Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod
We demonstrate that existing theories are insufficient to explain up/down asymmetries of argon x-ray emission in Alcator C-Mod ohmic plasmas. Instead of the poloidal variation, ñ[subscript z]/〈n[subscript z]〉, being of order the inverse aspect ratio, ϵ, and scaling linearly with B[subscript t][super...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | en_US |
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IOP Publishing
2014
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| Online Access: | http://hdl.handle.net/1721.1/84060 https://orcid.org/0000-0001-8319-5971 https://orcid.org/0000-0003-2951-9749 https://orcid.org/0000-0002-4438-729X https://orcid.org/0000-0002-0026-6939 |
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| author | Reinke, Matthew Logan Rice, John E. Greenwald, Martin J. Howard, Nathaniel Thomas Irby, James Henderson Podpaly, Yuri White, Anne E. Hutchinson, Ian Horner Hughes Jr, Jerry Terry, James L |
| author2 | Massachusetts Institute of Technology. Department of Nuclear Science and Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Reinke, Matthew Logan Rice, John E. Greenwald, Martin J. Howard, Nathaniel Thomas Irby, James Henderson Podpaly, Yuri White, Anne E. Hutchinson, Ian Horner Hughes Jr, Jerry Terry, James L |
| author_sort | Reinke, Matthew Logan |
| collection | MIT |
| description | We demonstrate that existing theories are insufficient to explain up/down asymmetries of argon x-ray emission in Alcator C-Mod ohmic plasmas. Instead of the poloidal variation, ñ[subscript z]/〈n[subscript z]〉, being of order the inverse aspect ratio, ϵ, and scaling linearly with B[subscript t][superscript _ over n][subscript e]/I[2 over p], it is observed over 0.8 < r/a < 1.0 to be of order unity and exhibits a threshold behaviour between 3.5 <B[subscript t][superscript _ over n][subscript e]/I[subscript p] < 4.0 (T10[superscript 20] m[superscript −3] MA[superscript −1]). The transition from a poloidally symmetric to asymmetric impurity distribution is shown to occur at densities just below those that trigger a reversal of the core toroidal rotation direction, thought to be linked to the transition between the linear and saturated ohmic confinement regimes. A possible drive is discussed by which anomalous radial transport might sustain the impurity density asymmetry as the ratio of the perpendicular to parallel equilibration times, τ[subscript ⊥,z]/τ[subscript ∥,z], approaches unity. This explanation requires a strong up/down asymmetry in radial flux which, while not observable on C-Mod, has been measured in TEXT and Tore Supra ohmic plasmas. |
| first_indexed | 2024-09-23T17:07:07Z |
| format | Article |
| id | mit-1721.1/84060 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T17:07:07Z |
| publishDate | 2014 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/840602023-02-26T02:26:09Z Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod Reinke, Matthew Logan Rice, John E. Greenwald, Martin J. Howard, Nathaniel Thomas Irby, James Henderson Podpaly, Yuri White, Anne E. Hutchinson, Ian Horner Hughes Jr, Jerry Terry, James L Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Massachusetts Institute of Technology. Plasma Science and Fusion Center Hutchinson, Ian Reinke, Matthew Logan Rice, John E. Hutchinson, Ian H. Greenwald, Martin J. Howard, Nathaniel Thomas Hughes, Jerry W. Irby, James Henderson Podpaly, Yuri Terry, James L. White, Anne E. We demonstrate that existing theories are insufficient to explain up/down asymmetries of argon x-ray emission in Alcator C-Mod ohmic plasmas. Instead of the poloidal variation, ñ[subscript z]/〈n[subscript z]〉, being of order the inverse aspect ratio, ϵ, and scaling linearly with B[subscript t][superscript _ over n][subscript e]/I[2 over p], it is observed over 0.8 < r/a < 1.0 to be of order unity and exhibits a threshold behaviour between 3.5 <B[subscript t][superscript _ over n][subscript e]/I[subscript p] < 4.0 (T10[superscript 20] m[superscript −3] MA[superscript −1]). The transition from a poloidally symmetric to asymmetric impurity distribution is shown to occur at densities just below those that trigger a reversal of the core toroidal rotation direction, thought to be linked to the transition between the linear and saturated ohmic confinement regimes. A possible drive is discussed by which anomalous radial transport might sustain the impurity density asymmetry as the ratio of the perpendicular to parallel equilibration times, τ[subscript ⊥,z]/τ[subscript ∥,z], approaches unity. This explanation requires a strong up/down asymmetry in radial flux which, while not observable on C-Mod, has been measured in TEXT and Tore Supra ohmic plasmas. United States. Dept. of Energy (Contract DE-FC02-99ER54512) United States. Dept. of Energy (Fusion Research Postdoctoral Research Program) 2014-01-17T16:11:25Z 2014-01-17T16:11:25Z 2013-03 2012-12 Article http://purl.org/eprint/type/JournalArticle 0029-5515 1741-4326 http://hdl.handle.net/1721.1/84060 Reinke, M.L., J.E. Rice, I.H. Hutchinson, M. Greenwald, N.T. Howard, J.W. Hughes, J. Irby, Y. Podpaly, J.L. Terry, and A. White. “Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod.” Nuclear Fusion 53, no. 4 (April 1, 2013): 043006. https://orcid.org/0000-0001-8319-5971 https://orcid.org/0000-0003-2951-9749 https://orcid.org/0000-0002-4438-729X https://orcid.org/0000-0002-0026-6939 en_US http://dx.doi.org/10.1088/0029-5515/53/4/043006 Nuclear Fusion Creative Commons Attribution-Noncommercial-Share Alike 3.0 http://creativecommons.org/licenses/by-nc-sa/3.0/ application/pdf IOP Publishing Prof. Hutchinson via Chris Sherratt |
| spellingShingle | Reinke, Matthew Logan Rice, John E. Greenwald, Martin J. Howard, Nathaniel Thomas Irby, James Henderson Podpaly, Yuri White, Anne E. Hutchinson, Ian Horner Hughes Jr, Jerry Terry, James L Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod |
| title | Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod |
| title_full | Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod |
| title_fullStr | Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod |
| title_full_unstemmed | Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod |
| title_short | Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod |
| title_sort | non neoclassical up down asymmetry of impurity emission on alcator c mod |
| url | http://hdl.handle.net/1721.1/84060 https://orcid.org/0000-0001-8319-5971 https://orcid.org/0000-0003-2951-9749 https://orcid.org/0000-0002-4438-729X https://orcid.org/0000-0002-0026-6939 |
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