Excitation of fishbone-like mode in tokamaks due to bounce resonances of trapped thermal ions
When the drift kinetic effect of thermal ions is taken into account, a high-frequency fishbone-like mode (FLM) is found to be driven unstable by trapped thermal ions (TTIs) in tokamak plasmas, according to self-consistent magneto-hydrodynamic (MHD)-kinetic hybrid modeling utilizing the MARS-K code [...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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AIP Publishing LLC
2021-04-01
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| Series: | AIP Advances |
| Online Access: | http://dx.doi.org/10.1063/5.0044341 |
| _version_ | 1818610847460622336 |
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| author | Weichao Xie Yueqiang Liu G. Z. Hao Ruirui Ma Qian Chen |
| author_facet | Weichao Xie Yueqiang Liu G. Z. Hao Ruirui Ma Qian Chen |
| author_sort | Weichao Xie |
| collection | DOAJ |
| description | When the drift kinetic effect of thermal ions is taken into account, a high-frequency fishbone-like mode (FLM) is found to be driven unstable by trapped thermal ions (TTIs) in tokamak plasmas, according to self-consistent magneto-hydrodynamic (MHD)-kinetic hybrid modeling utilizing the MARS-K code [Liu et al., Phys. Plasmas 15, 112503 (2008)] as well as an analytic theory. It is found that, similar to energetic particles, TTIs can also stabilize the internal kink mode, whereas the FLM is excited when the effective beta of TTIs exceeds a threshold value. The real frequency of the FLM is comparable to the bounce frequency of TTIs. The mode structure of the FLM can be significantly different from the conventional step-like function for the associated plasma radial displacement. This drift kinetic induced modification of the mode structure near the q = 1 surface is captured by non-perturbative MHD-kinetic hybrid computations with MARS-K. Furthermore, the FLM can only be triggered by TTIs at sufficiently high thermal temperatures. Both the FLM and the internal kink can be stabilized by sufficiently fast plasma toroidal rotation and parallel sound wave damping. These two conditions of high thermal temperature and (fast) flow stabilization, though making it challenging to observe the TTI-driven FLM in present day experiments, are favorable for the mode excitation in future reactor scale devices. |
| first_indexed | 2024-12-16T15:20:56Z |
| format | Article |
| id | doaj.art-fbbbb2d55a88438683d1980ce987a295 |
| institution | Directory Open Access Journal |
| issn | 2158-3226 |
| language | English |
| last_indexed | 2024-12-16T15:20:56Z |
| publishDate | 2021-04-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | AIP Advances |
| spelling | doaj.art-fbbbb2d55a88438683d1980ce987a2952022-12-21T22:26:38ZengAIP Publishing LLCAIP Advances2158-32262021-04-01114045313045313-610.1063/5.0044341Excitation of fishbone-like mode in tokamaks due to bounce resonances of trapped thermal ionsWeichao Xie0Yueqiang Liu1G. Z. Hao2Ruirui Ma3Qian Chen4Southwestern Institute of Physics, Chengdu 610041, ChinaGeneral Atomics, P.O. Box 85608, San Diego, California 92186-5608, USASouthwestern Institute of Physics, Chengdu 610041, ChinaSouthwestern Institute of Physics, Chengdu 610041, ChinaSouthwestern Institute of Physics, Chengdu 610041, ChinaWhen the drift kinetic effect of thermal ions is taken into account, a high-frequency fishbone-like mode (FLM) is found to be driven unstable by trapped thermal ions (TTIs) in tokamak plasmas, according to self-consistent magneto-hydrodynamic (MHD)-kinetic hybrid modeling utilizing the MARS-K code [Liu et al., Phys. Plasmas 15, 112503 (2008)] as well as an analytic theory. It is found that, similar to energetic particles, TTIs can also stabilize the internal kink mode, whereas the FLM is excited when the effective beta of TTIs exceeds a threshold value. The real frequency of the FLM is comparable to the bounce frequency of TTIs. The mode structure of the FLM can be significantly different from the conventional step-like function for the associated plasma radial displacement. This drift kinetic induced modification of the mode structure near the q = 1 surface is captured by non-perturbative MHD-kinetic hybrid computations with MARS-K. Furthermore, the FLM can only be triggered by TTIs at sufficiently high thermal temperatures. Both the FLM and the internal kink can be stabilized by sufficiently fast plasma toroidal rotation and parallel sound wave damping. These two conditions of high thermal temperature and (fast) flow stabilization, though making it challenging to observe the TTI-driven FLM in present day experiments, are favorable for the mode excitation in future reactor scale devices.http://dx.doi.org/10.1063/5.0044341 |
| spellingShingle | Weichao Xie Yueqiang Liu G. Z. Hao Ruirui Ma Qian Chen Excitation of fishbone-like mode in tokamaks due to bounce resonances of trapped thermal ions AIP Advances |
| title | Excitation of fishbone-like mode in tokamaks due to bounce resonances of trapped thermal ions |
| title_full | Excitation of fishbone-like mode in tokamaks due to bounce resonances of trapped thermal ions |
| title_fullStr | Excitation of fishbone-like mode in tokamaks due to bounce resonances of trapped thermal ions |
| title_full_unstemmed | Excitation of fishbone-like mode in tokamaks due to bounce resonances of trapped thermal ions |
| title_short | Excitation of fishbone-like mode in tokamaks due to bounce resonances of trapped thermal ions |
| title_sort | excitation of fishbone like mode in tokamaks due to bounce resonances of trapped thermal ions |
| url | http://dx.doi.org/10.1063/5.0044341 |
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