Journal article
Observation of coherent nonlinear interactions in the ion velocity distribution function
Physics of plasmas, Vol.13(11), pp.112108-112108-8
11/01/2006
DOI: 10.1063/1.2387143
Abstract
Using laser induced fluorescence (LIF) and higher order spectral analysis, we present the first measurements of phase space resolved coherent nonlinear interactions among the components of low frequency density fluctuations,
(
ω
⩽
ω
c
i
)
, in a linearly magnetized device. The bicoherence calculations employing the two point correlation technique suggest that there are two different coherent nonlinear wave-wave interactions in the measured spectrum. The first one, having a short correlation length and existing for slow moving ions, for which
∣
υ
i
‖
∣
⩽
∣
υ
i
th
∣
, is an interaction between fluctuations below the electron drift frequency,
ω
*
. The second one is the strongest for fast moving ions, for which
∣
υ
i
‖
∣
⩾
∣
υ
i
th
∣
, and is a mode coupling between the azimuthal drift wave modes,
m
=
1
and
m
=
2
. Combining these bispectral results with earlier linear analysis based on the power spectra of the fluctuations, we suggest that the nonlinear coupling observed between the spectral components below
ω
*
for the case of slow moving ions is associated with the anomalous kinetic component. For slow moving ions, as we increase the neutral collision frequencies, the nonlinear interaction observed for spectral components below
ω
*
decreases and the harmonic mode coupling for
ω
*
takes over.
Details
- Title: Subtitle
- Observation of coherent nonlinear interactions in the ion velocity distribution function
- Creators
- Ilker Ü. Uzun-Kaymak - Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242Frederick Skiff - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Physics of plasmas, Vol.13(11), pp.112108-112108-8
- DOI
- 10.1063/1.2387143
- ISSN
- 1070-664X
- eISSN
- 1089-7674
- Number of pages
- 8
- Language
- English
- Date published
- 11/01/2006
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984429029502771
Metrics
11 Record Views