Properties of Hall magnetohydrodynamic waves modified by electron inertia and finite Larmor radius effects

Journal Article · Mon Jun 15 04:00:00 EDT 2009 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3142479· OSTI ID:21277241

Damiano, P A; Wright, A N ^[1]; McKenzie, J F ^[2]

---

1. Mathematical Institute, University of St. Andrews, St. Andrews, Fife KY169SS (United Kingdom)
2. Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, University of KwaZulu-Natal, Durban 4000, South Africa and Department of Physics, CSPAR, University of Alabama, Hunstville, Alabama 35899 (United States)

The linear wave equation (sixth order in space and time) and the corresponding dispersion relation is derived for Hall magnetohydrodynamic (MHD) waves including electron inertial and finite Larmor radius effects together with several limiting cases for a homogeneous plasma. We contrast these limits with the solution of the full dispersion relation in terms of wave normal (k{sub perpendicular},k{sub ||}) diagrams to clearly illustrate the range of applicability of the individual approximations. We analyze the solutions in terms of all three MHD wave modes (fast, slow, and Alfven), with particular attention given to how the Alfven branch (including the cold ideal field line resonance (FLR) [D. J. Southwood, Planet. Space Sci. 22, 483 (1974)]) is modified by the Hall term and electron inertial and finite Larmor radius effects. The inclusion of these terms breaks the degeneracy of the Alfven branch in the cold plasma limit and displaces the asymptote position for the FLR to a line defined by the electron thermal speed rather than the Alfven speed. For a driven system, the break in this degeneracy implies that a resonance would form at one field line for small k{sub perpendicular} and then shift to another as k{sub perpendicular}{yields}{infinity}. However for very large {omega}k{sub perpendicular}/V{sub A}, Hall term effects lead to a coupling to the whistler mode, which would then transport energy away from the resonant layer. The inclusion of the Hall term also significantly effects the characteristics of the slow mode. This analysis reveals an interesting 'swapping' of the perpendicular root behavior between the slow and Alfven branches.

• OSTI ID: 21277241
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 6 Vol. 16; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALFVEN WAVES
COLD PLASMA
DISPERSION RELATIONS
ELECTRONS
HOMOGENEOUS PLASMA
LARMOR RADIUS
MAGNETOHYDRODYNAMICS
WAVE EQUATIONS
WHISTLER INSTABILITY