Evaluation of the turbulent energy cascade rates from the upper inertial range in the solar wind at 1 AU

We review some aspects of solar wind turbulence with an emphasis on the ability of the turbulence to account for the observed heating of the solar wind. Particular attention is paid to the use of structure functions in computing energy cascade rates and their general agreement with the measured thermal proton heating. We then examine the use of 1 h data samples that are comparable in length to the correlation length for the fluctuations to obtain insights into local inertial range dynamics and find evidence for intermittency in the computed energy cascade rates. When the magnetic energy dominates the kinetic energy, there is evidence of anti-correlation in the cascade of energy associated with the outward- and inward-propagating components that we can only partially explain.

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Solar Wind Heating by the Turbulent Energy Cascade

Turbulence in the Solar Wind - Lecture Notes in Physics ◽

10.1007/978-3-319-43440-7_8 ◽

2016 ◽

pp. 227-253

Author(s):

Roberto Bruno ◽

Vincenzo Carbone

Keyword(s):

Solar Wind ◽

Turbulent Energy ◽

Energy Cascade

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Heating the Solar Wind by a Magnetohydrodynamic Turbulent Energy Cascade

The Astrophysical Journal ◽

10.1086/587957 ◽

2008 ◽

Vol 677 (1) ◽

pp. L71-L74 ◽

Cited By ~ 80

Author(s):

R. Marino ◽

L. Sorriso-Valvo ◽

V. Carbone ◽

A. Noullez ◽

R. Bruno ◽

...

Keyword(s):

Solar Wind ◽

Turbulent Energy ◽

Energy Cascade

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Reflection-driven magnetohydrodynamic turbulence in the solar atmosphere and solar wind

Journal of Plasma Physics ◽

10.1017/s0022377819000540 ◽

2019 ◽

Vol 85 (4) ◽

Cited By ~ 13

Author(s):

Benjamin D. G. Chandran ◽

Jean C. Perez

Keyword(s):

Solar Wind ◽

Heating Rate ◽

Three Dimensional ◽

Power Spectra ◽

Inertial Range ◽

Magnetic Flux Tube ◽

Analytic Model ◽

Mhd Turbulence ◽

Background Magnetic Field ◽

Turbulent Heating

We present three-dimensional direct numerical simulations and an analytic model of reflection-driven magnetohydrodynamic (MHD) turbulence in the solar wind. Our simulations describe transverse, non-compressive MHD fluctuations within a narrow magnetic flux tube that extends from the photosphere, through the chromosphere and corona and out to a heliocentric distance $r$ of 21 solar radii $(R_{\odot })$ . We launch outward-propagating ‘ $\boldsymbol{z}^{+}$ fluctuations’ into the simulation domain by imposing a randomly evolving photospheric velocity field. As these fluctuations propagate away from the Sun, they undergo partial reflection, producing inward-propagating ‘ $\boldsymbol{z}^{-}$ fluctuations’. Counter-propagating fluctuations subsequently interact, causing fluctuation energy to cascade to small scales and dissipate. Our analytic model incorporates dynamic alignment, allows for strongly or weakly turbulent nonlinear interactions and divides the $\boldsymbol{z}^{+}$ fluctuations into two populations with different characteristic radial correlation lengths. The inertial-range power spectra of $\boldsymbol{z}^{+}$ and $\boldsymbol{z}^{-}$ fluctuations in our simulations evolve toward a $k_{\bot }^{-3/2}$ scaling at $r>10R_{\odot }$ , where $k_{\bot }$ is the wave-vector component perpendicular to the background magnetic field. In two of our simulations, the $\boldsymbol{z}^{+}$ power spectra are much flatter between the coronal base and $r\simeq 4R_{\odot }$ . We argue that these spectral scalings are caused by: (i) high-pass filtering in the upper chromosphere; (ii) the anomalous coherence of inertial-range $\boldsymbol{z}^{-}$ fluctuations in a reference frame propagating outwards with the $\boldsymbol{z}^{+}$ fluctuations; and (iii) the change in the sign of the radial derivative of the Alfvén speed at $r=r_{\text{m}}\simeq 1.7R_{\odot }$ , which disrupts this anomalous coherence between $r=r_{\text{m}}$ and $r\simeq 2r_{\text{m}}$ . At $r>1.3R_{\odot }$ , the turbulent heating rate in our simulations is comparable to the turbulent heating rate in a previously developed solar-wind model that agreed with a number of observational constraints, consistent with the hypothesis that MHD turbulence accounts for much of the heating of the fast solar wind.

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HelioSwarm: The Nature of Turbulence in Space Plasmas

10.5194/egusphere-egu21-12092 ◽

2021 ◽

Author(s):

Harlan Spence ◽

Kristopher Klein ◽

HelioSwarm Science Team

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Large Scale ◽

Solar Wind Plasma ◽

Turbulent Energy ◽

Space Plasmas ◽

Plasma Parameters ◽

Astrophysical Plasmas ◽

Ion Distributions ◽

Background Magnetic Field

Recently selected for phase A study for NASA&#8217;s Heliophysics MidEx Announcement of Opportunity, the HelioSwarm Observatory proposes to transform our understanding of the physics of turbulence in space and astrophysical plasmas by deploying nine spacecraft to measure the local plasma and magnetic field conditions at many points, with separations between the spacecraft spanning MHD and ion scales.&#160;&#160;HelioSwarm resolves the transfer and dissipation of turbulent energy in weakly-collisional magnetized plasmas with a novel configuration of spacecraft in the solar wind. These simultaneous multi-point, multi-scale measurements of space plasmas allow us to reach closure on two science goals comprised of six science objectives: (1) reveal how turbulent energy is transferred in the most probable, undisturbed solar wind plasma and distributed as a function of scale and time; (2) reveal how this turbulent cascade of energy varies with the background magnetic field and plasma parameters in more extreme solar wind environments; (3) quantify the transfer of turbulent energy between fields, flows, and ion heat; (4) identify thermodynamic impacts of intermittent structures on ion distributions; (5) determine how solar wind turbulence affects and is affected by large-scale solar wind structures; and (6) determine how strongly driven turbulence differs from that in the undisturbed solar wind.&#160;

