Numerical Test of Analytical Theories for Perpendicular Diffusion in Small Kubo Number Turbulence
Abstract
In the literature, one can find various analytical theories for perpendicular diffusion of energetic particles interacting with magnetic turbulence. Besides quasilinear theory, there are different versions of the nonlinear guiding center (NLGC) theory and the unified nonlinear transport (UNLT) theory. For turbulence with high Kubo numbers, such as twodimensional turbulence or noisy reduced magnetohydrodynamic turbulence, the aforementioned nonlinear theories provide similar results. For slab and small Kubo number turbulence, however, this is not the case. In the current paper, we compare different linear and nonlinear theories with each other and testparticle simulations for a noisy slab model corresponding to small Kubo number turbulence. We show that UNLT theory agrees very well with all performed testparticle simulations. In the limit of long parallel mean free paths, the perpendicular mean free path approaches asymptotically the quasilinear limit as predicted by the UNLT theory. For short parallel mean free paths we find a Rechester and Rosenbluth type of scaling as predicted by UNLT theory as well. The original NLGC theory disagrees with all performed simulations regardless what the parallel mean free path is. The random ballistic interpretation of the NLGC theory agrees much better with the simulations, but compared to UNLT theory themore »
 Authors:
 Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada)
 Publication Date:
 OSTI Identifier:
 22663676
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Astrophysical Journal; Journal Volume: 839; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COSMIC RADIATION; DIFFUSION; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MEAN FREE PATH; NONLINEAR PROBLEMS; RANDOMNESS; SIMULATION; SLABS; TURBULENCE; TWODIMENSIONAL CALCULATIONS
Citation Formats
Heusen, M., and Shalchi, A., Email: husseinm@myumanitoba.ca, Email: andreasm4@yahoo.com. Numerical Test of Analytical Theories for Perpendicular Diffusion in Small Kubo Number Turbulence. United States: N. p., 2017.
Web. doi:10.3847/15384357/AA6A55.
Heusen, M., & Shalchi, A., Email: husseinm@myumanitoba.ca, Email: andreasm4@yahoo.com. Numerical Test of Analytical Theories for Perpendicular Diffusion in Small Kubo Number Turbulence. United States. doi:10.3847/15384357/AA6A55.
Heusen, M., and Shalchi, A., Email: husseinm@myumanitoba.ca, Email: andreasm4@yahoo.com. Thu .
"Numerical Test of Analytical Theories for Perpendicular Diffusion in Small Kubo Number Turbulence". United States.
doi:10.3847/15384357/AA6A55.
@article{osti_22663676,
title = {Numerical Test of Analytical Theories for Perpendicular Diffusion in Small Kubo Number Turbulence},
author = {Heusen, M. and Shalchi, A., Email: husseinm@myumanitoba.ca, Email: andreasm4@yahoo.com},
abstractNote = {In the literature, one can find various analytical theories for perpendicular diffusion of energetic particles interacting with magnetic turbulence. Besides quasilinear theory, there are different versions of the nonlinear guiding center (NLGC) theory and the unified nonlinear transport (UNLT) theory. For turbulence with high Kubo numbers, such as twodimensional turbulence or noisy reduced magnetohydrodynamic turbulence, the aforementioned nonlinear theories provide similar results. For slab and small Kubo number turbulence, however, this is not the case. In the current paper, we compare different linear and nonlinear theories with each other and testparticle simulations for a noisy slab model corresponding to small Kubo number turbulence. We show that UNLT theory agrees very well with all performed testparticle simulations. In the limit of long parallel mean free paths, the perpendicular mean free path approaches asymptotically the quasilinear limit as predicted by the UNLT theory. For short parallel mean free paths we find a Rechester and Rosenbluth type of scaling as predicted by UNLT theory as well. The original NLGC theory disagrees with all performed simulations regardless what the parallel mean free path is. The random ballistic interpretation of the NLGC theory agrees much better with the simulations, but compared to UNLT theory the agreement is inferior. We conclude that for this type of small Kubo number turbulence, only the latter theory allows for an accurate description of perpendicular diffusion.},
doi = {10.3847/15384357/AA6A55},
journal = {Astrophysical Journal},
number = 2,
volume = 839,
place = {United States},
year = {Thu Apr 20 00:00:00 EDT 2017},
month = {Thu Apr 20 00:00:00 EDT 2017}
}

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