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5 results on '"Yunxin Cheng"'

1. Overview of recent experimental results on the EAST Tokamak

Author

X. Gong, on behalf of EAST Team and Collaborators, The EAST Team:, Yuntao Song, Baonian Wan, Jiangang Li, Yuanxi Wan, Xinchao Wu, Fukun Liu, Junling Chen, Jiansheng Hu, Guosheng Xu, Kun Lu, Xianzu Gong, Bingjia Xiao, Yu Wu, Xiang Gao, Damao Yao, Nong Xiang, Liqun Hu, Chundong Hu, Jiefeng Wu, Biao Shen, Ge Gao, Yiyun Huang, Liuwei Xu, Qiyong Zhang, Cheonho Bae, Bin Cao, Lei Cao, Jiafeng Chang, Dalong Chen, Ran Chen, Xiaojiao Chen, Yebin Chen, Yue Chen, Yunxin Cheng, Yong Cheng, Bojiang Ding, Fang Ding, Rui Ding, Shijun Du, Yanmin Duan, Jia Fu, Daming Gao, Wei Gao, Yongqi Gu, Bin Guo, Fei Guo, Yong Guo, Xiaofeng Han, Shiying He, Ailan Hu, Chang Hu, Guanghai Hu, Huaichuan Hu, Qingsheng Hu, Yanlan Hu, Zhenhua Hu, Juan Huang, Liansheng Huang, Ming Huang, Ronglin Huang, Xiang Ji, Hua Jia, Caichao Jiang, Yinxian Jie, Songqing Ju, Defeng Kong, Erzhong Li, Guoqiang Li, Jiahong Li, Junjun Li, Miaohui Li, Pan Li, Kedong Li, Shi Li, Yadong Li, Lizhen Liang, Yanchuan Liao, Shiyao Lin, Xin Lin, Bili Ling, Haiqing Liu, Huajun Liu, Jianwen Liu, Liang Liu, Shaocheng Liu, Sheng Liu, Wenbin Liu, Xiaoju Liu, Xiaoyan Liu, Yong Liu, Zhihong Liu, Zhimin Liu, Jianhua Lu, Zhengping Luo, Dengkui Ma, Huafeng Mao, Wendong Ma, Songtao Mao, Yuzhou Mao, Tingfeng Ming, Chao Pan, Chengkang Pan, Shengmin Pan, Jing Qian, Jinping Qian, Chengming Qin, Zhiyong Qiu, Qilong Ren, Zhicai Sheng, Shihua Song, Pengjun Sun, Xiaoyang Sun, Youwen Sun, Tian Tang, Ling Tao, Ang Ti, Baoguo Wang, Feng Wang, Fudi Wang, Huihui Wang, Jian Wang, Liang Wang, Linsen Wang, Mao Wang, Ping Wang, Xiaojie Wang, Shouxin Wang, Yating Wang, Yuehang Wang, Yong Wang, Zhengchu Wang, Jianglong Wei, Jing Wei, Xuechao Wei, Bin Wu, Dajun Wu, Hao Wu, Jinhua Wu, Xiangming Wu, Yibing Wu, Zege Wu, Weibin Xi, Tianyang Xia, Yezheng Xiao, Yahong Xie, Yuanlai Xie, Handong Xu, Liqing Xu, Weiye Xu, Ning Yan, Rong Yan, Jianhua Yang, Lei Yang, Qingxi Yang, Yao Yang, Zhongshi Yang, Min Yu, Yaowei Yu, Qiping Yuan, Shuai Yuan, Qing Zang, Bin Zhang, Jian Zhang, Jizong Zhang, Liyuan Zhang, Ling Zhang, Ruirui Zhang, Shoubiao Zhang, Tao Zhang, Wei Zhang, Xinjun Zhang, Xiuqing Zhang, Yang Zhang, Zuchao Zhang, Hailin Zhao, Lianmin Zhao, Guoqiang Zhong, Ruijie Zhou, Haishan Zhou, Tianhu Zhou, Yue Zhou, Dahuan Zhu, Haisheng Zhu, Ping Zhu, Zeying Zhu, Huidong Zhuang, Zibo Zhou, Zhiyong Zhou, Zhiwei Zhou, Guizhong Zuo, International and Domestic Collaborators:, Huishan Cai, Weixing Ding, Tao Lan, Adi Liu, Wandong Liu, Shaojie Wang, Minyou Ye, Yi Yu, Ge Zhuang, Wei Chen, Guangjiu Lei, Lin Nie, Min Xu, Huang Yuan, Nanhua Yao, Zhe Gao, Long Zeng, Tieshuan Fan, Liu Chen, Guoyong Fu, Zhiwei Ma, Zengmao Sheng, Yong Xiao, Xiaogang Wang, Zhongyong Chen, Yonghua Ding, Xiwei Hu, Zijiang Wang, Fangchuan Zhong, Hongbin Ding, Dezhen Wang, Zhengxiong Wang, Chenggang Jin, Xuemei Wu, Xiaofei