EAST-ICRH系统高功率同轴隔直器的研制

EAST超导托卡马克是我国开展受控核聚变研究的新一代实验装置,离子回旋波加热(ICRH)是在该装置中加热等离子体的重要手段之一。离子回旋加热系统中的发射机和天线两者各有一个地电平,两个地电平会存在严重的相互干扰。高功率同轴隔直器的作用是用来隔断两者之间的直流通路,从而把两端的地电平分开,保证发射机和天线系统的正常运行。论文介绍了隔直器的原理、工程结构和设计指标,分析了S参数、端口驻波比的计算和仿真,最后给出了实际的隔直器参数曲线。     

EAST装置ICRH数据与信息管理系统设计

ICRH数据与信息管理系统的主要功能是采集所有的离子回旋系统实验数据与信息,进行统一的保存和分析,最终建立一个数据与信息的交互平台,实现数据与信息的查看与交互。该系统的设计采用数据层,中间层和用户层的结构;同时,为了提高平台的兼容性,便于功能升级和扩展,采用.net平台下的C#编程语言为基本工具实现系统的功能。目前,已经完成系统的测试,实现了预期的功能,提高了实验数据的利用率。论文对系统的整体设计和具体实现进行了介绍。     

Current Status of ICRF Heating Experiments on EAST

Radio frequency (RF) heating in the ion cyclotron range of frequencies (ICRF) is one of the primary auxiliary heating methods for EAST. The ICRF system provides 6 MW power in primary phase and will be capable of 10 MW later. Three 1.5 MW ICRF systems in a frequency range of 25 to 70 MHz have already been in operation. The ICRF heating launchers are designed to have two current straps with each driven by a RF power source of 1.5 MW. In this paper a brief introduction of the ICRF heating system capability in EAST and the preliminary results in EAST are presented.     

Design and test of voltage and current probes for EAST ICRF antenna impedance measurement

On the experimental advanced superconducting tokamak(EAST), a pair of voltage and current probes(V/I probes) is installed on the ion cyclotron radio frequency transmission lines to measure the antenna input impedance, and supplement the conventional measurement technique based on voltage probe arrays. The coupling coefficients of V/I probes are sensitive to their sizes and installing locations, thus they should be determined properly to match the measurement range of data acquisition card. The V/I probes are tested in a testing platform at low power with various artificial loads. The testing results show that the deviation of coupling resistance is small for loads RL??2.5 Ω, while the resistance deviations appear large for loads RL??1.5 Ω, which implies that the power loss cannot be neglected at high VSWR. As the factors that give rise to the deviation of coupling resistance calculation, the phase measurement error is the more significant factor leads to deleterious results rather than the amplitude measurement error. To exclude the possible ingredients that may lead to phase measurement error, the phase detector can be calibrated in steady L-mode scenario and then use the calibrated data for calculation under H-mode cases in EAST experiments.     

Design of High Power DC Break For ICRH Of EAST

1.5MW Ion Cyclotron Wave Heating system was developed, the transmitter and the antenna both have their ground loops, which will severely perturb the system‘s normal operation. To avoid perturbation, a DC break was designed. The S parameter and the VSWR (voltage standing wave ratio) of incident port were calculated; the thermal effect caused by conductor loss and dielectric loss was analyzed.     

Theoretical Analysis of Triple Liquid Stub Tuner Impedance Matching for ICRH on Tokamaks

The impedance matching is crucial for continuous wave operation of ion cyclotron resonance heating(ICRH) antennae with high power injection into plasmas.A sudden increase in the reflected radio frequency power due to an impedance mismatch of the ICRH system is an issue which must be solved for present-day and future fusion reactors.This paper presents a method for theoretical analysis of ICRH system impedance matching for a triple liquid stub tuner under plasma operational conditions.The relationship of the antenna input impedance with the plasma parameters and operating frequency is first obtained using a global solution.Then,the relations of the plasma parameters and operating frequency with the matching liquid heights are indirectly obtained through numerical simulation according to transmission line theory and matching conditions.The method provides an alternative theoretical method,rather than measurements,to study triple liquid stub tuner impedance matching for ICRH,which may be beneficial for the design of ICRH systems on tokamaks.     

Design and control of coaxial switching system for ion cyclotron wave resonance heating system of EAST

Ion cyclotron wave resonance heating system(ICRH) which is one of the most important auxiliary system in EAST provides conditions for heating the plasma. In order to make the whole transmission network of ICRH form the required state, the coaxial switching system was developed, which mainly consists of 11 same coaxial switches. Each coaxial switch has a controller with an RS485 communication interface and is able to switch between two states. All controllers are integrated to an RS485 hub which connects to the computer. A master computer software is developed to control the coaxial switching system so as to achieve the state needs of ICRH. Moreover, several rounds of experiments show that the coaxial switching system operates reliably. The coaxial switching system has already been applied to normal use currently.     

