Dispersion relations and polarizations of low-frequency waves in two-fluid plasmas

Journal Article · Wed Apr 15 04:00:00 EDT 2015 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4919257· OSTI ID:22408299

Zhao, Jinsong ^[1]

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1. Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

Analytical expressions for the dispersion relations and polarizations of low-frequency waves in magnetized plasmas based on two-fluid model are obtained. The properties of waves propagating at different angles (to the ambient magnetic field B{sub 0}) and β (the ratio of the plasma to magnetic pressures) values are investigated. It is shown that two linearly polarized waves—namely, the fast and Alfvén modes in the low-β (β≪1) plasmas, the fast and slow modes in the β∼1 plasmas, and the Alfvén and slow modes in the high-β (β≫1) plasmas—become circularly polarized at the near-parallel (to B{sub 0}) propagation. The negative magnetic-helicity of the Alfvén mode occurs only at small or moderate angles in the low-β plasmas, and the ion cross-helicity of the slow mode is nearly the same as that of the Alfvén mode in the high-β plasmas. It is also shown that the electric polarization δE{sub z}/δE{sub y} decreases with the temperature ratio T{sub e}/T{sub i} for the long-wavelength waves, and the transition between left- and right-hand polarizations of the Alfvén mode in T{sub e}/T{sub i}≠0 plasmas can disappear when T{sub e}/T{sub i}=0. The approximate dispersion relations in the near-perpendicular propagation, low-β, and high-β limits can quite accurately describe the three modes.

• OSTI ID: 22408299
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 4 Vol. 22; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALFVEN WAVES
DISPERSION RELATIONS
HELICITY
HIGH-BETA PLASMA
LANDAU LIQUID HELIUM THEORY
LOW-BETA PLASMA
MAGNETIC FIELDS
PLASMA PRESSURE
POLARIZATION
WAVELENGTHS