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.     

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.     

Upgrade of plasma density feedback control systemin HT-7 tokamak

The HT-7 is a superconducting tokamak in China used to make researches on the controlled nuclear fusion as a national project for the fusion research. The plasma density feedback control subsystem is the one of the subsystems of the distributed control system in HT-7 tokamak (HT7DCS). The main function of the subsystem is to control the plasma density on real-time. For this reason, the real-time capability and good stability are the most significant factors, which will influence the control results. Since the former plasma density feedback control system (FPDFCS) based on Windows operation system could not fulfill such requirements well, a new subsystem has to be developed. The paper describes the upgrade of the plasma density feedback control system (UPDFCS), based on the dual operation system (Windows and Linux), in detail.     

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.     

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     

The BOUT Project; Validation and Benchmark of BOUT Code and Experimental Diagnostic Tools for Fusion Boundary Turbulence

1. IntroductionThe performance of tokarnaks and other toroidalmagnetic devices depends crucially on the dynamics of the boundary region, i.e., the transition regionfrOm the hot core plasma through the separatrix tothe matrial 8urfaC of the first wall. Plasma turbu-lence, and the resulting anomalous cross~field plasmatransport, are crucial physics processes in the bound-ary regiOn, Wting both core Plasma confinementand plasmawall interactions. ffeduction of anomalous plasma transport at the b…     

Experiment and Operation of a LHCD—35kV／2.8MW／1000s High—Voltage Power Supply on HT—7 Tokamak

A-35kV/2.8MW/1000s high-voltage power supply(HVPS) for HT-7 superconducting tokamak has been built successfully.The HVPS is scheduled to run on a 2.45 GHz/1MW lower hybrid current drive(LHCD)^[1] system of HT-7 superoonducting tokamak before the set-up of HT-7 superconducting tokamak in 2003.The HVPS has a series of advantages such as good steady and dynamic response,logical computer program controlling the HVPS without and fault,operationa panel and experimental board for data acquisition.which both are grounded distinctively in a normative way to protec the main body of HVPS along with its attached equipments from dangers.Electric power cables and other control cables are disposed reasonably,to prevent singals from magnetic interference and ensure the precision of signal transfer.This paper involves the experiment and operation of a 35kV/2.8 MW/1000s HVPS^[2] for 2.45 GHz/1 MW LHCD system.The reliability and feasibility of the HVPS has been demonstrated in comparison with experimental results of original design and simulation data.     

Finite Element Analyses and Instrumentation Layout for Single Coil Testing of TF Coils in HT-7U

The HT-7U tokamak is a magnetically-confined full superconducting fusion device, consisting of superconducting toroidal field (TF) coils and superconducting poloidal field (PF) coils. These coils are wound with cable-in-conductor (CICC) which is based on UNK NbTi wires made in Russian '. A single D-shaped toroidal field magnet coil will be tested for large and expensive magnets systems before assembling them in the toroidal configuration. This paper describes the layout of the instrumentation for a superconducting test facility based on the results of a finite element modeling of the single coil of toroidal magnetic field (TF) coils in HT-7U tokamak device. At the same time, the design of coil support structure in the test facility is particularly discussed in some detail.     

The Study of Heat Pulse Propagation on HT—7 Tokamak

The propagation of heat pulses originating from sawtooth activity has been studied on the HT-7 tokamak.Two theoretical models are used for determining electron heat diffusivity from the experimental data measured by a diagnostic system of soft x-ray diode-array.The results show that one model caaled dipole model is more suitable for HT-7 tokamak.In order to improve the signal-to-noise(S/N) ratio of the original signals,over a few tens of sawteeth are averaged to generatc nicc wavcforms.The apace-time evolution is found to be diffusive in character,which is consistent with the theoretical model.The electron heat diffusivity determined from heat pulse propagation is larger than determined from background plasma power balance.The variation of Xe in different discharge phases has been also discussed.     

The Development of Data Acquisition and Remote Real-Time Display System for EAST NBI

The data acquisition and remote real-time display system for the neutral beam injectors (NBI) on experimental advanced superconducting tokamak (EAST) are described in this paper. Distributed computer systems including local data acquisition (DAQ) facility, remote data server (DS), real-time display terminal are adopted with Linux and Windows operating system. Experimental signals are gathered by DAQ device at local working field. On the one hand, these gathered data will be sent to DS which runs on remote server main control layer on EAST NBI control network for saving and processing; on the other hand, these data will be sent to real-time display terminal which runs on remote monitoring layer on EAST NBI for displaying and monitoring experimental signals real-timely. Another point needs to be mentioned is that the real-time display software can call back historical data from DS for querying. The software of data acquisition and DS are programmed by C language while the real-time display software is programmed by Labview flow chart. The hardware mainly includes DAQ cards, server, industrial personal computer and others auxiliary hardware. Now the system proved to be performed well through experiments on NBI testing bed.     

