剖面不变性、反常电子热导及托卡马克装置约束性能分析

本文根据电子温度剖面不变性这一基本实验现象,通过分布量决定的广义对流能流的引入及其与局部量决定的局部反常电子热导关系的分析,在不涉及等离子体整体能量输运物理机制的情况下,给出了托卡马克装置约束性能更可信的描述方式。     

Thermal dynamics in the flux-coordinate independent turbulence code GRILLIX

GRILLIX employs the flux-coordinate independent approach (FCI), which allows us to study boundary plasma turbulence in realistic diverted configurations. Recently, the physical model in GRILLIX has been extended to a global drift-reduced Braginskii model, without any separation between background and fluctuations. It includes electromagnetic and thermal dynamics with hot ions, relaxation of the Boussinesq approximation and non-linear parametric dependencies. This contribution presents solutions to associated issues, that is, the ion diamagnetic polarization and the stiff parallel heat conduction. Simulations based on parameters characteristic for the Alcator C-Mod tokamak were carried out. In circular geometry, the self-consistent electric field contains zonal flows and geodesic acoustic modes in the confined region. In the scrape-off layer, the electron parallel heat conduction and its boundary condition determine the temperature and electric field, leading to sheared flows at the last closed flux surface.     

HL—1装置热脉冲传播分析

本文通过解析推导和数值计算,得到了适合于反转半径较小时用峰值时间差法计算电子热导率的解析公式,并对HL-1装置的实验数据进行处理,获得了等离子体电子热导率在4≤r≤9cm区域内的平均值为7.4m~2/s。并讨论了计算电子热导率的一种新方法,即强制边界条件法,结果表明,该方法是可行的。     

Disruption mitigation using laser ablation of high-Z impurities in HL-1M tokamak

A preliminary experiment triggering a plasma current quench by laser ablation of high-Z impurities has been performed in the HL-1M tokamak. The injection of impurities with higher electric charges into tokamak plasmas can increase the radiation cooling of the plasma. Resistive, highly radiating plasma formed prior to the thermal quench can dissipate both the thermal and magnetic energies, which is possibly a simple and potential approach to reducing significantly the plasma thermal energy and magnetic energy before a disruption thereby a safe plasma termination is obtained.     

HT-7托卡马克等离子体欧姆放电时电子热扩散系数的研究

主要介绍从能量平衡分析来研究HT-7托卡马克等离子体电子的热扩散系数.研究结果表明,HT-7托卡马克等离子体电子的热传导损失是主要的能量损失,热对流损失不及欧姆输入功率的1%,可以忽略.电子的反常热扩散系数随半径的增大逐渐增大,且比新经典理论预言的大2个量级.同时研究了壁处理硅化后的电子热扩散系数.结果显示,硅化后,在等离子体外围区域(r/a>0.5)电子的热扩散系数降低,从而等离子体能量约束得到改善 关键词： 托卡马克 欧姆放电 电子热扩散系数     

Zero-Dimensional Model to Study the Effectiveness of Plasma Heating and Thermal Energy Confinement in Globus-M Tokamak in Ohmic Heating Modes

Experimental study of thermal energy confinement in magnetic confinement devices is one of the fundamental problems in plasma physics. The data processing technique covering kinetic and magnetic measurements performed for the Globus-M tokamak is described. A zero-dimensional code has been developed on the basis of this approach making it possible to calculate important discharge parameters during the experiment (between discharges): the electron and ion stored thermal energy content, plasma effective charge, and confinement time. Good agreement of the zero-dimensional calculations and ASTRA modeling indicates that this approach can be applied for routine data processing in Globus-M in view of the specifics of the device.     

Application of the Model for Thermal Transport in Tokamaks

The anomalous electron thermal transport model baaed on collisionleas plasma instabilities driven by electron temperature gradient is applied to tokamak plasma with auxiliary heating. The steady state electron equation is solved and the results ahow good agreement with experimental observations including the principle of profile consltency, various scaling laws, and even some results for detached plasmas.     

Elucidation of the heat-flux limit from magnetic-island heating

Recent experiments on heating of magnetic islands in a tokamak are analyzed to assess plasma transport characteristics. By comparing with the experimental data, both perpendicular and parallel components of the electron heat conductivity in the island are determined. As a consequence, the so-called heat-flux limit factor xi, the ratio of the parallel heat conduction flux in a collisionless plasma to that transferred by free-streaming electrons, can be estimated. The found factor xi does not contradict that established earlier by interpreting laser plasma experiments.     

