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Ko J, Ko J. Sensitivity of motional Stark effect on different beam energy components for radial electric field measurements in tokamak plasmas. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:083532. [PMID: 39150549 DOI: 10.1063/5.0219593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Accepted: 08/02/2024] [Indexed: 08/17/2024]
Abstract
Measurement of the internal magnetic field is crucial for determining the equilibrium, stability, and current density of a plasma in a tokamak. A motional Stark Effect (MSE) diagnostic was developed to provide a measurement of the internal magnetic field in tokamaks by analyzing the emission from the interaction of the plasma particle with an injected neutral beam. The Stark effect causes the shifting and splitting of deuterium spectral lines due to the Lorentz electric field. However, it is difficult to accurately measure the internal magnetic field components since the radial electric field inherently formed inside the plasma is mixed with the Lorentz field. Under the circumstances in the Korea Superconducting Tokamak Advanced Research (KSTAR) device, one possible approach is to derive a radial electric field by measuring and comparing the polarization angles from the full and half-energy components of the neutral beam. To utilize the polychromatic MSE diagnostics in KSTAR, the half-energy component wavelength bands according to various magnetic field and beam energy combinations have been calculated, and the filter combinations required for those measurements have been selected. The Stokes-filter model used to evaluate the effect of multiple-ion-source neutral beam injection on the MSE measurements has been extended to infer the sensitivity of this approach to take the non-ideal bandpass filter effects into account.
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Affiliation(s)
- Juyoung Ko
- Korea Institute of Fusion Energy, Daejeon, South Korea
| | - Jinseok Ko
- Korea Institute of Fusion Energy, Daejeon, South Korea
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2
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Simulation of the multi-channel motional Stark effect diagnostic on EAST Tokamak. FUSION ENGINEERING AND DESIGN 2020. [DOI: 10.1016/j.fusengdes.2020.111516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
The concept and structure of the Simulation of Spectra (SOS) code is described starting with an introduction to the physics background of the project and the development of a simulation tool enabling the modeling of charge-exchange recombination spectroscopy (CXRS) and associated passive background spectra observed in hot fusion plasmas. The generic structure of the code implies its general applicability to any fusion device, the development is indeed based on over two decades of spectroscopic observations and validation of derived plasma data. Four main types of active spectra are addressed in SOS. The first type represents thermal low-Z impurity ions and the associated spectral background. The second type of spectra represent slowing-down high energy ions created from either thermo-nuclear fusion reactions or ions from injected high energy neutral beams. Two other modules are dedicated to CXRS spectra representing bulk plasma ions (H+, D+, or T+) and beam emission spectroscopy (BES) or Motional Stark Effect (MSE) spectrum appearing in the same spectral range. The main part of the paper describes the physics background for the underlying emission processes: active and passive CXRS emission, continuum radiation, edge line emission, halo and plume effect, or finally the charge exchange (CX) cross-section effects on line shapes. The description is summarized by modeling the fast ions emissions, e.g., either of the α particles of the fusion reaction or of the beam ions itself.
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Reimer R, Marchuk O, Geiger B, Mc Carthy PJ, Dunne M, Hobirk J, Wolf R. Influence of non-local thermodynamic equilibrium and Zeeman effects on magnetic equilibrium reconstruction using spectral motional Stark effect diagnostic. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:083509. [PMID: 28863658 DOI: 10.1063/1.4994889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The Motional Stark Effect (MSE) diagnostic is a well established technique to infer the local internal magnetic field in fusion plasmas. In this paper, the existing forward model which describes the MSE data is extended by the Zeeman effect, fine-structure, and relativistic corrections in the interpretation of the MSE spectra for different experimental conditions at the tokamak ASDEX Upgrade. The contribution of the non-Local Thermodynamic Equilibrium (non-LTE) populations among the magnetic sub-levels and the Zeeman effect on the derived plasma parameters is different. The obtained pitch angle is changed by 3°…4° and by 0.5°…1° including the non-LTE and the Zeeman effects into the standard statistical MSE model. The total correction is about 4°. Moreover, the variation of the magnetic field strength is significantly changed by 2.2% due to the Zeeman effect only. While the data on the derived pitch angle still could not be tested against the other diagnostics, the results from an equilibrium reconstruction solver confirm the obtained values for magnetic field strength.
