Numerical Study of Inertial Kinetic-Alfvén Turbulence

Roytershteyn, V.; Boldyrev, Stanislav; Delzanno, Gian Luca; Chen, Christopher H. K.; Grošelj, Daniel; Loureiro, Nuno

doi:10.3847/1538-4357/aaf288

Cited by 33 publications

(31 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(9). nhds, like other solvers of the hot-plasma dispersion relation (Roennmark 1982;Gary 1993;Klein & Howes 2015), determines the non-trivial solutions to the wave equation,…”

Section: Plasma Waves In Linear Theorymentioning

confidence: 99%

“…achieving this ordering of scales in simulations requires sufficiently large values for m i /m e and c/v Ai . However, typical values of |Ω e |/ω e used in fully kinetic studies of the solar wind are |Ω e |/ω e ∼ 0.1 − 1 (Karimabadi et al 2013;Saito & Nariyuki 2014;Parashar et al 2015b,a;Grošelj et al 2018;Parashar & Gary 2019;Roytershteyn et al 2019), in contrast to the realistic values |Ω e |/ω e ∼ 10 −3 −10 −2 (for example, see Verscharen et al 2019, table 1). Therefore, it is important to understand and quantify the effects of artificially large values of |Ω e |/ω e on the dynamics of the system.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dependence of kinetic plasma waves on ion-to-electron mass ratio and light-to-Alfvén speed ratio

Verscharen

Parashar

Gary

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

The magnetization |Ω e |/ω e is an important parameter in plasma astrophysics, where Ω e and ω e are the electron gyro-frequency and electron plasma frequency, respectively. It only depends on the mass ratio m i /m e and the light-to-Alfvén speed ratio c/v Ai , where m i (m e ) is the ion (electron) mass, c is the speed of light, and v Ai is the ion Alfvén speed. Nonlinear numerical plasma models such as particle-in-cell simulations must often assume unrealistic values for m i /m e and for c/v Ai . Because linear theory yields exact results for parametric scalings of wave properties at small amplitudes, we use linear theory to investigate the dispersion relations of Alfvén/ion-cyclotron and fast-magnetosonic/whistler waves as prime examples for collective plasma behaviour depending on m i /m e and c/v Ai . We analyse their dependence on m i /m e and c/v Ai in quasi-parallel and quasi-perpendicular directions of propagation with respect to the background magnetic field for a plasma with β j ∼ 1, where β j is the ratio of the thermal to magnetic pressure for species j. Although their dispersion relations are largely independent of c/v Ai for c/v Ai 10, the mass ratio m i /m e has a strong effect at scales smaller than the ion inertial length. Moreover, we study the impact of relativistic electron effects on the dispersion relations. Based on our results, we recommend aiming for a more realistic value of m i /m e than for a more realistic value of c/v Ai in nonrelativistic plasma simulations if such a choice is necessary, although relativistic and sub-Debye-length effects may require an additional adjustment of c/v Ai .

show abstract

“…(9). nhds, like other solvers of the hot-plasma dispersion relation (Roennmark 1982;Gary 1993;Klein & Howes 2015), determines the non-trivial solutions to the wave equation,…”

Section: Plasma Waves In Linear Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dependence of kinetic plasma waves on ion-to-electron mass ratio and light-to-Alfvén speed ratio

Verscharen

Parashar

Gary

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Furthermore, the multiplicative factor in the estimate of E(k ⊥ ) in terms of E B ⊥ (k ⊥ ) is responsible for a steepening of the latter at scales smaller than d e , an effect visible in particular in the simulation with hyper-diffusivity, χ = 1, and E + (k 0 )/E − (k 0 ) = 100. A k −11/3 ⊥ spectrum, classical for balanced IKAW turbulence (Chen & Boldyrev 2017;Passot et al 2018;Roytershteyn et al 2019) is still observed for this level of imbalance. Spectra, obtained with Landau damping and electron inertia, are also displayed in this figure: for χ = 0.6 with E + (k 0 )/E − (k 0 ) = 1 or E + (k 0 )/E − (k 0 ) = 100, showing that the spectra get steeper as the imbalance increases, and for χ = 1 with E + (k 0 )/E − (k 0 ) = 100, showing that the steepening is more pronounced as χ is decreased.…”

