Direct extraction of coherent mode properties from imaging measurements in a linear plasma column

Spectral properties of coherent waves in an argon plasma column are examined using fluctuation data from fast imaging. Visible light from ArII line emission is collected at high frame rates using a high-speed digital camera. A cross-spectral phase technique allows direct visualization of dominant ph...

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Bibliographic Details
Published in:Physics of plasmas 2013-08, Vol.20 (8)
Main Authors: Light, A. D., Thakur, S. C., Brandt, C., Sechrest, Y., Tynan, G. R., Munsat, T.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ARGON
Argon plasma
CAMERAS
Coherence
Columns (structural)
COMPARATIVE EVALUATIONS
Digital cameras
Dispersions
FLUCTUATIONS
FREQUENCY DEPENDENCE
HELMHOLTZ INSTABILITY
Imaging
PLASMA
Plasma (physics)
PLASMA DIAGNOSTICS
PLASMA DRIFT
PLASMA WAVES
Spectra
VISIBLE RADIATION
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Summary:Spectral properties of coherent waves in an argon plasma column are examined using fluctuation data from fast imaging. Visible light from ArII line emission is collected at high frame rates using a high-speed digital camera. A cross-spectral phase technique allows direct visualization of dominant phase structures as a function of frequency, as well as identification of azimuthal asymmetries present in the system. Experimental dispersion estimates are constructed from imaging data alone. Drift-like waves are identified by comparison with theoretical dispersion curves, and a tentative match of a low-frequency spectral feature to Kelvin-Helmholtz-driven waves is presented. Imaging measurements are consistent with previous results, and provide non-invasive, single-shot measurements across the entire plasma cross-section. Implications of the measured spectral properties for imaging measurements of mode dynamics are explored.
ISSN:1070-664X
1089-7674
DOI:10.1063/1.4818148