Experimental Signatures of Critically Balanced Turbulence in MAST
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...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | en_US |
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American Physical Society
2013
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| Online Access: | http://hdl.handle.net/1721.1/81999 https://orcid.org/0000-0001-9621-7404 |
| _version_ | 1811088662294691840 |
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| author | Ghim, Y.-c. Schekochihin, A. A. Field, A. R. Abel, I. G. Barnes, Michael Colyer, G. Cowley, S. C. Parra Diaz, Felix Ignacio Dunai, D. Zoletnik, S. MAST Team |
| author2 | Massachusetts Institute of Technology. Plasma Science and Fusion Center |
| author_facet | Massachusetts Institute of Technology. Plasma Science and Fusion Center Ghim, Y.-c. Schekochihin, A. A. Field, A. R. Abel, I. G. Barnes, Michael Colyer, G. Cowley, S. C. Parra Diaz, Felix Ignacio Dunai, D. Zoletnik, S. MAST Team |
| author_sort | Ghim, Y.-c. |
| collection | MIT |
| description | 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[superscript -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[superscript -0.8]. |
| first_indexed | 2024-09-23T14:05:33Z |
| format | Article |
| id | mit-1721.1/81999 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T14:05:33Z |
| publishDate | 2013 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/819992022-09-28T18:19:11Z Experimental Signatures of Critically Balanced Turbulence in MAST Ghim, Y.-c. Schekochihin, A. A. Field, A. R. Abel, I. G. Barnes, Michael Colyer, G. Cowley, S. C. Parra Diaz, Felix Ignacio Dunai, D. Zoletnik, S. MAST Team Massachusetts Institute of Technology. Plasma Science and Fusion Center Parra Diaz, Felix Ignacio Barnes, Michael 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[superscript -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[superscript -0.8]. Research Councils UK (Energy Programme under Grant No. EP/I501045) Kwanjeong Educational Foundation (Korea) EURATOM Culham Centre for Fusion Energy Leverhulme Trust (International Network for Magnetised Plasma Turbulence) European Commission 2013-11-06T16:40:35Z 2013-11-06T16:40:35Z 2013-04 2012-08 Article http://purl.org/eprint/type/JournalArticle 0031-9007 1079-7114 http://hdl.handle.net/1721.1/81999 Ghim, Y.-c., A. A. Schekochihin, A. R. Field, I. G. Abel, M. Barnes, G. Colyer, S. C. Cowley, F. I. Parra, D. Dunai, and S. Zoletnik. Experimental Signatures of Critically Balanced Turbulence in MAST. Physical Review Letters 110, no. 14 (April 2013). https://orcid.org/0000-0001-9621-7404 en_US http://dx.doi.org/10.1103/PhysRevLett.110.145002 Physical Review Letters Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Physical Society APS |
| spellingShingle | Ghim, Y.-c. Schekochihin, A. A. Field, A. R. Abel, I. G. Barnes, Michael Colyer, G. Cowley, S. C. Parra Diaz, Felix Ignacio Dunai, D. Zoletnik, S. MAST Team Experimental Signatures of Critically Balanced Turbulence in MAST |
| title | Experimental Signatures of Critically Balanced Turbulence in MAST |
| title_full | Experimental Signatures of Critically Balanced Turbulence in MAST |
| title_fullStr | Experimental Signatures of Critically Balanced Turbulence in MAST |
| title_full_unstemmed | Experimental Signatures of Critically Balanced Turbulence in MAST |
| title_short | Experimental Signatures of Critically Balanced Turbulence in MAST |
| title_sort | experimental signatures of critically balanced turbulence in mast |
| url | http://hdl.handle.net/1721.1/81999 https://orcid.org/0000-0001-9621-7404 |
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