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利用EAST装置单道远红外HCN激光干涉仪测量了等离子体中心道(R=1.82m)线平均电子密度。通过充气加料连续提升主等离子体密度,首次在EAST装置上观察到偏滤器等离子体的三种不同状态：低再循环(偏滤器靶板处等离子体温度较高,密度较低),高再循环(偏滤器靶板处等离子体温度较低,密度较高)和脱靶(偏滤器靶板处等离子体温度和密度都很低)等离子体状态。分析了EAST偏滤器在这三种不同状态下的物理现象。     

EAST远红外激光干涉仪与密度爬升实验研究

利用EAST装置单道远红外HCN激光干涉仪测量了等离子体中心道(R=1.82m)线平均电子密度。通过充气加料连续提升主等离子体密度,首次在EAST装置上观察到偏滤器等离子体的三种不同状态：低再循环(偏滤器靶板处等离子体温度较高,密度较低),高再循环(偏滤器靶板处等离子体温度较低,密度较高)和脱靶(偏滤器靶板处等离子体温度和密度都很低)等离子体状态。分析了EAST偏滤器在这三种不同状态下的物理现象。     

HL-2A偏滤器运行模式的探针测量

在HL-2A装置的偏滤器位形运行模式下,用偏滤器靶板上的平面型嵌入式静电探针阵列测量了同一环截面的内外和上下四个中性化板上的电子温度、密度、悬浮电位分布。偏滤器运行模式下的边缘电子温度高于孔栏运行模式下的边缘的电子温度。比较了内外靶板之间的温度不对称性。给出了由18个米尔诺夫线圈信号重建获得的磁分界面,并用强磁场快速电离规测量了偏滤器室的中性气体压强变化。测量结果表明,在偏滤器运行模式下,主真空室中边缘粒子再循环降低,杂质通量水平下降。     

用B2程序模拟HL-2A装置附着状态等离子体

用大型边缘多流体二维等离子体输运数值模拟程序B2模拟了HL-2A装置外偏滤器以及与之相连的刮削层内的等离子体。在不同的中心密度运行区，纯氢放电的HL-2A偏滤器可以形成不同的再循环运行模式，即线性或高再循环模式。通过控制模拟刮削层与芯部等离子体交界面处的等离子体参数，可实现对HL-2A装置再循环模式的控制。     

CFETR不同位置充气下的辐射偏滤器模拟研究

利用边缘等离子体数值模拟程序SOLPS对氩杂质注入下中国聚变工程试验堆装置辐射偏滤器运行模式进行了模拟研究。在达到相同的总辐射功率(P_rad～170MW)时,四种不同充气方案下(从上游充入氘氩混合气体,从外偏滤器充入氘氩混合气体,从内偏滤器充入氘氩混合气体,从上游充入氘气的同时从外偏滤器充入氩气)在外中平面的模拟区域内边界(ρ=0.9)处的有效离子电荷数Z_eff分别为2.8、3.1、3.4、2.7。模拟结果与DⅢ-D及C-MOD的实验结论一致。当从上游充入氘气时,可以增强刮削层中的本底等离子体流,从而得到相对更好的杂质屏蔽效果;同时由于偏滤器靶板再循环杂质源占主导作用,注入氩气的位置对于模拟结果影响不大。     

HL-2A装置偏滤器物理分析及其实验的初步证实

采用偏滤器物理分析的“两点”模型,分别计算了HL-2A装置线性状态和高再循环状态的边缘等离子体参数,包括偏滤器靶板的等离子体温度、密度和入射功率,以及上游等离子体温度、密度和平行功率密度的衰减长度。用该模型对线性状态预计的靶板温度和密度与实验结果进行了比较,结果符合较好。     

偏滤器靶板附近氦输运的蒙特卡洛模拟

本文用Monte Carlo方法模拟了偏滤器扁平抽气收集板附近区域的氦原子输运。考虑了氦原子被电子碰撞电离,氦原子与等离子体离子之间的弹性散射等原子过程以及离子的热运动和沿磁力线的流动。计算表明当偏滤器等离子体密度在7cm距离内从里向靶板逐渐增加约4.7倍,而温度分布保持不变时,氦灰返回靶板的几率比密度在7cm内向靶板递减4.7倍的通常正分布提高约45％。磁力线与靶板的交角、靶板的温度,边缘等离子体鞘层电位以及不同的靶材料对氦返回靶板几率的影响作了比较。得到的结果对托卡马克聚变裂变增殖堆孔栏和偏滤器工程设计有参考价值。     

