Fluctuations associated with a filamentary density depletion

Journal Article · Sat Feb 01 04:00:00 EST 1997 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.872089· OSTI ID:466896

Maggs, J E; Morales, G J ^[1]

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1. Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095 (United States)

Density and magnetic fluctuations arising spontaneously in a narrow field-aligned density striation in a magnetized discharge He plasma are found to exhibit a radial eigenmode structure. The nature of the fluctuations depends upon the electron plasma beta, {beta}{sub e}. For {beta}{sub e} greater than the electron to ion mass ratio ({beta}{sub e}{gt}m/M) the frequency spectrum exhibits sharply peaked eigenfrequencies with the density and magnetic fluctuations strongly coupled so that the growing mode is identified as the drift-Alfv{acute e}n wave. For {beta}{sub e} less than the mass ratio ({beta}{sub e}{lt}m/M) the density and magnetic fluctuations separate in frequency and broadband magnetic shear Alfv{acute e}n wave turbulence develops. The driving source for the fluctuations is the cross-field density and temperature gradients in the edge of the striation which have scale lengths on the order of the electron skin depth. The fluctuations associated with the striation are compared to the edge fluctuations of the plasma column which are found to exhibit a universal exponential frequency spectrum. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 466896
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 2 Vol. 4; ISSN 1070-664X; ISSN PHPAEN
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALFVEN WAVES
EIGENFREQUENCY
ELECTRIC DISCHARGES
FLUCTUATIONS
HELIUM
PLASMA
PLASMA DENSITY
TEMPERATURE GRADIENTS
TURBULENCE
WAVE PROPAGATION