PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE
We use a method developed by Roberts. that optimizes the phase angles of an ensemble of plane waves with amplitudes determined from a Kolmogorov-like power spectrum, to construct magnetic field vector fluctuations having nearly constant magnitude and large variances in its components. This is a repr...
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ndltd-arizona.edu-oai-arizona.openrepository.com-10150-6213892016-11-20T03:00:29Z PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE Sun, P. Jokipii, J. R. Giacalone, J. Univ Arizona, Lunar & Planetary Lab diffusion magnetic fields solar wind turbulence We use a method developed by Roberts. that optimizes the phase angles of an ensemble of plane waves with amplitudes determined from a Kolmogorov-like power spectrum, to construct magnetic field vector fluctuations having nearly constant magnitude and large variances in its components. This is a representation of the turbulent magnetic field consistent with that observed in the solar wind. Charged-particle pitch-angle diffusion coefficients are determined by integrating the equations of motion for a large number of charged particles moving under the influence of forces from our predefined magnetic field. We tested different cases by varying the kinetic energy of the particles (E-p) and the turbulent magnetic field variance (sigma(2)(B)). For each combination of E-p and sigma(2)(B), we tested three different models: (1) the so-called "slab" model, where the turbulent magnetic field depends on only one spatial coordinate and has significant fluctuations in its magnitude (b=root delta B-x(2)(z)+ delta B-y(2)(z) + B-0(2)); (2) the slab model optimized with nearly constant magnitude b; and. (3) the slab model turbulent magnetic field with nearly constant magnitude plus a "variance-conserving" adjustment. In the last case, this model attempts to conserve the variance of the turbulent components (sigma(2)(Bx) + sigma(2)(By)), which is found to decrease during the optimization with nearly constant magnitude. We found that there is little or no effect on the pitch-angle diffusion coefficient D mu mu between. models 1 and 2. However, the result from model 3. is significantly different. We also introduce a new method to accurately determine the pitch-angle diffusion coefficients as a function of mu. 2016-08-03 Article PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE 2016, 827 (1):16 The Astrophysical Journal 1538-4357 10.3847/0004-637X/827/1/16 http://hdl.handle.net/10150/621389 http://arizona.openrepository.com/arizona/handle/10150/621389 The Astrophysical Journal en http://stacks.iop.org/0004-637X/827/i=1/a=16?key=crossref.4a24fa0dcb1b34abebc8365e102a7f20 © 2016. The American Astronomical Society. All rights reserved. IOP PUBLISHING LTD |
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language |
en |
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topic |
diffusion magnetic fields solar wind turbulence |
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diffusion magnetic fields solar wind turbulence Sun, P. Jokipii, J. R. Giacalone, J. PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE |
description |
We use a method developed by Roberts. that optimizes the phase angles of an ensemble of plane waves with amplitudes determined from a Kolmogorov-like power spectrum, to construct magnetic field vector fluctuations having nearly constant magnitude and large variances in its components. This is a representation of the turbulent magnetic field consistent with that observed in the solar wind. Charged-particle pitch-angle diffusion coefficients are determined by integrating the equations of motion for a large number of charged particles moving under the influence of forces from our predefined magnetic field. We tested different cases by varying the kinetic energy of the particles (E-p) and the turbulent magnetic field variance (sigma(2)(B)). For each combination of E-p and sigma(2)(B), we tested three different models: (1) the so-called "slab" model, where the turbulent magnetic field depends on only one spatial coordinate and has significant fluctuations in its magnitude (b=root delta B-x(2)(z)+ delta B-y(2)(z) + B-0(2)); (2) the slab model optimized with nearly constant magnitude b; and. (3) the slab model turbulent magnetic field with nearly constant magnitude plus a "variance-conserving" adjustment. In the last case, this model attempts to conserve the variance of the turbulent components (sigma(2)(Bx) + sigma(2)(By)), which is found to decrease during the optimization with nearly constant magnitude. We found that there is little or no effect on the pitch-angle diffusion coefficient D mu mu between. models 1 and 2. However, the result from model 3. is significantly different. We also introduce a new method to accurately determine the pitch-angle diffusion coefficients as a function of mu. |
author2 |
Univ Arizona, Lunar & Planetary Lab |
author_facet |
Univ Arizona, Lunar & Planetary Lab Sun, P. Jokipii, J. R. Giacalone, J. |
author |
Sun, P. Jokipii, J. R. Giacalone, J. |
author_sort |
Sun, P. |
title |
PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE |
title_short |
PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE |
title_full |
PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE |
title_fullStr |
PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE |
title_full_unstemmed |
PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE |
title_sort |
pitch-angle scattering of energetic charged particles in nearly constant magnitude magnetic turbulence |
publisher |
IOP PUBLISHING LTD |
publishDate |
2016 |
url |
http://hdl.handle.net/10150/621389 http://arizona.openrepository.com/arizona/handle/10150/621389 |
work_keys_str_mv |
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