Control System of Neutral Beam Injection on HT-7

Neutral Beam Injection control system (NBICS) is constructed to measure the plasma current, Magnet current, vacuum pressure, cryopump temperature, control water cooling, filament voltage, and power supply， etc. The NBICS, consisting mainly of a Programmable Logic Controller (PLC) subsystem, data acquisition and processing subsystem and cryopump and vacuum pressure monitoring subsystem, has successfully been used on a NBI device. In this article, the design of NBICS on HT-7 is discussed and each subsystem is described in particular.In addition, some experimental results are reported which are very important data for further research related to the HT-7 tokamak.     

Analysis on Pressure Distribution in HT-7 Neutral BeamInjection System

Neutral Beam Injection (NBI) is an effective way to improve the efficiency of tokamak heating system. This article primarily introduces a work on the pressure distribution inside the tank of NBI heating system, especially inside the neutralizer, which is got by selecting a proper mathematical model and constructing a series of rational calculating formulas on pressure distribution. Furthermore, we simulate the pressure distribution by the Monte Carlo method. Comparing the result of simulation with that of theoretical calculation, we find that both the results are very close each other, showing their mutual validity.     

大功率NBI系统的PLC时序控制应用

论述了利用PLC逻辑关系对放电实验控制运行的工作原理,介绍了PLC梯形图应用程序和VB6.0环境下上位机监控程序的开发以及良好的人机操作界面,通过上位机监控界面来实时监控各电源及设备的运行状态.PLC控制系统的应用保障了实验装置的安全运行,极大地方便了实验中对放电参数的改变和设置.     

Experimental Study of Diagnosis Neutral Beam for HT-7 Tokamak

Parametrical effect on plasma discharge and beam extraction in the diagnosis neutral beam （DNB） system for HT-7 tokamak was studied experimentally. Useful results with an improved beam quality were obtained.     

诊断中性束电源的数据采集与处理系统

文中介绍了一种用于诊断中性束电源系统的数据采集与处理系统(DPAS).在电源系统的运行过程中,系统需要对18路电流/电压信号进行实时采集.DPAS采用网络技术以客户端/服务器模式进行开发.系统引进了一种高效的压缩算法从而大量地节约了数据存储所需的磁盘空间.系统所采用的数据存储格式与EastScope软件(一款用于查看实验数据的软件)兼容,从而使实验操作人员可以很容易对实验结果进行分析和总结.     

The Beam Profile Calculation for Diagnostic Neutral Beam on HT-7 Tokamak

A new calculation method is introduced for convergence beam intensity. The program based on this method is prepared for beam intensity distribution and beam power calculation. Taking the HT-7 DNB as a reference, the beam profile calculated by program is similar with that of Gaussian fit of experimental data.     

Conceptual Design of Neutral Beam Injection System for EAST

Neutral beam injection (NBI) system with two neutral beam injections will be con- structed on the Experimental Advanced Superconducting Tokamak (EAST) in two stages for high power auxiliary plasmas heating and non-inductive current drive. Each NBI can deliver 2-4 MW beam power with 50-80 keV beam energy in 10-100 s pulse length. Each elements of the NBI system are presented in this contribution.     

Numerical Calculation of the Attenuation of Neutral Beam Injection on HL-2A

The arrangement of the neutral beam line in HL-2A tokamak is introduced. Attenuation of neutral beam injection is analyzed numerically under different plasma conditions： different plasma densities, beam energies, electron temperatures, and impurity concentrations. Both optimized plasma density and beam energy for plasma heating are obtained.     

NBI双潘宁离子源参数的静电探针测量

介绍了静电探针在22cm双潘宁离子源中心等离子体参数测量中的应用.测出了探针的伏安特性曲线,由该曲线求出在弧流为200 A时,电子温度约为6.0 eV,密度约为2×1012 cm-3,这对于调整放电控制条件,获得高效率大功率的离子源有重要的参考价值,并且对于今后实现强而且均匀的中性束束流的引出也有着重要意义.     

Measurement of beam power and profile for DNB on HT-7 tokamak

In normal experimental operation, a diagnostic neutral beam (DNB) can produce 6 A of extracted beam current in hydrogen at an energy of 49 keV with a pulse length of 100 ms. Hydrogen and deuterium beams can be produced as well. The diagnostic neutral beam has been added to the diagnostic set so that charge-exchange recombination spectroscopy (CXRS) can be used to acquire ion temperature and rotation. The beam power and beam profile distribution of the DNB injection can be obtained with a thermocouple probe measurement system on the HT-7 superconducting tokamak. The thermocouple probe measurement system with 13 thermocouples crossly distributed on the probe plate was used to measure the temperature rise of each coppery target, so the profile distribution of the ion/neutral beam was obtained by calculation. In this paper, the structure of the probe plate on the DNB for HT-7 tokamak and some measurement results are presented.     

Data Processing and Acquisition System for the HT-7 Multipulse Thomson Scattering Diagnostic

This article describes the data processing and acquisition system for the HT-7 multipulse Thomson scattering diagnostic. An eight-pulse laser is used in the Thomson scattering system to obtain electron temperature profiles at eight different times throughout an entire plasma discharge. The major components of the diagnostic system consist of a multipulse iNd-glass laser,a photodetector‘‘s subsystem, a calibration set and a CAMAC data processing and acquisition system. The data processing software along with LeCroy 2250L will perform the data acquisition.In order to simplify the operation and extend the capability of its compatibility with other math softwares, the processing software has been improved by the authors. The new software based on the VC easily utilizes some math softwares to calculate the electron temperature. The new software is simpler and more operational than the old one.     

