scholarly journals Scaling laws in Hall inertial-range turbulence

2019 ◽  
Vol 37 (5) ◽  
pp. 825-834 ◽  
Author(s):  
Yasuhito Narita ◽  
Wolfgang Baumjohann ◽  
Rudolf A. Treumann
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Scaling Laws ◽  
Magnetic Energy ◽  
Electric Energy ◽  
Power Spectra ◽  
Inertial Range ◽  
Energy Spectra ◽  
Mhd Turbulence ◽  
The Magnetic Field

Abstract. There is an increasing amount of observational evidence in space plasmas for the breakdown of inertial-range spectra of magnetohydrodynamic (MHD) turbulence on spatial scales smaller than the ion-inertial length. Magnetic energy spectra often exhibit a steepening, which is reminiscent of dissipation of turbulence energy, for example in wave–particle interactions. Electric energy spectra, on the other hand, tend to be flatter than those of MHD turbulence, which is indicative of a dispersive process converting magnetic into electric energy in electromagnetic wave excitation. Here we develop a model of the scaling laws and the power spectra for the Hall inertial range in plasma turbulence. In the present paper we consider a two-dimensional geometry with no wave vector component parallel to the magnetic field as is appropriate in Hall MHD. A phenomenological approach is taken. The Hall electric field attains an electrostatic component when the wave vectors are perpendicular to the mean magnetic field. The power spectra of Hall turbulence are steep for the magnetic field with a slope of -7/3 for compressible magnetic turbulence; they are flatter for the Hall electric field with a slope of -1/3. Our model for the Hall turbulence gives a possible explanation for the steepening of the magnetic energy spectra in the solar wind as an indication of neither the dissipation range nor the dispersive range but as the Hall inertial range. Our model also reproduces the shape of energy spectra in Kelvin–Helmholtz turbulence observed at the Earth's magnetopause.

scholarly journals Scaling laws in Hall-inertial range turbulence

2019 ◽  
Author(s):  
Yasuhito Narita ◽  
Wolfgang Baumjohann ◽  
Rudolf A. Treumann
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Scaling Laws ◽  
Magnetic Energy ◽  
Spatial Scales ◽  
Electric Energy ◽  
Power Spectra ◽  
Inertial Range ◽  
Energy Spectra ◽  
Mhd Turbulence

Abstract. There is an increasing amount of observational evidence in space plasma for the breakdown of inertial-range spectra of magnetohydrodynamic (MHD) turbulence on spatial scales smaller than the ion inertial length. Magnetic energy spectra often exhibit a steepening, which is reminiscent of dissipation of turbulence energy, for example in wave-particle interactions. Electric energy spectra, on the other hand, tend to be flatter than those of MHD turbulence, which is indicative of a dispersive process converting magnetic into electric energy in electromagnetic wave excitation. Here we develop a model of the scaling laws and the power spectra for the Hall-inertial range in plasma turbulence. A phenomenological approach is taken. The Hall electric field attains an electrostatic component when the wave vectors are perpendicular to the mean magnetic field. The power spectra of Hall-turbulence are steep for the magnetic field with slope of −7/3 for compressible magnetic turbulence, they are flatter for the Hall electric field with slope −1/3. Our model for the Hall-turbulence serves as a likely candidate to explain the steepening of the magnetic energy spectra in the solar wind neither as indication of the dissipation range nor the dispersive range but as the Hall-inertial range. Our model also reproduces the shape of energy spectra in Kelvin-Helmholtz turbulence observed at the Earth magnetopause.

Fast magnetic field penetration into low resistivity plasma

2017 ◽  
Vol 83 (1) ◽  
Author(s):  
Amnon Fruchtman
Keyword(s):  
Magnetic Field ◽  
Energy Dissipation ◽  
Electric Field ◽  
Density Gradient ◽  
Magnetic Energy ◽  
Measured Velocity ◽  
Magnetic Field Penetration ◽  
The Magnetic Field ◽  
Uniform Plasma ◽  
Field Penetration

Penetration of a magnetic field into plasma that is faster than resistive diffusion can be induced by the Hall electric field in a non-uniform plasma. This mechanism explained successfully the measured velocity of the magnetic field penetration into pulsed plasmas. Major related issues have not yet been resolved. Such is the theoretically predicted, but so far not verified experimentally, high magnetic energy dissipation, as well as the correlation between the directions of the density gradient and of the field penetration.

