Journal article
Interpreting radial correlation Doppler reflectometry using gyrokinetic simulations
- Abstract:
- A linear response, local model for the DBS amplitude applied to gyrokinetic simulations shows that radial correlation Doppler reflectometry measurements (RCDR, Schirmer et al 2007 Plasma Phys. Control. Fusion 49 1019) are not sensitive to the average turbulence radial correlation length, but to a correlation length that depends on the binormal wavenumber k⊥ selected by the Doppler backscattering (DBS) signal. Nonlinear gyrokinetic simulations show that the turbulence naturally exhibits a nonseparable power law spectrum in wavenumber space, leading to a power law dependence of the radial correlation length with binormal wavenumber lr ∼ Ck−α ⊥ (α ≈ 1) which agrees with the inverse proportionality relationship between the measured lr and k⊥ observed in experiments (Fern´andez-Marina et al 2014 Nucl. Fusion 54 072001). This new insight indicates that RCDR characterizes the eddy aspect ratio in the perpendicular plane to the magnetic field. It also motivates future use of a nonseparable turbulent spectrum to quantitatively interpret RCDR and potentially other turbulence diagnostics. The radial correlation length is only measurable when the radial resolution at the cutoff location Wn satisfies Wn ≪ lr , while the measurement becomes dominated by Wn for Wn ≫ lr . This suggests that lr is likely to be inaccessible for electron-scale DBS measurements (k⊥ρs > 1). The effect of Wn on ion-scale radial correlation lengths could be nonnegligible.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, 4.3MB, Terms of use)
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- Publisher copy:
- 10.1088/1361-6587/ac5916
- Publisher:
- IOP Publishing
- Journal:
- Plasma Physics and Controlled Fusion More from this journal
- Volume:
- 64
- Issue:
- 5
- Article number:
- 55019
- Publication date:
- 2022-04-12
- Acceptance date:
- 2022-02-28
- DOI:
- EISSN:
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1361-6587
- ISSN:
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0741-3335
- Language:
-
English
- Keywords:
- Pubs id:
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1253200
- Local pid:
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pubs:1253200
- Deposit date:
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2022-07-07
Terms of use
- Copyright holder:
- Ruiz Ruiz et al.
- Copyright date:
- 2022
- Rights statement:
- © 2022 The Author(s). Published by IOP Publishing Ltd. Original Content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
- Licence:
- CC Attribution (CC BY)
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