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

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Plasma Science and Technology 2023年第8期25卷 28-37页

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 Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China

A broadband(BB)mode is observed by collective Thomson scattering diagnostics in repeatable shots of EAST and analyzed for the first *** BB mode usually grows during L–h transitions,featuring a BB quasi-coherent mode with increasing *** 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)he 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 *** 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 *** characteristics of BB are related to the theoretical density gradient-driven trapped electron *** 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

Simulations of h-mode Plasmas in Tokamak Using a Complete Core-Edge modeling in the BALDUR Code

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Plasma Science and Technology 2012年第9期14卷 778-788页

作者： Y.PIANROJ T.ONJUN School of Manufacturing Systems and Mechanical Engineering Sirindhorn International Institute of TechnologyThammasat UniversityPathum Thani 12121Thailand

A theory-based model for predicting the pedestal formation in both ion and electron temperatures, and hydrogenic and impurity density is developed and implemented in the 1.5D BALDUR codes for self-consistently simulating h-mode plasma in tokamak. In the simulation, the transports around pedestal, including the electron and ion thermal, hydrogenie and impurity particle transports are calculated using an （Mixed B/gB） model, which is modified to anomalous semi-empirical mixed Bohm/gyro-Bohm include the effects of ωE×B flow shear and magnetic shear. Because of the reduction of transport, the pedestal can be formed. For a preliminary test, this core-edge model is used to simulate the temporal evolution of plasma current, temperature, and density profiles for DIII-D discharges. It is found that the simulations successfully reproduce the experimental results. A statistical analysis, including RMSE and offset, is used to quantify the agreement between the prediction and the corresponding experimental results. The simulation results show an agreement with average RMSE of 11.87%, 14.53%, 7.59% and 12.21% for electron temperature, ion temperature, electron density, and deuterium density profiles, respectively. In addition, it is found that the suppression function developed is effective only in the edge region.

关键词： ITER pedestal h-mode BALDUR fusion performance transport

Realization of minute-long steady-state h-mode discharges on EAST

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Plasma Science and Technology 2017年第3期19卷 1-3页

作者： Xianzu GONG Baonian WAN Jiangang LI Jinping QIAN Erzhong LI Fukun LIU Yanping ZhAO Mao WANG handong XU A M GAROFALO Annika EKEDAh Siye. DINGJuan hUANG Ling ZhANG Qing ZANG haiqing LIU Long ZENG Shiyao LIN Biao ShEN Bin ZhANG Linming ShAO Bingjia XIAO Jiansheng hU Chundong hU Liqun hU Liang WANG Youwen SUN GuoshengXU Yunfeng LIANG Nong XIANG Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 People＇s Republic of China General Atomics San Diego CA 92186-5608 United States of America 3CEA IRFM F-13108 Saint PanMez-Durance France

In the 2016 EAST experimental campaign,a steady-state long-pulse h-mode discharge with an ITER-like tungsten divertor lasting longer than one minute has been obtained using only RF heating and current drive,through an integrated control of the wall conditioning,plasma configuration,divertor heat flux,particle exhaust,impurity management,and effective coupling of multiple RF heating and current drive sources at high injected *** plasma current（Ip - 0.45 MA） was fully-noninductively driven（Vloop 〈 0.0 V） by a combination of-2.5 MW LhW,-0.4 MW ECh and -0.8 MW *** result demonstrates the progress of physics and technology studies on EAST,and will benefit the physics basis for steady state operation of ITER and CFETR.

关键词： long pulse steady state RF heating h-mode

Transport Simulation of ECRh h-mode Experiments on hL-2A Tokamak

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Plasma Science and Technology 2015年第2期17卷 105-108页

作者：孙爱萍董家齐崔正英 Southwestern Institute of Physics

Transport simulation of ECRh h-mode experiments on hL-2A tokamak is carried out using ONETWO code, the GLF23 and PEDESTAL models, along with TORAY code for ECRh. It is found that the initial electron and ion temperature profiles affect L-h transition significantly, and larger initial temperature gradient at the edge plasma benefits the transition. The simulation results show that it is possible to achieve ECRh h-mode with appropriate initial electron and ion temperature profiles under present discharge conditions on hL-2A tokamak. In addition, the pedestal density, electron temperature and pedestal width are predicted, and the evolutions of electron and ion temperature profile are calculated.

关键词： plasma simulation ECRh h-mode

Investigation of lower hybrid current drive during h-mode in EAST tokamak

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Chinese Physics B 2011年第12期20卷 298-304页

作者：李妙辉丁伯江孔二华张磊张新军钱金平颜宁韩效锋单家方刘甫坤王茂徐旵东万宝年 Institute of Plasma Physics Chinese Academy of Sciences

h-mode discharges with lower hybrid current drive （LhCD） alone are achieved in EAST divertor plasma over a wide parameter range. These h-mode discharges are characterized by a sudden drop in Da emission and a spontaneous rise in main plasma density. Good lower hybrid （Lh） coupling during h-mode is obtained by putting the plasma close to the antenna and by injecting D2 gas from a pipe near the grill mouse. The analysis of lower hybrid current drive properties shows that the Lh deposition profile shifts off axis during h-mode, and current drive （CD） efficiency decreases due to the increase in density. modeling results of h-mode discharges with a general ray trueing code GENRAY are reported.

