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Hansen S, Nielsen S, Stober J, Rasmussen J, Stejner M. Observation and Modelling of the Onset of Parametric Decay Instabilities during Gyrotron Operation at ASDEX Upgrade. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201920302007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate parametric decay instabilities (PDIs) occurring for gyrotron radiation near the upper hybrid resonance at the ASDEX Upgrade tokamak. The PDIs are observed through anomalous millimeter-wave scattering which is recorded using the high-resolution, fast acquisition collective Thomson scattering system installed at ASDEX Upgrade, and an experiment in which such observations are made during a scan of the toroidal magnetic field is performed. A previously published theoretical model is used to calculate the gyrotron power necessary to excite PDIs in the experiment; the theoretical model is capable of predicting whether or not PDIs will be observed at a given toroidal magnetic field with a high degree of accuracy.
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Abramovic I, Pavone A, Moseev D, Lopes Cardozo NJ, Salewski M, Laqua HP, Stejner M, Stange T, Marsen S, Nielsen SK, Jensen T, Kasparek W. Forward modeling of collective Thomson scattering for Wendelstein 7-X plasmas: Electrostatic approximation. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:023501. [PMID: 30831775 DOI: 10.1063/1.5048361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
In this paper, we present a method for numerical computation of collective Thomson scattering (CTS). We developed a forward model, eCTS, in the electrostatic approximation and benchmarked it against a full electromagnetic model. Differences between the electrostatic and the electromagnetic models are discussed. The sensitivity of the results to the ion temperature and the plasma composition is demonstrated. We integrated the model into the Bayesian data analysis framework Minerva and used it for the analysis of noisy synthetic data sets produced by a full electromagnetic model. It is shown that eCTS can be used for the inference of the bulk ion temperature. The model has been used to infer the bulk ion temperature from the first CTS measurements on Wendelstein 7-X.
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Affiliation(s)
- I Abramovic
- University of Technology Eindhoven, Eindhoven, The Netherlands
| | - A Pavone
- Max-Planck Institut fur Plasma Physik, Greifswald, Germany
| | - D Moseev
- Max-Planck Institut fur Plasma Physik, Greifswald, Germany
| | | | - M Salewski
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - H P Laqua
- Max-Planck Institut fur Plasma Physik, Greifswald, Germany
| | - M Stejner
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - T Stange
- Max-Planck Institut fur Plasma Physik, Greifswald, Germany
| | - S Marsen
- Max-Planck Institut fur Plasma Physik, Greifswald, Germany
| | - S K Nielsen
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - T Jensen
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - W Kasparek
- University of Stuttgart, Stuttgart, Germany
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Moseev D, Stejner M, Stange T, Abramovic I, Laqua HP, Marsen S, Schneider N, Braune H, Hoefel U, Kasparek W, Korsholm SB, Lechte C, Leipold F, Nielsen SK, Salewski M, Rasmussen J, Weißgerber M, Wolf RC. Collective Thomson scattering diagnostic at Wendelstein 7-X. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:013503. [PMID: 30709181 DOI: 10.1063/1.5050193] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/29/2018] [Indexed: 06/09/2023]
Abstract
A Collective Thomson Scattering (CTS) diagnostic is installed at Wendelstein 7-X for ion temperature measurements in the plasma core. The diagnostic utilizes 140 GHz gyrotrons usually used for electron cyclotron resonance heating (ECRH) as a source of probing radiation. The CTS diagnostic uses a quasi-optical transmission line covering a distance of over 40 m. The transmission line is shared between the ECRH system and the CTS diagnostic. Here we elaborate on the design, installation, and alignment of the CTS diagnostic and present the first measurements at Wendelstein 7-X.
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Affiliation(s)
- D Moseev
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
| | - M Stejner
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - T Stange
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
| | - I Abramovic
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
| | - H P Laqua
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
| | - S Marsen
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
| | - N Schneider
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
| | - H Braune
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
| | - U Hoefel
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
| | - W Kasparek
- University of Stuttgart, Stuttgart, Germany
| | - S B Korsholm
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - C Lechte
- University of Stuttgart, Stuttgart, Germany
| | - F Leipold
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - S K Nielsen
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - M Salewski
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - J Rasmussen
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - M Weißgerber
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
| | - R C Wolf
- Max-Planck-Institut für Plasmaphysik, Greifswald and Garching, Germany
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