Yang, Jianhua Zhang, Qingyuan Hu, Xi Yuan, Changqi Chen, Shuyi Gan, Xudi Wang, Congzhong Wu, Chongwei Zhang, Ting Zhang, Wu Zhu, Erhua Kong, Kaisong Wang, Chuanli Wang, Hongtao Yang, Lixiang Zhang, Yuhong Xu, Paul Anderson, Gheni Abla, Vincent Chan, John L. Doane, Andrea Garofalo, Punit Gohil, Chung Lih Hsieh, Ruey Hong, David Humphreys, Alan Walter Hyatt, Gary Jackson, Lang Lao, Yueqiang Liu, James Leuer, John Lohr, Mohamad Ali Mahdavi, Robert Olstad, Ben Penaflor, Ron Prater, David Piglowski, Michael Schaffe, Tim Scoville, Wayne Solomon, Mike Walker, Anders Welander, Manfred Bitter, Robert Budny, Robert A. Ellis, Nat Fisch, Rich Hawryluk, Kenneth W. Hill, Joel Hosea, Michael A. Jaworski, Egemen Kolemen, Rajesh Maingi, Dennis Mansfield, Dana M. Mastrovito, Jonathan Menard, Dennis Mueller, Novmir Pablant, Lane Roquemore, Filippo Scotti, Gary Taylor, Kevin Tritz, Randy Wilson, Michael Zarnstorff, Seung Gyou Baek, Beck Bill, Paul T. Bonoli, Robert Granetz, Ron Parker, Shunichi Shiraiwa, Josh Stillerman, Greg Wallace, Stephen Wukitch, Lihua Zhou, He Huang, Kenneth Gentle, Ken Liao, Perry Philippe, William L. Rowan, Linjin Zheng, Patrick H. Diamond, George R. Tynan, Nicolas Fedorczak, Peter Manz, Lei Zhao, David Brower, William W. Heidbrink, Yubao Zhu, Calvin W. Domier, Neville C. Luhmann, Chris Holcomb, Xueqiao Xu, Eric Wang, Max E. Fenstermarcher, Mickey Wade, Donald L. Hillis, Steve Meitner, Igor V. Vinyar, Vladimir Davydenko, Igor Shikhovtsev, Naoko Ashikawa, Kasahara Hiroshi, Katsumi Ida, Shinichiro Kado, Tomita Kawamura, Saito Kenji, Ryuhei Kumazawa, Ogawa Kunihiro, Isobe Mitsutaka, Shigeru Morita, Haruhisa Nakano, Masaki Osakabe, Mizuki Sakamoto, Yasuhiko Takeiri, Kazuo Toi, Katsuyoshi Tsumori, Nobuta Yuji, Masaya Hanada, Mitsuru Kikuchi, Atsushi Kojima, Kazuhiro Watanabe, Jean-Francois Artaud, Vincent Basiuk, F. Bouquey, B. Bremond, Laurent Colas, Joan Decker, D. Douai, Annika Ekedahl, Christel Fenzi, Eric Gauthier, Gerardo Giruzzi, Marc Goniche, Dominique Guilhem, Walid Helou, Julien Hillairet, Tuong Hoang, Philippe Huynh, Frederic Imbeaux, Xavier Litaudon, Roland Magne, Yves Peysson, K. Vueillie, Xiaolan Zou, Alberto Loarte, Richard Pitts, Tom Wauters, Franz Braun, R. Bilato, Volodymyr Bobkov, J.M. Noterdaeme, Qingquan Yu, Yunfeng Liang, Jonny Pearson, Michael Rack, Joseph Banks, John Fessey, Charles Monroe, Damian King, Stefan Schmuck, Hongjuan Sun, Paul Trimble, Tom Todd, Jun-Gyo Bak, Suk-Ho Hong, Sangong Lee, Bae Young Soon, Oh Byung Hoon, Chang Doo Hee, Lee Kwang Won, Luca Amicucci, Giuseppe Calabro, Silvio Ceccuzzi, Roberto Cesario, Flavio Crisanti, Edmondo Giovannozzi, Giuseppe Ramogida, Gianmaria De Tommasi, Angelo Antonio Tuccillo, Bruno Viola, Raffaele Albanese, Roberto Ambrosino, Lucio Barbato, Stefano Mastrostefano, Alfredo Pironti, Vincenzo Pericoli Ridolfini, Rory Scannell, Fabio Villone, Volker Naulin, Anders H. Nielsen, Roman Zagorsky, Sandor Zoletnik, Chijin Xiao, B. Madsen, M. Salewski, and Eugenio Schuster

