Intermittent convective transport at the edge and in the scrape-off layer （SOL） of EAST was investigated by using fast reciprocating Langmuir probe. Holes, as part of plasma structures, were detected for the first t...Intermittent convective transport at the edge and in the scrape-off layer （SOL） of EAST was investigated by using fast reciprocating Langmuir probe. Holes, as part of plasma structures, were detected for the first time inside the shear layer. The amplitude probability distribution function of the turbulence is strongly skewed, with positive skewed events （＂blobs＂） prevailing in the SOL region and negative skewed events （＂holes＂） dominant inside the shear layer. The statistical properties coincide with previous observations from JET. The generation mechanism of blobs and holes is also discussed. In addition burst structure and dynamics character of them are also presented.展开更多
2D fast-ion velocity-space distributions have been reconstructed from two-view fast-ion D-alpha(FIDA)measurements on experimental advanced superconducting tokamak(EAST).To make up for the sparse data and incomplete ve...2D fast-ion velocity-space distributions have been reconstructed from two-view fast-ion D-alpha(FIDA)measurements on experimental advanced superconducting tokamak(EAST).To make up for the sparse data and incomplete velocity-space coverage with the dual-view,we use nonnegativity and null-measurements as prior information to reconstruct the velocity distribution in experiments with co-and counter-current neutral beam injection.An improved reconstructed fast-ion distribution is achieved by combining the existing O-and B-port FIDA measurements with the proposed A-port FIDA view.To further improve the reliability of FIDA-based reconstructions on EAST,based on real multi-view FIDA measurements on EAST in the near future,various bases will be studied further.展开更多
Discharge with a plasma current of 1 MA at a line-averaged density of 1.8× 10^19 m^-3 was realized in EAST, a fully superconducting tokamak. The key issues to achieve the discharge with 1 MA plasma current includ...Discharge with a plasma current of 1 MA at a line-averaged density of 1.8× 10^19 m^-3 was realized in EAST, a fully superconducting tokamak. The key issues to achieve the discharge with 1 MA plasma current include both early shaping and LHCD assistance during start-up phase to extend the voltage margin of poloidal field （PF） coils for easier plasma control, an optimization of the control methodology for PF coils to avoid over-current fault and a very good wall condition. A better wall condition was achieved mainly by extensive Lithium coating. Both stationary H- mode and diverted plasma discharge of 100 s were also obtained.展开更多
基于闪烁体原理的快离子损失探针(Fast Ion Loss Detector,FILD),可以同时测量损失快离子的能量和pitch-angle的值,是核聚变装置中对高能粒子诊断的重要方式。根据先进实验超导托卡马克(Experimental Advanced Superconducting Tokamak,...基于闪烁体原理的快离子损失探针(Fast Ion Loss Detector,FILD),可以同时测量损失快离子的能量和pitch-angle的值,是核聚变装置中对高能粒子诊断的重要方式。根据先进实验超导托卡马克(Experimental Advanced Superconducting Tokamak,EAST)的发展需求,为了更好地对损失快离子行为进行研究,设计并安装了快离子损失诊断,且探测到在中性束加热条件下产生的损失快离子。同时,探测到在放电中产生的逃逸电子,以及低杂波注入时快电子产生X射线对快离子损失背景信号的影响。并且在H-mode放电时边界扰动也对快离子损失信号产生影响,这些探测到的现象都为不断升级损失诊断系统提供依据。展开更多
Intermittent characteristics of turbulence induced by coherent structures （blobs） was clearly observed in the ion saturation current signal, density fluctuation, particle flux and heat flux in HT-7. It is obvious th...Intermittent characteristics of turbulence induced by coherent structures （blobs） was clearly observed in the ion saturation current signal, density fluctuation, particle flux and heat flux in HT-7. It is obvious that ion saturation current signal has deviated from Gaussian distribution and the skewness （S） and flatness （K） of signal increase radially outwards in the scrape-off layer （SOL）. Using conditional analysis （CA）, asymmetric character of the intermittent bursts are demonstrated. Owing to the radial propagation of the coherent structures, the particle density profile in SOL is non-exponential and flat outwards from the last close flux surface （LCFS）. It is found around LCFS that the large burst fluctuations （above 2.5 rms） are responsible for about 50% of the total particle transport. Burst events move radially outwards with Ee ~ B velocity, and the blob size can be calculated as 5r ~ V^rc. Our experiment shows that the blob size, life time and drift velocity experienced a pronounced decorrelation in the shear layer. The electrostatic Reynolds stress components become very strong and show a radially steep gradient in the proximity of the shear layer. These experimental findings may imply that the coherent structures are titled by the developed shear flow in the E × B shear layer.展开更多
In this work, population coefficients of hydrogen＇s n = 3 excited state from the hydrogen collisional-radiative （CR） model, from the data file of DEGAS 2, are used to calculate the photon emissivity coefficients （...In this work, population coefficients of hydrogen＇s n = 3 excited state from the hydrogen collisional-radiative （CR） model, from the data file of DEGAS 2, are used to calculate the photon emissivity coefficients （PECs） of hydrogen Balmer-α （n = 3 →n = 2） （Hα）. The results are compared with the PECs from Atomic Data and Analysis Structure （ADAS） database, and a good agreement is found. A magnetic surface-averaged neutral density profile of typical double-null （DN） plasma in EAST is obtained by using FRANTIC, the 1.5-D fluid transport code. It is found that the sum of integral Dα and Hα emission intensity calculated via the neutral density agrees with the measured results obtained by using the absolutely calibrated multi-channel poloidal photodiode array systems viewing the lower divertor at the last closed flux surface （LCFS）. It is revealed that the typical magnetic surface-averaged neutral density at LCFS is about 3.5×10^16 m^-3 .展开更多
