Modern gyrokinetic formulation of collisional and turbulent transport in toroidally rotating plasmas

Sugama, H.

doi:10.1007/s41614-017-0010-5

Cited by 21 publications

(20 citation statements)

References 65 publications

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“…Typically, we have ≲ O(10 −2 ) ≪ 1 . Since low-frequency but short-wavelength fluctuations are of interest here, one, thus, adopts the following linear gyrokinetic orderings (Catto 1978;Antonsen and Lane 1980;Frieman and Chen 1982;Sugama 2000;Brizard and Hahm 2007;Sugama 2017): and to include Landau resonance: 1) and i ≲ O(1) , with i = 8 P 0i ∕B 2 0 the ratio of plasma ion pressure to the background magnetic field energy density: compressional Alfvén (fast) waves are systematically suppressed in the gyrokinetic orderings.…”

Section: Linear Gyrokinetic Theorymentioning

confidence: 99%

Physics of kinetic Alfvén waves: a gyrokinetic theory approach

Chen

Zonca

Lin

2021

Rev. Mod. Plasma Phys.

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The transverse shear Alfvén wave (SAW) is a fundamental anisotropic electromagnetic oscillation in plasmas with a finite background magnetic field. In realistic plasmas with spatial inhomogeneities, SAW exhibits the interesting spectral feature of a continuous spectrum. That is, the SAW oscillation frequency varies in the non-uniform (radial) direction. This continuum spectral feature then naturally leads to the phase-mixing process; i.e., time asymptotically, the effective radial wave-number increases with time. Any initial perturbation of SAW structures will, thus, evolve eventually into short-wavelength structures; termed as kinetic Alfvén wave (KAW). Obviously, one needs to employ kinetic theory approach to properly describe the dynamics of KAW; including effects such as finite ion-Larmor radius (FILR) and/or wave–particle interactions. When KAW was first discovered and discussed in 1975–1976, it was before the introduction of the linear electromagnetic gyrokinetic theory (1978) and nonlinear electromagnetic gyrokinetic theory (1982). Kinetic treatments then often involved the complicated procedures of taking the low-frequency limit of the Vlasov kinetic theory and/or employing the drift-kinetic theory approach; forsaking, thus, the FILR effects. In recent years, the powerful nonlinear gyrokinetic theory has been employed to re-examine both the linear and nonlinear physics of KAWs. This brief review will cover results of linear and nonlinear analytical theories, simulations, as well as observational evidences. We emphasize, in particular, that due to the enhanced electron–ion de-coupling in the short-wavelength regime, KAWs possess significantly enhanced nonlinear coupling coefficients and, thereby, play important roles in the heating, acceleration, and transport processes of charged particles in magnetized plasmas.

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Section: Linear Gyrokinetic Theorymentioning

confidence: 99%

Physics of kinetic Alfvén waves: a gyrokinetic theory approach

Chen

Zonca

Lin

2021

Rev. Mod. Plasma Phys.

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“…Refs. [3,4]). It has been shown that phase space structures, obtained by averaging out dependencies on angle-like variables in the energetic particle distribution function, which are not rapidly damped by collisionless processes such as Landau damping, play a fundamental role in regulating EP transport induced by Alfvén instabilities in burning plasmas (see Ref.…”

Section: Introductionmentioning

confidence: 99%

Time evolution and finite element representation of Phase Space Zonal Structures in ORB5

Bottino

Falessi

Hayward-Schneider

et al. 2022

J. Phys.: Conf. Ser.

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Phase Space Zonal Structures (PSZSs), obtained by averaging out dependencies on angle-like variables in the energetic particle (EP) distribution function, play a fundamental role in regulating EP transport induced by Alfvén instabilities in burning plasmas, acting as a slowly varying nonlinear equilibrium state. Therefore, they are of great interest for the development of reduced models for the description of EP heat and particle transport on long time scales, comparable with the energy confinement time, for future burning plasma experiments. In this work, we propose an efficient finite element based projection of the time evolution of the PSZS, suited for global particle-in-cell (PIC) gyrokinetic (GK) codes. The resulting algorithm has been implemented in the global GK PIC code ORB5. PSZSs can not only be used for validating reduced models, but also as a diagnostic tool for characterizing the nonlinear interaction in phase space between Alfvén instabilities and EPs in global GK simulations.

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“…Rigorous models and thorough discussions on collision operators can be found in Ref. [27] and references therein.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent expansion of a weakly-collisional plasma beam in a paraxial magnetic nozzle

Zhou¹,

Sánchez‐Arriaga²,

Ahedo³

2021

Plasma Sources Sci. Technol.

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The transient and steady-state expansion of a weakly-collisional plasma beam in a paraxial magnetic nozzle is studied with a kinetic Boltzmann–Poisson model. Only intraspecies collisions involving electrons are considered and these are modeled with a Bhatnagar–Gross–Krook operator. Simulations show that occasional collisions progressively populate the phase-space region of isolated trapped electrons until a steady state is reached, which is independent of transient history. The steady state is characterized by a partial occupancy of that region increasing with the collisionality rate but far away from the full occupancy postulated by an alternative steady-state kinetic model. The changes on the amount of trapped electrons with the collisionality rate explain, in turn, the changes on the spatial profiles of main plasma magnitudes. Conclusions on the momentum and energy balances of ions and electrons agree, in terms of general trends, with those of the steady-state kinetic model. In the downstream region of the expansion, ions and electrons lose all their perpendicular energy but they still keep part of their parallel thermal energy. Electron heat fluxes of parallel energy are not negligible and are approximately proportional to enthalpy fluxes.

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Modern gyrokinetic formulation of collisional and turbulent transport in toroidally rotating plasmas

Cited by 21 publications

References 65 publications

Physics of kinetic Alfvén waves: a gyrokinetic theory approach

Physics of kinetic Alfvén waves: a gyrokinetic theory approach

Time evolution and finite element representation of Phase Space Zonal Structures in ORB5

Time-dependent expansion of a weakly-collisional plasma beam in a paraxial magnetic nozzle

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