中国环流器二号A装置工程与实验进展

介绍了中国环流器二号A(简称HL-2A)装置上关键聚变工程技术取得的新进展及在磁约束聚变科学若干关键课题研究取得的重要实验成果,特别是在HL-2A装置上成功实现了偏滤器位形下具有边缘局域模的高约束模式运行,是我国磁约束聚变实验研究史上具有里程碑意义的重大进展,使我国的磁约束聚变科学和等离子体物理实验研究进入了一个崭新的阶段。     

中国环流器二号A装置工程与实验进展

介绍了中国环流器二号A(简称HL-2A)装置上关键聚变工程技术取得的新进展及在磁约束聚变科学若干关键课题研究取得的重要实验成果,特别是在HL-2A装置上成功实现了偏滤器位形下具有边缘局域模的高约束模式运行,是我国磁约束聚变实验研究史上具有里程碑意义的重大进展,使我国的磁约束聚变科学和等离子体物理实验研究进入了一个崭新的阶段。     

HL-2A托卡马克装置的工程和实验概况

中国环流器二号A装置(HL-2A)是核工业西南物理研究院2002年投入实验运行的托卡马克,它是我国第1个具有偏滤器、等离子体截面具有一定垂直拉长的托卡马克.HL-2A的磁体使用铜导体,具有良好的灵活性和等离子体的可近性,其极向场线圈全部位于环向场线圈之内,位于真空室内的偏滤器的成形线圈可建立双零和单零的偏滤器位形.HL-2A已发展了30多套先进的等离子体诊断系统和总功率4 MW的辅助加热系统,加料技术得到持续发展.随着上述系统的建设和放电综合控制技术的提高,HL-2A装置已获得了高约束模式,这为开展先进托卡马克(AT)物理实验,ITER和聚变堆的科学、技术和工程问题等的研究奠定了基础.HL-2A也成为国际上最活跃的中型托卡马克,为国际托卡马克物理活动(ITPA)作出了积极贡献.     

HL-2A磁面位形的计算机绘图软件包的开发与研制

HL-2A是在原德国ASDEX基础上改进的大型托卡马克装置,该装置带有上下两组偏滤器线圈。从目前的HL-2A的改进方案看,其几何尺寸、磁场位形和物理参数大体和ASDEX相似,只是环向磁场、等离子体电流及拉长比稍有不同。由于未来的HL-2A装置上带有偏滤器,而我们以前的位形计算大多在没有偏滤器位形的HL-1及HL-1M上进行的,所以开展有关HL-2A位形的物理研究及相关的数值计算和程序设计是很重要的工作。     

中国聚变工程实验堆雪花偏滤器脱靶运行的SOLPS模拟

在中国聚变工程实验堆(China Fusion Engineering Test Reactor,CFETR)的工程概念设计中,为探索有效降低偏滤器靶板热负荷的途径,相对于国际热核聚变实验堆(International Thermonuclear Experimental Reactor,ITER)特别增加了两个极向场线圈用于产生近年来新提出的雪花偏滤器位形。脱靶运行状态下,偏滤器靶板上的热负荷显著降低,但同时由于偏滤器温度的降低,杂质约束性能会变差,因此需要对CFETR雪花偏滤器的脱靶运行状态进行研究。基于边界等离子体物理模拟软件SOLPS(Scrape-off Layer Plasma Simulation),通过数值模拟研究了CFETR雪花偏滤器的脱靶运行状态。模拟中通过主等离子体室内的D2充气改变等离子体密度。当充气速度足够高时,CFETR雪花偏滤器实现完全脱靶,靶板上的离子流和热负荷都显著降低。但此时偏滤器区域等离子体温度已经非常低,杂质将容易通过X点进入芯部,有产生辐射不稳定性的风险。因此,对于CFETR雪花偏滤器较为合适的工作状态应当是部分脱靶运行。     

中国环流器二号A(HL-2A)装置物理设计

文章是关于中国环流器二号A(HL-2A)装置物理设计的总结报告,包括以下几方面的内容:分析计算等离子体截面变形及由截面拉长引起的垂直不稳定性,提出对HL-2A极向磁场线圈电流和控制系统的要求;研究通过中性束注入加热(NBI)和低混杂波电流驱动(LHCD)实现等离子体剖面控制,模拟并设计HL-2A的高性能的运行模式;分析HL-2A先进约束位形(RS位形)下的磁流体力学不稳定性,为实现高性能模式稳态运行的等离子体控制指出方向;同时,利用数值模拟分析HL-2A偏滤器等离子体性能,为偏滤器的改进提供依据。     