Ion＇s toroidal velocity, vt, in both the outermost 4 cm of the confined region and the scrap-off layer of Ohmic L-mode plasmas in EAST was measured using Mach probes. At about 1 cm inside the separatrix a local minim...Ion＇s toroidal velocity, vt, in both the outermost 4 cm of the confined region and the scrap-off layer of Ohmic L-mode plasmas in EAST was measured using Mach probes. At about 1 cm inside the separatrix a local minimum in vt was observed, from which a cocurrent rotation increased both inwards and outwards. The radial width of the vt dip was 1 cm to 2 cm, and both the density and electron temperature profiles exhibited steep gradients at this dip position. It was observed in both divertor and limiter configurations. To find out its origin, the toroidal torques induced by neutral friction, neoclassical viscosity, collisional perpendicular shear viscosity, ion orbit loss and turbulent Reynolds stress were estimated using the measured parameters. Our results indicate that in this particular parameter regime the neutral friction was the dominant damping force. The calculated cocurrent toroidal torque by the neoclassical viscosity dominates over those from the collisional perpendicular shear viscosity, ion orbit loss and turbulent Reynolds stress. These results are potentially important for the understanding of boundary conditions for the intrinsic toroidal momentum in tokamak plasmas.展开更多
Divertor plasma properties for lower single-null （LSN） configuration in EAST, under a water-cooling graphite wall condition, are presented. A typical shot is selected for analyzing electron temperature, density and ...Divertor plasma properties for lower single-null （LSN） configuration in EAST, under a water-cooling graphite wall condition, are presented. A typical shot is selected for analyzing electron temperature, density and power flux at targets. Both higher electron density and lower electron temperature are found at the inboard target, compared to those at the outboard target. A higher power flux is also found to be at the outboard target because of in-out asymmetries for LSN-shaped discharge.展开更多
Edge profiles in Ohmic and lower hybrid （LH） wave heated discharges in EAST are presented. A comparison of the measured profiles is made with those from the theoretical prediction for the scrape-off-layer （SOL） wi...Edge profiles in Ohmic and lower hybrid （LH） wave heated discharges in EAST are presented. A comparison of the measured profiles is made with those from the theoretical prediction for the scrape-off-layer （SOL） width. The edge plasma parameters are diagnosed by a triple probe divertor diagnostic system and fast reciprocating probes at the outer mid-plane. The experimental results show that the SOL width of double-null （DN） divertor plasmas in EAST appears to exhibit a negative dependence on the power crossing the separatrix, which is consistent with the collisional SOL scalings of JET and Alcator C-Mod. This will provide useful information for extrapolation to the ITER SOL width scaling for power deposition.展开更多
Properties of the geodesic acoustic mode （GAM） density fluctuations are studied using two toroidally separated Langnmir triple-probe arrays on the top of HT-7 tokamak. The GAM scenario is identified in the potential...Properties of the geodesic acoustic mode （GAM） density fluctuations are studied using two toroidally separated Langnmir triple-probe arrays on the top of HT-7 tokamak. The GAM scenario is identified in the potential fluctuations with the toroidally symmetric structure （n =0） and satisfying the temperature scaling of GAM mode frequency. Some theoretical predictions about the mode features of GAM density fluctuations are verified in our experiments： the toroidal mode number of GAM density fluctuations is n = 0; its amplitude is consistent with the theoretical prediction in a factor of 2; the density and potential fluctuations of GAM is in anti-phase at the top of plasma cross-section. Strong nonlinear interactions are found between GAM density fluctuations and ambient turbulence （AT）. The results support the conclusions that the envelope modulation of potential fluctuations is dominantly caused by the direct regulation of GAM in the generation processing, and the envelope modulation of density fluctuation is due to the GAM shear effect.展开更多
基金supported by National Natural Science Foundation of China(Nos.11075181,10725523,10721505,10990212,10605028)the 973 Programme(No.2010GB104001)
文摘Intermittent convective transport at the edge and in the scrape-off layer （SOL） of EAST was investigated by using fast reciprocating Langmuir probe. Holes, as part of plasma structures, were detected for the first time inside the shear layer. The amplitude probability distribution function of the turbulence is strongly skewed, with positive skewed events （＂blobs＂） prevailing in the SOL region and negative skewed events （＂holes＂） dominant inside the shear layer. The statistical properties coincide with previous observations from JET. The generation mechanism of blobs and holes is also discussed. In addition burst structure and dynamics character of them are also presented.