Sawtooth Control Experiments on HT-7 and EAST Tokamak

Sawtooth control experiments were performed on HT-7 with a limiter configuration and on the Experimental Advanced Superconducting Tokamak （EAST） with a double null con- figuration. The sawtooth period can be modified by lower hybrid wave （LHW） and ion cyclotron resonance frequency （ICRF）. Different sawtooth behavior was observed with the same plasma density, LHW power but different plasma currents on HT-7. There was a dwell time between LHW added and the sawtooth stabilization on HT-7 while the sawtooth stabilization immediately happened when LHW power was injected on EAST. The possible mechanism of the sawtooth control is discussed in this paper. All the experimental results have proved that power deposition of the radio frequency （RF） should be the key factor for sawtooth control.     

Preliminary design of the control and data acquisition systems for the Neutral Beam Test Facility

The Neutral Beam Test Facility, which will be built in Padova, Italy, is aimed at developing the ITER heating neutral beam injector (HNB) and at testing and optimizing its operation up to nominal performance before installation on ITER. It requires the development of two independent experiments referred to as SPIDER (source for production of ions of deuterium extracted from Rf plasma) and MITICA (megavolt ITer injector & concept advancement). SPIDER will explore the full-size negative ion source for ITER, whereas MITICA will explore the full-size ITER neutral beam injector. Both experiments will be designed for long-pulse operation, up to 3600 s, as ITER itself. MITICA includes three functional components: the heating neutral beam injector plant system (HNB), which is the device under test; the auxiliary plant system (AUX), which includes all equipment to operate the HNB in the test facility (e.g. the local electric grid to feed the HNB power supplies), and MITICA supervisory system that is an electronics/informatics infrastructure to operate the facility. The paper introduces the requirements for the control and data acquisition systems of the experiments and proposes a preliminary design for both systems. SPIDER, which is preparatory to MITICA and will be developed on a shorter time scale, has no constraints coming from ITER CODAC, whereas MITICA includes the ITER neutral beam injector and therefore must be fully compatible with ITER CODAC.     

Discharge Characteristics of Large-Area High-Power RF Ion Source for Positive and Negative Neutral Beam Injectors

A large-area high-power radio-frequency(RF) driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute(KAERI). The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argongas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter,such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the shortand long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region.     

A poloidal field control system based on VxWorks in HT-7 Tokamak

The PF (Poloidal Field) control system is one of the most important control systems in HT-7 Tokamak.Most of parameters such as plasma current, plasma horizontal position and plasma vertical position will be monitored.For the purpose of long-pulse discharge and the more precise control to plasma, the real-time operation system VxWorks is applied, instead of the behindhand and unbefitting DOS operation system. This paper describes the development process of HT-7 PF control system based on VxWorks on Intel X86 platforms. The method of using hardware cards in VxWorks, and the network communication with other operation systems are discussed especially. Results of the comparison between VxWorks and DOS operation systems are given too.     

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。     

LHCD Properties with a New Lower Hybrid Wave Antenna on HT-7 Tokamak

1 IntroductionLower hybrid current drive (LHCD) has become aneffective method to maintain plasma current in a toka-mak. Plenty of experimental results on the HT-7 toka-mak also show that LHCD is an important auxiliarymeans to achieve steady state operation of the toka-mak and to obtain plasmas with improved confine-ments [1~4]. In the experiments, lower hybrid wave(LHW) with a frequency of 2.45 GHz is launched intothe plasma by an LHW antenna. Since the power spec-trum of the launched …     

填充因子对K-V分布束晕-混沌控制效果的影响

系统地研究了周期磁聚焦束流传输网络中填充因子对强流离子加速器K V分布束晕 混沌控制效果的影响。通过数值模拟,确定了束晕 混沌控制效果较好的填充因子的取值范围为 0.75~0.99,从而把以往填充因子只凭经验取个别值的研究扩大到可在一个较大的范围取值。另外,还发现了填充因子取值为0.59~0.67时束截面上离子数密度分布由均匀分布变为沿径向出现一峰状分布现象,从而为离子束应用提供了新的参考。     

Using Adaptive Discrete-Time Gas Supply Control for Long Pulse Arc Discharge of Ion Source on NBI

A control model of gas supply system is introduced for ion source and an adaptive discrete-time control algorithm to regulate the hydrogen injection. A real-time feedback control system （RFCS） is designed to control the gas supply for ion source based on the control model and the discrete-time control algorithm. The experimental results have proved that RFCS could regulate the gas supply smoothly, suppress the arc＇s abrupt over-current at the end of the ion source discharging, prolong the discharge pulse and stabilize the ion concentration. With RFCS, the ion source for neutral beam injection has reached its longest pulse with a length of 4.5 seconds in a stable status.     

在束流输运网络中强流离子束的复杂性及其控制研究进展

讨论了在束流输运网络中强流离子束在国防与民用等许多方面极其重要的应用潜力和诱人的发展前景。指出在束流输运网络中强流离子束形成的束晕-混沌的复杂性已经成为强流离子束应用中的关键问题之一;必须深入研究这类束晕-混沌的复杂特性及其产生的物理机制,并实现对束晕-混沌的有效控制。考虑到这是一个特殊的复杂的时空混沌的控制问题,解决这一难题已经成为强流离子束涉及的高科技领域、非线性-复杂性科学及复杂网络交叉领域中极富挑战性的一个新课题。最后,对上述课题当前的最新进展进行了评论,指出了该课题今后的研究方向。