Parametric investigation of self-similar decay laws in MHD turbulent flows

1999 ◽  
Vol 61 (3) ◽  
pp. 507-541 ◽  
Author(s):  
S. GALTIER ◽  
E. ZIENICKE ◽  
H. POLITANO ◽  
A. POUQUET
Keyword(s):  
Magnetic Field ◽  
Turbulent Flows ◽  
Magnetic Energy ◽  
Nauk Sssr ◽  
Mhd Turbulence ◽  
Integral Scale ◽  
Self Similar ◽  
Grid Points ◽  
The One ◽  
The Magnetic Field

An investigation of the decay laws of energy and of higher moments of the Elsässer fields z±=v±b in the self-similar regime of magnetohydrodynamic (MHD) turbulence is presented, using phenomenological models as well as two-dimensional numerical simulations with periodic boundary conditions and up to 20482 grid points. The results are compared with the generalization of the parameter-free model derived by Galtier et al. [Phys. Rev. Lett.79, 2807 (1997)], which takes into account the slowing down of the dynamics due to the propagation of Alfvén waves. The new model developed here allows for a study in terms of one parameter governing the wavenumber dependence of the energy spectrum at scales of the order of (and larger than) the integral scale of the flow. The one-dimensional compressible case is also dealt with in two of its simplest configurations. Computations are performed for a standard Laplacian diffusion as well as with a hyperdiffusive algorithm. The results are sensitive to the amount of correlation between the velocity and the magnetic field, but rather insensitive to all other parameters such as the initial ratio of kinetic to magnetic energy or the presence or absence of a uniform component of the magnetic field. In all cases, the decay is significantly slower than for neutral fluids in a way that favours for MHD flows the phenomenology of Iroshnikov [Soviet Astron.7, 566 (1963)] and Kraichnan [Phys. Fluids8, 1385 (1965)] as opposed to that of Kolmogorov [Dokl. Akad. Nauk. SSSR31, 538 (1941)]. The temporal evolution of q-moments of the generalized vorticities 〈[mid ]ω±[mid ]q〉 =〈[mid ]ω±j[mid ]q〉 up to order q=10 is also given, and is compared with the prediction of the model. Less agreement obtains as q grows – a fact probably due to intermittency and the development of coherent structures in the form of eddies, and of vorticity and current sheets.

Solar turbulence from sunspot records

2019 ◽  
Vol 492 (1) ◽  
pp. 1416-1420
Author(s):  
J L Le Mouël ◽  
F Lopes ◽  
V Courtillot
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Spectral Density ◽  
Convection Zone ◽  
Magnetic Energy ◽  
Singular Spectrum Analysis ◽  
Inertial Range ◽  
Period Range ◽  
Power Spectral ◽  
The Magnetic Field

ABSTRACT It is generally assumed that coupling between the turbulent flow and the magnetic field at the top of the Sun's convection zone leads to a Kolmogorov cascade of kinetic to magnetic energy. An inertial range and a slope value close to −5/3 have been recognized in a log–log diagram of power spectral density versus frequency (or period). However, published values of the slope have large uncertainties and the inertial period range is limited to 0.1 s to 2 yr. We have applied an adapted version of the singular spectrum analysis (SSA) method to the series of (quasi-) daily sunspot numbers ISSN (an indirect way of monitoring solar activity) from 1868 to 2019. The log–log diagram of ISSN variance of SSA components versus frequency displays an inertial slope value of −1.66 ± 0.16 and an inertial range from about 4 to 100 yr. This is consistent with the existence of Kolmogorov turbulent behaviour in the Sun's convection zone.

scholarly journals Variable Energy Fluxes and Exact Relations in Magnetohydrodynamics Turbulence

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 225
Author(s):  
Mahendra Verma ◽  
Manohar Sharma ◽  
Soumyadeep Chatterjee ◽  
Shadab Alam
Keyword(s):  
Magnetic Field ◽  
Velocity Field ◽  
Numerical Simulations ◽  
Inertial Range ◽  
Energy Fluxes ◽  
Mhd Turbulence ◽  
Conservation Of Energy ◽  
Exact Relations ◽  
The Magnetic Field ◽  
Variable Energy

In magnetohydrodynamics (MHD), there is a transfer of energy from the velocity field to the magnetic field in the inertial range itself. As a result, the inertial-range energy fluxes of velocity and magnetic fields exhibit significant variations. Still, these variable energy fluxes satisfy several exact relations due to conservation of energy. In this paper, using numerical simulations, we quantify the variable energy fluxes of MHD turbulence, as well as verify several exact relations. We also study the energy fluxes of Elsässer variables that are constant in the inertial range.

scholarly journals 3D-MHD simulations of the evolution of magnetic fields in FR II radio sources

2010 ◽  
Vol 6 (S275) ◽  
pp. 170-171
Author(s):  
Martín Huarte-Espinosa ◽  
Martin Krause ◽  
Paul Alexander
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Numerical Simulations ◽  
Magnetic Structure ◽  
Magnetic Energy ◽  
Power Spectra ◽  
Radio Sources ◽  
Viewing Angle ◽  
Mhd Simulations ◽  
The Magnetic Field

