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Title: Kinetic Cascade in Solar-wind Turbulence: 3D3V Hybrid-kinetic Simulations with Electron Inertia

Abstract

Understanding the nature of the turbulent fluctuations below the ion gyroradius in solar-wind (SW) turbulence is a great challenge. Recent studies have been mostly in favor of kinetic Alfvén wave (KAW)-type fluctuations, but other kinds of fluctuations with characteristics typical of magnetosonic, whistler, and ion-Bernstein modes could also play a role depending on the plasma parameters. Here, we investigate the properties of the subproton-scale cascade with high-resolution hybrid-kinetic simulations of freely decaying turbulence in 3D3V phase space, including electron inertia effects. Two proton plasma beta are explored: the “intermediate” β {sub p} = 1 and “low” β {sub p} = 0.2 regimes, both typically observed in the SW and corona. The magnetic energy spectum exhibits k{sub ⊥}{sup −8/3} and k{sub ∥}{sup −7/2} power laws at β {sub p} = 1, while they are slightly steeper at β {sub p} = 0.2. Nevertheless, both regimes develop a spectral anisotropy consistent with k{sub ∥}∼k{sub ⊥}{sup 2/3} at k{sub ⊥}ρ{sub p}>1 and pronounced small-scale intermittency. In this context, we find that the kinetic-scale cascade is dominated by KAW-like fluctuations at β {sub p} = 1, whereas the low-β case presents a more complex scenario suggesting the simultaneous presence of different types of fluctuations. In both regimes, however, a possible role of the ion-Bernstein-typemore » fluctuations at the smallest scales cannot be excluded.« less

Authors:
;  [1];  [2]
  1. Dipartimento di Fisica “E. Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa (Italy)
  2. Dipartimento di Fisica, Università della Calabria, I-87036 Rende (CS) (Italy)
Publication Date:
OSTI Identifier:
22872550
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 846; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United Kingdom
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; BERNSTEIN MODE; ELECTRONS; KINETIC EQUATIONS; PHASE SPACE; PLASMA; PROTONS; SIMULATION; SOLAR WIND; TURBULENCE; WHISTLERS

Citation Formats

Cerri, Silvio Sergio, Califano, Francesco, and Servidio, Sergio. Kinetic Cascade in Solar-wind Turbulence: 3D3V Hybrid-kinetic Simulations with Electron Inertia. United Kingdom: N. p., 2017. Web. doi:10.3847/2041-8213/AA87B0.
Cerri, Silvio Sergio, Califano, Francesco, & Servidio, Sergio. Kinetic Cascade in Solar-wind Turbulence: 3D3V Hybrid-kinetic Simulations with Electron Inertia. United Kingdom. https://doi.org/10.3847/2041-8213/AA87B0
Cerri, Silvio Sergio, Califano, Francesco, and Servidio, Sergio. Sun . "Kinetic Cascade in Solar-wind Turbulence: 3D3V Hybrid-kinetic Simulations with Electron Inertia". United Kingdom. https://doi.org/10.3847/2041-8213/AA87B0.
@article{osti_22872550,
title = {Kinetic Cascade in Solar-wind Turbulence: 3D3V Hybrid-kinetic Simulations with Electron Inertia},
author = {Cerri, Silvio Sergio and Califano, Francesco and Servidio, Sergio},
abstractNote = {Understanding the nature of the turbulent fluctuations below the ion gyroradius in solar-wind (SW) turbulence is a great challenge. Recent studies have been mostly in favor of kinetic Alfvén wave (KAW)-type fluctuations, but other kinds of fluctuations with characteristics typical of magnetosonic, whistler, and ion-Bernstein modes could also play a role depending on the plasma parameters. Here, we investigate the properties of the subproton-scale cascade with high-resolution hybrid-kinetic simulations of freely decaying turbulence in 3D3V phase space, including electron inertia effects. Two proton plasma beta are explored: the “intermediate” β {sub p} = 1 and “low” β {sub p} = 0.2 regimes, both typically observed in the SW and corona. The magnetic energy spectum exhibits k{sub ⊥}{sup −8/3} and k{sub ∥}{sup −7/2} power laws at β {sub p} = 1, while they are slightly steeper at β {sub p} = 0.2. Nevertheless, both regimes develop a spectral anisotropy consistent with k{sub ∥}∼k{sub ⊥}{sup 2/3} at k{sub ⊥}ρ{sub p}>1 and pronounced small-scale intermittency. In this context, we find that the kinetic-scale cascade is dominated by KAW-like fluctuations at β {sub p} = 1, whereas the low-β case presents a more complex scenario suggesting the simultaneous presence of different types of fluctuations. In both regimes, however, a possible role of the ion-Bernstein-type fluctuations at the smallest scales cannot be excluded.},
doi = {10.3847/2041-8213/AA87B0},
url = {https://www.osti.gov/biblio/22872550}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 846,
place = {United Kingdom},
year = {2017},
month = {9}
}