Subjects
steady state long pulse, EAST tokamak, ITPA, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Since the last IAEA-FEC in 2021, significant progress on the development of long pulse steady state scenario and its related key physics and technologies have been achieved, including the reproducible 403 s long-pulse steady-state H-mode plasma with pure radio frequency (RF) power heating. A thousand-second time scale (∼1056 s) fully non-inductive plasma with high injected energy up to 1.73 GJ has also been achieved. The EAST operational regime of high β _P has been significantly extended ( H _98y2 > 1.3, β _P ∼ 4.0, β _N ∼ 2.4 and n _e / n _GW ∼ 1.0) using RF and neutral beam injection (NBI). The full edge localized mode suppression using the n = 4 resonant magnetic perturbations has been achieved in ITER-like standard type-I ELMy H-mode plasmas with q _95 ≈ 3.1 on EAST, extrapolating favorably to the ITER baseline scenario. The sustained large ELM control and stable partial detachment have been achieved with Ne seeding. The underlying physics of plasma-beta effect for error field penetration, where toroidal effect dominates, is disclosed by comparing the results in cylindrical theory and MARS-Q simulation in EAST. Breakdown and plasma initiation at low toroidal electric fields (

Published
2024
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2. First observation of edge impurity behavior with n = 1 RMP application in EAST L-mode plasma

Author

Wenmin Zhang, Ling Zhang, Yunxin Cheng, Shigeru Morita, Hui Sheng, Darío Mitnik, Youwen Sun, Zhengxiong Wang, Yuqi Chu, Ailan Hu, Yinxian Jie, and Haiqing Liu

Subjects
EAST tokamak, impurity ion flux, resonant magnetic perturbations, screening layer, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