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Affiliation(s)
- R Reimer
- Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany
| | - O Marchuk
- Institut für Energie und Klimaforschung-Plasmaphysik, Forschungszentrum Juelich GmbH, 52425 Jülich, Germany
| | - B Geiger
- Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstraße 2, 85748 Garching, Germany
| | - P J Mc Carthy
- Department of Physics, University College Cork, Association EURATOM-DCU, Cork, Ireland
| | - M Dunne
- Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstraße 2, 85748 Garching, Germany
| | - J Hobirk
- Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstraße 2, 85748 Garching, Germany
| | - R Wolf
- Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany
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Dinklage A, Reimer R, Wolf R, Reich M. Forward Modeling of Motional Stark Effect Spectra. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst11-a11655] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- A. Dinklage
- Max-Planck-Institut für Plasmaphysik, EURATOM-Association, Wendelsteinstr. 1, Greifswald, Germany
| | - R. Reimer
- Max-Planck-Institut für Plasmaphysik, EURATOM-Association, Wendelsteinstr. 1, Greifswald, Germany
| | - R. Wolf
- Max-Planck-Institut für Plasmaphysik, EURATOM-Association, Wendelsteinstr. 1, Greifswald, Germany
| | - M. Reich
- Max-Planck-Institut für Plasmaphysik, EURATOM-Association, Boltzmannstr. 2, Garching, Germany
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Coelho R, Äkäslompolo S, Dinklage A, Kus A, Reimer R, Sundén E, Conroy S, Blanco E, Conway G, Hacquin S, Heuraux S, Lechte C, Silva FD, Sirinelli A, ITM-TF C. Synthetic Diagnostics in the European Union Integrated Tokamak Modelling Simulation Platform. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst12-473] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- R. Coelho
- Associação EURATOM0IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico Universidade Técnica de Lisboa, P-1049-001 Lisboa, Portugal
| | - S. Äkäslompolo
- Aalto University, Euratom-Tekes Association, P.O. Box 14100, FI-00076 AALTO, Finland
| | - A. Dinklage
- Max-Planck-Institut für Plasma physik, EURATOM-Association, Wendelsteinstr. 1, Greifswald, Germany
| | - A. Kus
- Max-Planck-Institut für Plasma physik, EURATOM-Association, Wendelsteinstr. 1, Greifswald, Germany
| | - R. Reimer
- Max-Planck-Institut für Plasma physik, EURATOM-Association, Wendelsteinstr. 1, Greifswald, Germany
| | - E. Sundén
- Uppsala University, VR-Euratom Association, Box 516, 751 20 Uppsala, Sweden
| | - S. Conroy
- Uppsala University, VR-Euratom Association, Box 516, 751 20 Uppsala, Sweden
| | - E. Blanco
- Asociación EURATOM-CIEMAT para Fusión, CIEMAT, Madrid, Spain Association
| | - G. Conway
- Max-Planck-Institut für Plasma physik, EURATOM-IPP Association, Garching, Germany
| | - S. Hacquin
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
| | - S. Heuraux
- Université de Lorraine, IJL, UMR 7198, BP 70239, Vandoeuvre, F-54506 Cedex, France
| | - C. Lechte
- Institute for Plasma Research, University of Stuttgart, 70569 Stuttgart, Germany
| | - F. Da Silva
- Associação EURATOM0IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico Universidade Técnica de Lisboa, P-1049-001 Lisboa, Portugal
| | - A. Sirinelli
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
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Reimer R, Dinklage A, Fischer R, Hobirk J, Löbhard T, Mlynek A, Reich M, Sawyer L, Wolf R. Spectrally resolved motional Stark effect measurements on ASDEX Upgrade. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:113503. [PMID: 24295436 DOI: 10.1063/1.4829665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A spectrally resolved Motional Stark Effect (MSE) diagnostic has been installed at ASDEX Upgrade. The MSE data have been fitted by a forward model providing access to information about the magnetic field in the plasma interior [R. Reimer, A. Dinklage, J. Geiger et al., Contrib. Plasma Phys. 50, 731-735 (2010)]. The forward model for the beam emission spectra comprises also the fast ion Dα signal [W. W. Heidbrink and G. J. Sadler, Nucl. Fusion 34, 535-615 (1994)] and the smearing on the CCD-chip. The calculated magnetic field data as well as the revealed (dia)magnetic effects are consistent with the results from equilibrium reconstruction solver. Measurements of the direction of the magnetic field are affected by unknown and varying polarization effects in the observation.
