HT-7装置上充气对低杂波耦合影响的实验及分析

在低杂波（LHW）天线端口充D₂和CD₄,发现LHW的耦合效果能得到明显改善,充气后LHW的反射系数基本降为6%左右。不同窗口充气对波的耦合和等离子体密度的影响不同,其原因是改善耦合的关键是提高刮削层（SOL）内等离子体的密度。D₂与CH₄对LHW耦合影响的实验结果表明：D₂对LHW的耦合效果影响略好于CH₄,但D₂对等离子体密度的影响明显高于CH₄,原因是D₂对电子密度的贡献更大。     

基于FPGA的PID光束稳定控制系统研制

为了抑制外来振动对上海光源红外光束稳定性的影响,提高实验站的供光品质,研制了一种以数字PID控制器为核心的反馈控制系统。同时分析了数字PID控制算法,并应用FPGA技术,采用自顶向下的方法进行Verilog语言和原理图相结合的方式编程,设计了增量式数字PID控制器。测试结果表明:该反馈控制系统能有效地抑制红外光束的光斑位置抖动,最大工作带宽250 Hz。     

基于PID控制的密度锁启动方案计算验证

对某非能动余热排出系统,在自平衡启动方案基础上,增加了泵转速控制系统,提出了基于PID控制的密度锁启动方案.余热排出回路截止阀打开后,根据密度锁内流体温度变化调节主泵转速,使冷热流体温度分界面维持在密度锁中,确保主回路和余热排出回路的隔离.依据一维连续性方程、能量方程及动量方程对密度锁启动过程进行数值模拟.结果表明:在控制系统调节作用下,通过改变主回路质量流量,可逐渐建立2个回路之间的压力平衡,最终实现密度锁的成功启动.采用该方案可有效降低密度锁启动条件,提高密度锁启动成功率.     

积分切除法在核电厂控制系统中的应用分析

针对控制系统最常用的比例积分微分(PID)控制中的积分饱和问题,提出了基于积分切除法的3种控制算法,并将3种算法应用于核电厂稳压器压力及蒸汽向大气排放系统中。仿真结果表明,对不同的控制系统选用适当积分切除算法后,在满足系统功能要求的同时可以有效避免系统因饱和作用带来的不利影响。     

HT-7中长时间低漂移模拟积分器的研制

电磁测量是托卡马克装置中最基本的诊断方法,通常利用磁感应原理来测量HT-7装置内部磁场和磁通,因此需要用积分器对磁测量的输出信号进行积分。讨论了单运放模拟积分器的特点,提出了利用实时积分漂移补偿的方法设计新型积分器,解决了积分过程中积分器本身的等效输入偏移量、温度漂移及地噪声等带来的积分误差。给出了系统原理和设计框图,并在HT-7超导托卡马克的实验中,验证了该积分器能够满足等离子体长时间放电对积分器在积分精度和噪声精度上的要求。     

TMSR核功率控制系统的PID设计与仿真

功率控制系统(Power Control System,PCS)是反应堆控制系统(Reactor Control System,RCS)的重要组成部分,它完成功率提升、功率保持与功率调节的作用。在钍基熔盐堆(Thorium Molten Salt Reactor,TMSR)核能系统固态堆设计方案中,功率控制器根据实测功率与设定功率值之间的偏差和偏差的变化趋势,按照经典的比例-积分-微分(Proportional Integral Derivative,PID)控制算法,给出调节控制棒的运动距离和运动方向等信号。PCS的PID算法设计与基于反应堆中子物理、热工及控制棒的传动性能构成的闭环控制系统的特性有关,其不同参数的确定与系统的静态和动态性能指标的要求相对应。本文从控制的角度出发,在已有的控制棒样机中设计的棒控棒位系统及相关中子物理的基础上对PCS的PID算法进行多层次仿真与参数分析,并对系统的可控性与可测性进行分析验证。分析及仿真结果表明两种控制模型下的系统均是完全可控及完全可测的,在合适的PID参数集下均能体现响应的快速性及系统的良好鲁棒性和抗干扰能力,具有实际的应用意义。     