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Uncertainties of the solar wind in-situ velocity measurements

Communications of the Byurakan Astrophysical Observatory ◽

10.52526/25792776-2020.67.2-193 ◽

2020 ◽

pp. 193-197

Author(s):

G. Gogoberidze ◽

E. Gorgaslidze

Keyword(s):

Solar Wind ◽

Independent Method ◽

Inertial Range ◽

Velocity Measurements ◽

Fast Solar Wind ◽

Magnetohydrodynamic Turbulence ◽

Velocity Fluctuations ◽

Measurement Uncertainties ◽

General Instrument

We study spectral features of Alfvénic turbulence in fast solar wind. We propose a general, instrument independent method to estimate the uncertainty in velocity fluctuations obtained by in-situ satellite observations in the solar wind. We show that when the measurement uncertainties of the velocity fluctuations are taken into account the less energetic Elsasser spectrum obeys a unique power law scaling throughout the inertial range as prevailing theories of magnetohydrodynamic turbulence predict.

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Turbulent energy transfer in bidimensional numerical models of plasma

10.5194/egusphere-egu21-8898 ◽

2021 ◽

Author(s):

Rocio Manobanda ◽

Christian Vasconez ◽

Denise Perrone ◽

Raffaele Marino ◽

Dimitri Laveder ◽

...

Keyword(s):

Solar Wind ◽

Energy Transfer ◽

Numerical Models ◽

Collisionless Plasma ◽

Space Plasma ◽

Turbulent Energy ◽

Turbulent Medium ◽

Scaling Properties ◽

Magnetic Diffusivity ◽

Out Of Plane

Structured, highly variable and virtually collision-free. Space plasma is an unique laboratory for studying the transfer of energy in a highly turbulent environment. This turbulent medium plays an important role in various aspects of the Solar--Wind generation, particles acceleration and heating, and even in the propagation of cosmic rays. Moreover, the Solar Wind continuous expansion develops a strong turbulent character, which evolves towards a state that resembles the well-known hydrodynamic turbulence (Bruno and Carbone). This turbulence is then dissipated from magnetohydrodynamic (MHD) through kinetic scales by different -not yet well understood- mechanisms. In the MHD approach, Kolmogorov-like behaviour is supported by power-law spectra and intermittency measured in observations of magnetic and velocity fluctuations. In this regime, the intermittent cross-scale energy transfer has been extensively described by the Politano--Pouquet (global) law, which is based on conservation laws of the MHD invariants, and was recently expanded to take into account the physics at the bottom of the inertial (or Hall) range, e.g. (Ferrand et al., 2019). Following the 'Turbulence Dissipation Challenge', we study the properties of the turbulent energy transfer using three different bi-dimensional numerical models of space plasma. The models, Hall-MHD (HMHD), Landau Fluid (LF) and Hybrid Vlasov-Maxwell (HVM), were ran in collisionless-plasma conditions, with an out-of-plane ambient magnetic field, and with magnetic diffusivity carefully calibrated in the fluid models. As each model has its own range of validity, it allows us to explore a long-enough range of scales at a period of maximal turbulence activity. Here, we estimate the local and global scaling properties of different energy channels using a, recently introduced, proxy of the local turbulent energy transfer (LET) rate (Sorriso-Valvo et al., 2018). This study provides information on the structure of the energy fluxes that transfers (and dissipates) most of the energy at small scales throughout the turbulent cascade.&#160;

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On the energy cascade rate of solar wind turbulence in high cross helicity flows

Journal of Geophysical Research Atmospheres ◽

10.1029/2010ja016306 ◽

2011 ◽

Vol 116 (A5) ◽

Cited By ~ 15

Author(s):

J. J. Podesta

Keyword(s):

Solar Wind ◽

Energy Cascade ◽

Solar Wind Turbulence ◽

Wind Turbulence

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Mutual Iinformation exchange in solar wind density fluctuations

10.5194/egusphere-egu2020-11410 ◽

2020 ◽

Author(s):

Luca Sorriso-Valvo ◽

Francesco Carbone ◽

Daniele Telloni

Keyword(s):

Solar Wind ◽

Mutual Information ◽

Information Flow ◽

Information Exchange ◽

Turbulent Energy ◽

Density Fluctuations ◽

Slow Solar Wind ◽

Proton Density ◽

Mode Decomposition ◽

Turbulent Cascade

The fluctuations of proton density in the slow solar wind are analyzed by means of joint Empirical Mode Decomposition (EMD) and Mutual Information (MI) analysis. The analysis reveal that, within the turbulent inertial range, the EMD modes associated with nearby scales have their phases correlated, as shown by the large information exchange. This is a qunatitative measure of the information flow occurring in the turbulent cascade. On the other hand, at scales smaller than the ion gyroscale, the information flow is lost, and the mutual information is low, suggesting that in the kinetic range the nonlinear interacions are no longer sustaining a turbulent energy cascade.

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