磁约束等离子体中杂质(特别是高Z杂质)的存在将大大增强等离子体辐射功率损失,破坏等离子体的约束性能。杂质行为的定量研究首先要求对杂质测量的光谱诊断系统进行绝对强度标定,获得灵敏度响应曲线。介绍了EAST托卡马克上的快速极紫外...磁约束等离子体中杂质(特别是高Z杂质)的存在将大大增强等离子体辐射功率损失,破坏等离子体的约束性能。杂质行为的定量研究首先要求对杂质测量的光谱诊断系统进行绝对强度标定,获得灵敏度响应曲线。介绍了EAST托卡马克上的快速极紫外光谱仪系统绝对强度的原位标定方法。在波长范围20~150内,通过对比极紫外(EUV)波段连续轫致辐射强度的计算值和测量值得到光谱仪的绝对强度标定。在此过程中,首先由(523±1)nm范围内可见连续轫致辐射强度的绝对测量值计算出有效电荷数Z_(eff),进而结合电子温度和密度分布计算EUV波段连续轫致辐射强度;EUV波段连续轫致辐射强度的测量值即为不同波长处探测器的连续本底计数扣除背景噪声计数值。对于较长波段范围130~280,通过对比等离子体中类锂杂质离子(Fe^(23+),Cr^(21+),Ar^(15+))和类钠杂质离子(Mo^(31+),Fe^(15+))发出的共振谱线对(跃迁分别为1s^22s^(2 )S_(1/2)—1s^22p^(2 )P_(1/2,3/2)及2p^63s ^(2 )S_(1/2)—2p^63p^(2 )P_(1/2,3/2))强度比的理论和实验值进行相对强度标定。其中共振谱线对强度比的理论值由辐射碰撞模型计算得到,模型中处在各个能级的离子数主要由电子碰撞激发,去激发以及辐射衰变三个过程决定。两种方法相结合,实现了光谱仪20~280范围的绝对强度标定。考虑轫致辐射、电子温度及电子密度的测量误差,绝对标定误差约为30%。在绝对标定的基础上,我们对杂质特征谱线强度进行绝对测量,并将测量结果与杂质输运程序结合ADAS(Atomic Data and Analysis Structure)原子数据库计算得到的模拟值进行比较,进而估算等离子体中的杂质浓度。展开更多
The influence of a molybdenum dust buildup on plasma edge turbulence has been studied in the EAST tokamak.The motion of the dust from the upper divertor region is detected by a fast visible CCD camera,the XUV spectrom...The influence of a molybdenum dust buildup on plasma edge turbulence has been studied in the EAST tokamak.The motion of the dust from the upper divertor region is detected by a fast visible CCD camera,the XUV spectrometer arrays,and the EUV spectrometer.The MoXV emission intensity sharply increases compared with the spectral lines of various ionization states of other elements,which implies that the dust particles are the molybdenum impurities.The radial distribution of Mo^(14+)ion simulated by a simplified 1 D transport model indicates that the molybdenum dust mainly deposits in the pedestal bottom region.Moreover,it is observed that the coherent mode(CM)appears atρ=0.94 after the molybdenum impurities enter the main plasma region.The influx of molybdenum impurities results in increasing pedestal electron density and decreasing pedestal electron temperature in contrast to that before the event of impurities dropping.It is also found that the electron density gradient in the pedestal increases when the ablation of the molybdenum impurities is observed in the pedestal region.The qualitative experimental results indicate that the onset of CM is likely related to the increase of the density gradient and edge collisionality in the pedestal.In comparison to the density gradient,the enhancement of CM amplitude largely depends on the increase of the edge collisionality.展开更多
Plasma radiation characteristics in EAST argon（Ar） gas and neon（Ne） gas seeding experiments are studied.The radiation profiles reconstructed from the fast bolometer measurement data by tomography method are compar...Plasma radiation characteristics in EAST argon（Ar） gas and neon（Ne） gas seeding experiments are studied.The radiation profiles reconstructed from the fast bolometer measurement data by tomography method are compared with the ones got from the simulation program based on corona model.And the simulation results coincide roughly with the experimental data.For Ar seeding discharges,the substantial enhanced radiations can be generally observed in the edge areas at normalized radius ρ_（pol）~0.7–0.9,while the enhanced regions are more outer for Ne seeding discharges.The influence of seeded Ar gas on the core radiation is related to the injected position.In discharges with LSN divertor configuration,the Ar ions can permeate into the core region more easily when being injected from the opposite upper divertor ports.In USN divertor configuration,the W impurity sputtered from the upper divertor target plates are observed to be an important contributor to the increase of the core radiation no matter impurity seeding from any ports.The maximum radiated power fractions f_（rad）（P_（rad）/P_（heat）） about 60%–70% have been achieved in the recent EAST experimental campaign in 2015–2016.展开更多