基金supported by National Natural Science Foundation of China(No.11975276)Anhui Provincial Natural Science Foundation(No.2008085J04)+3 种基金Anhui Provincial Key R&D Programmes(No.202104b11020003)the National Key Research and Development Program of China(No.2019YFE03020004)the Excellence Program of Hefei Science Center CAS(No.2021HSC-UE015)。
文摘2D fast-ion velocity-space distributions have been reconstructed from two-view fast-ion D-alpha(FIDA)measurements on experimental advanced superconducting tokamak(EAST).To make up for the sparse data and incomplete velocity-space coverage with the dual-view,we use nonnegativity and null-measurements as prior information to reconstruct the velocity distribution in experiments with co-and counter-current neutral beam injection.An improved reconstructed fast-ion distribution is achieved by combining the existing O-and B-port FIDA measurements with the proposed A-port FIDA view.To further improve the reliability of FIDA-based reconstructions on EAST,based on real multi-view FIDA measurements on EAST in the near future,various bases will be studied further.
基金supported by National Natural Science Foundation of China (Nos. 10725523, 10990212 and 10721505)
文摘Discharge with a plasma current of 1 MA at a line-averaged density of 1.8× 10^19 m^-3 was realized in EAST, a fully superconducting tokamak. The key issues to achieve the discharge with 1 MA plasma current include both early shaping and LHCD assistance during start-up phase to extend the voltage margin of poloidal field （PF） coils for easier plasma control, an optimization of the control methodology for PF coils to avoid over-current fault and a very good wall condition. A better wall condition was achieved mainly by extensive Lithium coating. Both stationary H- mode and diverted plasma discharge of 100 s were also obtained.
文摘基于闪烁体原理的快离子损失探针(Fast Ion Loss Detector,FILD),可以同时测量损失快离子的能量和pitch-angle的值,是核聚变装置中对高能粒子诊断的重要方式。根据先进实验超导托卡马克(Experimental Advanced Superconducting Tokamak,EAST)的发展需求,为了更好地对损失快离子行为进行研究,设计并安装了快离子损失诊断,且探测到在中性束加热条件下产生的损失快离子。同时,探测到在放电中产生的逃逸电子,以及低杂波注入时快电子产生X射线对快离子损失背景信号的影响。并且在H-mode放电时边界扰动也对快离子损失信号产生影响,这些探测到的现象都为不断升级损失诊断系统提供依据。
基金supported by National Natural Science Foundation of China (Nos.10605028, 10675127, 10675126 and 10675124)
文摘Intermittent characteristics of turbulence induced by coherent structures （blobs） was clearly observed in the ion saturation current signal, density fluctuation, particle flux and heat flux in HT-7. It is obvious that ion saturation current signal has deviated from Gaussian distribution and the skewness （S） and flatness （K） of signal increase radially outwards in the scrape-off layer （SOL）. Using conditional analysis （CA）, asymmetric character of the intermittent bursts are demonstrated. Owing to the radial propagation of the coherent structures, the particle density profile in SOL is non-exponential and flat outwards from the last close flux surface （LCFS）. It is found around LCFS that the large burst fluctuations （above 2.5 rms） are responsible for about 50% of the total particle transport. Burst events move radially outwards with Ee ~ B velocity, and the blob size can be calculated as 5r ~ V^rc. Our experiment shows that the blob size, life time and drift velocity experienced a pronounced decorrelation in the shear layer. The electrostatic Reynolds stress components become very strong and show a radially steep gradient in the proximity of the shear layer. These experimental findings may imply that the coherent structures are titled by the developed shear flow in the E × B shear layer.