关键词： h-mode edge localized mode lower hybrid current drive

The Calibration of high-Speed Camera Imaging System for ELMs Observation on EAST Tokamak

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Plasma Science and Technology 2016年第9期18卷 884-889页

作者： FU Chao ZhONG Fangchuan hU Liqun YANG Jianhua YANG Zhendong GAN Zaifu ZhANG Bin EAST Team College of Science Donghua University Shanghai 201620 China Member of Magnetic Confinement Fusion Research Center Ministry of Education Shanghai 201620 China Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 China

A tangential fast visible camera has been set up in EAST tokamak for the study of edge MhD instabilities such as ELM. To determine the 3-D information from CCD images, Tsai＇s two-stage technique was utilized to calibrate the high-speed camera imaging system for ELM study. By applying tiles of the passive stabilizers in the tokamak device as the calibration pattern, transformation parameters for transforming from a 3-D world coordinate system to a 2-D image coordinate system were obtained, including the rotation matrix, the translation vector, the focal length and the lens distortion. The calibration errors were estimated and the results indicate the reliability of the method used for the camera imaging system. Through the calibration, some information about ELM filaments, such as positions and velocities were obtained from images of h-mode CCD videos.

关键词： CCD calibration h-mode ELM filamentary structure high-speed camera

Observation of Pedestal Plasma Turbulence on EAST Tokamak

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Plasma Science and Technology 2013年第8期15卷 732-737页

作者：高翔张涛韩翔张寿彪王嵎民刘子奚杨曜刘少承史楠凌必利李建刚 the EAST team Institute of Plasma Physics Chinese Academy of Sciences

Pedestal plasma turbulence was experimentally studied by microwave reflectometry on EAST tokamak. The characteristics of edge pedestal turbulence during dithering L-h transition, ELM-free h-mode phase and inter-ELM phase have recently been studied on EAST. An edge spatial structure of density fluctuation and its dithering temporal evolution is observed for the first time on the EAST tokamak during the L-h transition phase. A coherent mode usually appears during the ELM-free phase prior to the first ELM on EAST tokamak. The mode frequency gradually decreases as the pedestal evolves. Analysis shows that the coherent mode is in the pedestal region inside the separatrix. In plasma with type-III ELMs, a precursor mode before ELM is usually observed. The frequency of the precursor was initially about 150 khz and gradually decreased till the next ELM. The mode amplitude increases or shows saturation before ELM. In the plasma with compound ELMs composed of high and low frequency ELMs, the precursor was also observed before the high frequency ELM while the harmonic oscillations with frequencies of 20 khz, 40 khz and 60 khz appear before the low frequency ELM.

关键词： h-mode pedestal turbulence reflectometry

X-mode Frequency Modulated Density Profile Reflectometer on EAST Tokamak

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Plasma Science and Technology 2013年第9期15卷 857-862页

作者：张重阳刘阿娣李弘李斌周楚张小辉胡健强谢锦林兰涛刘万东俞昌旋 CAS Key Laboratory of Geospace Environment Department of Modern PhysicsUniversity of Science and Technology of China

An extraordinary-mode （X-mode） frequency-modulated continuous-wave （FMCW） profile reflectometer has been built on EAST. In the reflectometer, continuous waves with fre- quency sweeping from 12.5 Ghz to 18 Ghz were generated through a hyperabrupt Tuned-varactor Oscillator （hTO） source and a four times active multiplier was used to increase the frequency to V-band （50 Ghz to 72 Ghz）. The polarization of horn lens antenna is perpendicular to the mag- netic field line at the edge plasmas. According to the V-band frequency range and polarization, the system cover density range from 0.5 x 1019m-3 to 3.0 x 1019m-3 （when toroidal magnetic field is 1.8 T）, with time resolution of 12.5 ~ 50 #s. The density profile could be calculated by assuming the edge profile through an empirical equation. The maximum spatial error deduced by the method is about 4 cm. This reflectometer has been successfully applied in 2010 autumn EAST campaign, the temporal evolution of density profiles was acquired during the low confine- ment mode to high confinement mode transition. The density pedestal of EAST Tokamak was observed and the top value and gradient of the density pedestal were estimated.

关键词： ceflectometer electron density h-mode CDM

Experimental observations of naturally occurring dust using a high-speed vacuum ultraviolet imaging system in EAST

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Plasma Science and Technology 2023年第5期25卷 1-7页

作者：侯善伟明廷凤石奇奇张文敏龙飞飞李邦邓荣婧庄清刘晓菊张凌提昂曾龙李国强 Naoko AShIKAWA Satoshi OhDAChI 高翔 Anhui University Hefei 230601People’s Republic of China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People’s Republic of China University of Science and Technology of China Hefei 230026People’s Republic of China Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic EngineeringShenzhen UniversityShenzhen 518060People’s Republic of China hangzhou Dianzi University Hangzhou 310018People’s Republic of China National Institute for Fusion Sciences Toki 509-5292Japan SOKENDAI Toki 509-5292Japan

In the ELMy h-mode experiment,naturally occurring dust originating at the high-field side is clearly observed using the high-speed vacuum ultraviolet imaging system developed on the Experimental Advanced Superconducting Tokamak(EAST).The main ablation cloud shape is similar to the classical shape observed in pellet fueling ***,during the dust penetration,an erupted secondary cloudlet with a bent‘cigar’shape is observed and moves upwards along the direction perpendicular to the magnetic field line,which is different to the obviation in the pellet fueling *** may be due to the ion diamagnetic drift *** velocities of the secondary cloudlet are estimated to be 50–80 m s^(-1).In addition,a significant degradation of the plasma confinement is observed during the dust penetration.

关键词： h-mode hFS VUVI EAST tokamak dust cloudlet