Section: Direct Cascades In Imbalanced Turbulencementioning

confidence: 82%

“…Simulations were performed for β e = 2, τ = 1 (case I) typical of the SW at 1 AU, and β e = 0.04, τ = 10 (case II), more suitable for regions closer to the Sun (Roytershteyn et al 2019). For small β e , d e significantly exceeds the electron Larmor radius ρ e = √ 2δρ s , thus permitting electron inertia to be retained, while electron FLR corrections are neglected.…”

Section: The Modelmentioning

confidence: 99%

Modeling Imbalanced Collisionless Alfvén Wave Turbulence with Nonlinear Diffusion Equations

Miloshevich

Passot

Sulem

2019

ApJL

View full text Add to dashboard Cite

A pair of nonlinear diffusion equations in Fourier space is used to study the dynamics of strong Alfvénwave turbulence, from MHD to electron scales. Special attention is paid to the regime of imbalance between the energies of counter-propagating waves commonly observed in the solar wind (SW), especially in regions relatively close to the Sun. In the collisionless regime where dispersive effects arise at scales comparable to or larger than those where dissipation becomes effective, the imbalance produced by a given injection rate of generalized cross-helicity (GCH), which is an invariant, is much larger than in the corresponding collisional regime described by the usual (or reduced) magnetohydrodynamics. The combined effect of high imbalance and ion Landau damping induces a steep energy spectrum for the transverse magnetic field at sub-ion scales. This spectrum is consistent with observations in highly Alfvenic regions of the SW, such as trailing edges, but does not take the form of a transition range continued at smaller scales by a shallower spectrum. This suggests that the observed spectra displaying such a transition result from the superposition of contributions originating from various streams with different degrees of imbalance. Furthermore, when imbalanced energy injection is supplemented at small scales in an already fully developed turbulence, for example under the effect of magnetic reconnection, a significant enhancement of the imbalance at all scales is observed.

show abstract

“…A more appropriate name for the considered equations is the “inertial kinetic‐Alfvén system” since the electron‐inertia effects play an important role in the plasma dynamics (e.g., Boldyrev & Loureiro, 2019; Roytershteyn et al, 2019). Such a system is applicable to environments with low electron plasma beta, which include the solar corona, the Earth's magnetosheath, and possibly collisionless shocks (e.g., Chandran et al, 2011; C. H. K. Chen & Boldyrev, 2017; Cranmer et al, 2009; Ghavamian et al, 2013).…”

Section: Kinetic‐alfvén Turbulence In a Low Electron‐beta Plasmamentioning

confidence: 99%

Tearing Instability in Alfvén and Kinetic‐Alfvén Turbulence

Boldyrev

Loureiro

2020

JGR Space Physics

Self Cite

View full text Add to dashboard Cite

Recently, it has been realized that magnetic plasma turbulence and magnetic field reconnection are inherently related phenomena. Turbulent fluctuations generate regions of sheared magnetic field that become unstable to the tearing instability and reconnection, thus modifying turbulence at the corresponding scales. In this contribution, we give a brief review of some recent results on tearing-mediated magnetic turbulence. We illustrate the main ideas of this rapidly developing field of study by concentrating on two important examples-magnetohydrodynamic Alfvén turbulence and small-scale kinetic-Alfvén turbulence. Due to various potential applications of these phenomena in space physics and astrophysics, we specifically try not to overload the text by heavy analytical derivations but rather present a qualitative discussion accessible to a non-expert in the theories of turbulence and reconnection.

show abstract

Numerical Study of Inertial Kinetic-Alfvén Turbulence

Cited by 33 publications

References 55 publications

Dependence of kinetic plasma waves on ion-to-electron mass ratio and light-to-Alfvén speed ratio

Dependence of kinetic plasma waves on ion-to-electron mass ratio and light-to-Alfvén speed ratio

Modeling Imbalanced Collisionless Alfvén Wave Turbulence with Nonlinear Diffusion Equations

Tearing Instability in Alfvén and Kinetic‐Alfvén Turbulence

Contact Info

Product

Resources

About