scholarly journals Structure function measurements of the intermittent MHD turbulent cascade

1997 ◽  
Vol 4 (3) ◽  
pp. 185-199 ◽  
Author(s):  
T. S. Horbury ◽  
A. Balogh
Keyword(s):  
Energy Transfer ◽  
High Speed ◽  
Solar Wind Plasma ◽  
Turbulent Energy ◽  
Structure Functions ◽  
Order Structure ◽  
Data Sets ◽  
Magnetic Field Data ◽  
Spacecraft Data ◽  
Turbulent Cascade

Abstract. The intertmittent nature of turbulence within solar wind plasma has been demonstrated by several studies of spacecraft data. Using magnetic field data taken in high speed flows at high heliographic latitudes by the Ulysses probe, the character of fluctuations within the inertia] range is discussed. Structure functions are used extensively. A simple consideration of errors associated with calculations of high moment structure functions is shown to be useful as a practical estimate of the reliability of such calculations. For data sets of around 300 000 points, structure functions of moments above 5 are rarely reliable on the basis of this test, highlighting the importance of considering uncertainties in such calculations. When unreliable results are excluded, it is shown that inertial range polar fluctuations are well described by a multifractal model of turbulent energy transfer. Detailed consideration of the scaling of high order structure functions suggests energy transfer consistent with a "Kolmogorov" cascade.

scholarly journals Multi-spacecraft measurement of anisotropic power levels and scaling in solar wind turbulence

2009 ◽  
Vol 27 (8) ◽  
pp. 3019-3025 ◽  
Author(s):  
K. T. Osman ◽  
T. S. Horbury
Keyword(s):  
Solar Wind ◽  
Spectral Index ◽  
Mean Field ◽  
Structure Functions ◽  
Inertial Range ◽  
Order Structure ◽  
Parallel Direction ◽  
The Mean ◽  
Time Lagged ◽  
Turbulent Cascade

Abstract. Measurements by the four Cluster spacecraft in the solar wind are used to determine quantitatively the field-aligned anisotropy of magnetohydrodynamic inertial range turbulence power levels and spectral indexes. We find, using time-lagged second order structure functions, that the spectral index is near 2 around the field-parallel direction, which is consistent with a "critical balance" turbulent cascade. Solar wind fluctuations are found to be anisotropic with power mainly in wavevectors perpendicular to the mean field, where the spectral index is around 5/3.

scholarly journals Third-order structure functions for isotropic turbulence with bidirectional energy transfer

2019 ◽  
Vol 877 ◽  
Author(s):  
Jin-Han Xie ◽  
Oliver Bühler
Keyword(s):  
Energy Transfer ◽  
Isotropic Turbulence ◽  
Full Range ◽  
Structure Functions ◽  
Spectral Energy ◽  
Order Structure ◽  
Stratified Turbulence ◽  
Mhd Turbulence ◽  
Third Order ◽  
Transfer Rates

We derive and test a new heuristic theory for third-order structure functions that resolves the forcing scale in the scenario of simultaneous spectral energy transfer to both small and large scales, which can occur naturally, for example, in rotating stratified turbulence or magnetohydrodynamical (MHD) turbulence. The theory has three parameters – namely the upscale/downscale energy transfer rates and the forcing scale – and it includes the classic inertial-range theories as local limits. When applied to measured data, our global-in-scale theory can deduce the energy transfer rates using the full range of data, therefore it has broader applications compared with the local theories, especially in situations where the data is imperfect. In addition, because of the resolution of forcing scales, the new theory can detect the scales of energy input, which was impossible before. We test our new theory with a two-dimensional simulation of MHD turbulence.

scholarly journals Observation of an inertial-range energy cascade within a reconnection jet in the Earth’s magnetotail

2020 ◽  
Vol 500 (1) ◽  
pp. L6-L10
Author(s):  
Riddhi Bandyopadhyay ◽  
Alexandros Chasapis ◽  
D J Gershman ◽  
B L Giles ◽  
C T Russell ◽  
...  
Keyword(s):  
Broad Band ◽  
Structure Functions ◽  
Inertial Range ◽  
Order Structure ◽  
Linear Scaling ◽  
Tail Region ◽  
Scale Invariant ◽  
Third Order ◽  
Velocity Spectra ◽  
Turbulent Cascade

ABSTRACT The Earth’s magnetotail region provides a unique environment for the study of plasma turbulence. We investigate the turbulence developed in an exhaust produced by magnetic reconnection in the terrestrial magnetotail region. Magnetic and velocity spectra show broad-band fluctuations corresponding to the inertial range, with Kolmorogov scaling of −5/3, indicative of a well-developed turbulent cascade. We examine the mixed, third-order structure functions, and obtain a linear scaling in the inertial range. This linear scaling of the third-order structure functions implies a scale-invariant cascade of energy through the inertial range. A Politano–Pouquet third-order analysis gives an estimate of the incompressive energy transfer rate of ${\sim}10^{7}~\mathrm{J\, kg^{-1}\, s^{-1}}$. This is four orders of magnitude higher than the values typically measured in the 1-au solar wind, suggesting that the turbulence cascade plays an important role as a pathway of energy dissipation during reconnection events in the tail region.

scholarly journals Characteristics of the Taylor microscale in the solar wind/foreshock: magnetic field and electron velocity measurements

