scholarly journals Ion heat and parallel momentum transport by stochastic magnetic fields and turbulence

Author(s):  
Chang-Chun Chen ◽  
Patrick Diamond ◽  
Steve Tobias

Abstract The theory of turbulent transport of parallel momentum and ion heat by the interaction of stochastic magnetic fields and turbulence is presented. Attention is focused on determining the kinetic stress and the compressive energy flux. A critical parameter is identified as the ratio of the turbulent scattering rate to the rate of parallel acoustic dispersion. For the parameter large, the kinetic stress takes the form of a viscous stress. For the parameter small, the quasilinear residual stress is recovered. In practice, the viscous stress is the relevant form, and the quasilinear limit is not observable. This is the principal prediction of this paper. A simple physical picture is developed and shown to recover the results of the detailed analysis.

2021 ◽  
Vol 28 (2) ◽  
pp. 022309
Author(s):  
A. E. Fraser ◽  
P. W. Terry ◽  
E. G. Zweibel ◽  
M. J. Pueschel ◽  
J. M. Schroeder

2000 ◽  
Vol 175 ◽  
pp. 617-620
Author(s):  
John M. Porter

AbstractIt is assumed that the dynamics of Be star discs is dominated by the effects of viscous stresses. By examining angular momentum transport in discs, we show that many, if not all observed Be star discs should be accretion discs unless (i) the disc is acted upon by another agent (e.g. magnetic fields or the stellar radiation field), or (ii) the disc cools significantly as it flows outwards.


1997 ◽  
Vol 4 (2) ◽  
pp. 270-276 ◽  
Author(s):  
E. Vanden Eijnden ◽  
R. Balescu

1995 ◽  
Vol 2 (6) ◽  
pp. 2026-2032 ◽  
Author(s):  
H. Lin ◽  
R. F. Gandy ◽  
S. F. Knowlton ◽  
G. J. Hartwell ◽  
D. Prichard ◽  
...  

1993 ◽  
Vol 157 ◽  
pp. 395-401 ◽  
Author(s):  
Harald Lesch

Stimulated by recent high frequency radio polarization measurements of M83 and M51, we consider the influence of non-axisymmetric features (bars, spiral arms, etc…) on galactic magnetic fields. The time scale for the field amplification due to the non-axisymmetric velocity field is related to the time scale of angular momentum transport in the disk by the non-axisymmetric features. Due to its dissipational character (cooling and angular momentum transport) the gas plays a major role for the excitation of non-axisymmetric instabilities. Since it is the gaseous component of the interstellar gas in which magnetic field amplification takes place we consider the interplay of gasdynamical processes triggered by gravitational instabilities and magnetic fields. A comparison with the time scale for dynamo action in a disk from numerical models for disk dynamos gives the result that field amplification by non-axisymmetric features is faster in galaxies like M83 (strong bar) and M51 (compagnion and very distinct spiral structure), than amplification by an axisymmetric dynamo. Furthermore, we propose that axisymmetric gravitational instabilities may provide the turbulent magnetic diffusivity ηT. Based on standard galaxy models we obtain a radially dependent diffusivity whose numerical value rises from 1025cm2s−1 to 1027cm2s−1, declining for large radii.


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