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介绍了EAST偏滤器充气系统的改进措施,压电阀与冷屏一起安装在EAST颈管中,以缩短充气管道,将充气系统的延迟时间减少约200ms。冷屏起冷却阀门并屏蔽电磁场的作用。讨论了在准稳态条件下,延迟时间给偏滤器热流反馈控制带来的负面效应。在中性束加热条件下,通过在外靶板注入 Ar/D2(1：4)混合气体研究了靶板离子饱和流和热流分布的变化及充气对主等离子体的影响,得到了靶板离子饱和流显著降低、热流减少的结果。     

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利用SOLPS和DINA程序,对偏滤器的数值模拟进行综合研究。结合HL-2M装置,针对偏滤器的结构优化、脱靶物理过程、偏滤器送气与抽气、垂直位移事件(VDE)等问题进行了模拟研究。分析了偏滤器靶板位形以及脱靶对偏滤器靶板热载荷的影响,研究了偏滤器的送气位置、送气速率、抽气速率等因素对于偏滤器性能的影响;同时,利用DINA程序对HL-2M装置的VDE过程进行了预测分析,并给出了HL-2M装置发生VDE过程的等离子体电流剖面变化,从而为HL-2M装置的偏滤器结构设计和分析提供输入数据。     

EAST辐射偏滤器充气系统改造及初步实验结果

介绍了EAST偏滤器充气系统的改进措施,压电阀与冷屏一起安装在EAST颈管中,以缩短充气管道,将充气系统的延迟时间减少约200ms。冷屏起冷却阀门并屏蔽电磁场的作用。讨论了在准稳态条件下,延迟时间给偏滤器热流反馈控制带来的负面效应。在中性束加热条件下,通过在外靶板注入Ar/D2(1:4)混合气体研究了靶板离子饱和流和热流分布的变化及充气对主等离子体的影响,得到了靶板离子饱和流显著降低、热流减少的结果。     

Numerical analysis of high Mach flow and flow reversal in the experimental advanced superconducting tokamak divertor

The B2-Eirene (SOLPS 4.0) code package is used to investigate the plasma parallel flow, i.e., the scrape-off layer (SOL) flow, in the experimental advanced superconducting tokamak (EAST) divertor. Simulation results show that the SOL flow in the divertor region can exhibit complex behaviour, such as a high Mach flow and flow reversal in different plasma regimes. When the divertor plasma is in the detachment state, the high Mach flow with approaching or exceeding sonic speed is observed away from the target plate in our simulation. When the divertor plasma is in the high recycling state, the flow reversal with a small Mach number (|M|< 0.2) is observed near the X-point along the separatrix region. The driving mechanisms for the high Mach flow and the reversed flow are analysed theoretically through momentum and continuity equations, respectively. The profile of the ionization sources is shown to be a possible formation condition causing the complex behaviour of the SOL flow. In addition, the effects of the high Mach flow and the flow reversal on the impurity transport are also discussed in this paper.     

Evolution of the high-field-side radiation belts during the neon seeding plasma discharge in EAST tokamak

Divertor detachment achieved by injecting impurities or increasing density is always accompanied with various local radiation phenomena in the boundary or core plasma. This paper presents the formation and evolution of the high-field-side (HFS) radiation belts during the neon seeding plasma discharge in upper single null configuration with two directions of toroidal magnetic field in EAST tokamak. The neon mixed with deuterium seeding can induce the divertor detachment with strong radiation belts in the HFS scrape-off layer (SOL) region. With the increase of the radiation power, the plasma discharge will transit from H-mode to L-mode, and meanwhile the radiation belts move away from the near X-point to HFS SOL. When the radiation power is high enough, the radiation belts begin to move further to the other X-point along the HFS SOL, and even cause plasma disruption. The results indicate that the behavior of the radiation belts is related to the radiation power, plasma confinement performance and state of divertor detachment, which is useful for developing better feedback control methods to achieve high-performance radiative divertor operation mode.     

Measurement of natural plasma flow along the field lines in the scrape-Off layer on the JT-60U divertor tokamak

The plasma profile and parallel plasma flow in the scrape-off layer (SOL) were systematically measured using reciprocating Mach probes installed at the outer midplane and near the divertor magnetic null (x point) in the JT-60U tokamak with a single null divertor. For the ion vertical drift due to the toroidal magnetic field gradient (ion nablaB drift) directed towards the divertor, SOL plasma flow along the magnetic field lines away from the divertor ("flow reversal") was discovered at the midplane far from the divertor. A quantitative evaluation of the ion "Pfirsch-Schluter flow," wherein the parallel flow is naturally produced in a toroidal plasma, was consistent with the measurement.     

