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 calib...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.展开更多
Divertor heat patterns induced by Lower Hybrid Current Drive （LHCD） L-mode plasmas are investigated using an infra-red （IR） camera system on an Experimental Advanced Superconducting Tokamak （EAST）. A two-dimensi...Divertor heat patterns induced by Lower Hybrid Current Drive （LHCD） L-mode plasmas are investigated using an infra-red （IR） camera system on an Experimental Advanced Superconducting Tokamak （EAST）. A two-dimensional finite element analysis code DFlux is used to compute heat flux along the poloidal divertor target and corresponding quantities. Outside the Origin Strike Zone （OSZ）, a Second Peak Heat Flux （SPHF） zone, where the heat flux is even stronger than that at the OSZ, appears on the lower-outer （LO） divertor plates with LHCD and disappears immediately after switching off the LHCD. The main heat-flux shifts from the SPHF zone towards the OSZ when the divertor configuration converts from double null to lower single null, indicating that the growth of the SPHF zone is apparently affected by a plasma magnetic configuration. The heat patterns on the LO divertor plates are observed to be different from that on the lower-inner （LI） targets as the SPHF zone appears only on the LO divertor target. It is also found that the heat flux at the SPHF zone was obviously enhanced after the Supersonic Molecule Beam Injection （SMBI） pulse.展开更多
Resonant magnetic perturbations(RMPs)with high toroidal mode number n are considered for controlling edge-localized modes(ELMs)and divertor heat flux in future ITER H-mode operations.In this paper,characteristics of d...Resonant magnetic perturbations(RMPs)with high toroidal mode number n are considered for controlling edge-localized modes(ELMs)and divertor heat flux in future ITER H-mode operations.In this paper,characteristics of divertor heat flux under high-nRMPs(n=3 and 4)in H-mode plasma are investigated using newly upgraded infrared thermography diagnostic in EAST.Additional splitting strike point(SSP)accompanying with ELM suppression is observed under both RMPs with n=3 and n=4,the SSP in heat flux profile agrees qualitatively with the modeled magnetic footprint.Although RMPs suppress ELMs,they increase the stationary heat flux during ELM suppression.The dependence of heat flux on q_(95)during ELM suppression is preliminarily investigated,and further splitting in the original strike point is observed at q 495=during ELM suppression.In terms of ELM pulses,the presence of RMPs shows little influence on transient heat flux distribution.展开更多
Based on the surface temperature measured by the infrared camera on the experimental advanced superconducting tokamak （EAST）, the heat fluxes on the lower outer divertor target plate during H-mode with the lower-hyb...Based on the surface temperature measured by the infrared camera on the experimental advanced superconducting tokamak （EAST）, the heat fluxes on the lower outer divertor target plate during H-mode with the lower-hybrid wave current drive （LHCD） only and with the LHCD combined with the neutral beam injection （NBI） are calculated by the DFLUX code and compared. The analyzed discharges are lower single null divertor configuration discharges. In the case with the LHCD only （Ip ~ 400kA, PLHCD ~ 2 MW）, ELM-free appears after L-H transition with the peak heat flux on the lower outer target plate less than 1 MW/m2. However, there is no ELM- free appearing after the L-H transition in the case with the LHCD＋NBI （Ip ~ 300 kA, PLHCD ＋ PNBI ~ 2 MW）. The results show that the peak heat fluxes on the lower outer target plate in the LHCD＋NBI H-mode cases are larger than those in the LHCD H-mode under the similar auxiliary heating power. This is because the heat flux profiles of the lower outer target plate as a function of plate location in ELMing with the LHCD＋NBI are narrower than those with the LHCD only. The results are consistent with the results in terms of the scrape-off layer width observed in the EAST.展开更多
Detailed investigations on the filamentary structures associated with the type-I edge-localized modes（ELMs） should be helpful for protecting the materials of a plasma-facing wall on a future large device.Related exp...Detailed investigations on the filamentary structures associated with the type-I edge-localized modes（ELMs） should be helpful for protecting the materials of a plasma-facing wall on a future large device.Related experiments have been carefully conducted in the Experimental Advanced Superconducting Tokamak（EAST） using combined Langmuir-magnetic probes.The experimental results indicate that the radially outward velocity of type-I ELMy filaments can be up to 1.7 kms^（-1） in the far scrape-off layer（SOL） region.It is remarkable that the electron temperature of these filaments is detected to be ~50eV,corresponding to a fraction of 1/6 to the temperature near the pedestal top,while the density ~3×10^（19）m^（-3） of these filaments could be approximate to the line-averaged density.In addition,associated magnetic fluctuations have been clearly observed at the same time,which show good agreement with the density perturbations.A localized current on the order of ~100kA could be estimated within the filaments.展开更多
基金supported by National Natural Science Foundation of China(No.11275047)the National Magnetic Confinement Fusion Science Program of China(No.2013GB102000)
文摘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.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2014GB101001 and 2014GB101002)
文摘Divertor heat patterns induced by Lower Hybrid Current Drive （LHCD） L-mode plasmas are investigated using an infra-red （IR） camera system on an Experimental Advanced Superconducting Tokamak （EAST）. A two-dimensional finite element analysis code DFlux is used to compute heat flux along the poloidal divertor target and corresponding quantities. Outside the Origin Strike Zone （OSZ）, a Second Peak Heat Flux （SPHF） zone, where the heat flux is even stronger than that at the OSZ, appears on the lower-outer （LO） divertor plates with LHCD and disappears immediately after switching off the LHCD. The main heat-flux shifts from the SPHF zone towards the OSZ when the divertor configuration converts from double null to lower single null, indicating that the growth of the SPHF zone is apparently affected by a plasma magnetic configuration. The heat patterns on the LO divertor plates are observed to be different from that on the lower-inner （LI） targets as the SPHF zone appears only on the LO divertor target. It is also found that the heat flux at the SPHF zone was obviously enhanced after the Supersonic Molecule Beam Injection （SMBI） pulse.