托卡马克等离子体逃逸放电中的驰豫振荡与电子回旋激射不稳定性

我们研究了托卡马克等离子体进制电子引起的电子回旋激射不稳定性发生的条件，发现由反常多普勒效应及切伦科夫效应确定的准稳态速度分布又会激发电子回旋激射不稳定性，且其对本底电子回旋辐射的放大频段低于回旋频率，这与ＨＬ－１实验观察一致。     

HT-7电子加热实验的软X射线能谱诊断

介绍了HT-7装置上软X射线能谱诊断系统,用软X射线能谱对HT-7托卡马克上电子温度进行了测量。在离子伯恩斯坦波和低杂波协同实验中,观察到了对等离子体的较好的加热效果。     

Flare heating by energetic nonthermal electrons

A model has been developed which includes, in a self-consistent fashion, the energy degradation and attendant bremsstrahlung emission of a high energy electron beam, the heating of the plasma by the beam and the subsequent cooling by thermal conduction and radiation. To assist in the interpretation of experimental diagnostics the model also characterizes the radiative behavior of iron ions present in the flare plasma. The electron deposition is described by the Fokker-Planck equation for an initial power law particle distribution. Results are presented for the bremsstrahlung radiation emitted by the incident beam as it impinges on the disturbed atmosphere. A comparison is made between the direct beam heating and thermal conduction heating of the flare plasma. Finally, the radiation emitted by several selected spectral lines from the Fe ions are shown as a function of time during and after the deposition.     

剖面不变性与托卡马克放电中的

从通常的局部输运模型的角度分析,托卡马克等离子体中有相当多的输运现象会被视为“奇怪”的或“反常”的,即难于被正确的理解,也难于给出统一的描述方式。基于温度剖面不变性的－－这里称炎这相容模型的描述方法,在不涉及非局部输运任何具体物理机制的情况下,给出了包含非局部效应的热导系数及其与局部反常热导系数的关系。利用这种相容热导模型统一地描述并分析了一些看似奇怪或反常的输运现象。     

HL-1装置等离子体可见光谱实验

本文给出了HL-1装置等离子体光谱杂质分析,测量了清洗放电时电子温度随环电流的变化关系,根据积分光谱估计了放电时等离子体的离子温度,得到了放电时CV2270.91A线的马鞍形波形。     

利用软X射线锯齿振荡研究托卡马克等离子体的热输运

用Au(Si)面垒探测器阵列测定了CT-6B托卡马克等离子体的软X射线辐射及其涨落。本文给出了内破裂期间等离子体中心区的软X射线锯齿振荡的经验定标律,利用电子温度的锯齿振荡研究了内破裂期间中心区的电子加热率,电子能量平衡,电子能量约束时间,电流密度分布和电子温度等电子热输运结果。 关键词：     

HL—1装置偏压电极类H模能量约束时间研究

能量约束时间是衡量环流器等离子体约束性能的重要参数。分析表明，在加偏压电Ｌ模过渡到类Ｈ模的过程中，如果等离子体的辐射损失功率与总损失功率之比显著变化，则扣除辐射损失的能量约束时间的增量是一种更好的衡量约束得到改善的尺度。在这种考虑之下，我们讨论ＨＬ－１等离子体偏压电极Ｌ模－类Ｈ模过的能量约束及电子热传导特性。     

托卡马克等离子体的热平衡特性与脱栏现象

本文利用欧姆加热条件下简化的能量平衡方程研究了热传导与杂质辐射的综合效应。首先指出边缘辐射带的建立与随半径增大而增大的K=nx模型紧密相关(x为电子热传导系数,n为等离子体密度),然后利用删削层中能量平衡关系确定边界温度,自洽地求解了能量平衡方程,得出的脱栏等离子体形成条件能较好地解释有关实验观察到的多种现象。     

Stability-transport modeling of the SINP tokamak discharges

A one-dimensional stability transport code has been developed to simulate the evolution of tokamak plasma discharges. Explicit finite-difference methods have been used to follow the temporal evolution of the electron temperature equation. The poloidal field diffusion equation has been solved at every time step. The effects of MHD instabilities have been incorporated by solving equations for MHD mixing and tearing modes as and when required. The code has been applied to follow the evolution of tokamak plasma discharges obtained in the Saha Institute of Nuclear Physics (SINP) tokamak. From these simulations, we have been able to identify the possible models of thermal conductivity, diffusion and impurity contents in these discharges. Effects of different MHD modes have been estimated. It has been found that in low q ₀ discharge m=1, n=1 and m=2, n=1 modes play major role in discharge evolution. These modes are found to result in the positive jump in the loop voltage which was also observed in the experiments. Hollow current density profile j _φ and negative shear in the q profile have also been found in the rising phase of a discharge.     

HL-2A 装置中利用可见光谱段轫致辐射测量有效离子电荷数

通过测量可见光谱段的轫致辐射(λ=535.1nm)强度,结合等离子体电子密度和电子温度,HL-2A     

POTENTIAL SAFE TERMINATION BY LASER ABLATION OF HIGH Z IMPURITY IN THE HL-1M TOKAMAK

A preliminary experiment for triggering a plasma current quench by high Z impurities has been performed on the HL-1 M tokamak. Using injection of impurity with the higher charge of the nuclei allows us to increase the radiation cooling. It can be a simple and potential approach for decreasing significantly the plasma thermal energy before a disruption and for safe termination of the plasma.     

Ion Temperature Measurement in the Edge Region of SINP Tokamak by a Retarding Field Analyser

Based on the principle of retarding field analyser an ion energy analyser has been developed for the measurement of ion temperature in the edge plasma region of the SINP tokamak. This has been used to determine the dependence of the ion temperature on the safety factor q in the normal q region (q=2 to 4), plasma current, plasma electron temperature and also the Spitzer resistivity.