Test particle acceleration in three-dimensional Hall MHD turbulence

2006 ◽  
Vol 111 (A12) ◽  
Author(s):  
P. Dmitruk ◽  
W. H. Matthaeus
Keyword(s):  
Particle Acceleration ◽  
Test Particle ◽  
Three Dimensional ◽  
Mhd Turbulence ◽  
Hall Mhd

scholarly journals Particle acceleration in three-dimensional reconnection regions: A new test particle approach

1999 ◽  
Vol 6 (11) ◽  
pp. 4318-4327 ◽  
Author(s):  
Rüdiger Schopper ◽  
Guido T. Birk ◽  
Harald Lesch
Keyword(s):  
Particle Acceleration ◽  
Test Particle ◽  
Three Dimensional ◽  
Particle Approach

scholarly journals Test Particle Acceleration in Three-dimensional Magnetohydrodynamic Turbulence

2003 ◽  
Vol 597 (1) ◽  
pp. L81-L84 ◽  
Author(s):  
P. Dmitruk ◽  
W. H. Matthaeus ◽  
N. Seenu ◽  
M. R. Brown
Keyword(s):  
Particle Acceleration ◽  
Test Particle ◽  
Three Dimensional ◽  
Magnetohydrodynamic Turbulence

scholarly journals TEST-PARTICLE ACCELERATION IN A HIERARCHICAL THREE-DIMENSIONAL TURBULENCE MODEL

2014 ◽  
Vol 783 (2) ◽  
pp. 143 ◽  
Author(s):  
S. Dalena ◽  
A. F. Rappazzo ◽  
P. Dmitruk ◽  
A. Greco ◽  
W. H. Matthaeus
Keyword(s):  
Particle Acceleration ◽  
Turbulence Model ◽  
Test Particle ◽  
Three Dimensional

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.

scholarly journals Anisotropic three-dimensional MHD turbulence

1996 ◽  
Vol 101 (A4) ◽  
pp. 7619-7629 ◽  
Author(s):  
William H. Matthaeus ◽  
Sanjoy Ghosh ◽  
Sean Oughton ◽  
D. Aaron Roberts
Keyword(s):  
Three Dimensional ◽  
Mhd Turbulence

scholarly journals Spectral properties of magnetohydrodynamic convection with mean horizontal temperature gradient

2006 ◽  
Vol 2 (S239) ◽  
pp. 513-513
Author(s):  
D. Skandera ◽  
W.-Ch. Müller
Keyword(s):  
Temperature Field ◽  
Rayleigh Number ◽  
Temperature Gradient ◽  
Numerical Simulations ◽  
Spectral Properties ◽  
Three Dimensional ◽  
Numerical Code ◽  
Dimensional System ◽  
Horizontal Temperature Gradient ◽  
Mhd Turbulence

AbstractSpectral properties of convective magnetohydrodynamic (MHD) turbulence in two and three dimensions are studied by means of direct numerical simulations (Skandera D. & Müller W.-C. 2006). The investigated system is set up with a mean horizontal temperature gradient in order to avoid a development of elevator instabilities in a fully periodic box. All simulations are performed without mean magnetic field. The applied resolution is 5123 and 20482. The MHD equation are solved by a numerical code (Müller & Biskamp 2000) that uses a standard pseudospectral scheme. For removing of aliasing errors a spherical truncation method is employed. Obtained results are compared with predictions of various existing phenomenological theories for magnetohydrodynamic and convective turbulence (Müller & Biskamp 2000). While the three-dimensional system is found to operate in a Kolmogorov-like regime where buoyant forces have a negligible impact on the turbulence dynamics (relatively low Rayleigh number achieved in the simulation; Ra ∼106), the two-dimensional system exhibits interesting irregular quasi-oscillations between a buoyancy dominated Bolgiano-Obukhov-like regime of turbulence and a standard Iroshnikov-Kraichnan-like regime of turbulence (Müller & Biskamp 2000). The most important parameter determining the turbulent regime of 2D magnetoconvection, apart from a high Rayleigh number, seems to be the mutual alignment of velocity and magnetic fields. The non-linear dynamics and the interplay between individual fields are examined with different transfer functions that confirm basic assumptions about directions of energy transfer in spectral space. Kinetic, magnetic and temperature energy are transported by a turbulent cascade from large to smaller scales. The local/nonlocal character of the transport is tested for several individual terms in the governing equations. Moreover, other statistical quantities, e.g. probability density functions, are computed as well. A passive character of the temperature field in the investigated three-dimensional magnetoconvection is supported by computations of intermittency using extended self-similarity. The intermittency of the Elsasser field z+ is in agreement with results from numerical simulations of isotropic MHD turbulence (Müller & Biskamp 2000). The intermittency of the temperature field is found to approximately agree with results of passive scalar measurements in hydrodynamic turbulence (Ruiz-Chavarria, Baudet & Ciliberto 1996).

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