基金supported by the National Key Research and Development Program of China (No. 2017YFA0402500)the National MCF Energy R&D Program of China (No. 2019YFE03040000)+5 种基金National Natural Science Foundation of China (Nos. 12005262 and 11975274)the Foundation of President of Hefei Institutes of Physical Science, CAS (No. YZJJ2018QN8)the Anhui Provincial Natural Science Foundation (No. 2108085J06)the Users with Excellence Program of Hefei Science Center CAS (Nos. 2021HSC-UE018 and 2020HSC-UE011)External Cooperation Program of Chinese Academy of Sciences (No. 116134KYSB20180035)Science Foundation of Institute of Plasma Physics, Chinese Academy of Sciences (No. DSJJ-2021-04)
文摘Resonant magnetic perturbations(RMPs)with high toroidal mode number n are considered for controlling edge-localized modes(ELMs)and divertor heat flux in future ITER H-mode operations.In this paper,characteristics of divertor heat flux under high-nRMPs(n=3 and 4)in H-mode plasma are investigated using newly upgraded infrared thermography diagnostic in EAST.Additional splitting strike point(SSP)accompanying with ELM suppression is observed under both RMPs with n=3 and n=4,the SSP in heat flux profile agrees qualitatively with the modeled magnetic footprint.Although RMPs suppress ELMs,they increase the stationary heat flux during ELM suppression.The dependence of heat flux on q_(95)during ELM suppression is preliminarily investigated,and further splitting in the original strike point is observed at q 495=during ELM suppression.In terms of ELM pulses,the presence of RMPs shows little influence on transient heat flux distribution.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11505290,51576208 and 11575239the National Magnetic Confinement Fusion Science Program of China under Grant Nos 2013GB113004 and 2015GB102004
文摘Based on the surface temperature measured by the infrared camera on the experimental advanced superconducting tokamak （EAST）, the heat fluxes on the lower outer divertor target plate during H-mode with the lower-hybrid wave current drive （LHCD） only and with the LHCD combined with the neutral beam injection （NBI） are calculated by the DFLUX code and compared. The analyzed discharges are lower single null divertor configuration discharges. In the case with the LHCD only （Ip ~ 400kA, PLHCD ~ 2 MW）, ELM-free appears after L-H transition with the peak heat flux on the lower outer target plate less than 1 MW/m2. However, there is no ELM- free appearing after the L-H transition in the case with the LHCD＋NBI （Ip ~ 300 kA, PLHCD ＋ PNBI ~ 2 MW）. The results show that the peak heat fluxes on the lower outer target plate in the LHCD＋NBI H-mode cases are larger than those in the LHCD H-mode under the similar auxiliary heating power. This is because the heat flux profiles of the lower outer target plate as a function of plate location in ELMing with the LHCD＋NBI are narrower than those with the LHCD only. The results are consistent with the results in terms of the scrape-off layer width observed in the EAST.
基金supported by National Natural Science Foundation of China under Contracts Nos.11275047,11705128,11422546,11575235,11575236 and 11505222Key Research Program of Frontier Sciences,CAS,Grant No.QYZDB-SSWSLH001National Magnetic Confinement Fusion Science Program of China under Contract Nos.2015GB101000 and 2013GB107003
文摘Detailed investigations on the filamentary structures associated with the type-I edge-localized modes（ELMs） should be helpful for protecting the materials of a plasma-facing wall on a future large device.Related experiments have been carefully conducted in the Experimental Advanced Superconducting Tokamak（EAST） using combined Langmuir-magnetic probes.The experimental results indicate that the radially outward velocity of type-I ELMy filaments can be up to 1.7 kms^（-1） in the far scrape-off layer（SOL） region.It is remarkable that the electron temperature of these filaments is detected to be ~50eV,corresponding to a fraction of 1/6 to the temperature near the pedestal top,while the density ~3×10^（19）m^（-3） of these filaments could be approximate to the line-averaged density.In addition,associated magnetic fluctuations have been clearly observed at the same time,which show good agreement with the density perturbations.A localized current on the order of ~100kA could be estimated within the filaments.
