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Modelling of Neutron Markers for the COMPASS Upgrade Tokamak and Generation of Synthetic Neutron Spectra. JOURNAL OF FUSION ENERGY 2022. [DOI: 10.1007/s10894-022-00328-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Février O, Theiler C, De Oliveira H, Labit B, Fedorczak N, Baillod A. Analysis of wall-embedded Langmuir probe signals in different conditions on the Tokamak à Configuration Variable. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:053502. [PMID: 29864827 DOI: 10.1063/1.5022459] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This paper presents the current wall-embedded Langmuir probe system installed on the Tokamak à Configuration Variable (TCV), as well as the analysis tool chain used to interpret the current-voltage characteristic obtained when the probes are operated in swept-bias conditions. The analysis is based on a four-parameter fit combined with a minimum temperature approach. In order to reduce the effect of plasma fluctuations and measurement noise, several current-voltage characteristics are usually averaged before proceeding to the fitting. The impact of this procedure on the results is investigated, as well as the possible role of finite resistances in the circuitry, which could lead to an overestimation of the temperature. We study the application of the procedure in a specific regime, the plasma detachment, where results from other diagnostics indicate that the electron temperature derived from the Langmuir probes might be overestimated. To address this issue, we explore other fitting models and, in particular, an extension of the asymmetric double probe fit, which features effects of sheath expansion. We show that these models yield lower temperatures (up to approximately 60%) than the standard analysis in detached conditions, particularly for a temperature peak observed near the plasma strike point, but a discrepancy with other measurements remains. We explore a possible explanation for this observation, the presence of a fast electron population, and assess how robust the different methods are in such conditions.
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Affiliation(s)
- O Février
- Swiss Plasma Center (SPC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - C Theiler
- Swiss Plasma Center (SPC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - H De Oliveira
- Swiss Plasma Center (SPC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - B Labit
- Swiss Plasma Center (SPC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - N Fedorczak
- CEA, IRFM, F-13108 Saint Paul-lez-Durance, France
| | - A Baillod
- Swiss Plasma Center (SPC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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3
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Affiliation(s)
- E. S. Marmar
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts
| | - Alcator C-Mod Group
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts
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Greenwald M, Basse N, Bonoli P, Bravenec R, Edlund E, Ernst D, Fiore C, Granetz R, Hubbard A, Hughes J, Hutchinson I, Irby J, LaBombard B, Lin L, Lin Y, Lipschultz B, Marmar E, Mikkelsen D, Mossessian D, Phillips P, Porkolab M, Rice J, Rowan W, Scott S, Snipes J, Terry J, Wolfe S, Wukitch S, Zhurovich K. Confinement and Transport Research in Alcator C-Mod. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst07-a1422] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- M. Greenwald
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - N. Basse
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - P. Bonoli
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | | | - E. Edlund
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - D. Ernst
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - C. Fiore
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - R. Granetz
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - A. Hubbard
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - J. Hughes
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - I. Hutchinson
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - J. Irby
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - B. LaBombard
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - L. Lin
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - Y. Lin
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - B. Lipschultz
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - E. Marmar
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - D. Mikkelsen
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - D. Mossessian
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | | | - M. Porkolab
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - J. Rice
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - W. Rowan
- University of Texas, Austin, Texas
| | - S. Scott
- Princeton Plasma Physics Laboratory, Princeton, New Jersey
| | - J. Snipes
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - J. Terry
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - S. Wolfe
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - S. Wukitch
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
