Lower hybrid wave edge power loss quantification on the Alcator C-Mod tokamak
For the first time, the power deposition of lower hybrid RF waves into the edge plasma of a diverted tokamak has been systematically quantified. Edge deposition represents a parasitic loss of power that can greatly impact the use and efficiency of Lower Hybrid Current Drive (LHCD) at reactor-relevan...
| Κύριοι συγγραφείς: | , , , , , , , , , , , , , , |
|---|---|
| Άλλοι συγγραφείς: | |
| Μορφή: | Άρθρο |
| Γλώσσα: | en_US |
| Έκδοση: |
American Institute of Physics (AIP)
2017
|
| Διαθέσιμο Online: | http://hdl.handle.net/1721.1/108781 https://orcid.org/0000-0001-5049-2769 https://orcid.org/0000-0002-8753-1124 https://orcid.org/0000-0002-7841-9261 https://orcid.org/0000-0003-4432-5504 https://orcid.org/0000-0002-9001-5606 https://orcid.org/0000-0001-8029-3525 https://orcid.org/0000-0002-8917-2911 https://orcid.org/0000-0001-8324-4227 |
| _version_ | 1826198524687024128 |
|---|---|
| author | Faust, Ian Charles Brunner, Daniel Frederic Labombard, Brian Terry, James L Whyte, Dennis G Baek, Seung Gyou Edlund, Eric Matthias Hubbard, Amanda E Hughes Jr, Jerry Kuang, Adam QingYang Reinke, Matthew Logan Shiraiwa, Shunichi Wallace, Gregory Marriner Walk Jr, John R Parker, R. |
| author2 | Massachusetts Institute of Technology. Department of Biological Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Biological Engineering Faust, Ian Charles Brunner, Daniel Frederic Labombard, Brian Terry, James L Whyte, Dennis G Baek, Seung Gyou Edlund, Eric Matthias Hubbard, Amanda E Hughes Jr, Jerry Kuang, Adam QingYang Reinke, Matthew Logan Shiraiwa, Shunichi Wallace, Gregory Marriner Walk Jr, John R Parker, R. |
| author_sort | Faust, Ian Charles |
| collection | MIT |
| description | For the first time, the power deposition of lower hybrid RF waves into the edge plasma of a diverted tokamak has been systematically quantified. Edge deposition represents a parasitic loss of power that can greatly impact the use and efficiency of Lower Hybrid Current Drive (LHCD) at reactor-relevant densities. Through the use of a unique set of fast time resolution edge diagnostics, including innovative fast-thermocouples, an extensive set of Langmuir probes, and a Lyα ionization camera, the toroidal, poloidal, and radial structure of the power deposition has been simultaneously determined. Power modulation was used to directly isolate the RF effects due to the prompt (t<[Greel letter tau lower case][subscript E upper case]) response of the scrape-off-layer (SOL) plasma to Lower Hybrid Radiofrequency (LHRF) power. LHRF power was found to absorb more strongly in the edge at higher densities. It is found that a majority of this edge-deposited power is promptly conducted to the divertor. This correlates with the loss of current drive efficiency at high density previously observed on Alcator C-Mod, and displaying characteristics that contrast with the local RF edge absorption seen on other tokamaks. Measurements of ionization in the active divertor show dramatic changes due to LHRF power, implying that divertor region can be a key for the LHRF edge power deposition physics. These observations support the existence of a loss mechanism near the edge for LHRF at high density (n[subscript e]>1.0×10[superscript 20] (m[superscript −3])). Results will be shown addressing the distribution of power within the SOL, including the toroidal symmetry and radial distribution. These characteristics are important for deducing the cause of the reduced LHCD efficiency at high density and motivate the tailoring of wave propagation to minimize SOL interaction, for example, through the use of high-field-side launch. |
| first_indexed | 2024-09-23T11:06:13Z |
| format | Article |
| id | mit-1721.1/108781 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:06:13Z |
| publishDate | 2017 |
| publisher | American Institute of Physics (AIP) |
| record_format | dspace |
| spelling | mit-1721.1/1087812023-02-26T03:30:12Z Lower hybrid wave edge power loss quantification on the Alcator C-Mod tokamak Faust, Ian Charles Brunner, Daniel Frederic Labombard, Brian Terry, James L Whyte, Dennis G Baek, Seung Gyou Edlund, Eric Matthias Hubbard, Amanda E Hughes Jr, Jerry Kuang, Adam QingYang Reinke, Matthew Logan Shiraiwa, Shunichi Wallace, Gregory Marriner Walk Jr, John R Parker, R. Massachusetts Institute of Technology. Department of Biological Engineering Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology. Department of Mathematics Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Massachusetts Institute of Technology. Department of Physics Massachusetts Institute of Technology. Plasma Science and Fusion Center Whyte, Dennis Faust, Ian Charles Brunner, Daniel Frederic Labombard, Brian Parker, Ronald R Terry, James L Whyte, Dennis G Baek, Seung Gyou Edlund, Eric Matthias Hubbard, Amanda E Hughes Jr, Jerry Kuang, Adam QingYang Reinke, Matthew Logan Shiraiwa, Shunichi Wallace, Gregory Marriner Walk Jr, John R For the first time, the power deposition of lower hybrid RF waves into the edge plasma of a diverted tokamak has been systematically quantified. Edge deposition