Tungsten control in type-I ELMy H-mode plasmas on EAST

• Published in: Nuclear science and techniques Vol. 32; no. 9; pp. 61 - 72
• Main Authors: Xu, Zong, Wu, Zhen-Wei, Zhang, Ling, Cheng, Yun-Xing, Gao, Wei, Lin, Xiao-Dong, Gao, Xiang, Chen, Ying-Jie, Huang, Yue-Heng, Huang, Juan, Zang, Qing, Jie, Yin-Xian, Duan, Yan-Min, Li, Ying-Ying, Liu, Hai-Qing, Xu, Guo-Sheng, team, EAST
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01.09.2021; University of Science&Technology of China, Hefei 230031, China%Advanced Energy Research Center, Shenzhen University, Shenzhen 518060, China; Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China%Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031, China%Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; Advanced Energy Research Center, Shenzhen University, Shenzhen 518060, China
• Subjects: Beam Physics; Nuclear Energy; Particle Acceleration and Detection; Particle and Nuclear Physics; Physics; Physics and Astronomy; ELMy H-mode; Tungsten accumulation; Favorable; EAST; Counter-NBI; Favorable Bt
• ISSN: 1001-8042; 2210-3147
• DOI: 10.1007/s41365-021-00929-4

The first experimental investigation of the tungsten behavior in ELMy H-mode plasmas with co-/counter neutral beam injection (NBI) and unfavorable/favorable B t was performed on EAST. Tungsten was found to accumulate easily in ELMy H-mode plasma with co-NBI heating and unfavorable B t . Thus, in this case the tungsten concentration can exceed 10 −4 , resulting in degradation of the plasma confinement and periodic H–L transitions. To reduce the tungsten concentration in steady-state type-I ELMy H-mode operation, counter-NBI is applied to modify the density and temperature and brake the plasma toroidal rotation. The applied counter-NBI decreases the PHZ +  E r inward pinch velocity and reverses the direction of neoclassical inward convection, thus decreasing the tungsten concentration from ~ 7 × 10 −5 to ~ 2 × 10 −5 in type-I ELMy H-mode plasma with favorable B t . A comparison of the effects of different B t directions on the tungsten behavior also shows that favorable B t is beneficial for reducing the tungsten concentration in the core plasma. These results imply that counter-NBI with favorable B t can effectively prevent tungsten accumulation and expand the operating window for exploring steady-state type-I ELMy H-mode operation of EAST.