| | - K. Zhurovich
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02138
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McDonald DC, Andrew Y, Huysmans GTA, Loarte A, Ongena J, Rapp J, Saarelma S. Chapter 3: ELMy H-Mode Operation in JET. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst08-a1743] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- D. C. McDonald
- Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon Oxfordshire OX14 3DB, United Kingdom
| | - Y. Andrew
- Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon Oxfordshire OX14 3DB, United Kingdom
| | - G. T. A. Huysmans
- Association Euratom-CEA, CEA/DSM/DRFC, Centre de Cadarache 13108 St. Paul lez Durance, France
| | - A. Loarte
- EFDA Close Support Unit Garching, Boltzmannstrasse 2 D-85748 Garching bei München, Germany
| | - J. Ongena
- LPP-ERM0KMS, Euratom-Belgian State Association, Brussels, Belgium
| | - J. Rapp
- Forschungszentrum Jülich GmbH, Euratom Association, Jülich, Germany
| | - S. Saarelma
- Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon Oxfordshire OX14 3DB, United Kingdom
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Li J, Guo HY, Wan BN, Liang YF, Xu GS, Gong XZ, Xiaoa BJ. Recent Progress on EAST. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst13-a19131] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- J. Li
- Affiliation Information: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, P. R. China
| | - H. Y. Guo
- Affiliation Information: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, P. R. China
| | - B. N. Wan
- Affiliation Information: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, P. R. China
| | - Y. F. Liang
- Forschungszentrum Jülich GmbH, Association EURATOM-FZ Jülich, Institut für Energie- und Klimaforschung - Plasmaphysik, Trilateral Euregio Cluster, D-52425 Jülich, Germany
| | - G. S. Xu
- Affiliation Information: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, P. R. China
| | - X. Z. Gong
- Affiliation Information: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, P. R. China
| | - B. J. Xiaoa
- Affiliation Information: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, P. R. China
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Leyland MJ, Beurskens MNA, Flanagan JC, Frassinetti L, Gibson KJ, Kempenaars M, Maslov M, Scannell R. Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:013507. [PMID: 26827321 DOI: 10.1063/1.4939855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The Joint European Torus (JET) high resolution Thomson scattering (HRTS) system measures radial electron temperature and density profiles. One of the key capabilities of this diagnostic is measuring the steep pressure gradient, termed the pedestal, at the edge of JET plasmas. The pedestal is susceptible to limiting instabilities, such as Edge Localised Modes (ELMs), characterised by a periodic collapse of the steep gradient region. A common method to extract the pedestal width, gradient, and height, used on numerous machines, is by performing a modified hyperbolic tangent (mtanh) fit to overlaid profiles selected from the same region of the ELM cycle. This process of overlaying profiles, termed ELM synchronisation, maximises the number of data points defining the pedestal region for a given phase of the ELM cycle. When fitting to HRTS profiles, it is necessary to incorporate the diagnostic radial instrument function, particularly important when considering the pedestal width. A deconvolved fit is determined by a forward convolution method requiring knowledge of only the instrument function and profiles. The systematic error due to the deconvolution technique incorporated into the JET pedestal fitting tool has been documented by Frassinetti et al. [Rev. Sci. Instrum. 83, 013506 (2012)]. This paper seeks to understand and quantify the systematic error introduced to the pedestal width due to ELM synchronisation. Synthetic profiles, generated with error bars and point-to-point variation characteristic of real HRTS profiles, are used to evaluate the deviation from the underlying pedestal width. We find on JET that the ELM synchronisation systematic error is negligible in comparison to the statistical error when assuming ten overlaid profiles (typical for a pre-ELM fit to HRTS profiles). This confirms that fitting a mtanh to ELM synchronised profiles is a robust and practical technique for extracting the pedestal structure.
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Affiliation(s)
- M J Leyland
- Department of Physics, York Plasma Institute, University of York, Heslington, York YO10 5DD, United Kingdom
| | - M N A Beurskens
- Max-Planck Institute für Plasma Physik, D-17491 Greifswald, Germany
| | - J C Flanagan
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - L Frassinetti
- Division of Fusion Plasma Physics, KTH, SE-10044 Stockholm, Sweden
| | - K J Gibson
- Department of Physics, York Plasma Institute, University of York, Heslington, York YO10 5DD, United Kingdom
| | - M Kempenaars
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - M Maslov
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - R Scannell
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
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