Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U
© 2020 Author(s). An extensive validation effort performed for a modest-beta NSTX NBI-heated H-mode discharge predicts that electron thermal transport can be entirely explained by electron-scale turbulence fluctuations driven by the electron temperature gradient mode (ETG), both in conditions of str...
| Main Authors: | , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
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AIP Publishing
2023
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| Online Access: | https://hdl.handle.net/1721.1/147149 |
| _version_ | 1811093706769432576 |
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| author | Ruiz Ruiz, J Guttenfelder, W White, AE Howard, NT Candy, J Ren, Y Smith, DR Loureiro, NF Holland, C Domier, CW |
| author2 | Massachusetts Institute of Technology. Department of Nuclear Science and Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Ruiz Ruiz, J Guttenfelder, W White, AE Howard, NT Candy, J Ren, Y Smith, DR Loureiro, NF Holland, C Domier, CW |
| author_sort | Ruiz Ruiz, J |
| collection | MIT |
| description | © 2020 Author(s). An extensive validation effort performed for a modest-beta NSTX NBI-heated H-mode discharge predicts that electron thermal transport can be entirely explained by electron-scale turbulence fluctuations driven by the electron temperature gradient mode (ETG), both in conditions of strong and weak ETG turbulence drive. Thermal power-balance estimates computed by TRANSP as well as the shape of the high-k density fluctuation wavenumber spectrum and the fluctuation level ratio between strongly driven and weakly driven ETG-turbulence conditions can be matched by nonlinear gyrokinetic simulations and a synthetic diagnostic for high-k scattering. Linear gyrokinetic simulations suggest that the ion-scale instability in the weak ETG condition is close to the critical threshold for the kinetic ballooning mode instability, and nonlinear ion-scale gyrokinetic simulations show that turbulence might be in a state reminiscent of a Dimits' shift regime, opening speculation on the role that ion-scale turbulence might play for the weak ETG condition. A simulation that matched all experimental constraints is chosen to project high-k turbulence spectra in NSTX-U, revealing that the new high-k system [R. Barchfeld et al., Rev. Sci. Instrum. 89, 10C114 (2018)] should be sensitive to density fluctuations from radially elongated streamer structures. Two schemes are designed to characterize the radial and poloidal wavenumber dependence of the density fluctuation wavenumber power spectrum around the streamer peak, suggesting future high-k fluctuation measurements could be sensitive to an asymmetry in the kr spectrum introduced due to the presence of strong background flow shear. |
| first_indexed | 2024-09-23T15:49:21Z |
| format | Article |
| id | mit-1721.1/147149 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T15:49:21Z |
| publishDate | 2023 |
| publisher | AIP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1471492023-01-18T03:05:17Z Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U Ruiz Ruiz, J Guttenfelder, W White, AE Howard, NT Candy, J Ren, Y Smith, DR Loureiro, NF Holland, C Domier, CW Massachusetts Institute of Technology. Department of Nuclear Science and Engineering © 2020 Author(s). An extensive validation effort performed for a modest-beta NSTX NBI-heated H-mode discharge predicts that electron thermal transport can be entirely explained by electron-scale turbulence fluctuations driven by the electron temperature gradient mode (ETG), both in conditions of strong and weak ETG turbulence drive. Thermal power-balance estimates computed by TRANSP as well as the shape of the high-k density fluctuation wavenumber spectrum and the fluctuation level ratio between strongly driven and weakly driven ETG-turbulence conditions can be matched by nonlinear gyrokinetic simulations and a synthetic diagnostic for high-k scattering. Linear gyrokinetic simulations suggest that the ion-scale instability in the weak ETG condition is close to the critical threshold for the kinetic ballooning mode instability, and nonlinear ion-scale gyrokinetic simulations show that turbulence might be in a state reminiscent of a Dimits' shift regime, opening speculation on the role that ion-scale turbulence might play for the weak ETG condition. A simulation that matched all experimental constraints is chosen to project high-k turbulence spectra in NSTX-U, revealing that the new high-k system [R. Barchfeld et al., Rev. Sci. Instrum. 89, 10C114 (2018)] should be sensitive to density fluctuations from radially elongated streamer structures. Two schemes are designed to characterize the radial and poloidal wavenumber dependence of the density fluctuation wavenumber power spectrum around the streamer peak, suggesting future high-k fluctuation measurements could be sensitive to an asymmetry in the kr spectrum introduced due to the presence of strong background flow shear. 2023-01-17T19:30:59Z 2023-01-17T19:30:59Z 2020 2023-01-17T19:03:03Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/147149 Ruiz Ruiz, J, Guttenfelder, W, White, AE, Howard, NT, Candy, J et al. 2020. "Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U." Physics of Plasmas, 27 (12). en 10.1063/5.0009620 Physics of Plasmas Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf AIP Publishing DOE repository |
| spellingShingle | Ruiz Ruiz, J Guttenfelder, W White, AE Howard, NT Candy, J Ren, Y Smith, DR Loureiro, NF Holland, C Domier, CW Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U |
| title | Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U |
| title_full | Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U |
| title_fullStr | Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U |
| title_full_unstemmed | Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U |
| title_short | Validation of gyrokinetic simulations in NSTX and projections for high-k turbulence measurements in NSTX-U |
| title_sort | validation of gyrokinetic simulations in nstx and projections for high k turbulence measurements in nstx u |
| url | https://hdl.handle.net/1721.1/147149 |
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