MHD theory of field line resonance in the magnetosphere

Technical Report · Wed Jan 01 04:00:00 EST 1992

DOI:https://doi.org/10.2172/6021925· OSTI ID:6021925

Cheng, C Z ^[1]; Chang, T C; Lin, C A; Tsai, W H ^[2]

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1. Princeton Univ., NJ (United States). Plasma Physics Lab.
2. National Central Univ., Chung Li (Taiwan, Province of China). Inst. of Space Science

The linearized ideal MHD equations are cast into a set of global differential equations from which the field line resonance equations of the shear Alfven waves and slow magnetosonic waves are naturally obtained for finite pressure plasmas in general magnetic field geometries with flux surfaces. The coupling between the shear Alfven waves and the magnetosonic waves is through the geodesic magnetic field curvature. For axisymmetric magnetospheric equilibria, there is no coupling between the shear Alfven waves and slow magnetosonic waves because the geodesic magnetic field curvature vanishes. The asymptotic singular solutions of the MHD equations near the field line resonant surface are derived. Numerical solutions of the field line resonance equations are performed for the dipole magnetic field, and it is found that the shear Alfven wave field line resonant frequency is proportional to L{sup {minus}4}{rho}{sup {minus}1/2}. The slow magnetosonic wave resonant frequency is much smaller than the Shear Alfven wave resonant frequency and is roughly proportional to P/{rho}L{sup 2}, where L is the equatorial L-shell distance, P is the plasma pressure, and {rho} is the plasma mass density. The results help to understand the continuous spectra observed by AMPTE/CCE.

• Research Organization: Princeton Univ., NJ (United States). Plasma Physics Lab.
• Sponsoring Organization: DOE; NSF; USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 6021925
• Report Number(s): PPPL-2814; ON: DE92006653; CNN: ATM-8911638; NSC 80-0202-M008-14
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALFVEN WAVES
AXIAL SYMMETRY
DIFFERENTIAL EQUATIONS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
EIGENFUNCTIONS
EQUATIONS
FLUID MECHANICS
FUNCTIONS
HYDRODYNAMICS
HYDROMAGNETIC WAVES
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MECHANICS
SYMMETRY