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Title: Numerical simulation of Li-pellet injection experiments for ELM-pacing in EAST

Abstract

The injection of light impurity granules into fusion research discharges has shown a great potential for ELM pacing in future nuclear devices. The present work employed a model considering both pellet ablation and transport to systematically study for the first time the evolution of both impurity Li species and target plasma in the edge plasma during single and repeated Li pellet injections, with all initial information extracted from the EAST experiments. The evolutionary distributions of atomic and ionized Li species were presented and show good consistency with experimental CCD camera images. Simulation studies were carried out for single and repeated pellet injections at the outer mid-plane, and statistical uncertainty of ELM pacing rates triggering ELMs is discussed with regard to related injection conditions. It is found that the pressure locally caused by an ELM pacing pellet (with a diameter of 0.6 ~ 0.7 mm) was 1.8–2.4 times its unperturbed magnitude in the EAST shots of interest. Accumulation from repeated pellet injections results in the rise of pedestal height at a high injection frequency and this effect becomes stronger with increasing pellet size. Pressure changes are also evident in a scenario of multiple small pellets per stroke, which could lead tomore » a nonnegligible, probabilistic ELM triggering rate observed experimentally. The effects of other possible factors are also discussed. With the assumption that the ELM trigger rate of a Li pellet of 0.7 mm diameter is 100%, the predicted trigger rates are in good agreement with those observed in experiments. This work can help understand the statistically probabilistic behavior of ELM triggering efficiency observed in previous studies.« less

Authors:
 [1];  [1]; ORCiD logo [2];  [3];  [3];  [4];  [4];  [1];  [1]
  1. Dalian Univ. of Technology, Dalian (China)
  2. Chinese Academy of Sciences (CAS), Beijing (China); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Chinese Academy of Sciences (CAS), Beijing (China)
  4. ITER Organization (France)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1619198
Grant/Contract Number:  
AC02-09CH11466; 11575039; 11505022; 11625524; 2017YFE0301100; DUT18GF112; DUT18LK2017YFA0402500
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 60; Journal Issue: 6; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Gao, Fang, Sun, Jizhong, Sun, Zhen, Zuo, Guizhong, Hu, Jiansheng, Loarte, Alberto, Bonnin, Xavier, Peng, Lei, and Liu, Jinyuan. Numerical simulation of Li-pellet injection experiments for ELM-pacing in EAST. United States: N. p., 2020. Web. doi:10.1088/1741-4326/ab8340.
Gao, Fang, Sun, Jizhong, Sun, Zhen, Zuo, Guizhong, Hu, Jiansheng, Loarte, Alberto, Bonnin, Xavier, Peng, Lei, & Liu, Jinyuan. Numerical simulation of Li-pellet injection experiments for ELM-pacing in EAST. United States. https://doi.org/10.1088/1741-4326/ab8340
Gao, Fang, Sun, Jizhong, Sun, Zhen, Zuo, Guizhong, Hu, Jiansheng, Loarte, Alberto, Bonnin, Xavier, Peng, Lei, and Liu, Jinyuan. Tue . "Numerical simulation of Li-pellet injection experiments for ELM-pacing in EAST". United States. https://doi.org/10.1088/1741-4326/ab8340. https://www.osti.gov/servlets/purl/1619198.
@article{osti_1619198,
title = {Numerical simulation of Li-pellet injection experiments for ELM-pacing in EAST},
author = {Gao, Fang and Sun, Jizhong and Sun, Zhen and Zuo, Guizhong and Hu, Jiansheng and Loarte, Alberto and Bonnin, Xavier and Peng, Lei and Liu, Jinyuan},
abstractNote = {The injection of light impurity granules into fusion research discharges has shown a great potential for ELM pacing in future nuclear devices. The present work employed a model considering both pellet ablation and transport to systematically study for the first time the evolution of both impurity Li species and target plasma in the edge plasma during single and repeated Li pellet injections, with all initial information extracted from the EAST experiments. The evolutionary distributions of atomic and ionized Li species were presented and show good consistency with experimental CCD camera images. Simulation studies were carried out for single and repeated pellet injections at the outer mid-plane, and statistical uncertainty of ELM pacing rates triggering ELMs is discussed with regard to related injection conditions. It is found that the pressure locally caused by an ELM pacing pellet (with a diameter of 0.6 ~ 0.7 mm) was 1.8–2.4 times its unperturbed magnitude in the EAST shots of interest. Accumulation from repeated pellet injections results in the rise of pedestal height at a high injection frequency and this effect becomes stronger with increasing pellet size. Pressure changes are also evident in a scenario of multiple small pellets per stroke, which could lead to a nonnegligible, probabilistic ELM triggering rate observed experimentally. The effects of other possible factors are also discussed. With the assumption that the ELM trigger rate of a Li pellet of 0.7 mm diameter is 100%, the predicted trigger rates are in good agreement with those observed in experiments. This work can help understand the statistically probabilistic behavior of ELM triggering efficiency observed in previous studies.},
doi = {10.1088/1741-4326/ab8340},
journal = {Nuclear Fusion},
number = 6,
volume = 60,
place = {United States},
year = {Tue May 12 00:00:00 EDT 2020},
month = {Tue May 12 00:00:00 EDT 2020}
}

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