Analyses of edge plasma characteristics in HL-2A

The edge plasma characteristics are studied by both a movable array of Mach/Reynolds stress/Langmuir 10-probes in the boundary region and the fixed flush probe arrays on the 4 divertor neutralization plates at the same toroidal cross-section in the HL-2A tokamak. The dependence of the Reynolds stress on poloidal flow in the edge plasma is analysed. The result indicates that the sheared poloidal flow in tokamak plasma can be induced by the radial gradient of Reynolds stress. In the divertor experiments of HL-2A, the profiles of the electron temperature, density and floating potential on divertor plates are measured by the flush probe arrays. The edge electron temperature in divertor configuration is higher than that in limiter configuration. The temperature asymmetry between outer and inner target plates is observed. The result of magnetic surface reconstructed from 18 Mirnov coils signals is presented. Both the particle recycling and the impurity flux in the bulk plasma during divertor discharges are discussed. Neutral gas pressure in divertor chamber, measured by fast ionization gauge during divertor discharge, is given.     

FEB-E动态气靶偏滤器的研究

在ＦＥＢ－Ｅ设计阶段,偏波器从开放式固定板靶优化为封闭式气体靶,以改善偏滤器的杂质控制和增加离子与气体的相互作用,通过喷气和注入杂质获得的部分脱靶等离子体形成了动态气体靶,喷气能降低删削层（ＳＯＬ）处等离子体温度,沪入的杂质增加了ＳＯＬ处的辐射功率,使靶板的负载降低,用ＮＥＷＴ１Ｄ编码模拟了ＳＯＬ处等离子体和杂质（硼杂质）的输运,得到了杂质、等离本温度和等离了体密度分布。着眼于杂质的滞留物辐射,优     

Time-dependent plasma transport simulation for the study of edge impurity radiation dynamics with magnetic island in large helical device

The dynamics of impurity radiation distribution during detachment transition with edge magnetic island induced by the application of resonant magnetic perturbation (RMP) is studied numerically by solving time-dependent plasma fluid equations together with impurity and neutral transports in a 2D grid system. Computations provide the appearance of a macroscopic structure in the heat transfer along the island separatrix and outside the island. The resultant parallel temperature gradient generates the plasma flow and the density gradient according to the parallel momentum balance. The resulting plasma flow effectively transports impurity towards the X-point region. As a result, the impurity radiation is more intense near the X-point than in the vicinity of the O-point. This leads to the predominant cooling of the region around the X-point. These results are in agreement with experimental observation with RMP application in the large helical device (LHD). The time scale of the thermal condensation instability is found to be of the order of 10 ms.     

New bipartition model of neutral particle transport in the HL-2A divertor region

A new bipartition neutral transport model has been developed for simulation of the hydrogenic neutral particle transport in the vicinity of HL-2A divertor target plate. The numerical calculation results on the basis of this model are fairly consistent with the results obtained with the “multi-generation method”. One possible application of this model is to provide a source term originating from neutral transport calculation for any other edge plasma transport code, for instance, B-2 code, which has been used to simulate edge plasma transport of the HL-2A divertor configuration. Especially it can be utilized to quickly classify the plasma in divertor region as high or low recycling regime.     

HL-2A单零偏滤器的位形特征

利用积分方法对多种电流剖面下HL2A装置单零偏滤器位形特征进行了计算研究。积分方法的优点是可以在任意电流剖面下求解具有X-点的自由边界的Grad-Shafranov方程。对HL2A装置而言,大体上可以在合理设定的分界面形状下,经几次叠代计算出各组极向场线圈(垂直场,三对多极场和多极补偿场以及水平场)中的电流。HL-2A的单零偏滤器位形基本上是圆截面加上在X-点附近的局部形变。对刮离区和偏滤器靶板区磁力线特性进行了分析以确定偏滤器的品质。     

Study of multiple impurity seeding effect using SONIC integrated divertor code for JT-60SA plasma prediction

In order to study the potential impurity seeding operation regime of the future fusion devices, the first application of the integrated divertor code SONIC to the Ar + Ne mixed-impurity seeding operation of JT-60SA steady-state high-β plasma has been carried out. In the case, Ne is added to Ar-only seeding, the separatrix electron density has fell into the desired low separatrix electron density of the scenario. This is mainly because the D⁺ flow velocity towards the inner divertor has been increased by the Ne seeding. The resultant friction force transports Ar impurities towards the inner divertor region, while impurities are stagnated in the top of scrape-off layer (SOL) in the Ar-only seeding case. The higher impurity radiation power in the divertor regions and lower one in the SOL region above the X point have been obtained in mixed-impurity seeding cases, which show similar tendency as the Ar + Ne mixed-impurity seeding experiment in JT-60 U. At the core edge, Z_eff has been slightly increased and the radiation power has been decreased as the Ne seeding rate increases. The core plasma/impurity transport has been also evaluated by the TOPICS code using the impurity density at the core edge computed by the SONIC as a boundary parameter. The results show lower Z_eff and radiation power, and higher electron temperature in the core in the mixed-impurity seeding cases. Above possible contributors to the better energy confinement indicate that the mixed-impurity seeding operation might be more effective than Ar-only seeding operation.