2013 ◽  
Vol 31 (11) ◽  
pp. 2063-2075 ◽  
Author(s):  
C. Gurgiolo ◽  
M. L. Goldstein ◽  
W. H. Matthaeus ◽  
A. Viñas ◽  
A. N. Fazakerley
Keyword(s):  
Magnetic Field ◽  
Field Data ◽  
Fluid Velocity ◽  
Electron Velocity ◽  
Data Sets ◽  
Velocity Data ◽  
Data Set ◽  
Magnetic Field Data ◽  
Spacecraft Data ◽  
The Magnetic Field

Abstract. The Taylor microscale is one of the fundamental turbulence scales. Not easily estimated in the interplanetary medium employing single spacecraft data, it has generally been studied through two point correlations. In this paper we present an alternative, albeit mathematically equivalent, method for estimating the Taylor microscale (λT). We make two independent determinations employing multi-spacecraft data sets from the Cluster mission, one using magnetic field data and a second using electron velocity data. Our results using the magnetic field data set yields a scale length of 1538 ± 550 km, slightly less than, but within the same range as, values found in previous magnetic-field-based studies. During time periods where both magnetic field and electron velocity data can be used, the two values can be compared. Relative comparisons show λT computed from the velocity is often significantly smaller than that from the magnetic field data. Due to a lack of events where both measurements are available, the absolute λT based on the electron fluid velocity is not able to be determined.

scholarly journals Local and global properties of energy transfer in models of plasma turbulence

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
Christian L. Vásconez ◽  
D. Perrone ◽  
R. Marino ◽  
D. Laveder ◽  
F. Valentini ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Low Frequency ◽  
Turbulent Energy ◽  
Scaling Properties ◽  
Global Properties ◽  
Collisionless Plasmas ◽  
Global Scaling ◽  
Kinetic Effects ◽  
Turbulent Cascade ◽  
Energy Channels

The nature of the turbulent energy transfer rate is studied using direct numerical simulations of weakly collisional space plasmas. This is done comparing results obtained from hybrid Vlasov–Maxwell simulations of collisionless plasmas, Hall magnetohydrodynamics and Landau fluid models reproducing low-frequency kinetic effects, such as the Landau damping. In this turbulent scenario, estimates of the local and global scaling properties of different energy channels are obtained using a proxy of the local energy transfer. This approach provides information on the structure of energy fluxes, under the assumption that the turbulent cascade transfers most of the energy that is then dissipated at small scales by various kinetic processes in these kinds of plasmas.

A compact exact law for compressible isothermal Hall magnetohydrodynamic turbulence

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Renaud Ferrand ◽  
Sébastien Galtier ◽  
Fouad Sahraoui
Keyword(s):  
Source Term ◽  
Reynolds Numbers ◽  
Space Plasmas ◽  
Order Structure ◽  
Magnetohydrodynamic Turbulence ◽  
Statistical Homogeneity ◽  
Background Magnetic Field ◽  
Taylor Hypothesis ◽  
Spacecraft Data

Using mixed second-order structure functions, a compact exact law is derived for isothermal compressible Hall magnetohydrodynamic turbulence with the assumptions of statistical homogeneity, time stationarity and infinite kinetic/magnetic Reynolds numbers. The resulting law is written as the sum of a Yaglom-like flux term, with an overall expression strongly reminiscent of the incompressible law, and a pure compressible source. Being mainly a function of the increments, the compact law is Galilean invariant but is dependent on the background magnetic field if one is present. Only the magnetohydrodynamic source term requires multi-spacecraft data to be estimated whereas the other components, which include those introduced by the Hall term, can be fully computed with single-spacecraft data using the Taylor hypothesis. These properties make this compact law more appropriate for analysing both numerical simulations and in situ data gathered in space plasmas, in particular when only single-spacecraft data are available.

Distributed and collaborative visualization of large data sets using high-speed networks

2006 ◽  
Vol 22 (8) ◽  
pp. 1004-1010 ◽  
Author(s):  
Andrei Hutanu ◽  
Gabrielle Allen ◽  
Stephen D. Beck ◽  
Petr Holub ◽  
Hartmut Kaiser ◽  
...  
Keyword(s):  
High Speed ◽  
Large Data ◽  
Large Data Sets ◽  
Data Sets ◽  
High Speed Networks ◽  
Collaborative Visualization

HelioSwarm: The Nature of Turbulence in Space Plasmas

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

<p>Recently selected for phase A study for NASA’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.  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. </p>

scholarly journals Asymmetric multifractal model for solar wind intermittent turbulence

2008 ◽  
Vol 15 (4) ◽  
pp. 615-620 ◽  
Author(s):  
A. Szczepaniak ◽  
W. M. Macek
Keyword(s):  
Solar Wind ◽  
Solar Maximum ◽  
Solar Wind Plasma ◽  
Intermittent Turbulence ◽  
Proposed Model ◽  
Scaling Parameters ◽  
Generalized Dimensions ◽  
Multifractal Nature ◽  
Turbulent Cascade

Abstract. We consider nonuniform energy transfer rate for solar wind turbulence depending on the solar cycle activity. To achieve this purpose we determine the generalized dimensions and singularity spectra for the experimental data of the solar wind measured in situ by Advanced Composition Explorer spacecraft during solar maximum (2001) and minimum (2006) at 1 AU. By determining the asymmetric singularity spectra we confirm the multifractal nature of different states of the solar wind. Moreover, for explanation of this asymmetry we propose a generalization of the usual so-called p-model, which involves eddies of different sizes for the turbulent cascade. Naturally, this generalization takes into account two different scaling parameters for sizes of eddies and one probability measure parameter, describing how the energy is transferred to smaller eddies. We show that the proposed model properly describes multifractality of the solar wind plasma.

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