EAST电子回旋波与低杂波双波协同的数值模拟

为在EAST装置中优化电子回旋波与低杂波双波协同的电流驱动效率,从而获得更大的协同驱动电流以维持长脉冲运行,本文以双波协同驱动电流的物理机制为基础,运用模拟程序C3PO/LUKE对EAST参数下电子回旋电流驱动与低杂波电流驱动的协同效果进行了数值模拟计算,给出了协同电流和协同因子。计算结果表明：当两波驱动电流密度峰值的位置一致时协同效果最佳;而电子密度和电子温度的增加可能导致两波重叠区域的变化进而影响协同效果。     

Development of Data Acquisition Card Driver for ICRH System on EAST

Presented in this paper is the development of the driver for the data acquisition card with a peripheral component interconnection （PCI） local bus on the ion cyclotron range of frequency heating （1CRH） system. The driver is mainly aimed at the embedded VxWorks system （real-time operating system） which is widely used in various fields of real-time systems. An efficient way is employed to develop this driver, which will advance the real-time control of the ICRH system on the experimental advanced superconductor tokamak （EAST）. The driver is designed using the TORNADO integrated development environment （IDE）, and implemented in C plus language. The details include the hardware configuration, analogue/digital （A/D） and digital/analogue （D/A） conversion, input and output （I/O） operation of the driver to support over five cards. The data acquisition card can be manipulated in a low-level program and meet the requirements of A/D conversion and D/A outputs.     

Modelling of First Discharge in EAST Tokamak

An 1.5D equilibrium evolution code was used to model the time evolution of the first ohmic discharges in the EAST experiment. Good agreement between the simulation and the experimental results was obtained in the plasma current, major radius, electron temperature, loop voltage and poloidal field （PF） current for the entire duration of the discharge, which indicates that the code is highly reliable and will allow to further study the EAST discharge. At the same time, the code also simulates some important plasma parameters without experimental measured data yet, such as the plasma minor radius, central and edge safety factors, elongation and triangilarity, which are important in the analysis of EAST data.     

Thermal analysis on the EAST tungsten plasma facing components with shaping structure counteracting the misalignment issues

Tungsten monoblock type tiles with ITER dimensions along with supporting cassette components were installed at EAST's upper diverter during 2014 and EAST's lower diverter will also be upgraded in the future.These cassette structures pose critical issues on the high cumulative incident heat flux due to the leading edges and misalignments(0 ~ 1.5 mm),which may result in the destruction or even melting of the tungsten tile.The present work summarizes the thermal analysis using ANSYS multiphysics software 15.0 performed on the actively cooled W tiles to evaluate the shaping effect on surface temperature.In the current heat flux conditions(Q_Ⅱ ~ 100 MW m~(-2)),the adopted chamfer shaping(1×1 mm) can only reduce the maximum temperature by about 14%,but it also has a melting risk at the maximum misalignment of1.5 mm.The candidate shaping solutions elliptical(round) edge,dome and fish-scale are analyzed for comparison and are identified not as good as the dual chamfer structure.A relatively good dual chamfer(2×13 mm) shaping forming a symmetrical sloping roof structure can effectively counteract the 1.5 mm misalignment,reducing the maximum temperature by up to50%.However,in the future heat flux conditions(Q_Ⅱ ~ 287 MW m~(-2)),it may only endure about0.5 mm misalignment.Moreover,no proper shaping solution has been found that can avoid melting at the maximum misalignment of 1.5 mm.Thus,the engineering misalignment has to be limited to an acceptable level.     

EAST低温系统的故障树分析

EAST是世界上进行聚变研究的先进超导托卡马克实验装置.低温冷却系统是EAST的主要子系统之一,担负着纵向和极向场线圈、纵场线圈盒、冷屏和电流引线的冷却功能,需保证其能长期稳定运行.本文运用故障树分析法来评价低温系统的可靠性,使用自主开发的软件RiskA建立低温系统的故障树模型并进行定量计算,得到系统的失效概率和部件的重要度,并提出改进建议,为系统的优化设计和提高可靠性提供参考.     

EASTICRF天线真空馈口电特性评估

本文对EASTICRF天线真空馈口进行了相关的电特性分析,获得了真空馈口电场分布、电势分布,以及电压驻波比随加热频率的变化情况,分析结果验证了真空馈口的可行性和合理性,并为真空馈口电特性评估提供理论依据。另外,在相同条件下,运用相同的方法对一种新型结构的真空馈口进行了相同的电特性分析,分析结果验证了新型结构真空馈口的优越性。     

DIVIMP Modeling of Impurity Transport in EAST

Simulations of carbon impurity transport in SOL/divertor plasmas with Ohmic heating on EAST tokamak were performed using the two-dimensional（2D）Monte Carlo impurity transport code DIVIMP.The background plasmas for DIVIMP simulations were externally taken from B2.5/Eirene calculation.Besides the basic output of DIVIMP,the 2D density distributions of the carbon impurity with different ionization states and neutral carbon atoms were obtained,the2D distributions of CII and CIII emissivities from C＋1and C＋2radiation respectively were also calculated.Comparison between the measured and calculated CIII emissivities showed favorable agreement,indicating that the impurity physics transport models,as implemented in the DIVIMP code,are suitable for the EAST tokamak plasma condition.     

