Type-I ELM mitigation by continuous lithium granule gravitational injection into the upper tungsten divertor in EAST

Sun, Zhen; Yuzhong, Qian; Maingi, Rajesh; Wang, Yifeng; Wang, Yumin; Nagy, Alex; Tritz, Kevin; Lunsford, Robert; Gilson, Erik; Zuo, Guizhong; Xu, Wei; Huang, Ming; Meng, Xiancai; Mansfield, Dennis K; Zang, Qing; Zhu, Xiang; Lin, Xin; Liu, Haiqing; Duan, Yanmin; Zhang, Ling; Lyu, Bo; Liu, Yong; Wang, Liang; Bortolon, Ale; Xu, Guosheng; Gong, Xianzu; Hu, Jiansheng

doi:10.11578/1814955

Title: Type-I ELM mitigation by continuous lithium granule gravitational injection into the upper tungsten divertor in EAST

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Abstract

Large edge-localized modes (ELMs) were mitigated by gravitational injection of lithium granules into the upper X-point region of the EAST device with tungsten plasma-facing components. The maximum ELM size was reduced by ~ 70% in high βN H-mode plasmas. Large ELM stabilization was sustained for up to about 40 energy confinement times, with constant core radiated power and no evidence of high-Z or low-Z impurity accumulation. The lithium granules injection reduced the edge plasma pedestal density and temperature and their gradients, due to increased edge radiation and reduced recycling from the plasma-facing components. Ideal stability calculations using the ELITE code indicate that the stabilization of large ELMs correlates with improved stability of intermediate-n peeling-ballooning modes, due to reduced edge current resulting from the profile changes. The pedestal pressure reduction was partially offset by a core density increase, which resulted in a modest ~ 7% drop in core stored energy and normalized energy confinement time. We surmise that the remnant small ELMs are triggered by the penetration of multiple Li granules just past the separatrix, similar to small ELMs triggered by deuterium pellet [S. Futatani et al., Nucl. Fusion 54 (2014) 073008]. This study extends previous ELM elimination with Li powdermore »« less

Publication Date:: Thu May 06 04:00:00 UTC 2021

DOE Contract Number:: AC02-09CH11466

Research Org.:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

Subject:: EAST; Edge localized modes; Impurity seeding; Lithium

OSTI Identifier:: 1814955

DOI:: https://doi.org/10.11578/1814955

Citation Formats


                    Sun, Zhen, Yuzhong, Qian, Maingi, Rajesh, Wang, Yifeng, Wang, Yumin, Nagy, Alex, Tritz, Kevin, Lunsford, Robert, Gilson, Erik, Zuo, Guizhong, Xu, Wei, Huang, Ming, Meng, Xiancai, Mansfield, Dennis K, Zang, Qing, Zhu, Xiang, Lin, Xin, Liu, Haiqing, Duan, Yanmin, Zhang, Ling, Lyu, Bo, Liu, Yong, Wang, Liang, Bortolon, Ale, Xu, Guosheng, Gong, Xianzu, and Hu, Jiansheng. Type-I ELM mitigation by continuous lithium granule gravitational injection into the upper tungsten divertor in EAST.  United States: N. p., 2021. 
        Web.  doi:10.11578/1814955.

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                    Sun, Zhen, Yuzhong, Qian, Maingi, Rajesh, Wang, Yifeng, Wang, Yumin, Nagy, Alex, Tritz, Kevin, Lunsford, Robert, Gilson, Erik, Zuo, Guizhong, Xu, Wei, Huang, Ming, Meng, Xiancai, Mansfield, Dennis K, Zang, Qing, Zhu, Xiang, Lin, Xin, Liu, Haiqing, Duan, Yanmin, Zhang, Ling, Lyu, Bo, Liu, Yong, Wang, Liang, Bortolon, Ale, Xu, Guosheng, Gong, Xianzu, & Hu, Jiansheng. Type-I ELM mitigation by continuous lithium granule gravitational injection into the upper tungsten divertor in EAST.  United States.  doi:https://doi.org/10.11578/1814955

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                    Sun, Zhen, Yuzhong, Qian, Maingi, Rajesh, Wang, Yifeng, Wang, Yumin, Nagy, Alex, Tritz, Kevin, Lunsford, Robert, Gilson, Erik, Zuo, Guizhong, Xu, Wei, Huang, Ming, Meng, Xiancai, Mansfield, Dennis K, Zang, Qing, Zhu, Xiang, Lin, Xin, Liu, Haiqing, Duan, Yanmin, Zhang, Ling, Lyu, Bo, Liu, Yong, Wang, Liang, Bortolon, Ale, Xu, Guosheng, Gong, Xianzu, and Hu, Jiansheng. 2021.  
"Type-I ELM mitigation by continuous lithium granule gravitational injection into the upper tungsten divertor in EAST".  United States.  doi:https://doi.org/10.11578/1814955.  https://www.osti.gov/servlets/purl/1814955. Pub date:Thu May 06 04:00:00 UTC 2021

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@article{osti_1814955,

  title        = {Type-I ELM mitigation by continuous lithium granule gravitational injection into the upper tungsten divertor in EAST},

  author       = {Sun, Zhen and Yuzhong, Qian and Maingi, Rajesh and Wang, Yifeng and Wang, Yumin and Nagy, Alex and Tritz, Kevin and Lunsford, Robert and Gilson, Erik and Zuo, Guizhong and Xu, Wei and Huang, Ming and Meng, Xiancai and Mansfield, Dennis K and Zang, Qing and Zhu, Xiang and Lin, Xin and Liu, Haiqing and Duan, Yanmin and Zhang, Ling and Lyu, Bo and Liu, Yong and Wang, Liang and Bortolon, Ale and Xu, Guosheng and Gong, Xianzu and Hu, Jiansheng},

  abstractNote = {Large edge-localized modes (ELMs) were mitigated by gravitational injection of lithium granules into the upper X-point region of the EAST device with tungsten plasma-facing components. The maximum ELM size was reduced by ~ 70% in high βN H-mode plasmas. Large ELM stabilization was sustained for up to about 40 energy confinement times, with constant core radiated power and no evidence of high-Z or low-Z impurity accumulation. The lithium granules injection reduced the edge plasma pedestal density and temperature and their gradients, due to increased edge radiation and reduced recycling from the plasma-facing components. Ideal stability calculations using the ELITE code indicate that the stabilization of large ELMs correlates with improved stability of intermediate-n peeling-ballooning modes, due to reduced edge current resulting from the profile changes. The pedestal pressure reduction was partially offset by a core density increase, which resulted in a modest ~ 7% drop in core stored energy and normalized energy confinement time. We surmise that the remnant small ELMs are triggered by the penetration of multiple Li granules just past the separatrix, similar to small ELMs triggered by deuterium pellet [S. Futatani et al., Nucl. Fusion 54 (2014) 073008]. This study extends previous ELM elimination with Li powder injection [R. Maingi et al., Nucl. Fusion 58 (2018) 024003] in EAST because 1) use of small, dust-like powder and the related potential health hazards were eliminated, and 2) use of macroscopic granules should be more applicable to future devices, due to deeper penetration than dust particles, e.g. inside the separatrix with velocities ~ 10 m/s in EAST.},

  doi          = {10.11578/1814955},

  journal      = {},

  number       = ,

  volume       = ,

  place        = {United States},

  year         = {Thu May 06 04:00:00 UTC 2021},

  month        = {Thu May 06 04:00:00 UTC 2021}

}

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DOI: https://doi.org/10.11578/1814955

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Type-I ELM mitigation by continuous lithium granule gravitational injection into the upper tungsten divertor in EAST

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