Shafranov-shift destabilization of ballooning-type micro-instabilities
Contrary to common wisdom, we argue that the Shafranov shift is destabilizing for the ambient ballooning-type instabilities, which account for most of the transport flux in tokamak core plasmas. Higher Shafranov shift indeed reduces the magnetic drift frequency ${\omega _{\text{d}}}$ , i.e. improves...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2025-01-01
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| Series: | Nuclear Fusion |
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| Online Access: | https://doi.org/10.1088/1741-4326/adf122 |
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| author | X. Jian V. Chan Z. Qiu S. Ding C. Holland E. Bass A. Garofalo X. Liu |
| author_facet | X. Jian V. Chan Z. Qiu S. Ding C. Holland E. Bass A. Garofalo X. Liu |
| author_sort | X. Jian |
| collection | DOAJ |
| description | Contrary to common wisdom, we argue that the Shafranov shift is destabilizing for the ambient ballooning-type instabilities, which account for most of the transport flux in tokamak core plasmas. Higher Shafranov shift indeed reduces the magnetic drift frequency ${\omega _{\text{d}}}$ , i.e. improves the bad curvature mildly, around the outboard midplane. However, this improvement is limited to a very narrow spatial region while ${\omega _{\text{d}}}$ is increased over the remaining poloidal space. The eigenfunction averaged $\langle {\omega _{\text{d}}}\rangle $ is effectively enhanced due to the finite mode width of the eigenfunction and is thus destabilizing to the ballooning-type mode, as demonstrated by gyrokinetic simulations with the CGYRO code using local Miller equilibrium geometry. The predicted nonlinear flux also increases with Shafranov shift, consistent with linear simulations. The reduced transport model TGLF can capture the physics reasonably well. |
| format | Article |
| id | doaj-art-e76d5d8789e34fe6b73e35e1b4f145cd |
| institution | DOAJ |
| issn | 0029-5515 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Nuclear Fusion |
| spelling | doaj-art-e76d5d8789e34fe6b73e35e1b4f145cd2025-08-20T03:13:39ZengIOP PublishingNuclear Fusion0029-55152025-01-0165808603810.1088/1741-4326/adf122Shafranov-shift destabilization of ballooning-type micro-instabilitiesX. Jian0https://orcid.org/0000-0003-3052-1694V. Chan1Z. Qiu2https://orcid.org/0000-0002-7548-8819S. Ding3https://orcid.org/0000-0002-1930-0439C. Holland4https://orcid.org/0000-0001-6029-2306E. Bass5A. Garofalo6https://orcid.org/0000-0002-8244-2448X. Liu7https://orcid.org/0000-0002-0331-8730Key Laboratory of Frontier Physics in Controlled Nuclear Fusion and Institute of Plasma Physics, Chinese Academy of Science , Hefei, Anhui 230031, China; General Atomics , P.O. Box 85608, San Diego, CA 92186-5608, United States of AmericaUniversity of Science and Technology of China , Hefei 230026, ChinaKey Laboratory of Frontier Physics in Controlled Nuclear Fusion and Institute of Plasma Physics, Chinese Academy of Science , Hefei, Anhui 230031, ChinaGeneral Atomics , P.O. Box 85608, San Diego, CA 92186-5608, United States of AmericaUniversity of California , San Diego, La Jolla, CA 92093-0417, United States of AmericaUniversity of California , San Diego, La Jolla, CA 92093-0417, United States of AmericaGeneral Atomics , P.O. Box 85608, San Diego, CA 92186-5608, United States of AmericaKey Laboratory of Frontier Physics in Controlled Nuclear Fusion and Institute of Plasma Physics, Chinese Academy of Science , Hefei, Anhui 230031, ChinaContrary to common wisdom, we argue that the Shafranov shift is destabilizing for the ambient ballooning-type instabilities, which account for most of the transport flux in tokamak core plasmas. Higher Shafranov shift indeed reduces the magnetic drift frequency ${\omega _{\text{d}}}$ , i.e. improves the bad curvature mildly, around the outboard midplane. However, this improvement is limited to a very narrow spatial region while ${\omega _{\text{d}}}$ is increased over the remaining poloidal space. The eigenfunction averaged $\langle {\omega _{\text{d}}}\rangle $ is effectively enhanced due to the finite mode width of the eigenfunction and is thus destabilizing to the ballooning-type mode, as demonstrated by gyrokinetic simulations with the CGYRO code using local Miller equilibrium geometry. The predicted nonlinear flux also increases with Shafranov shift, consistent with linear simulations. The reduced transport model TGLF can capture the physics reasonably well.https://doi.org/10.1088/1741-4326/adf122ballooning-type turbulenceadvanced scenariosShafranov shift |
| spellingShingle | X. Jian V. Chan Z. Qiu S. Ding C. Holland E. Bass A. Garofalo X. Liu Shafranov-shift destabilization of ballooning-type micro-instabilities Nuclear Fusion ballooning-type turbulence advanced scenarios Shafranov shift |
| title | Shafranov-shift destabilization of ballooning-type micro-instabilities |
| title_full | Shafranov-shift destabilization of ballooning-type micro-instabilities |
| title_fullStr | Shafranov-shift destabilization of ballooning-type micro-instabilities |
| title_full_unstemmed | Shafranov-shift destabilization of ballooning-type micro-instabilities |
| title_short | Shafranov-shift destabilization of ballooning-type micro-instabilities |
| title_sort | shafranov shift destabilization of ballooning type micro instabilities |
| topic | ballooning-type turbulence advanced scenarios Shafranov shift |
| url | https://doi.org/10.1088/1741-4326/adf122 |
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