Experimental Verification of Entropy Cascade in Two-Dimensional Electrostatic Turbulence in Magnetized Plasma

Kawamori, Eiichirou

doi:10.1103/physrevlett.110.095001

Cited by 13 publications

(10 citation statements)

References 16 publications

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“…(2009) and Bañón Navarro et al. (2011) (see also Kawamori 2013, who claims experimental confirmation). Thus, gyrokinetic turbulence has a 5-D phase space.…”

Section: Discussionmentioning

confidence: 81%

A solvable model of Vlasov-kinetic plasma turbulence in Fourier–Hermite phase space

Adkins

Schekochihin

2018

J. Plasma Phys.

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A class of simple kinetic systems is considered, described by the 1D Vlasov-Landau equation with Poisson or Boltzmann electrostatic response and an energy source. Assuming a stochastic electric field, a solvable model is constructed for the phase-space turbulence of the particle distribution. The model is a kinetic analog of the Kraichnan-Batchelor model of chaotic advection. The solution of the model is found in Fourier-Hermite space and shows that the free-energy flux from low to high Hermite moments is suppressed, with phase mixing cancelled on average by anti-phase-mixing (stochastic plasma echo). This implies that Landau damping is an ineffective route to dissipation (i.e., to thermalisation of electric energy via velocity space). The full Fourier-Hermite spectrum is derived. Its asymptotics are m −3/2 at low wave numbers and high Hermite moments (m) and m −1/2 k −2 at low Hermite moments and high wave numbers (k). These conclusions hold at wave numbers below a certain cut off (analog of Kolmogorov scale), which increases with the amplitude of the stochastic electric field and scales as inverse square of the collision rate. The energy distribution and flows in phase space are a simple and, therefore, useful example of competition between phase mixing and nonlinear dynamics in kinetic turbulence, reminiscent of more realistic but more complicated multi-dimensional systems that have not so far been amenable to complete analytical solution.

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“…(2009) and Bañón Navarro et al. (2011) (see also Kawamori 2013, who claims experimental confirmation). Thus, gyrokinetic turbulence has a 5-D phase space.…”

Section: Discussionmentioning

confidence: 81%

A solvable model of Vlasov-kinetic plasma turbulence in Fourier–Hermite phase space

Adkins

Schekochihin

2018

J. Plasma Phys.

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“…2010; Howes et al. 2011; Kawamori 2013; Numata & Loureiro 2015), and phase un-mixing from the plasma echo (Kanekar 2014; Parker & Dellar 2015; Schekochihin et al. 2016).…”

Section: Discussionmentioning

confidence: 99%

Laguerre–Hermite pseudo-spectral velocity formulation of gyrokinetics

2018

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First-principles simulations of tokamak turbulence have proven to be of great value in recent decades. We develop a pseudo-spectral velocity formulation of the turbulence equations that smoothly interpolates between the highly efficient but lower resolution 3D gyrofluid representation and the conventional but more expensive 5D gyrokinetic representation. Our formulation is a projection of the nonlinear gyrokinetic equation onto a Laguerre-Hermite velocity-space basis. We discuss issues related to collisions, closures, and entropy. While any collision operator can be used in the formulation, we highlight a model operator that has a particularly sparse Laguerre-Hermite representation, while satisfying conservation laws and the H theorem. Free streaming, magnetic drifts, and nonlinear phase mixing each give rise to closure problems, which we discuss in relation to the instabilities of interest and to free energy conservation. We show that the model is capable of reproducing gyrokinetic results for linear instabilities and zonal flow dynamics. Thus the final model is appropriate for the study of instabilities, turbulence, and transport in a wide range of geometries, including tokamaks and stellarators.

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“…In kinetic theory, this process leads to spatial perpendicular mixing of ion distributions with different gyrocenters and hence to the creation of small-scale structure in the gyro-center distribution. Small-scale structure in the fields in physical space thus leads to small-scale structure in the distribution function in velocity space perpendicular to v ⊥ as the result of this nonlinear phase mixing (Tatsuno et al, 2009;Bañón Navarro et al, 2011;Kawamori, 2013;Navarro et al, 2016;Cerri et al, 2018). Once these velocity-space structures are small enough, collisions can efficiently smooth them -see Equation (106) and the associated discussionand thereby increase entropy and the perpendicular temperature of the ions.…”

Section: Entropy Cascade and Nonlinear Phase Mixingmentioning

confidence: 99%

The multi-scale nature of the solar wind

Verscharen¹,

Klein²,

Maruca³

2019

Living Rev Sol Phys

335

285

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The solar wind is a magnetized plasma and as such exhibits collective plasma behavior associated with its characteristic spatial and temporal scales. The characteristic length scales include the size of the heliosphere, the collisional mean free paths of all species, their inertial lengths, their gyration radii, and their Debye lengths. The characteristic timescales include the expansion time, the collision times, and the periods associated with gyration, waves, and oscillations. We review the past and present research into the multi-scale nature of the solar wind based on in-situ spacecraft measurements and plasma theory. We emphasize that couplings of processes across scales are important for the global dynamics and thermodynamics of the solar wind. We describe methods to measure in-situ properties of particles and fields. We then discuss the role of expansion effects, non-equilibrium distribution functions, collisions,

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Experimental Verification of Entropy Cascade in Two-Dimensional Electrostatic Turbulence in Magnetized Plasma

Cited by 13 publications

References 16 publications

A solvable model of Vlasov-kinetic plasma turbulence in Fourier–Hermite phase space

A solvable model of Vlasov-kinetic plasma turbulence in Fourier–Hermite phase space

Laguerre–Hermite pseudo-spectral velocity formulation of gyrokinetics

The multi-scale nature of the solar wind

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