High-Z impurity accumulation suppression and mitigation in core plasma is frequently observed in EAST edge localized mode mitigation experiments by using resonant magnetic perturbations (RMP) coils. To study the individual effects of the RMP field on impurity transport, based on high-performance extreme ultraviolet impurity spectroscopic diagnostics, the effect of the n = 1 ( n is the toroidal mode number) RMP field on the behavior of intrinsic impurity ions at the plasma edge, e.g. He ^+ , Li ^2+ , C ^2+ –C ^5+ , O ^5+ , Fe ^8+ , Fe ^15+ , Fe ^17+ , Fe ^22+ , Cu ^17+ , Mo ^12+ , Mo ^13+ and W ^27+ , is analyzed for the first time in L-mode discharges. Based on the evaluation of the location of these impurity ions, it is found that with the increase in RMP current ( I _RMP ), an impurity screening layer inside the last closed flux surface is formed, e.g. at ρ = 0.74–0.96, which is also the region that the RMP field affects. Outside this screening layer, the impurity ion flux of He ^+ , Li ^2+ , C ^2+ , C ^3+ , O ^5+ , Fe ^8+ , Mo ^12+ and Mo ^13+ ions increases gradually, while inside this screening layer, the impurity ion flux of C ^4+ , C ^5+ , Cu ^17+ , W ^27+ , Fe ^15+ , Fe ^17+ and Fe ^22+ ions decreases gradually. When I _RMP is higher than a threshold value, RMP field penetration occurs, accompanied with m / n = 2/1 mode locking, and the position of this screening layer moves to the plasma core region, i.e. ρ = 0.66–0.76, close to the q = 2 surface, and the opposite behavior of the impurity ion flux at two sides of the screening layer is strengthened dramatically. As a result, significant decontamination effects in the plasma core region, indicated by the factor of (( Γ _Imp ^Z+ ) _w/o –( Γ _Imp ^Z+ ))/( Γ _Imp ^Z+ ) _w/o (where ( Γ _Imp ^Z+ )/( Γ _Imp ^Z+ ) _w/o denotes the impurity ion flux ratio with and without RMP), is observed, i.e. 30%–60% for heavy impurity (Fe, Cu, Mo, W), and ∼27% for light impurity of C. In addition, the analysis of the decontamination effects of C and Fe impurities under four different RMP phase configurations shows that it may be related to the strength of the response of the plasma to RMP. These results enhance the understanding of impurity accumulation suppression by the n = 1 RMP field and demonstrate a candidate approach using RMP coils for W control in magnetic confinement devices.

Published
2024
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3. Illustrating the physics of core tungsten (W) transport in a long-pulse steady-state H-mode discharge on EAST

Author

Shengyu Shi, Jiale Chen, Xiang Jian, Tomáš Odstrčil, Bourdelle Clarrisse, Muquan Wu, Mingfu Wu, Yanmin Duan, Yan Chao, Ling Zhang, Yunxin Cheng, Jinping Qian, Andrea M. Garofalo, Xianzu Gong, Xiang Gao, Yuanxi Wan, and the EAST Team

Subjects
Nuclear and High Energy Physics, Condensed Matter Physics
Abstract

The behavior of core tungsten (W) in a pure radio-frequency-heated long-pulse steady-state H-mode discharge in the Experimental Advanced Superconducting Tokamak (EAST) with an ITER-like divertor (ILD) is analyzed using experimental diagnostic data and modeled using a combination of drift-kinetic neoclassical and gyro-fluid turbulent software. In the steady state, the experimental core line-averaged W concentration (C W) is about 2 × 10−5, which is evaluated using the intensity of the W unresolved transition array (W-UTA) spectral structure in the region of 45–70 Å (which is composed of W 27+–W 45+ line emissions) through spectroscopy in the extreme ultraviolet region. W produces a peak of the radiated power density profile around a normalized radius of ρ ∼ 0.3. Therefore, W does not centrally accumulate in the experiment. A time slice of the steady-state is modeled, which accounts for both the neoclassical and turbulent transport components of W based on the self-consistent background plasma profiles simulated by TGYRO (Candy et al 2009 Phys. Plasmas 16 060704). It is found that turbulent transport dominates over neoclassical transport for W. In addition, the turbulent diffusion coefficient is large enough to offset the sum of the neoclassical and turbulent pinch (convection) velocities, so that the W density profile for a zero particle flux is not strongly peaked. By combining TGLF (Staebler et al 2017 Nucl. Fusion 57 066046) and NEO (Belli and Candy 2008 Plasma Phys. Control. Fusion 50 095010; 2012 Plasma Phys. Control. Fusion 54 015015) for the W transport coefficient with the impurity transport code STRAHL (Dux 2006 STRAHL User Manual), the experimental C W and the information radiated by W can be reproduced closely. In addition, the effect of toroidal rotation on the W transport is also clarified.