Abstract3D-MHD numerical simulations of bipolar, hypersonic, weakly magnetized jets and synthetic synchrotron observations are presented to study the structure and evolution of magnetic fields in FR II radio sources. The magnetic field setup in the jet is initially random. The power of the jets as well as the observational viewing angle are investigated. We find that synthetic polarization maps agree with observations and show that magnetic fields inside the sources are shaped by the jets' backflow. Polarimetry statistics correlates with time, the viewing angle and the jet-to-ambient density contrast. The magnetic structure inside thin elongated sources is more uniform than for ones with fatter cocoons. Jets increase the magnetic energy in cocoons, in proportion to the jet velocity. Both, filaments in synthetic emission maps and 3D magnetic power spectra suggest that turbulence develops in evolved sources.

scholarly journals Trans-Alfvénic magnetohydrodynamic turbulence in the vicinity of supernova remnant Cassiopeia-A shocks

2020 ◽  
Vol 498 (1) ◽  
pp. 1093-1100
Author(s):  
Pavan Kumar Vishwakarma ◽  
Jais Kumar
Keyword(s):  
Magnetic Field ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Magnetic Energy ◽  
Energy Spectra ◽  
Magnetohydrodynamic Turbulence ◽  
Cassiopeia A ◽  
Point Correlation ◽  
Frequency Observation ◽  
The Magnetic Field

ABSTRACT Statistics of the magnetic field disturbances in supernova remnants (SNRs) can be accessed using the second-order correlation function of the synchrotron intensities. Here we measure the magnetic energy spectra in the supernova remnant Cassiopeia-A by two-point correlation of the synchrotron intensities, using a recently developed unbiased method. The measured magnetic energy spectra in the vicinity of supernova remnant shocks are found to be a 2/3 power law over the decade of range scales, showing the developed trans-Alfvénic magnetohydrodynamic turbulence. Our results are globally consistent with the theoretical prediction of trans-Alfvénic Mach number in developed magnetohydrodynamic turbulence and can be explained by amplification of the magnetic field in the vicinity of SNR shocks. The magnetic energy spectra predict SNR Cassiopeia-A to have an additional subshock in the radio frequency observation along with forward and reverse shocks, with a radial window of the amplified magnetic field of ∼ 0.115 pc near the shocks.

PEMANFAATAN RADIASI ENERGI TEGANGAN 150 KV UNTUK LAMPU LED PENERANGAN JALAN

Jurnal Teknik ◽  
2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Mauludi Manfaluthy
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
High Voltage ◽  
Low Frequency ◽  
Energy Utilization ◽  
World Health ◽  
Electromagnetic Signals ◽  
Health Organization ◽  
The Magnetic Field ◽  
Low Frequency Waves

WHO (World Health Organization) concludes that not much effect is caused by electric field up to 20 kV / m in humans. WHO standard also mentions that humans will not be affected by the magnetic field under  100 micro tesla and that the electric field will affect the human body with a maximum standard of 5,000 volts per meter. In this study did not discuss about the effect of high voltage radiation SUTT (High Voltage Air Channel) with human health. The research will focus on energy utilization of SUTT radiation. The combination of electric field and magnetic field on SUTT (70-150KV) can generate electromagnetic (EM) and radiation waves, which are expected to be converted to turn on street lights around the location of high voltage areas or into other forms. The design of this prototype works like an antenna in general that captures electromagnetic signals and converts them into AC waves. With a capacitor that can store the potential energy of AC and Schottky diode waves created specifically for low frequency waves, make the current into one direction (DC). From the research results obtained the current generated from the radiation is very small even though the voltage is big enough.Keywords : Radiance Energy, Joule Thief, and  LED Module.

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

2019 ◽  
Vol 85 (4) ◽  
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.

Investigating flexible textile-based coils for wireless charging wearable electronics

2019 ◽  
Vol 50 (3) ◽  
pp. 333-345 ◽  
Author(s):  
Danmei Sun ◽  
Meixuan Chen ◽  
Symon Podilchak ◽  
Apostolos Georgiadis ◽  
Qassim S Abdullahi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Electromagnetic Field ◽  
Electric Field ◽  
Dimensional Stability ◽  
Screen Printing ◽  
Wearable Electronics ◽  
Wireless Charging ◽  
The Magnetic Field ◽  
Screen Printed

Smart and interactive textiles have been attracted great attention in recent years. This research explored three different techniques and processes in developing textile-based conductive coils that are able to embed in a garment layer. Coils made through embroidery and screen printing have good dimensional stability, although the resistance of screen printed coil is too high due to the low conductivity of the print ink. Laser cut coil provided the best electrical conductivity; however, the disadvantage of this method is that it is very difficult to keep the completed coil to the predetermined shape and dimension. The tested results show that an electromagnetic field has been generated between the textile-based conductive coil and an external coil that is directly powered by electricity. The magnetic field and electric field worked simultaneously to complete the wireless charging process.

Sign in / Sign up

Export Citation Format

Share Document