EAST ICRF天线驱动结构改进设计

针对ICRF天线原有的驱动结构由于无自锁而导致天线移动过程中无法精确定位的缺点,给出了两种新的驱动结构设计方案,两种方案主要由步进电机和涡轮蜗杆减速器组成,均具有启动速度慢,推、拉力大,能精确定位的特点。在设计过程中,对两种驱动结构的启动转矩、丝杠的强度和稳定性进行了校核,通过理论计算分析,两种驱动结构设计均满足设计要求。整个驱动结构改进设计方案和方法可为其他同类装置提供有益的借鉴。     

SN方法自动建模程序SNAM在EAST纵场线圈核热计算中的应用

在核领域的中子学计算中,离散纵标(SN)方法三维粒子输运计算程序得到了广泛应用.SNAM作为离散纵标法粒子输运自动建模程序系统,其主要功能是CAD模型与SN计算模型之间的相互转换.一方面,SNAM可以将通用格式的CAD模型转换成SN计算模型,另一方面可以以CAD模型的方式显示SN计算模型中几何及材料等相关信息.本文主要介绍使用SNAM程序对EAST三维模型进行中子学建模,并计算分析了EAST装置纵场线圈的中子注量率与核热沉积.     

Design of a multi-voltage probe system forICRF antenna coupling resistancemeasurement on EAST

A multi-voltage probe array system is designed to measure the coupling resistance of an ioncyclotron resonance frequency antenna. In the process of the antenna coupling resistance dataextraction, the minimization algorithm, the original Levenberg–Marquardt algorithm, is replacedby the Broyden–Fletcher–Goldfarb–Shanno algorithm to achieve more stable and accurateresults. Moreover, a simple model of the multi-voltage probe array was applied to simulate theperformance of the Kalman filter, and to optimize the distance and position of the probes andprobe number to mitigate the influence of the system noise on the rebuilt results. During theEAST experiment in 2019, a four-voltage probe array was applied to measure the couplingresistance of line 6 during high confined mode discharge. The measurement results by the multi-voltage probe array system and the voltage/current probe pair show a good agreement.     

RF calculation and thermal-stress analysis of the ECRH launcher on EAST tokamak

EAST is a medium sized superconducting tokamak with major radius R = 1.8 m, minor radius a = 0.45 m, plasma current I_p ≤ 1 MA, toroidal field B_T ≤ 3.5 T and expected plasma pulse length up to 1000 s. An electron cyclotron resonance heating (ECRH) launcher for four-beam injection is being installed on EAST tokamak. Four electron cyclotron wave beams which are generated from four sets of 140 GHz/1 MW/1000 s gyrotrons will be injected into the plasma by the spherical focusing mirrors and plane mobile mirrors. The focusing mirrors are spherical to focus Gaussian beams after reflection. Four plane mobile mirrors independently steer continuously in the poloidal and toroidal direction controlled by motors. With the suitable distance between mirrors and appropriate focal length of focusing mirror, the beam radius in the resonance layer of plasma is 31.145 mm. The heat from plasma radiation and metal losses is loaded on the mobile mirror. In order to decrease the temperature and thermal stress, the inner equivalent diameter of water channels is 8 mm and the suggested water velocity is 4 m/s.     

Thermo-mechanical analysis of RMP coil system for EAST tokamak

Resonant magnetic perturbation (RMP) has been proved to be an efficient approach on edge localized modes (ELMs) control, resistive wall mode (RWM) control, and error field correction (EFC), RMP coil system under design in EAST tokamak will realize the above-mentioned multi-functions. This paper focuses on the thermo-mechanical analysis of EAST RMP coil system on the basis of sensitivity analysis, both normal and off-normal working conditions are considered. The most characteristic set of coil system is chosen with a complete modelling by means of three-dimensional (3D) finite element method, thermo-hydraulic and thermal-structural performances are investigated adequately, both locally and globally. The compromise is made between thermal performance and structural design requirements, and the results indicate that the optimized design is feasible and reasonable.     

EAST装置通用数据分析软件的设计与实现

介绍了EAST 装置聚变实验数据分析与可视化集成软件EastScope的设计与实现.该软件采用ActiveX技术实现了多种格式数据访问方式的统一,调用了MATLAB引擎进行信号表达式运算,使用OpenGL技术完成了阵列信号的三维显示等.只需操作鼠标就可以完成信号的处理、分析、对比以及二维、三维显示,并能用交互式方式实现二维图形的任意轴缩放,三维图形的旋转、平移与缩放.