Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system

L. Schmitz; G. Wang; J. C. Hillesheim; T. L. Rhodes; W. A. Peebles; A. E. White; L. Zeng; T. A. Carter; W. Solomon

doi:10.1063/1.2953675

Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system

L. Schmitz
, G. Wang
, J. C. Hillesheim
, T. L. Rhodes
, W. A. Peebles
, A. E. White
, L. Zeng
, T. A. Carter
, W. Solomon

Research output: Contribution to journal › Article › peer-review

42 Scopus citations

Abstract

Doppler backscattering (DBS) has been successfully used to measure the E×B flow velocity and local intermediate wavenumber density fluctuation levels in the DIII-D tokamak. Depending on the launch angle and the frequency of the probing beam, the signal backscattered from the plasma cut-off layer is sensitive to density fluctuations at a specific perpendicular wavenumber (1≤ k⊥ ρ s ≤4). Due to the localization and high time resolution for poloidal flow measurements, DBS is well suited to detect stationary and time-dependent shear flows [zonal flows (ZFs)]. We present a novel scheme to measure ZF spectra using a dual-channel DBS system capable of simultaneously probing two minor radii separated by a distance of 0.2 cm<Δr<3 cm. Frequency spectra of geodesic acoustic modes and low frequency ZFs (f≤10 kHz) have been obtained for 0.6<ra<0.95.

Original language	English
Article number	10F113
Journal	Review of Scientific Instruments
Volume	79
Issue number	10
DOIs	https://doi.org/10.1063/1.2953675
State	Published - 2008
Externally published	Yes

Funding

We gratefully acknowledge the support of the DIII-D team. This work was supported by the U.S. Department of Energy under Grant Nos. DE-FG03-01ER54615, DE-FC02-04ER54698, and DE-AC02-76CH03073.

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10.1063/1.2953675

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title = "Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system",

abstract = "Doppler backscattering (DBS) has been successfully used to measure the E×B flow velocity and local intermediate wavenumber density fluctuation levels in the DIII-D tokamak. Depending on the launch angle and the frequency of the probing beam, the signal backscattered from the plasma cut-off layer is sensitive to density fluctuations at a specific perpendicular wavenumber (1≤ k⊥ ρ s ≤4). Due to the localization and high time resolution for poloidal flow measurements, DBS is well suited to detect stationary and time-dependent shear flows [zonal flows (ZFs)]. We present a novel scheme to measure ZF spectra using a dual-channel DBS system capable of simultaneously probing two minor radii separated by a distance of 0.2 cm<Δr<3 cm. Frequency spectra of geodesic acoustic modes and low frequency ZFs (f≤10 kHz) have been obtained for 0.6",

author = "L. Schmitz and G. Wang and Hillesheim, \{J. C.\} and Rhodes, \{T. L.\} and Peebles, \{W. A.\} and White, \{A. E.\} and L. Zeng and Carter, \{T. A.\} and W. Solomon",

year = "2008",

doi = "10.1063/1.2953675",

language = "English",

volume = "79",

journal = "Review of Scientific Instruments",

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T1 - Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system

AU - Schmitz, L.

AU - Wang, G.

AU - Hillesheim, J. C.

AU - Rhodes, T. L.

AU - Peebles, W. A.

AU - White, A. E.

AU - Zeng, L.

AU - Carter, T. A.

AU - Solomon, W.

PY - 2008

Y1 - 2008

N2 - Doppler backscattering (DBS) has been successfully used to measure the E×B flow velocity and local intermediate wavenumber density fluctuation levels in the DIII-D tokamak. Depending on the launch angle and the frequency of the probing beam, the signal backscattered from the plasma cut-off layer is sensitive to density fluctuations at a specific perpendicular wavenumber (1≤ k⊥ ρ s ≤4). Due to the localization and high time resolution for poloidal flow measurements, DBS is well suited to detect stationary and time-dependent shear flows [zonal flows (ZFs)]. We present a novel scheme to measure ZF spectra using a dual-channel DBS system capable of simultaneously probing two minor radii separated by a distance of 0.2 cm<Δr<3 cm. Frequency spectra of geodesic acoustic modes and low frequency ZFs (f≤10 kHz) have been obtained for 0.6

AB - Doppler backscattering (DBS) has been successfully used to measure the E×B flow velocity and local intermediate wavenumber density fluctuation levels in the DIII-D tokamak. Depending on the launch angle and the frequency of the probing beam, the signal backscattered from the plasma cut-off layer is sensitive to density fluctuations at a specific perpendicular wavenumber (1≤ k⊥ ρ s ≤4). Due to the localization and high time resolution for poloidal flow measurements, DBS is well suited to detect stationary and time-dependent shear flows [zonal flows (ZFs)]. We present a novel scheme to measure ZF spectra using a dual-channel DBS system capable of simultaneously probing two minor radii separated by a distance of 0.2 cm<Δr<3 cm. Frequency spectra of geodesic acoustic modes and low frequency ZFs (f≤10 kHz) have been obtained for 0.6

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Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system

Abstract

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