstract In the present paper, we revisit observations performed in FT‐2 tokamak from previous works. Improvements of core confinement are observed and believed to be caused by wide orbits going from collisionless to collisional regimes. Similar phenomena can occur whenever gradient lengths are comparable to the orbit widths at the top of the pedestal ...
Riccardo Nicolò Iorio +5 more
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Effect of toroidal particle sources on SOL physics in the FT‐2 tokamak
Contributions to Plasma Physics, Volume 62, Issue 5-6, June‐July 2022., 2022 Abstract Two gas‐puffs are used near limiters in the FT‐2 tokamak for the purpose of hydrogen refuelling during plasma discharges. This creates toroidal and poloidal asymmetry in particle sources near limiters which has to be considered in modelling. Here, the effect of toroidal asymmetry is simulated using the gyrokinetic code ELMFIRE.
Francis Clinton Prasanth Albert Devasagayam +10 more
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Journal of Geophysical Research: Space Physics, Volume 127, Issue 2, February 2022., 2022 Abstract Vlasov solvers that operate on a phase‐space grid are highly accurate but also numerically demanding. Coarse velocity space resolutions, which are largely unproblematic in particle‐in‐cell (PIC) simulations, can lead to numerical heating or oscillations in continuum Vlasov methods.
F. Allmann‐Rahn +2 more
wiley +1 more source
Van Allen Probes Observations of Symmetric Stormtime Compressional ULF Waves
Journal of Geophysical Research: Space Physics, Volume 127, Issue 2, February 2022., 2022 Abstract Previous spacecraft studies showed that stormtime poloidal ultralow‐frequency (ULF) waves in the ring current region have an antisymmetric (second harmonic) mode structure about the magnetic equator. This paper reports Van Allen Probes observations of symmetric ULF waves in the postnoon sector during a moderate geomagnetic storm.
Kazue Takahashi +8 more
wiley +1 more source
Zonal flow excitation in electron-scale tokamak turbulence
Nuclear Fusion, 2023 The derivation of an intermediate-scale gyrokinetic-electron theory in nonuniform tokamak plasmas (Chen et al 2021 Nucl. Fusion 61 https://doi.org/10.1088/1741-4326/abf81a ) has shown that a Navier–Stokes type nonlinearity couples electron-temperature ...
Stefan Tirkas +4 more
doaj +1 more source