Estimation of tungsten production from the upper divertor in EAST during edge localized modes  

作　　者：Jing Ou Nong Xiang Zong-Zheng Men Ling Zhang Ji-Chan Xu Wei Gao 欧靖;项农;门宗政;张凌;许吉禅;高伟(Institute of Plasma Physics,Chinese Academy of Sciences,Hefei 230031,China;Magnetic Fusion Theory,Chinese Academy ofSciences,Hefei 230031,China)

机构地区：[1]Institute of Plasma Physics,Chinese Academy of Sciences,Hefei 230031,China [2]Magnetic Fusion Theory,Chinese Academy of Sciences,Hefei 230031,China

出　　处：《Chinese Physics B》2019年第12期223-230,共8页中国物理B（英文版）

基　　金：Project supported by the National Key R&D Program of China(Grant Nos.2017YFE0300400 and 2017YFE0301300);the National Natural Science Foundation of China(Grant Nos.11475223 and 11775257);the National Magnetic Confinement Fusion Science Program of China(Grant No.2015GB101003);partly supported by AHNSF of China(Grant No.1808085J07)

摘　　要：During edge localized modes(ELMs), the sheath evolution in front of the Experimental Advanced Superconducting Tokamak(EAST) upper divertor is studied to estimate the sputtered tungsten(W) atoms from the divertor target. A large potential drop across the sheath is formed during ELMs by compared with inter-ELMs, and the maximum of sheath potential drop can exceed one thousand of e V in current EAST operation. Due to the enhancement of the sheath potential drop during ELMs, the W physical sputtering yield from the deuterium(D) ions and the impurity ions on the upper divertor target is found to be significant. It is established that the sputtered W yield during ELMs is at least higher by an order of magnitude than inter-ELMs, and D ions and carbon(C) ions are the main ions governing the W production for the current H-mode with ELMs discharges. With increase in the pedestal electron temperature, the maximum of the D and C ion impact energy during ELMs shows a nearly linear increase, and the D ions have sufficient impact energy to cause the strong W physical sputtering. As a consequence, the D ions may dominate the sputtered W flux from the divertor target when the C concentration is controlled less than one percent for the higher heating power H-mode with ELM discharges in near future.During edge localized modes(ELMs), the sheath evolution in front of the Experimental Advanced Superconducting Tokamak(EAST) upper divertor is studied to estimate the sputtered tungsten(W) atoms from the divertor target. A large potential drop across the sheath is formed during ELMs by compared with inter-ELMs, and the maximum of sheath potential drop can exceed one thousand of e V in current EAST operation. Due to the enhancement of the sheath potential drop during ELMs, the W physical sputtering yield from the deuterium(D) ions and the impurity ions on the upper divertor target is found to be significant. It is established that the sputtered W yield during ELMs is at least higher by an order of magnitude than inter-ELMs, and D ions and carbon(C) ions are the main ions governing the W production for the current H-mode with ELMs discharges. With increase in the pedestal electron temperature, the maximum of the D and C ion impact energy during ELMs shows a nearly linear increase, and the D ions have sufficient impact energy to cause the strong W physical sputtering. As a consequence, the D ions may dominate the sputtered W flux from the divertor target when the C concentration is controlled less than one percent for the higher heating power H-mode with ELM discharges in near future.

关 键 词：SHEATH edge localized modes impact energy 

分 类 号：TL6[核科学技术—核技术及应用]