Interpreting radial correlation doppler reflectometry using gyrokinetic simulations
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...
| Main Authors: | , , , , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2023
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| Online Access: | https://hdl.handle.net/1721.1/147632 |
| _version_ | 1811092925051830272 |
|---|---|
| author | Ruiz Ruiz, J Parra, FI Hall-Chen, VH Christen, N Barnes, M Candy, J Garcia, J Giroud, C Guttenfelder, W Hillesheim, JC Holland, C Howard, NT Ren, Y White, AE |
| author2 | Massachusetts Institute of Technology. Department of Nuclear Science and Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Ruiz Ruiz, J Parra, FI Hall-Chen, VH Christen, N Barnes, M Candy, J Garcia, J Giroud, C Guttenfelder, W Hillesheim, JC Holland, C Howard, NT Ren, Y White, AE |
| author_sort | Ruiz Ruiz, J |
| collection | MIT |
| description | 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. |
| first_indexed | 2024-09-23T15:35:20Z |
| format | Article |
| id | mit-1721.1/147632 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T15:35:20Z |
| publishDate | 2023 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1476322023-01-24T03:06:39Z Interpreting radial correlation doppler reflectometry using gyrokinetic simulations Ruiz Ruiz, J Parra, FI Hall-Chen, VH Christen, N Barnes, M Candy, J Garcia, J Giroud, C Guttenfelder, W Hillesheim, JC Holland, C Howard, NT Ren, Y White, AE Massachusetts Institute of Technology. Department of Nuclear Science and Engineering 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. 2023-01-23T15:48:56Z 2023-01-23T15:48:56Z 2022 2023-01-23T14:51:40Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/147632 Ruiz Ruiz, J, Parra, FI, Hall-Chen, VH, Christen, N, Barnes, M et al. 2022. "Interpreting radial correlation doppler reflectometry using gyrokinetic simulations." Plasma Physics and Controlled Fusion, 64 (5). en 10.1088/1361-6587/AC5916 Plasma Physics and Controlled Fusion Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ application/pdf IOP Publishing IOP Publishing |
| spellingShingle | Ruiz Ruiz, J Parra, FI Hall-Chen, VH Christen, N Barnes, M Candy, J Garcia, J Giroud, C Guttenfelder, W Hillesheim, JC Holland, C Howard, NT Ren, Y White, AE Interpreting radial correlation doppler reflectometry using gyrokinetic simulations |
| title | Interpreting radial correlation doppler reflectometry using gyrokinetic simulations |
| title_full | Interpreting radial correlation doppler reflectometry using gyrokinetic simulations |
| title_fullStr | Interpreting radial correlation doppler reflectometry using gyrokinetic simulations |
| title_full_unstemmed | Interpreting radial correlation doppler reflectometry using gyrokinetic simulations |
| title_short | Interpreting radial correlation doppler reflectometry using gyrokinetic simulations |
| title_sort | interpreting radial correlation doppler reflectometry using gyrokinetic simulations |
| url | https://hdl.handle.net/1721.1/147632 |
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