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Affiliation(s)
- R Reimer
- Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany
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Ghim YC, Schekochihin AA, Field AR, Abel IG, Barnes M, Colyer G, Cowley SC, Parra FI, Dunai D, Zoletnik S. Experimental signatures of critically balanced turbulence in MAST. PHYSICAL REVIEW LETTERS 2013; 110:145002. [PMID: 25166998 DOI: 10.1103/physrevlett.110.145002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Indexed: 06/03/2023]
Abstract
Beam emission spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that the turbulence correlation time, the drift time associated with ion temperature or density gradients, the particle (ion) streaming time along the magnetic field, and the magnetic drift time are consistently comparable, suggesting a "critically balanced" turbulence determined by the local equilibrium. The resulting scalings of the poloidal and radial correlation lengths are derived and tested. The nonlinear time inferred from the density fluctuations is longer than the other times; its ratio to the correlation time scales as ν(*i)(-0.8 ± 0.1), where ν(*i) = ion collision rate/streaming rate. This is consistent with turbulent decorrelation being controlled by a zonal component, invisible to the BES, with an amplitude exceeding those of the drift waves by ∼ ν(*i)(-0.8).
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Affiliation(s)
- Y-C Ghim
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, United Kingdom and EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB, United Kingdom and Department of Nuclear and Quantum Engineering, KAIST, Daejeon 305-701, Republic of Korea
| | - A A Schekochihin
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, United Kingdom and Merton College, Oxford OX1 4JD, United Kingdom
| | - A R Field
- EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB, United Kingdom
| | - I G Abel
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, United Kingdom and Merton College, Oxford OX1 4JD, United Kingdom
| | - M Barnes
- Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139, USA and Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831, USA
| | - G Colyer
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, United Kingdom and EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB, United Kingdom
| | - S C Cowley
- EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB, United Kingdom and Blackett Laboratory, Imperial College, London SW7 2AZ, United Kingdom
| | - F I Parra
- Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139, USA
| | - D Dunai
- Wigner Research Centre for Physics, Association EURATOM/HAS, P.O. Box 49, H-1525 Budapest, Hungary
| | - S Zoletnik
- Wigner Research Centre for Physics, Association EURATOM/HAS, P.O. Box 49, H-1525 Budapest, Hungary
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De Bock MFM, Aussems D, Huijgen R, Scheffer M, Chung J. Real-time MSE measurements for current profile control on KSTAR. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:10D524. [PMID: 23126864 DOI: 10.1063/1.4732854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
To step up from current day fusion experiments to power producing fusion reactors, it is necessary to control long pulse, burning plasmas. Stability and confinement properties of tokamak fusion reactors are determined by the current or q profile. In order to control the q profile, it is necessary to measure it in real-time. A real-time motional Stark effect diagnostic is being developed at Korean Superconducting Tokamak for Advanced Research for this purpose. This paper focuses on 3 topics important for real-time measurements: minimize the use of ad hoc parameters, minimize external influences and a robust and fast analysis algorithm. Specifically, we have looked into extracting the retardance of the photo-elastic modulators from the signal itself, minimizing the influence of overlapping beam spectra by optimizing the optical filter design and a multi-channel, multiharmonic phase locking algorithm.
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Affiliation(s)
- M F M De Bock
- Eindhoven University of Technology, Eindhoven, The Netherlands.
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Conway NJ, De Bock MFM, Michael CA, Walsh MJ, Carolan PG, Hawkes NC, Rachlew E, McCone JFG, Shibaev S, Wearing G. The MAST motional Stark effect diagnostic. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:10D738. [PMID: 21033929 DOI: 10.1063/1.3494254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A motional Stark effect (MSE) diagnostic is now installed and operating routinely on the MAST spherical tokamak, with 35 radial channels, spatial resolution of ∼2.5 cm, and time resolution of ∼1 ms at angular noise levels of ∼0.5°. Conventional (albeit very narrow) interference filters isolate π or σ polarized emission. Avalanche photodiode detectors with digital phase-sensitive detection measure the harmonics of a pair of photoelastic modulators operating at 20 and 23 kHz, and thus the polarization state. The π component is observed to be significantly stronger than σ, in reasonably good agreement with atomic physics calculations, and as a result, almost all channels are now operated on π. Trials with a wide filter that admits the entire Stark pattern (relying on the net polarization of the emission) have demonstrated performance almost as good as the conventional channels. MSE-constrained equilibrium reconstructions can readily be produced between pulses.
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Affiliation(s)
- N J Conway
- EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB, United Kingdom.
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