Relativistic analysis of upper hybrid wave propagation and trapping
We investigate the impact of relativistic effects on upper hybrid (UH) waves in plasmas with thermal electrons, particularly focusing on modifications of the conditions under which UH wave trapping and related low-threshold parametric decay instabilities (PDIs) may occur. A moderately relativistic (...
| Main Authors: | , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
AIP Publishing
2023
|
| Subjects: | |
| Online Access: | https://hdl.handle.net/1721.1/153228 |
| _version_ | 1826195144955658240 |
|---|---|
| author | Hansen, S. K. Nielsen, S. K. Stober, J. |
| author2 | Massachusetts Institute of Technology. Plasma Science and Fusion Center |
| author_facet | Massachusetts Institute of Technology. Plasma Science and Fusion Center Hansen, S. K. Nielsen, S. K. Stober, J. |
| author_sort | Hansen, S. K. |
| collection | MIT |
| description | We investigate the impact of relativistic effects on upper hybrid (UH) waves in plasmas with thermal electrons, particularly focusing on modifications of the conditions under which UH wave trapping and related low-threshold parametric decay instabilities (PDIs) may occur. A moderately relativistic (MR) dispersion relation for UH waves, valid for electron temperatures up to 25 keV and wave frequencies up to twice the electron cyclotron frequency, is obtained from previous results and shown to reduce to the warm non-relativistic result commonly used for PDI studies at low electron temperatures. The conditions under which MR UH waves propagate are then determined and compared with warm and cold plasma theory, showing a general increase in the electron density and background magnetic field strength at which the UH resonance occurs for finite electron temperatures. We next investigate the impact of the MR corrections on the possibility of UH wave trapping for X-mode electron cyclotron resonance heated (ECRH) plasmas at the ASDEX Upgrade tokamak and scaled versions of the ASDEX Upgrade parameters with core electron temperatures resembling those expected in ITER X-mode ECRH plasmas. The MR UH wave trapping conditions are virtually unchanged for ASDEX Upgrade relative to warm theory, due to the low electron temperatures, while potentially important differences between warm and MR theory exist for ITER-like core electron temperatures; cold theory is found to be insufficient in both cases. Finally, the MR dispersion relation is shown to qualitatively reproduce the PDI thresholds from warm theory for previously studied ASDEX Upgrade cases. |
| first_indexed | 2024-09-23T10:07:59Z |
| format | Article |
| id | mit-1721.1/153228 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:07:59Z |
| publishDate | 2023 |
| publisher | AIP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1532282024-01-24T21:46:18Z Relativistic analysis of upper hybrid wave propagation and trapping Hansen, S. K. Nielsen, S. K. Stober, J. Massachusetts Institute of Technology. Plasma Science and Fusion Center Condensed Matter Physics We investigate the impact of relativistic effects on upper hybrid (UH) waves in plasmas with thermal electrons, particularly focusing on modifications of the conditions under which UH wave trapping and related low-threshold parametric decay instabilities (PDIs) may occur. A moderately relativistic (MR) dispersion relation for UH waves, valid for electron temperatures up to 25 keV and wave frequencies up to twice the electron cyclotron frequency, is obtained from previous results and shown to reduce to the warm non-relativistic result commonly used for PDI studies at low electron temperatures. The conditions under which MR UH waves propagate are then determined and compared with warm and cold plasma theory, showing a general increase in the electron density and background magnetic field strength at which the UH resonance occurs for finite electron temperatures. We next investigate the impact of the MR corrections on the possibility of UH wave trapping for X-mode electron cyclotron resonance heated (ECRH) plasmas at the ASDEX Upgrade tokamak and scaled versions of the ASDEX Upgrade parameters with core electron temperatures resembling those expected in ITER X-mode ECRH plasmas. The MR UH wave trapping conditions are virtually unchanged for ASDEX Upgrade relative to warm theory, due to the low electron temperatures, while potentially important differences between warm and MR theory exist for ITER-like core electron temperatures; cold theory is found to be insufficient in both cases. Finally, the MR dispersion relation is shown to qualitatively reproduce the PDI thresholds from warm theory for previously studied ASDEX Upgrade cases. 2023-12-21T21:07:10Z 2023-12-21T21:07:10Z 2023-04-01 Article http://purl.org/eprint/type/JournalArticle 1070-664X 1089-7674 https://hdl.handle.net/1721.1/153228 S. K. Hansen, S. K. Nielsen, J. Stober, EUROfusion MST1 Team, ASDEX Upgrade Team; Relativistic analysis of upper hybrid wave propagation and trapping. Phys. Plasmas 1 April 2023; 30 (4): 042103. en_US 10.1063/5.0138249 Physics of Plasmas Creative Commons Attribution https://creativecommons.org/licenses/by/4.0/ application/pdf AIP Publishing AIP Publishing |
| spellingShingle | Condensed Matter Physics Hansen, S. K. Nielsen, S. K. Stober, J. Relativistic analysis of upper hybrid wave propagation and trapping |
| title | Relativistic analysis of upper hybrid wave propagation and trapping |
| title_full | Relativistic analysis of upper hybrid wave propagation and trapping |
| title_fullStr | Relativistic analysis of upper hybrid wave propagation and trapping |
| title_full_unstemmed | Relativistic analysis of upper hybrid wave propagation and trapping |
| title_short | Relativistic analysis of upper hybrid wave propagation and trapping |
| title_sort | relativistic analysis of upper hybrid wave propagation and trapping |
| topic | Condensed Matter Physics |
| url | https://hdl.handle.net/1721.1/153228 |
| work_keys_str_mv | AT hansensk relativisticanalysisofupperhybridwavepropagationandtrapping AT nielsensk relativisticanalysisofupperhybridwavepropagationandtrapping AT stoberj relativisticanalysisofupperhybridwavepropagationandtrapping |