Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak
© 2018 American Physical Society. Efficient lower hybrid current drive (LHCD) is demonstrated at densities up to ne≈1.5×1020 m-3 in diverted plasmas on the Alcator C-Mod tokamak by operating at increased plasma current - and therefore reduced Greenwald density fraction. This density exceeds the nomi...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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American Physical Society (APS)
2021
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| Online Access: | https://hdl.handle.net/1721.1/135803 |
| _version_ | 1826213425545478144 |
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| author | Baek, SG Wallace, GM Bonoli, PT Brunner, D Faust, IC Hubbard, AE Hughes, JW LaBombard, B Parker, RR Porkolab, M Shiraiwa, S Wukitch, S |
| author2 | Massachusetts Institute of Technology. Plasma Science and Fusion Center |
| author_facet | Massachusetts Institute of Technology. Plasma Science and Fusion Center Baek, SG Wallace, GM Bonoli, PT Brunner, D Faust, IC Hubbard, AE Hughes, JW LaBombard, B Parker, RR Porkolab, M Shiraiwa, S Wukitch, S |
| author_sort | Baek, SG |
| collection | MIT |
| description | © 2018 American Physical Society. Efficient lower hybrid current drive (LHCD) is demonstrated at densities up to ne≈1.5×1020 m-3 in diverted plasmas on the Alcator C-Mod tokamak by operating at increased plasma current - and therefore reduced Greenwald density fraction. This density exceeds the nominal "LH density limit" at ne≈1.0×1020 m-3 reported previously, above which an anomalous loss of current drive efficiency was observed. The recovery of current drive efficiency to a level consistent with engineering scalings is correlated with a reduction in density shoulders and turbulence levels in the far scrape-off layer. Concurrently, rf wave interaction with the edge and/or scrape-off-layer plasma is reduced, as indicated by a minimal broadening of the wave frequency spectrum measured at the plasma edge. These results have important implications for sustaining steady-state tokamak operation and indicate a pathway forward for implementing efficient LHCD in a reactor. |
| first_indexed | 2024-09-23T15:49:20Z |
| format | Article |
| id | mit-1721.1/135803 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T15:49:20Z |
| publishDate | 2021 |
| publisher | American Physical Society (APS) |
| record_format | dspace |
| spelling | mit-1721.1/1358032023-03-15T17:46:19Z Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak Baek, SG Wallace, GM Bonoli, PT Brunner, D Faust, IC Hubbard, AE Hughes, JW LaBombard, B Parker, RR Porkolab, M Shiraiwa, S Wukitch, S Massachusetts Institute of Technology. Plasma Science and Fusion Center © 2018 American Physical Society. Efficient lower hybrid current drive (LHCD) is demonstrated at densities up to ne≈1.5×1020 m-3 in diverted plasmas on the Alcator C-Mod tokamak by operating at increased plasma current - and therefore reduced Greenwald density fraction. This density exceeds the nominal "LH density limit" at ne≈1.0×1020 m-3 reported previously, above which an anomalous loss of current drive efficiency was observed. The recovery of current drive efficiency to a level consistent with engineering scalings is correlated with a reduction in density shoulders and turbulence levels in the far scrape-off layer. Concurrently, rf wave interaction with the edge and/or scrape-off-layer plasma is reduced, as indicated by a minimal broadening of the wave frequency spectrum measured at the plasma edge. These results have important implications for sustaining steady-state tokamak operation and indicate a pathway forward for implementing efficient LHCD in a reactor. 2021-10-27T20:29:22Z 2021-10-27T20:29:22Z 2018 2019-06-04T13:23:53Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/135803 en 10.1103/PHYSREVLETT.121.055001 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) APS |
| spellingShingle | Baek, SG Wallace, GM Bonoli, PT Brunner, D Faust, IC Hubbard, AE Hughes, JW LaBombard, B Parker, RR Porkolab, M Shiraiwa, S Wukitch, S Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak |
| title | Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak |
| title_full | Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak |
| title_fullStr | Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak |
| title_full_unstemmed | Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak |
| title_short | Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak |
| title_sort | observation of efficient lower hybrid current drive at high density in diverted plasmas on the alcator c mod tokamak |
| url | https://hdl.handle.net/1721.1/135803 |
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