Grant Rutherford, Samuel J Frank, Andrew H Seltzman, Paul T Bonoli, Stephen J Wukitch
{"title":"Optimization of the N∥ Upshift in the DIII-D high field side lower hybrid current drive experiment","authors":"Grant Rutherford, Samuel J Frank, Andrew H Seltzman, Paul T Bonoli, Stephen J Wukitch","doi":"10.1088/1361-6587/ad44d6","DOIUrl":null,"url":null,"abstract":"High field side lower hybrid current drive (LHCD) is one potential candidate for efficient non-inductive current drive in tokamak power plants, and the first test of this technology will occur on the DIII-D tokamak during the 2024 campaign. Previous LFS launch experiments operated in the multi-pass regime and relied on scrape-off layer interactions to close the spectral gap. In the DIII-D experiment, single-pass damping is achievable via an upshift in the parallel refractive index <inline-formula>\n<tex-math><?CDATA $N_\\parallel$?></tex-math>\n<mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>N</mml:mi><mml:mo>∥</mml:mo></mml:msub></mml:mrow></mml:math>\n<inline-graphic xlink:href=\"ppcfad44d6ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\n</inline-formula> caused by mode converting twice (slow <inline-formula>\n<tex-math><?CDATA $\\rightarrow$?></tex-math>\n<mml:math overflow=\"scroll\"><mml:mrow><mml:mo stretchy=\"false\">→</mml:mo></mml:mrow></mml:math>\n<inline-graphic xlink:href=\"ppcfad44d6ieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\n</inline-formula> fast <inline-formula>\n<tex-math><?CDATA $\\rightarrow$?></tex-math>\n<mml:math overflow=\"scroll\"><mml:mrow><mml:mo stretchy=\"false\">→</mml:mo></mml:mrow></mml:math>\n<inline-graphic xlink:href=\"ppcfad44d6ieqn4.gif\" xlink:type=\"simple\"></inline-graphic>\n</inline-formula> slow). This mode conversion affects the ray trajectories and can lead to enhanced <inline-formula>\n<tex-math><?CDATA $N_\\parallel$?></tex-math>\n<mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>N</mml:mi><mml:mo>∥</mml:mo></mml:msub></mml:mrow></mml:math>\n<inline-graphic xlink:href=\"ppcfad44d6ieqn5.gif\" xlink:type=\"simple\"></inline-graphic>\n</inline-formula> upshift depending on where mode conversion occurs. Compared to multi-pass absorption experiments, the optimization of launched <inline-formula>\n<tex-math><?CDATA $N_\\parallel$?></tex-math>\n<mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>N</mml:mi><mml:mo>∥</mml:mo></mml:msub></mml:mrow></mml:math>\n<inline-graphic xlink:href=\"ppcfad44d6ieqn6.gif\" xlink:type=\"simple\"></inline-graphic>\n</inline-formula> and plasma parameters can be counter-intuitive: increased density may increase efficiency and smaller <inline-formula>\n<tex-math><?CDATA $N_{\\parallel,\\mathrm{launch}}$?></tex-math>\n<mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>N</mml:mi><mml:mrow><mml:mo>∥</mml:mo><mml:mo>,</mml:mo><mml:mrow><mml:mi>launch</mml:mi></mml:mrow></mml:mrow></mml:msub></mml:mrow></mml:math>\n<inline-graphic xlink:href=\"ppcfad44d6ieqn7.gif\" xlink:type=\"simple\"></inline-graphic>\n</inline-formula> tend to damp closer to the separatrix. A hard x-ray camera installed to measure the bremsstrahlung (50–250 keV) radiation from LHCD-generated fast electrons is capable of verifying the trends reporting in this paper through comparison to the ray-tracing/Fokker–Planck codes GENRAY/CQL3D.","PeriodicalId":20239,"journal":{"name":"Plasma Physics and Controlled Fusion","volume":"105 1","pages":""},"PeriodicalIF":2.1000,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Plasma Physics and Controlled Fusion","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1088/1361-6587/ad44d6","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"PHYSICS, FLUIDS & PLASMAS","Score":null,"Total":0}
引用次数: 0
Abstract
High field side lower hybrid current drive (LHCD) is one potential candidate for efficient non-inductive current drive in tokamak power plants, and the first test of this technology will occur on the DIII-D tokamak during the 2024 campaign. Previous LFS launch experiments operated in the multi-pass regime and relied on scrape-off layer interactions to close the spectral gap. In the DIII-D experiment, single-pass damping is achievable via an upshift in the parallel refractive index N∥ caused by mode converting twice (slow → fast → slow). This mode conversion affects the ray trajectories and can lead to enhanced N∥ upshift depending on where mode conversion occurs. Compared to multi-pass absorption experiments, the optimization of launched N∥ and plasma parameters can be counter-intuitive: increased density may increase efficiency and smaller N∥,launch tend to damp closer to the separatrix. A hard x-ray camera installed to measure the bremsstrahlung (50–250 keV) radiation from LHCD-generated fast electrons is capable of verifying the trends reporting in this paper through comparison to the ray-tracing/Fokker–Planck codes GENRAY/CQL3D.
期刊介绍：
Plasma Physics and Controlled Fusion covers all aspects of the physics of hot, highly ionised plasmas. This includes results of current experimental and theoretical research on all aspects of the physics of high-temperature plasmas and of controlled nuclear fusion, including the basic phenomena in highly-ionised gases in the laboratory, in the ionosphere and in space, in magnetic-confinement and inertial-confinement fusion as well as related diagnostic methods.
Papers with a technological emphasis, for example in such topics as plasma control, fusion technology and diagnostics, are welcomed when the plasma physics is an integral part of the paper or when the technology is unique to plasma applications or new to the field of plasma physics. Papers on dusty plasma physics are welcome when there is a clear relevance to fusion.
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