氖杂质注入条件下CFETR芯部钨杂质浓度的模拟研究

由于低质量数材料不可接受的高腐蚀率以及氚共沉积的问题,未来聚变堆中更希望使用全钨壁。由于钨在芯部的高辐射冷却率,芯部的钨杂质浓度需要限制在非常低的水平(约10~(-5))。中国聚变工程试验堆(China Fusion Engineering Test Reactor,CFETR)要求其高功率稳态运行,全钨壁是优先考虑的方案。为了估计全钨壁CFETR的芯部钨杂质浓度,用边界等离子体物理模拟软件SOLPS(Scrape-off Layer Plasma Simulation)对下单零偏滤器位形不同氖气(Ne)辐射杂质注入速率下模拟得到边界等离子体背景,再利用蒙特卡罗杂质输运程序DIVIMP(DIVertor and IMPurity)对钨杂质的输运进行了模拟。当Ne注入速率较低、靶板温度仍然较高时,即使仅考虑靶板为钨材料,芯部钨杂质浓度依然过高。当外靶板峰值温度降低至约10 eV时,钨靶板对芯部钨杂质浓度的贡献降至可接受的水平;但当包含主等离子体室壁的贡献时,芯部钨杂质浓度仍然达到10~(-4)的水平。因此当Ne杂质注入速率较高时,过高的芯部钨杂质浓度主要来源于主等离子体室壁。未来的工作中需要进一步关注钨壁对芯部钨杂质浓度的影响。     

FEB实验混合堆偏滤器工程结构与热工分析

在FEB偏滤器物理研究的基础上,描述FEB偏滤器的结构设计与热工分析。在工程概要设计(FEB-E)阶段,偏滤器的结构从开式固板靶优化为闭式气室靶,以改善偏滤器的杂质控制和增强原子损失过程。偏滤器运行在喷气和注杂组合下的脱靶等离子体或部分脱靶等离子体模式(Partial Detached Plasma Mode)。应用改进了的NEWT1D编码模拟了喷气和注杂状态下删削层/偏滤器中等离子体及杂质的输运。着眼于杂质居留和杂质辐射,优化了喷气口的位置。偏滤器主体结构由48个气室模件环绕组成。应用COSMOS/M-HSTAR编码对偏滤器靶板进行了热工计算,结果表明以4MPa压力的氦气对靶板进行径向循环冷却是可行的。     

HL-2A中多路分时积分器的研制

中国环流器二号 A 装置(HL-2A)是我国第-个具有偏滤器位形的托卡马克装置,利用其极向偏滤器在高参数等离子体条件下开展与偏滤器位形运行有关的研究.直观的观测核放射过程中核脉冲信号随放射时间的强弱变化规律对于掌握受控核聚变有着重大的意义.我们为HL-2A装置研制的多路分时积分器具有自动削掉输入信号的负向反脉冲,积分时间0.2～1 ms五档可调,统一起始TTL触发脉冲,20 s自动定时工作,同时有十路信号积分的特点.     

用不同限制器材料的FTU实验

在过去几年，为解决偏滤器为功率和粒子处理的问题，已作了很大努力，人们已认识到这是磁聚变堆运行的关键问题，特别是，为了给偏滤器靶板发展抗热和抗腐蚀的材料，已检验了所选择的面向等离子体的部件的材料，现已有了托卡职低Ｚ材料行为的大数据库，而对于高Ｚ材料，还几乎没有现代磁变装置中的经验，弗拉斯卡蒂托卡马克扩大装置是一个强场紧凑托卡马克，它的部分实验已致力于研究其限制器材料从通常的因康镍合金变化到钼和钨时的     

Magnetic configuration flexibility of snowflake divertor for HL-2M

HL-2M (Li, 2013 [1]) is a tokamak device that is under construction. Based on the magnetic coils design of HL-2M, four kinds of divertor configurations are calculated by CORSICA code (Pearlstein et al., 2001 [2]) with the same main plasma parameters, which are standard divertor, exact snowflake divertor, snowflake-plus divertor and snowflake-minus divertor configurations. The potential properties of these divertors are analyzed and presented in this paper: low poloidal field area around X-point, connection length from outside mid-plane to the primary X-point, target plate design and magnetic field shear. The results show that the snowflake configurations not only can reduce the heat load at divertor target plates, but also may improve the magneto-hydrodynamic stability by stronger magnetic shear at the edge. A new divertor configuration, named “tripod divertor”, is designed by adjusting the positions of the two X-points according to plasma parameters and magnetic coils current of HL-2M.     

Numerical Study of High Heat Flux Performances of Flat-Tile Divertor Mock-ups with Hypervapotron Cooling Concept

The hypervapotron (HV), as an enhanced heat transfer technique, will be used for ITER divertor components in the dome region as well as the enhanced heat flux first wall panels. W-Cu brazing technology has been developed at SWIP (Southwestern Institute of Physics), and one W/CuCrZr/316LN component of 450 mm×52 mm×166 mm with HV cooling channels will be fabricated for high heat flux (HHF) tests. Before that a relevant analysis was carried out to optimize the structure of divertor component elements. ANSYS-CFX was used in CFD analysis and ABAQUS was adopted for thermal–mechanical calculations. Commercial code FE-SAFE was adopted to compute the fatigue life of the component. The tile size, thickness of tungsten tiles and the slit width among tungsten tiles were optimized and its HHF performances under International Thermonuclear Experimental Reactor (ITER) loading conditions were simulated. One brand new tokamak HL-2M with advanced divertor con?guration is under construction in SWIP, where ITER-like ?at-tile divertor components are adopted. This optimized design is expected to supply valuable data for HL-2M tokamak.     

