Edge turbulence effect on ultra-fast swept reflectometry core measurements in tokamak plasmas
| Autor: | S. Hacquin, Roland Sabot, G. Zadvitskiy, Stéphane Heuraux, C. Lechte |
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| Přispěvatelé: | Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut für Grenzflächenverfahrenstechnik und Plasmatechnologie (IGVP), Universität Stuttgart [Stuttgart], Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), EUROfus Program Management Unit PMU, Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS) |
| Rok vydání: | 2018 |
| Předmět: |
Spectral shape analysis
Tokamak Computation 01 natural sciences 010305 fluids & plasmas law.invention Optics law [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph] 0103 physical sciences Born approximation 010306 general physics Reflectometry tokamak plasma reflectometry Physics business.industry Turbulence edge turbulence Inverse problem Condensed Matter Physics sweeping frequency reflectometry Amplitude swept reflectometry Nuclear Energy and Engineering plasma turbulence business |
| Zdroj: | Plasma Physics and Controlled Fusion Plasma Physics and Controlled Fusion, IOP Publishing, 2018, 60 (2), pp.025025. ⟨10.1088/1361-6587/aa9807⟩ Plasma Physics and Controlled Fusion, 2018, 60 (2), pp.025025. ⟨10.1088/1361-6587/aa9807⟩ |
| ISSN: | 0741-3335 1361-6587 0809-103X 0029-5515 0032-1028 1367-2630 |
| DOI: | 10.1088/1361-6587/aa9807 |
| Popis: | International audience; Ultra-fast frequency-swept reflectometry (UFSR) enables one to provide information about the turbulence radial wave-number spectrum and perturbation amplitude with good spatial and temporal resolutions. However, a data interpretation of USFR is quiet tricky. An iterative algorithm to solve this inverse problem was used in past works, Gerbaud (2006 Rev. Sci. Instrum. 77 10E928). For a direct solution, a fast 1D Helmholtz solver was used. Two-dimensional effects are strong and should be taken into account during data interpretation. As 2D full-wave codes are still too time consuming for systematic application, fast 2D approaches based on the Born approximation are of prime interest. Such methods gives good results in the case of small turbulence levels. However in tokamak plasmas, edge turbulence is usually very strong and can distort and broaden the probing beam Sysoeva et al (2015 Nucl. Fusion 55 033016). It was shown that this can change reflectometer phase response from the plasma core. Comparison between 2D full wave computation and the simplified Born approximation was done. The approximated method can provide a right spectral shape, but it is unable to describe a change of the spectral amplitude with an edge turbulence level. Computation for the O-mode wave with the linear density profile in the slab geometry and for realistic Tore-Supra density profile, based on the experimental data turbulence amplitude and spectrum, were performed to investigate the role of strong edge turbulence. It is shown that the spectral peak in the signal amplitude variation spectrum which rises with edge turbulence can be a signature of strong edge turbulence. Moreover, computations for misaligned receiving and emitting antennas were performed. It was found that the signal amplitude variation peak changes its position with a receiving antenna poloidal displacement. |
| Databáze: | OpenAIRE |
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