Lower-hybrid drift and Buneman instabilities in current sheets with guide field

Journal Article · Sat Nov 15 04:00:00 EST 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2996115· OSTI ID:21259650

Yoon, P H ^[1]; Lui, A T. Y. ^[2]

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1. Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)
2. Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland 20723 (United States)

Lower-hybrid drift and Buneman instabilities operate in current sheets with or without the guide field. The lower-hybrid drift instability is a universal instability in that it operates for all parameters. In contrast, the excitation of Buneman instability requires sufficiently thin current sheet. That is, the relative electron-ion drift speed must exceed the threshold in order for Buneman instability to operate. Traditionally, the two instabilities were treated separately with different mathematical formalisms. In a recent paper, an improved electrostatic dispersion relation was derived that is valid for both unstable modes [P. H. Yoon and A. T. Y. Lui, Phys. Plasmas 15, 072101 (2008)]. However, the actual numerical analysis was restricted to a one-dimensional situation. The present paper generalizes the previous analysis and investigates the two-dimensional nature of both instabilities. It is found that the lower-hybrid drift instability is a flute mode satisfying k{center_dot}B=0 and k{center_dot}{nabla}n=0, where k represents the wave number for the most unstable mode, B stands for the total local magnetic field, and {nabla}n is the density gradient. This finding is not totally unexpected. However, a somewhat surprising finding is that the Buneman instability is a field-aligned mode characterized by kxB=0 and k{center_dot}{nabla}n=0, rather than being a beam-aligned instability.

• OSTI ID: 21259650
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 11 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DISPERSION RELATIONS
DRIFT INSTABILITY
ION DRIFT
LOWER HYBRID CURRENT DRIVE
LOWER HYBRID HEATING
NUMERICAL ANALYSIS
PLASMA WAVES