Internal measurements of electromagnetic geodesic acoustic mode (GAM) in EAST plasmas
Velocity, density, and magnetic fluctuations of the geodesic acoustic mode (GAM) have been measured using the Doppler backscattering system, Faraday-effect polarimeter-interferometer, and external pick-up coils in the Experimental Advanced Superconducting Tokamak. Simultaneous measurements of density and velocity fluctuations at the midplane and top of plasmas demonstrate that m = 1 density fluctuations are quantitatively balanced by the compression of perpendicular flow fluctuations. Furthermore, internal magnetic fluctuations associated with GAM have now been directly measured by laser-based Faraday-effect polarimetry for the first time. Line-averaged magnetic fluctuations (up to 16 Gauss, B̃¯R,GAMBT∼0.066%) are significantly larger than those extrapolated from edge coils (a few Gauss) and that magnetic fluctuations increase with β. The observed discrepancy between finite β theory and experimental data indicates the need for further theoretical investigations.
Authors
- S. F. Wang (ORCID: https://orcid.org/0009-0007-5639-6883)
- X. Zhong (ORCID: https://orcid.org/0000-0002-1751-111X)
- Zhe Chen (ORCID: https://orcid.org/0000-0001-8002-8641)
- Yuqi Chu (ORCID: https://orcid.org/0000-0002-7379-0117)
- Adi Liu (ORCID: https://orcid.org/0000-0002-3164-7320)
- Chu Zhou (ORCID: https://orcid.org/0000-0003-2928-242X)
- Xi Feng (ORCID: https://orcid.org/0000-0003-2191-7398)
- Jinlin Xie (ORCID: https://orcid.org/0000-0002-8902-672X)
- Ruiping Zhu (ORCID: https://orcid.org/0009-0009-5161-9915)
- Wenzhe Mao (ORCID: https://orcid.org/0000-0002-0676-8462)
- Y. H. Wang (ORCID: https://orcid.org/0009-0006-1073-6670)
- Lifu Gao (ORCID: https://orcid.org/0000-0002-6922-557X)
- Haijun Ren (ORCID: https://orcid.org/0000-0002-5802-8095)
- Weixing Ding (ORCID: https://orcid.org/0000-0003-2363-405X)
- D. L. Brower (ORCID: https://orcid.org/0000-0002-9153-6702)
- W. X. Shi
- Haiqing Liu (ORCID: https://orcid.org/0000-0001-6892-358X)
- Hui Lian
Institutions
- University of Science and Technology of China (CN)
- University of California, Los Angeles (US)
- Shenzhen University (CN)
- Chinese Academy of Sciences (CN)
- Culham Centre for Fusion Energy (GB)
- Institute of Plasma Physics (CN)
Publication Details
- Journal
- Physics of Plasmas
- Published
- 2024-09-01
- DOI
- https://doi.org/10.1063/5.0211489
- Citations
- 5
- Primary Topic
- Magnetic confinement fusion research
- Type
- article
- Field-Weighted Citation Impact
- 3.30
Funders
- U.S. Department of Energy
- National Natural Science Foundation of China