文摘介绍了东方超环(experimental advanced supereonducting tokamak, EAST)托卡马克上的两套快速极紫外(EUV)光谱仪系统波长的原位标定方法、结果及其应用。这两套谱仪均为掠入射平场谱仪,时间分辨均为5 ms·frame -1 。两套谱仪分别工作在20~500和10~130 的波段范围,由步进电机控制探测器在焦平面上移动实现整个观测波段上的波长扫描。利用这两套谱仪系统观测极紫外波段光谱,计算EAST中低-高Z杂质离子特征线辐射强度随时间的演化,监测和研究等离子体中杂质的行为。高Z杂质尤其是钨、钼等金属元素,发出的EUV波段光谱的构成非常复杂,准确识谱对谱仪精确的波长测量能力以及谱分辨能力要求很高,因此精确的波长标定是识别钨、钼等高Z杂质谱线以及研究它们行为的最关键的技术之一。利用EAST等离子体中类氢到类铍的低、中Z杂质的特征谱线以及它们的二阶甚至三阶谱线,结合谱仪系统的色散能力,对这两套快速极紫外光谱仪的波长进行了精确的原位标定。用于波长标定的杂质谱线有O Ⅷ 18.97 , O Ⅶ 21.60 , C Ⅵ 33.73 , Li Ⅲ 113.9 , Li Ⅲ 135.0 , Li Ⅱ 199.28 , Ar ⅩⅤ 221.15 , He Ⅱ 256.317 , He Ⅱ 303.78 , Ar ⅩⅥ 353.853 及C Ⅳ 384.174 等。利用波长标定的结果对观测到的EUV光谱进行谱线识别,两套谱仪观测到的绝大多数谱线波长与美国技术标准局(National Institute of Standards and Technology, NIST)数据库的标准波长相差分别小于0.08和0.03 。开发了谱仪波长原位标定程序模块,将这个模块内嵌到谱仪数据实时上传的交互式软件中,实现了全谱数据以及特征谱线强度随时间演化数据的实时处理和上传。同时利用开发的全谱分析交互式软件以及EAST上的数据查看软件,最终实现了快速EUV谱仪自采数据的准实时分析、读取和查看。
文摘磁约束等离子体中杂质(特别是高Z杂质)的存在将大大增强等离子体辐射功率损失,破坏等离子体的约束性能。杂质行为的定量研究首先要求对杂质测量的光谱诊断系统进行绝对强度标定,获得灵敏度响应曲线。介绍了EAST托卡马克上的快速极紫外光谱仪系统绝对强度的原位标定方法。在波长范围20~150内,通过对比极紫外(EUV)波段连续轫致辐射强度的计算值和测量值得到光谱仪的绝对强度标定。在此过程中,首先由(523±1)nm范围内可见连续轫致辐射强度的绝对测量值计算出有效电荷数Z_(eff),进而结合电子温度和密度分布计算EUV波段连续轫致辐射强度;EUV波段连续轫致辐射强度的测量值即为不同波长处探测器的连续本底计数扣除背景噪声计数值。对于较长波段范围130~280,通过对比等离子体中类锂杂质离子(Fe^(23+),Cr^(21+),Ar^(15+))和类钠杂质离子(Mo^(31+),Fe^(15+))发出的共振谱线对(跃迁分别为1s^22s^(2 )S_(1/2)—1s^22p^(2 )P_(1/2,3/2)及2p^63s ^(2 )S_(1/2)—2p^63p^(2 )P_(1/2,3/2))强度比的理论和实验值进行相对强度标定。其中共振谱线对强度比的理论值由辐射碰撞模型计算得到,模型中处在各个能级的离子数主要由电子碰撞激发,去激发以及辐射衰变三个过程决定。两种方法相结合,实现了光谱仪20~280范围的绝对强度标定。考虑轫致辐射、电子温度及电子密度的测量误差,绝对标定误差约为30%。在绝对标定的基础上,我们对杂质特征谱线强度进行绝对测量,并将测量结果与杂质输运程序结合ADAS(Atomic Data and Analysis Structure)原子数据库计算得到的模拟值进行比较,进而估算等离子体中的杂质浓度。
基金supported by Shenzhen Clean Energy Research Institutesupported by the National Key R&D Program of China (No. 2017YFE0301205)National Natural Science Foundation of China (Nos. 11875289, 11975271, 11605244, 11675211, 12075284, 12075283, 12075155 and 11875294)
文摘The influence of a molybdenum dust buildup on plasma edge turbulence has been studied in the EAST tokamak.The motion of the dust from the upper divertor region is detected by a fast visible CCD camera,the XUV spectrometer arrays,and the EUV spectrometer.The MoXV emission intensity sharply increases compared with the spectral lines of various ionization states of other elements,which implies that the dust particles are the molybdenum impurities.The radial distribution of Mo^(14+)ion simulated by a simplified 1 D transport model indicates that the molybdenum dust mainly deposits in the pedestal bottom region.Moreover,it is observed that the coherent mode(CM)appears atρ=0.94 after the molybdenum impurities enter the main plasma region.The influx of molybdenum impurities results in increasing pedestal electron density and decreasing pedestal electron temperature in contrast to that before the event of impurities dropping.It is also found that the electron density gradient in the pedestal increases when the ablation of the molybdenum impurities is observed in the pedestal region.The qualitative experimental results indicate that the onset of CM is likely related to the increase of the density gradient and edge collisionality in the pedestal.In comparison to the density gradient,the enhancement of CM amplitude largely depends on the increase of the edge collisionality.
基金supported by National Natural Science Foundation of China (Grant Nos.11575247,11605243,11575244)National Magnetic Confinement Fusion Science Program of China (Grant No.2014GB124006)
文摘Plasma radiation characteristics in EAST argon（Ar） gas and neon（Ne） gas seeding experiments are studied.The radiation profiles reconstructed from the fast bolometer measurement data by tomography method are compared with the ones got from the simulation program based on corona model.And the simulation results coincide roughly with the experimental data.For Ar seeding discharges,the substantial enhanced radiations can be generally observed in the edge areas at normalized radius ρ_（pol）~0.7–0.9,while the enhanced regions are more outer for Ne seeding discharges.The influence of seeded Ar gas on the core radiation is related to the injected position.In discharges with LSN divertor configuration,the Ar ions can permeate into the core region more easily when being injected from the opposite upper divertor ports.In USN divertor configuration,the W impurity sputtered from the upper divertor target plates are observed to be an important contributor to the increase of the core radiation no matter impurity seeding from any ports.The maximum radiated power fractions f_（rad）（P_（rad）/P_（heat）） about 60%–70% have been achieved in the recent EAST experimental campaign in 2015–2016.
