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Title: Validation study of a drift-wave turbulence model for CSDX linear plasma device

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1];  [1]
  1. Center for Energy Research, University of California at San Diego, San Diego, California 92093, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1389113
Grant/Contract Number:
FG02-06ER54871
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 9; Related Information: CHORUS Timestamp: 2018-02-14 15:07:41; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Vaezi, P., Holland, C., Thakur, S. C., and Tynan, G. R. Validation study of a drift-wave turbulence model for CSDX linear plasma device. United States: N. p., 2017. Web. doi:10.1063/1.4995305.
Vaezi, P., Holland, C., Thakur, S. C., & Tynan, G. R. Validation study of a drift-wave turbulence model for CSDX linear plasma device. United States. doi:10.1063/1.4995305.
Vaezi, P., Holland, C., Thakur, S. C., and Tynan, G. R. 2017. "Validation study of a drift-wave turbulence model for CSDX linear plasma device". United States. doi:10.1063/1.4995305.
@article{osti_1389113,
title = {Validation study of a drift-wave turbulence model for CSDX linear plasma device},
author = {Vaezi, P. and Holland, C. and Thakur, S. C. and Tynan, G. R.},
abstractNote = {},
doi = {10.1063/1.4995305},
journal = {Physics of Plasmas},
number = 9,
volume = 24,
place = {United States},
year = 2017,
month = 9
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4995305

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  • Using laser induced fluorescence (LIF), radial profiles of azimuthal ion fluid velocity and ion temperature are measured in the controlled shear de-correlation experiment (CSDX) linear helicon plasma device. Ion velocities and temperatures are derived from the measured Doppler broadened velocity distribution functions of argon ions. The LIF system employs a portable, high power (>300 mW), narrowband ({approx}1 MHz) tunable diode laser-based system operating at 668.614 nm. Previous studies in CSDX have shown the existence of a radially sheared azimuthal flow as measured with time delay estimation methods and Mach probes. Here, we report the first LIF measurements of sheared plasmamore » fluid flow in CSDX. Above a critical magnetic field, the ion fluid flow profile evolves from radially uniform to peaked on axis with a distinct reversed flow region at the boundary, indicating the development of a sheared azimuthal flow. Simultaneously, the ion temperature also evolves from a radially uniform profile to a profile with a gradient. Measurements in turbulent and coherent drift wave mode dominated plasmas are compared.« less
  • The experimental observations of the dynamics of the coupled drift wave turbulence (DWT)/sheared zonal flow (ZF) system in a cylindrical plasma device using a combination of Langmuir probe and fast-framing imaging measurements are reported. The results show the presence of an azimuthal ZF that exhibits low frequency (approx250 Hz) fluctuations. The envelope of the higher frequency (above 5 kHz) floating potential fluctuations associated with the DWT, the density gradient, and the turbulent radial particle flux are all modulated out of phase with the strength of the ZF. The divergence of the turbulent Reynolds stress is also modulated at the samemore » slow time scale in a phase-coherent manner consistent with a turbulent-driven shear flow sustained against the collisional and viscous damping. The radial turbulence correlation length and cross-field particle transport are reduced during periods of strong flow shear. The results are qualitatively consistent with theoretical expectations for coupled DWT-ZF dynamics.« less
  • For drift wave turbulence, due to charge conservation, the divergence of the parallel current is coupled to the divergence of the perpendicular polarization current, which determines the effective radial momentum flux, i.e., the Reynolds stress. Changes in the current flow patterns also affect the nonlinear energy transfer from smaller to larger scales. Here, we show that by changing the end plate boundary conditions in a cylindrical plasma device, the radial currents through the plasma and hence the net momentum transport and the nonlinear coupling for the inverse energy transfer are strongly modified. The transition to drift wave turbulence and themore » formation of low frequency zonal flows can be either suppressed with conducting boundaries or enhanced with insulating boundaries.« less
  • A study on the amplification of ion acoustic wave in an inhomogeneous plasma has been made on the basis of a nonlinear wave-particle interaction process called plasma maser effect. The drift wave instability, which is a universal phenomenon of an inhomogeneous confined plasma system, is found to be strongly in phase relation with thermal particles and may transfer its wave energy nonlinearly through a modulated field to ion acoustic wave. Considering a Maxwellian distribution function model for inhomogeneous plasmas under the standard local approximation, we have estimated the growth rate for ion acoustic wave, which is obtained by using themore » nonlinear dispersion relation. It has been found that amplification of ion acoustic wave is possible at the expense of drift wave turbulent energy. This result may be particularly important for stability of various drift modes in magnetically confined plasma as well as for transport of momentum and energy in such inhomogeneous systems.« less