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| Auteurs principaux: | , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| Accès en ligne: | https://arxiv.org/abs/2505.02710 |
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| _version_ | 1866915273792028672 |
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| author | Liu, Jiaxing Zhu, Ping Escande, Dominique Franck Liu, Wenbin Xue, Shiwei Lin, Xin Tang, Panjun Wang, Liang Yan, Ning Yang, Jinju Duan, Yanmin Jia, Kai Wu, Zhenwei Cheng, Yunxin Zhang, Ling Qian, Jinping Ding, Rui Zhou, Ruijie team, the EAST |
| author_facet | Liu, Jiaxing Zhu, Ping Escande, Dominique Franck Liu, Wenbin Xue, Shiwei Lin, Xin Tang, Panjun Wang, Liang Yan, Ning Yang, Jinju Duan, Yanmin Jia, Kai Wu, Zhenwei Cheng, Yunxin Zhang, Ling Qian, Jinping Ding, Rui Zhou, Ruijie team, the EAST |
| contents | High plasma density operation is crucial for a tokamak to achieve energy breakeven and a burning plasma. However, there is often an empirical upper limit of electron density in tokamak operation, namely the Greenwald density limit $n_G$, above which tokamaks generally disrupt. Achieving high-density operations above the density limit has been a long-standing challenge in magnetic confinement fusion research. Here, we report experimental results on EAST tokamak achieving the line-averaged electron density in the range of 1.3 $n_G$ to 1.65 $n_G$,while the usual range in EAST is (0.8-1.0)$n_G$. This is performed with ECRH-assisted Ohmic start-up and a sufficiently high initial neutral density. This is motivated by and consistent with predictions of a recent plasma-wall self-organization (PWSO) theory, that increasing ECRH power or pre-filled gas pressure leads to lower plasma temperatures around divertor target and higher density limits. In addition, the experiments are shown to operate in the density-free regime predicted by the PWSO model. These results suggest a promising scheme for substantially increasing the density limit in tokamaks, a critical advancement toward achieving the burning plasma. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_02710 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Increasing the density limit with ECRH-assisted Ohmic start-up on EAST Liu, Jiaxing Zhu, Ping Escande, Dominique Franck Liu, Wenbin Xue, Shiwei Lin, Xin Tang, Panjun Wang, Liang Yan, Ning Yang, Jinju Duan, Yanmin Jia, Kai Wu, Zhenwei Cheng, Yunxin Zhang, Ling Qian, Jinping Ding, Rui Zhou, Ruijie team, the EAST Plasma Physics High plasma density operation is crucial for a tokamak to achieve energy breakeven and a burning plasma. However, there is often an empirical upper limit of electron density in tokamak operation, namely the Greenwald density limit $n_G$, above which tokamaks generally disrupt. Achieving high-density operations above the density limit has been a long-standing challenge in magnetic confinement fusion research. Here, we report experimental results on EAST tokamak achieving the line-averaged electron density in the range of 1.3 $n_G$ to 1.65 $n_G$,while the usual range in EAST is (0.8-1.0)$n_G$. This is performed with ECRH-assisted Ohmic start-up and a sufficiently high initial neutral density. This is motivated by and consistent with predictions of a recent plasma-wall self-organization (PWSO) theory, that increasing ECRH power or pre-filled gas pressure leads to lower plasma temperatures around divertor target and higher density limits. In addition, the experiments are shown to operate in the density-free regime predicted by the PWSO model. These results suggest a promising scheme for substantially increasing the density limit in tokamaks, a critical advancement toward achieving the burning plasma. |
| title | Increasing the density limit with ECRH-assisted Ohmic start-up on EAST |
| topic | Plasma Physics |
| url | https://arxiv.org/abs/2505.02710 |