基金supported by National Natural Science Foundation of China(Nos.11075181,10605028 and 11075180)in part by the JSPS-CAS Core-University program in the field of 'Plasma and Nuclear Fusion'
文摘In this work, population coefficients of hydrogen＇s n = 3 excited state from the hydrogen collisional-radiative （CR） model, from the data file of DEGAS 2, are used to calculate the photon emissivity coefficients （PECs） of hydrogen Balmer-α （n = 3 →n = 2） （Hα）. The results are compared with the PECs from Atomic Data and Analysis Structure （ADAS） database, and a good agreement is found. A magnetic surface-averaged neutral density profile of typical double-null （DN） plasma in EAST is obtained by using FRANTIC, the 1.5-D fluid transport code. It is found that the sum of integral Dα and Hα emission intensity calculated via the neutral density agrees with the measured results obtained by using the absolutely calibrated multi-channel poloidal photodiode array systems viewing the lower divertor at the last closed flux surface （LCFS）. It is revealed that the typical magnetic surface-averaged neutral density at LCFS is about 3.5×10^16 m^-3 .
基金supported by National Natural Science Foundation of China(Nos.11075181,10725523,10721505,10990212 and 10605028)the ITER project of China(No.2010GB104001)
文摘Ion＇s toroidal velocity, vt, in both the outermost 4 cm of the confined region and the scrap-off layer of Ohmic L-mode plasmas in EAST was measured using Mach probes. At about 1 cm inside the separatrix a local minimum in vt was observed, from which a cocurrent rotation increased both inwards and outwards. The radial width of the vt dip was 1 cm to 2 cm, and both the density and electron temperature profiles exhibited steep gradients at this dip position. It was observed in both divertor and limiter configurations. To find out its origin, the toroidal torques induced by neutral friction, neoclassical viscosity, collisional perpendicular shear viscosity, ion orbit loss and turbulent Reynolds stress were estimated using the measured parameters. Our results indicate that in this particular parameter regime the neutral friction was the dominant damping force. The calculated cocurrent toroidal torque by the neoclassical viscosity dominates over those from the collisional perpendicular shear viscosity, ion orbit loss and turbulent Reynolds stress. These results are potentially important for the understanding of boundary conditions for the intrinsic toroidal momentum in tokamak plasmas.
基金National Natural Science Foundation of China (No.10605028)the JSPS-CAS Core-University Program in the field of Plasma and Nuclear Fusion
文摘Divertor plasma properties for lower single-null （LSN） configuration in EAST, under a water-cooling graphite wall condition, are presented. A typical shot is selected for analyzing electron temperature, density and power flux at targets. Both higher electron density and lower electron temperature are found at the inboard target, compared to those at the outboard target. A higher power flux is also found to be at the outboard target because of in-out asymmetries for LSN-shaped discharge.
基金supported by National Natural Science Foundation of China(No.11075181)the ITER Project of China(No.2010GB104001)
文摘Edge profiles in Ohmic and lower hybrid （LH） wave heated discharges in EAST are presented. A comparison of the measured profiles is made with those from the theoretical prediction for the scrape-off-layer （SOL） width. The edge plasma parameters are diagnosed by a triple probe divertor diagnostic system and fast reciprocating probes at the outer mid-plane. The experimental results show that the SOL width of double-null （DN） divertor plasmas in EAST appears to exhibit a negative dependence on the power crossing the separatrix, which is consistent with the collisional SOL scalings of JET and Alcator C-Mod. This will provide useful information for extrapolation to the ITER SOL width scaling for power deposition.
基金supported by National Natural Science Foundation of China (Nos. 10725523, 10875124, 10905057 and 10990212)National Basic Research Program of China (No.2008CB717800)+2 种基金Research Fund for the Doctoral Program of Higher Education of China (No.20060358059)China Postdoctoral Science Foundation (No.20080440104)Knowledge Innovation Program of the Chinese Academy of Sciences (No.kjcx-yw-n28)
文摘Properties of the geodesic acoustic mode （GAM） density fluctuations are studied using two toroidally separated Langnmir triple-probe arrays on the top of HT-7 tokamak. The GAM scenario is identified in the potential fluctuations with the toroidally symmetric structure （n =0） and satisfying the temperature scaling of GAM mode frequency. Some theoretical predictions about the mode features of GAM density fluctuations are verified in our experiments： the toroidal mode number of GAM density fluctuations is n = 0; its amplitude is consistent with the theoretical prediction in a factor of 2; the density and potential fluctuations of GAM is in anti-phase at the top of plasma cross-section. Strong nonlinear interactions are found between GAM density fluctuations and ambient turbulence （AT）. The results support the conclusions that the envelope modulation of potential fluctuations is dominantly caused by the direct regulation of GAM in the generation processing, and the envelope modulation of density fluctuation is due to the GAM shear effect.
