Determination of poloidal mode numbers of MHD modes and their radial location using a soft x-ray camera array in the Wendelstein 7-X stellarator
| Autor: | W7-X Team, Dreval, M. B., Brandt, C., Schilling, J., Thomsen, H., Beletskii, A., Könies, A., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg |
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| Přispěvatelé: | W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society |
| Rok vydání: | 2021 |
| Předmět: |
Physics
Technology Soft x ray business.industry Mode (statistics) Camera array Condensed Matter Physics 01 natural sciences 010305 fluids & plasmas law.invention Optics Nuclear Energy and Engineering Physics::Plasma Physics law 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Wendelstein 7-X Magnetohydrodynamics 010306 general physics business ddc:600 Stellarator |
| Zdroj: | Plasma Physics and Controlled Fusion Plasma physics and controlled fusion, 63 (6), Art.-Nr.: 065006 |
| ISSN: | 1361-6587 0741-3335 2018-0918 |
| DOI: | 10.1088/1361-6587/abf449 |
| Popis: | A forward modeling technique is developed for determining the characteristic features of observed MHD modes from the line-of-sight data of the soft x-ray (SXR) tomography diagnostics in the Wendelstein 7-X (W7-X) stellarator. In particular, forward modeling is used to evaluate the poloidal mode numbers m, radial location, poloidal rotation direction and ballooning character of the MHD modes. The poloidal mode structures have been modeled by the radially localized Gaussian-shaped emission regions rotating along the magnetic surfaces. In the present study the cases of rigid-shape emission regions and flexible emission regions are modeled. Various mode phase velocity dependences on the magnetic surface position are simulated. The modeled phase dynamics of line-integrated oscillations and the distribution of oscillation amplitudes are compared with the experimental signals of the SXR cameras which observe the plasma at various viewing angles in the poloidal cross-section. Application of this technique enables describing of the 1–50 kHz modes. In particular, in the discharge W7X-PID 20180918.045 three identified branches with the poloidal mode numbers m= 8, m= 10 and m= 11 localized at ρ ≈ 0.3 are rotating in the clockwise poloidal direction. The present paper reports the first application of the forward modeling technique to the data from the SXR diagnostics in W7-X. The high m-modes are identified by forward modeling in W7-X. |
| Databáze: | OpenAIRE |
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