HT-7低杂波相控天线阵的耦合特性分析

HT-72.45GHz低混杂波系统利用相控波导阵列将微波能量耦合到等离子体中。本工作基于二维线性耦合理论,主要利用Step+Ramp的等离子体密度剖面模型,详细分析了HT-7装置上各种关键参数(如边缘密度、密度梯度、相邻主波导相位差等)下低杂波波导阵列天线的耦合特性。分析表明,通过调节主波导之间－90°～90°的相差,天线的n_∥谱可在1.93～3.15之间灵活调节;当天线口边缘密度为0.5×10¹⁸～2×10¹⁸m^-3时,波导阵天线的反射系数可保持在5%以下,方向性系数很大;主波导之间相位差的改变对波导阵的驱动效率有很大影响。     

HL-1M装置低杂波电流驱动与激光吹气等离子体中的类锯齿密度振荡

在最近的HL-1M装置实验中,利用多道远红外HCN激光干涉系统观察到了一种新型的类锯齿密度振荡。这种类锯齿密度振荡存在于低杂波电流驱动与激光吹气等离子体中,在诸如软硬X射线及热辐射等测量中也观察到了对应的振荡信号。本文描述了这类“密度锯齿”,并对其进行了初步分析。     

在低混杂波频率范围大功率微波辅助下实现HT-7托卡马克低环电压启动

在HT－7托卡马克放电实验中，使用N∥谱实时可调，频率在等离子体低混杂波频率范围，功率达150－200kW的大功率微波，辅助托卡马克装置的加热场进行了等离子体放电。在低环电压下实现了托卡马克的成功启动。使用这种方法使HT－7装置的启动环电压由通常的20V左右下降到5V以下。这相当于实现了放电启动的最大加热场副边场强由2.5-3V/m降低到0.6V/m左右。实验还观察到，在这种微波辅助低环电压启动条件下，气体电离过程和等离子体电流建立过程中的伏秒数的消耗，初始等离子体的辐射等一系列不同于单纯欧姆放电过程的物理现象。     

The Compression Algorithm for the Data Acquisition System in HT－7 Tokamak

HT-7 superconducting tokamak in the Institute of Plasma Physics of the Chinese Academy of Sciences is an experimental device for fusion research in China. The main task of the data acquisition system of HT-? is to acquire, store, analyze and index the data. The volume of the data is nearly up to hundreds of million bytes. Besides the hardware and software support, agreat capacity of data storage, process and transfer is a more important problem. To deal with this problem, the key technology is data compression algorithm. In the paper, the data format in HT-7 is introduced first, then the data compression algorithm, LZO, being a kind of portable lossless data compression algorithm with ANSI C, is analyzed. This compression algorithm, which fits well with the data acquisition and distribution in the nuclear fusion experiment, offers a pretty fast compression and extremely fast decompression. At last the performance evaluation of LZO application in HT-7 is given.     

Preliminary Design of Control Network for HT-7U Tokamak Cryogenic System

In the course of the cryoplant modernization,a control network will be set up inorder to facilitate the control,the supervision,the centralized data acquisition and the alarmhandling of the cryogenic system for HT-7U tokamak.The paper introduces the preliminarydesign of control network based on the Controller Link Network for HT-7U tokamak cryogenic     

Magnetic Sensorless Sensing of Plasma Position in the Superconducting Tokamak HT-7

Magnetic sensorless sensing experiments of the plasma horizontal position have been carried out in the superconducting tokamak HT-7. The horizontal position is calculated from the vertical field coil current and voltage without using signals of magnetic probes placed nearby a plasma. The calculations are focused on the ripple frequency component of the power supply.There is no drift problem with the time integration of magnetic probe signals. The error of the derived plasma position is lower than 2% of the plasma minor radius.     

Design of Amplifier Circuit for the HT-7 Tokamak Thomson Scattering System

Thomson scattering diagnostic is important for measuring electron temperature and density profiles. To improve the signal-to-noise ratio, a silicon avalanche photodiode （APD） with high quantum efficiency, high sensitivity, and high gain up to 100 was adopted to measure the Thomson scattering spectrum. A preamplifier, which has low noise, high bandwidth, and high sensitivity, was designed with suitable transimpedance. Using AD8367 as the post-amplifier, good performance of the APD readout electronics have been obtained. A discussion is presented on the performance of the amplifier using a laser diode to simulate the Thomson scattering light. The test results indicate that the designed circuit has a high amplifying factor and fast rising edge. So reduction of the integral gate of the CAMAC ADC converter can improve the signal-to-noise ratio.     

