Experimental study of density gradient-driven micro-instabilities and the confinement degradation during H-mode in EAST  

作　　者：陈斐 李亚东 王晓洁 吴国将 李磐 耿靖森 汪宇豪 孙鹏军 李二众 周天富 赵海林 臧庆 王守信 刘海庆 金仡飞 吕波 裴千镐 李建刚 Fei CHEN;Yadong LI;Xiaojie WANG;Guojiang WU;Pan LI;Jingsen GENG;Yuhao WANG;Pengjun SUN;Erzhong LI;Tianfu ZHOU;Hailin ZHAO;Qing ZANG;Shouxin WANG;Haiqing LIU;Yifei JIN;Bo LYU;Cheonho BAE;Jiangang LI(Institute of Plasma Physics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,People's Republic of China;University of Science and Technology of China,Hefei 230026,People's Republic of China)

机构地区：[1]Institute of Plasma Physics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,People's Republic of China [2]University of Science and Technology of China,Hefei 230026,People's Republic of China

出　　处：《Plasma Science and Technology》2023年第8期28-37,共10页等离子体科学和技术（英文版）

基　　金：supported by National Natural Science Foundation of China(No.11875286);the National Key R&D Program of China(No.2019YFE03010002);CAS President’s International Fellowship Initiative(No.2022VMB0007)。

摘　　要：A broadband(BB)mode is observed by collective Thomson scattering diagnostics in repeatable shots of EAST and analyzed for the first time.This BB mode usually grows during L–H transitions,featuring a BB quasi-coherent mode with increasing frequency.During H-mode operations,it is characterized by steady-state BB in the high-frequency range(f~200–2000 k Hz),at the electron scale(k_(θ)ρ_(s)=1–2),mainly driven by the density gradient,and is sensitive to the value ofηein the region of interest(ρ=0.4–0.8),wherehe=(R/L_(Te))/(R/L_(ne))is the ratio of the normalized electron temperature gradient and density gradient,and the regionρ=0.4–0.8 usually has a relatively low collisionality(v_(eff)<5).The frequency of BB is found to be dependent on the electron temperature and density gradient,which is a typical feature of electron-driven turbulence.A negative correlation between the energy confinement and the intensity of the BB turbulence during H-mode has been found,which indicates a strong electron thermal transport induced by the BB turbulence.The BB significantly decreases the electron temperature and causes flatter electron temperature profiles in the region of interest(ρ=0.4–0.8),thus makingηedecrease and the BB destabilize further.These characteristics of BB are related to the theoretical density gradient-driven trapped electron mode.It should be noted that this mode is not observed by other diagnostics in EAST,and shows very different features to the coherent modes in the edge.

关 键 词：micro-instabilities H-MODE confinement degradation 

分 类 号：TL631.24[核科学技术—核技术及应用]