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.     

Ions Measurement at the Edge of HT-7 Tokamak

A reliable method of measuring ions and ion temperature in tokamak plasma is necessary, for which an omegatron-like instrument has been developed on the HT-7 tokamak. The basic layout of the omegatron-like instrument is shown in this article. The measurement of working gas ion has been performed in the last experimental campaign on HT-7 tokamak. The relations among ion current, the electron repeller voltage and trap voltage have been investigated. This omegatron-like instrument has also provided the edge-plasma ion temperature.     

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 …     

Measurement of Magnetic Island Width by Multi-Channel ECE Radiometer on HT-7 Tokamak

A 16-channel electron cyclotron emission (ECE) radiometer has been employed to observe the (m; n) = (2; 1) magnetic island structure on HT-7 tokamak, where m and n represent the poloidal and toroidal mode number respectively. The results indicate that the island width is about 7 cm when the magnetic island is saturated during the m=n = 2=1 mode. The location of resonance surface can be determined by plotting the contour of ECE relative fluctuation.This method could be applied to the HT-7 and EAST campaigns in the future for the research of neoclassical tearing modes (NTMs).     

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.     

基于CAMAC总线的交替式数据采集及实时监控系统研究

进行了一种称为交替式数据采集及实时监控系统的研究。该系统不仅能实现以较高频率进行任意时间的数据采集,还能在放电过程中以图形方式实时显示等离子体的各种参数供实验人员在线分析及控制。     

A Hybrid Heating Method for the HT-7U Coils during Vacuum-Pressure Impregnation

1. IntroductionA program to design and fabricate a tokamakphysics experimental device of HT-7U using superconducting coils has been undertaken by the institute of Plasma Physics, the Chinese Academy of Sciences .The aim of HT-7U is to develop a scientificbasis for a low--cost, clean and continuously operating TOkamak fusion reator. The HT-7U magnet system consists of 16 magnets in the toroidal field (TF)system and 6 pairs of magnets in the poloidal field(PF) system located symmetricall…     

Alternate Data Acquisition and Real-time Monitoring System on HT-7 Tokamak

1 Introduction There are many tokamak devices over the world. Be- cause the tokamak device is based on the principle of a transformer, almost all tokamaks are pulse-operated and most of their discharge duration is within one or two minutes. A conventional data acquisition and anal- ysis system would be good enough for such devices. However, recent lower hybrid current-drive (LHCD) ex- periments such as those on the HT-7 and Tore Supra have generated discharges lasting several hundred sec- …     

Plan of ITER remote experimentation center

Plan of ITER remote experimentation center (REC) based on the broader approach (BA) activity of the joint program of Japan and Europe (EU) is described. Objectives of REC activity are (1) to identify the functions and solve the technical issues for the construction of the REC for ITER at Rokkasho, (2) to develop the remote experiment system and verify the functions required for the remote experiment by using the Satellite Tokamak (JT-60SA) facilities in order to make the future experiments of ITER and JT-60SA effectively and efficiently implemented, and (3) to test the functions of REC and demonstrate the total system by using JT-60SA and existing other facilities in EU. Preliminary identified items to be developed are (1) Functions of the remote experiment system, such as setting of experiment parameters, shot scheduling, real time data streaming, communication by video-conference between the remote-site and on-site, (2) Effective data transfer system that is capable of fast transfer of the huge amount of data between on-site and off-site and the network connecting the REC system, (3) Storage system that can store/access the huge amount of data, including database management, (4) Data analysis software for the data viewing of the diagnostic data on the storage system, (5) Numerical simulation for preparation and estimation of the shot performance and the analysis of the plasma shot. Detailed specifications of the above items will be discussed and the system will be made in these four years in collaboration with tokamak facilities of JT-60SA and EU tokamak, experts of informatics, activities of plasma simulation and ITER. Finally, the function of REC will be tested and the total system will be demonstrated by the middle of 2017.