Published
2022
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4. Understanding core heavy impurity transport in a hybrid discharge on EAST

Author

Ling Zhang, A.M. Garofalo, Xiang Gao, Yan Chao, Jinping Qian, Fang Ding, Tomas Odstrcil, Xiang Jian, Clarisse Bourdelle, yunxin cheng, Yanmin Duan, Shengyu Shi, Jiale Chen, and Mingfu Wu

Subjects
Core (optical fiber), Nuclear and High Energy Physics, Materials science, Impurity, Condensed Matter Physics, Molecular physics
Abstract

The behavior of heavy/high-Z impurity tungsten (W) in the core of hybrid (high normalized beta β N plasmas) scenario on EAST with international thermonuclear experimental reactor-like divertor is analyzed. W accumulation is often observed and seriously degrades the plasma performance (Gao et al 2017 Nucl. Fusion 57 056021). The dynamics of the W accumulation process of a hybrid discharge are examined considering the concurrent evolution of the background plasma parameters. It is found that the toroidal rotation and density peaking of the bulk plasma are usually large in the central region, which is particularly prone to the W accumulation. A time slice during the W accumulation phase is modeled, accounting for both neoclassical and turbulent transport components of W, through NEO with poloidal asymmetry effects induced by toroidal rotation, and TGLF, respectively. This modeling reproduces the experimental observations of W accumulation and identifies the neoclassical inward convection/pinch velocity of W due to the large density peaking of the bulk plasma and toroidal rotation in the central region as one of the main reasons for the W accumulation. In addition, the NEO + TGLF + STRAHL modeling can not only predict the core W density profile but also closely reconstruct the radiated information mainly produced by W in the experiment.

Published
2022
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5. Understanding core tungsten (W) transport and control in an improved high-performance fully non-inductive discharge on EAST

Author

Jiale Chen, M. Q. Wu, Clarisse Bourdelle, Yuanxi Wan, Yingying Li, Jinping Qian, Ling Zhang, Xiang Jian, Shengyu Shi, Fang Ding, Juan Huang, A.M. Garofalo, yunxin cheng, Yanmin Duan, Xiang Gao, Yan Chao, and Tomas Odstrcil

Subjects
Core (optical fiber), Nuclear and High Energy Physics, Materials science, chemistry, Nuclear engineering, chemistry.chemical_element, Tungsten, Condensed Matter Physics
Abstract

The behavior of heavy/high-Z impurity tungsten (W) in an improved high-performance fully non-inductive discharge on EAST with ITER-like divertor (ILD) is analyzed. It is found that W could be well controlled. The causes of no W accumulation are clarified by analyzing the background plasma parameters and modeling the W transport. It turns out that the electron temperature (T e) and its gradient are usually high while the toroidal rotation and density peaking of the bulk plasma are small. In this condition, the modeled W turbulent diffusion coefficient is big enough to offset the total turbulent and neoclassical pinch, so that W density profile for zero particle flux will not be very peaked. Combining NEO and TGLF for the W transport coefficient and the impurity transport code STRAHL, not only the core W density profile is predicted but also the radiated information mainly produced by W in the experiment can be closely reconstructed. At last, the physics of controlling W accumulation by electron cyclotron resonance heating (ECRH) is illustrated considering the effects of changed T e by ECRH on ionization balance and transport of W. It shows that the change of ionization and recombination balance by changed T e is not enough to explain the experimental observation of W behavior, which should be attributed to the changed W transport. By comparing the W transport coefficients in two kinds of plasmas with different T e profiles, it is shown that high T e and its gradient play a key role to generate large turbulent diffusion through increasing the growth rate of linear instability so that W accumulation is prevented.

Published
2022
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