represents a parasitic loss of power that can greatly impact the use and efficiency of Lower Hybrid Current Drive (LHCD) at reactor-relevant densities. Through the use of a unique set of fast time resolution edge diagnostics, including innovative fast-thermocouples, an extensive set of Langmuir probes, and a Lyα ionization camera, the toroidal, poloidal, and radial structure of the power deposition has been simultaneously determined. Power modulation was used to directly isolate the RF effects due to the prompt (t<[Greel letter tau lower case][subscript E upper case]) response of the scrape-off-layer (SOL) plasma to Lower Hybrid Radiofrequency (LHRF) power. LHRF power was found to absorb more strongly in the edge at higher densities. It is found that a majority of this edge-deposited power is promptly conducted to the divertor. This correlates with the loss of current drive efficiency at high density previously observed on Alcator C-Mod, and displaying characteristics that contrast with the local RF edge absorption seen on other tokamaks. Measurements of ionization in the active divertor show dramatic changes due to LHRF power, implying that divertor region can be a key for the LHRF edge power deposition physics. These observations support the existence of a loss mechanism near the edge for LHRF at high density (n[subscript e]>1.0×10[superscript 20] (m[superscript −3])). Results will be shown addressing the distribution of power within the SOL, including the toroidal symmetry and radial distribution. These characteristics are important for deducing the cause of the reduced LHCD efficiency at high density and motivate the tailoring of wave propagation to minimize SOL interaction, for example, through the use of high-field-side launch. United States. Department of Energy. Office of Fusion Energy Sciences (Award No. DE-FC02-99ER54512-CMOD) 2017-05-09T16:54:34Z 2017-05-09T16:54:34Z 2016-05 2016-05 Article http://purl.org/eprint/type/JournalArticle 1070-664X 1089-7674 http://hdl.handle.net/1721.1/108781 Faust, I. C., D. Brunner, B. LaBombard, R. R. Parker, J. L. Terry, D. G. Whyte, S. G. Baek, et al. “Lower Hybrid Wave Edge Power Loss Quantification on the Alcator C-Mod Tokamak.” Physics of Plasmas 23, no. 5 (May 2016): 056115. https://orcid.org/0000-0001-5049-2769 https://orcid.org/0000-0002-8753-1124 https://orcid.org/0000-0002-7841-9261 https://orcid.org/0000-0003-4432-5504 https://orcid.org/0000-0002-9001-5606 https://orcid.org/0000-0001-8029-3525 https://orcid.org/0000-0002-8917-2911 https://orcid.org/0000-0001-8324-4227 en_US http://dx.doi.org/10.1063/1.4951736 Physics of Plasmas Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf American Institute of Physics (AIP) Prof. Whyte via Chris Sherratt |
| spellingShingle | Faust, Ian Charles Brunner, Daniel Frederic Labombard, Brian Terry, James L Whyte, Dennis G Baek, Seung Gyou Edlund, Eric Matthias Hubbard, Amanda E Hughes Jr, Jerry Kuang, Adam QingYang Reinke, Matthew Logan Shiraiwa, Shunichi Wallace, Gregory Marriner Walk Jr, John R Parker, R. Lower hybrid wave edge power loss quantification on the Alcator C-Mod tokamak |
| title | Lower hybrid wave edge power loss quantification on the Alcator C-Mod tokamak |
| title_full | Lower hybrid wave edge power loss quantification on the Alcator C-Mod tokamak |
| title_fullStr | Lower hybrid wave edge power loss quantification on the Alcator C-Mod tokamak |
| title_full_unstemmed | Lower hybrid wave edge power loss quantification on the Alcator C-Mod tokamak |
| title_short | Lower hybrid wave edge power loss quantification on the Alcator C-Mod tokamak |
| title_sort | lower hybrid wave edge power loss quantification on the alcator c mod tokamak |
| url | http://hdl.handle.net/1721.1/108781 https://orcid.org/0000-0001-5049-2769 https://orcid.org/0000-0002-8753-1124 https://orcid.org/0000-0002-7841-9261 https://orcid.org/0000-0003-4432-5504 https://orcid.org/0000-0002-9001-5606 https://orcid.org/0000-0001-8029-3525 https://orcid.org/0000-0002-8917-2911 https://orcid.org/0000-0001-8324-4227 |
| work_keys_str_mv | AT faustiancharles lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT brunnerdanielfrederic lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT labombardbrian lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT terryjamesl lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT whytedennisg lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT baekseunggyou lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT edlundericmatthias lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT hubbardamandae lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT hughesjrjerry lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT kuangadamqingyang lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT reinkematthewlogan lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT shiraiwashunichi lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT wallacegregorymarriner lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT walkjrjohnr lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak AT parkerr lowerhybridwaveedgepowerlossquantificationonthealcatorcmodtokamak |