Double-null divertor configuration discharge and disruptive heat flux simulation using TSC on EAST

The tokamak simulation code (TSC) is employed to simulate the complete evolution of a disruptive discharge in the experimental advanced superconducting tokamak.The multiplication factor of the anomalous transport coefficient was adjusted to model the major disruptive discharge with double-null divertor configuration based on shot 61 916.The real-time feed-back control system for the plasma displacement was employed.Modeling results of the evolution of the poloidal field coil currents,the plasma current,the major radius,the plasma configuration all show agreement with experimental measurements.Results from the simulation show that during disruption,heat flux about 8 MW m-2 flows to the upper divertor target plate and about 6 MW m-2 flows to the lower divertor target plate.Computations predict that different amounts of heat fluxes on the divertor target plate could result by adjusting the multiplication factor of the anomalous transport coefficient.This shows that TSC has high flexibility and predictability.     

Realization of divertor configuration discharge in J-TEXT tokamak

To extend the operation region of the Joint-Texas Experimental tokamak (J-TEXT) to the divertor configuration and even the H-mode, the divertor configuration discharge has been realized for the first time in the J-TEXT tokamak. Along with the establishment of a power supply for the divertor configuration, the construction of relevant diagnostics, and the installation of the divertor target on the high-field side, divertor discharge has been tested. Through the equilibrium calculation and position stability analysis, the control strategy has evolved to be more stable. High-density experiments and auxiliary heating experiments have been carried out on the divertor configuration. The special midplane single-null (MSN) divertor configuration is shown to be more stable than the limiter configuration in the density limit condition and can reach a higher density in the experiment. In the ECRH experiment, the power injection enhances the electron temperature and density, while more heat outflux is loaded on the divertor target tiles and causes more intensive recycling and impurity release. The future plan for the divertor configuration operation in the J-TEXT tokamak is also included.     

Numerical Simulation and Experimental Identification of Divertor Configuration in the HL-2A Tokamak

Single- and double-null divertor configurations in HL-2A are simulated by SWEQU equilibrium code. Lower divertor discharges in the first physics campaign have been achieved by two kinds of power supply method of multipole-field coils. Single-null divertor configuration has been identified by visible photography, target probe arrays and the reconstructed magnetic surface. Magnetic separatrix and minor radius of plasma column are obtained by a reconstructed code of multiple current filaments using 18 Mirnov signals.     

Structural Modification and Thermal and Structural Analysis of the Divertor in HL-2A

The re-design of the adoptable structure and the cooling manner of the divertor in the HL-2A tokamak is based on the parameters confirmed by the optimum divertor configuration and the primary modification scheme. The characteristics of the new divertor system include the double shear joint design on the domes and the outer target plates as well as the poloidal flow with toroidal manifolds. The results of the thermal and structural analysis of the outer target plates show that the design of the poloidal flow with toroidal manifolds can improve the capability of the target plates to withstand the heat loads, and the double shear joint design is compatible with the stress intensity requirements by the electromagnetic loads due to halo currents.     

Impurity Measurement and Study on HL-2A Divertor Tokamak

HL-2A tokamak with two close divertors has been operated since 2003. In the experimental campaign of 2004 the divertor configuration has been successfully formed and the sillconization as a wall conditioning has been firstly done in this device. The divertor configuration can be reconstructed by the CFc code. Impurity behavior has been investigated during the experiment with divertor configuration and wall conditioning. The reduction of impurity is clear under both conditions of divertor configuration and siliconization.     

Impurity Measured by VUV Spectrometer and OMA on HL-2A Tokamak

Impurity is one of the key issues on a great impact to the quality of tokamak plasma.HL-2A is the first divertor tokamak in China. In this paper the experimental results are presented on impurity through the line emission measurement in the campaign in 2003 under the limiter and divertor configurations. The low-Z impurities such as carbon and oxygen are the most important components in the plasma, but their content are not so high to affect the discharge quality. The high-Z impurities such as copper and ferrum are not essential. The emission intensity of impurity is clearly decreased during the divertor configuration formed.     

HL-2A Tokamak Edge Modeling with B2

The outer divertor plasma of HL-2A and its associated scrape-off plasma have been simulated using a two-dimensional multi-species fluid code of Braams with a simplified neutral gas model. HL-2A has a double-null closed divertor in separate divertor chambers above and below the nearly circular plasma tours. The computed numerical grid is developed according to an ideal magnetic surface. The calculation is involved only with pure hydrogen plasma. The emphasis has been focused on parametric studies involving variation of the assumptions made for the core plasma. The peak temperatures and the heat flux near the target are of the principal concern。