Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks
Recently-proposed tokamak concepts use magnetic fields up to 12 T, far higher than in conventional devices, to reduce size and cost. Theoretical and computational study of trends in plasma behavior with increasing field strength is critical to such proposed devices. This paper considers trends in Al...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2020
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| Online Access: | https://hdl.handle.net/1721.1/124222 |
| _version_ | 1811093384202289152 |
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| author | Tolman, Elizabeth Ann Gomes Loureiro, Nuno F Rodrigues, P. Hughes, J.W. Marmar, Earl S. |
| author2 | Massachusetts Institute of Technology. Plasma Science and Fusion Center |
| author_facet | Massachusetts Institute of Technology. Plasma Science and Fusion Center Tolman, Elizabeth Ann Gomes Loureiro, Nuno F Rodrigues, P. Hughes, J.W. Marmar, Earl S. |
| author_sort | Tolman, Elizabeth Ann |
| collection | MIT |
| description | Recently-proposed tokamak concepts use magnetic fields up to 12 T, far higher than in conventional devices, to reduce size and cost. Theoretical and computational study of trends in plasma behavior with increasing field strength is critical to such proposed devices. This paper considers trends in Alfvén eigenmode (AE) stability. Energetic particles, including alphas from deuterium-tritium fusion, can destabilize AEs, possibly causing loss of alpha heat and damage to the device. AEs are sensitive to device magnetic field via the field dependence of resonances, alpha particle beta, and alpha orbit width. We describe the origin and effect of these dependences analytically and by using recently-developed numerical techniques (Rodrigues et al 2015 Nucl. Fusion 55 083003). The work suggests high-field machines where fusion-born alphas are sub-Alfvénic or nearly sub-Alfvénic may partially cut off AE resonances, reducing growth rates of AEs and the energy of alphas interacting with them. High-field burning plasma regimes have non-negligible alpha particle beta and AE drive, but faster slowing down time, provided by high electron density, and higher field strength reduces this drive relative to low-field machines with similar power densities. The toroidal mode number of the most unstable modes will tend to be higher in high magnetic field devices. The work suggests that high magnetic field devices have unique, and potentially advantageous, AE instability properties at both low and high densities. © 2019 IAEA, Vienna. |
| first_indexed | 2024-09-23T15:44:24Z |
| format | Article |
| id | mit-1721.1/124222 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T15:44:24Z |
| publishDate | 2020 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1242222022-10-02T03:47:18Z Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks Tolman, Elizabeth Ann Gomes Loureiro, Nuno F Rodrigues, P. Hughes, J.W. Marmar, Earl S. Massachusetts Institute of Technology. Plasma Science and Fusion Center Recently-proposed tokamak concepts use magnetic fields up to 12 T, far higher than in conventional devices, to reduce size and cost. Theoretical and computational study of trends in plasma behavior with increasing field strength is critical to such proposed devices. This paper considers trends in Alfvén eigenmode (AE) stability. Energetic particles, including alphas from deuterium-tritium fusion, can destabilize AEs, possibly causing loss of alpha heat and damage to the device. AEs are sensitive to device magnetic field via the field dependence of resonances, alpha particle beta, and alpha orbit width. We describe the origin and effect of these dependences analytically and by using recently-developed numerical techniques (Rodrigues et al 2015 Nucl. Fusion 55 083003). The work suggests high-field machines where fusion-born alphas are sub-Alfvénic or nearly sub-Alfvénic may partially cut off AE resonances, reducing growth rates of AEs and the energy of alphas interacting with them. High-field burning plasma regimes have non-negligible alpha particle beta and AE drive, but faster slowing down time, provided by high electron density, and higher field strength reduces this drive relative to low-field machines with similar power densities. The toroidal mode number of the most unstable modes will tend to be higher in high magnetic field devices. The work suggests that high magnetic field devices have unique, and potentially advantageous, AE instability properties at both low and high densities. © 2019 IAEA, Vienna. National Science Foundation Graduate Research Fellowship Grant (No. DGE-1122374) US Department of Energy (Award DE-SC0014264) US Department of Energy (Award DE-FG02-91ER54109) Fundação para a Ciência e a Tecnologia (FCT, Lisbon) (Project UID/FIS/50010/2013) 2020-03-24T13:16:04Z 2020-03-24T13:16:04Z 2019-03 2018-09 2020-02-27T14:12:02Z Article http://purl.org/eprint/type/JournalArticle 1741-4326 0029-5515 https://hdl.handle.net/1721.1/124222 Tolman, E.A., et al., "Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks." Nuclear fusion 59 (2019): no. 046020, doi: 10.1088/1741-4326/ab058f ©2019 Author(s) en 10.1088/1741-4326/AB058F Nuclear fusion Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf IOP Publishing IOP Publishing |
| spellingShingle | Tolman, Elizabeth Ann Gomes Loureiro, Nuno F Rodrigues, P. Hughes, J.W. Marmar, Earl S. Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks |
| title | Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks |
| title_full | Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks |
| title_fullStr | Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks |
| title_full_unstemmed | Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks |
| title_short | Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks |
| title_sort | dependence of alpha particle driven alfven eigenmode linear stability on device magnetic field strength and consequences for next generation tokamaks |
| url | https://hdl.handle.net/1721.1/124222 |
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