Upgraded data service system for HT-7 Tokamak

A data service system plays an indispensable role in HT-7 Tokamak experiment. Since the former system doesn＇t provide the function of timely data procession and analysis, and all client software are based on Windows, it can＇t fulfill virtual fusion laboratory for remote researchers. Therefore, a new system which is simplified by three kinds of data servers and one data analysis and visualization software tool has been developed. The data servers include a data acquisition server based on file system, an MDSplus server used as the central repository for analysis data, and a web server. Users who prefer the convenience of application that can be run in a Web Browser can easily access the experiment data without knowing X-Windows. In order to adjust instruments to control experiment the operators need to plot data duly as soon as they are gathered. To satisfy their requirement, an upgraded data analysis and visualization software GT-7 is developed. It not only makes 2D data visualization more efficient, but also it can be capable of processing, analyzing and displaying interactive 2D and 3D graph of raw. analyzed data by the format of ASCII, LZO and MDSplus.     

A Web-Based System for Remote Data Browsing in HT-7 Tokamak

HT-7 is the first superconducting tokamak device for fusion research in China.Many experiments have been performed on the HT-7 tokamak since 1994 with numerous satisfactory results achieved in the fusion research field. As more and better communication is required with other fusion research laboratories, remote access to experimental data is becoming increasingly important in order to raise the degree of openness of experiments and to expand research results. The web-based remote data browsing system enables authorized users in geographically different locations to view and search for experimental data without having to install any utility software at their terminals. The three-tier software architecture and thin client technology are used to operate the system effectively. This paper describes the structure of the system and the realization of its functions, focusing on three main points： the communication between the participating tiers, the data structure of the system and the visualization of the raw data on web pages.     

Recent Progress of HT-7U Superconducting Tokamak

HT-7U is a superconducting tokamak. which is being constructed in Institute of Plasma Physics, Chinese Academy of Sciences. The mission of the HT-7U project is to develop a scientific and engineering basis of the steady state operation of advanced tokamak.The engineering design of the device has been optimized. The R&D program is going on. Short samples of the conductor and a CS model coil were tested. All the TF and PF coils will be manufactured and tested in Institute of Plasma Physics. Therefore, a 600-meter long jacketing line for cable-in-conduit conductors along with two winding machines, a set of VPI equipment and a test facility for the TF and PF coils are ready in ASIPP now. In this paper, the recent progress of the HT-7U is described.     

Superconducting Busline Design for HT—7U Tokamak

Superconducting (SC) tokamak HT-7U has seven pairs of buslines connecting toroidal/Poloidal coils and the current leads,These SC buslines(SCBLs) share a common cryostat and are made of the calbe in conduit conductors(CICCs) arranged as a decoupling configuration.In order to reduce the heat loads conducted from the seven current leads with a capacity of 15kA during the magnets cooldown.the buslines with a much lower thermal conduction were employed in comparison with the current leads,and a special cooling loop was designed.     

Influence of Long-Term Plasma Irradiation on Metallic First Mirrors in HT-7 Tokamak

The first mirror （FM） samples made of polycrystal （PC） stainless steel （SS）, molybdenum （Mo） and tungsten （W） were mounted at different locations in HT-7 tokamak to investigate the surface modifications caused by erosion and deposition. The optical transmission characteristics of first mirror samples were measured by a spectrophotometer. It was found that different irradiation environment had different influences on the first mirror surfaces, especially with wave antenna nearby. In addition, the erosion made the reflectivity of FM degrade to some extents as a whole. But the deposition on the mirror influences more than erosion does. Comparing the mirrors of SS, W and Mo, irradiated in the same environment, the W-mirror had the least changes in reflectivity with regularity, while the SS-mirror had most serious changes.     

Remote Control for the HT-7 Distributed Data Acquisition System

HT-7 is the first superconducting tokamak device for fusion research in China. Many experiments have been done in the machine since 1994, and lots of satisfactory results have been achieved in the fusion research field on HT-7 tokamak^[1]. With the development of fusion research, remote control of experiment becomes more and more important to improve experimental efficiency and expand research results. This paper will describe a RCS (Remote Control System),the combined model of Browser/Server and Client/Server, based on Internet of HT-7 distributed data acquisition system (HT7DAS). By means of RCS, authorized users all over the world can control and configure HT7DAS remotely. The RCS is designed to improve the flexibility, opening, reliability and efficiency of HT7DAS. In the paper, the whole process of design along with implementation of the system and some key items are discussed in detail. The System has been successfully operated during HT-7 experiment in 2002 campaign period.