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。     

Development and Integration of a Data Acquisition System for SST-1 Phase-1 Plasma Diagnostics

Long pulse(of the order of 1000 s or more) SST-1 tokamak experiments demand a data acquisition system that is capable of acquiring data from various diagnostics channels without losing useful data(and hence physics information) while avoiding unnecessary generation of a large volume data.SST-1 Phase-1 tokamak operation has been envisaged with data acquisition of several essential diagnostics channels.These channels demand data acquisition at a sampling rate ranging from 1 kilo samples per second(KSPS) to 1 mega samples per second(MSPS).Considering the technical characteristics and requirements of the diagnostics,a data acquisition system based on PXI and CAMAC has been developed for SST-1 plasma diagnostics.Both these data acquisition systems are scalable.Present data acquisition needs involving slow plasma diagnostics are catered by the PXI based data acquisition system.On the other hand,CAMAC data acquisition hardware meets all requirements of the SST-1 Phase-1 fast plasma diagnostics channels.A graphical user interface for both data acquisition systems(PXI and CAMAC) has been developed using LabVIEW application development software.The collected data on the local hard disk are directly streaming to the central server through a dedicated network for post-shot data analysis.This paper describes the development and integration of the data acquisition system for SST-1 Phase-1 plasma diagnostics.The integrated testing of the developed data acquisition system has been performed using SST-1 central control and diagnostics signal conditioning units.In the absence of plasma shots,the integrated testing of the data acquisition system for the initial diagnostics of SST-1 Phase-1 operation has been performed with simulated physical signals.The primary engineering objective of this integrated testing is to validate the performance of the developed data acquisition system under simulated conditions close to that of actual tokamak operation.The data acquisition is synchronized with a clock and trigger provided by the central timing system.     

Imaging System and Plasma Imaging on HL-2A Tokamak

As a new diagnostic means, plasma-imaging system has been developed on the HL-2A tokamak, with a basic understanding of plasma discharge scenario of the entire torus, checking the plasma position and the clearance between the plasma and the first wall during discharge. The plasma imaging system consists of (1) color video camera, (2) observation window and turn mirror, (3) viewing & collecting optics, (4) video cable, (5) Video capture card as well as PC. This paper mainly describes the experimental arrangement, plasma imaging system and detailed part in the system, along with the experimental results. Real-time monitoring of plasma discharge process, particularly distinguishing limitor and divertor configuration, the imaging system has become key diagnostic means and laid the foundation for further physical experiment on the HL-2A tokamak.     

Fast data acquisition system based on digital oscilloscopes for fluctuation measurements in a long pulse JT-60U tokamak plasma

We have developed a new data acquisition (DAQ) system with fast sampling rate for fluctuation measurements in a long pulse JT-60U tokamak plasma. This system is based on a powerful digital oscilloscope, which has a large acquisition memory up to 50 Mwords/ch, 1 MHz sampling rate and 16 bits high resolution AD convertors. The system is composed of plural digital oscilloscopes and mass storages. On this system, most of data acquisition processes are executed at each digital oscilloscope. This feature of the system leads to an advantage that the processing loads are distributed among the digital oscilloscopes. This system has been successfully employed for measurements of various fluctuations obtained through magnetic probes, beam emission spectroscopy and so on. The size of the acquired data using this system has reached up to 10 GB/shot so far. It has demonstrated that this system is very powerful for data acquisition of multi-channeled signals with high time resolution in a long pulse plasma.     

Research on the real-time signal conditioning method for dispersion interferometer in HL-2M

A new CO₂ laser dispersion interferometer has been developed in the HL-2M tokamak to measure the electron density. In order to meet the needs of high-precision measurement, a data acquisition system with real-time signal conditioning (RSC) method is proposed. It can eliminate part of the impacts of environmental factors, such as mechanical vibration, light path changes, and plasma refraction effect during experiments. In harsh environments, the system can measure the line-integrated density with a high precision of 2 × 10¹⁸ m⁻² with the RSC method. The system has been tested in a recent HL-2A experimental campaign, and the results show that the RSC method plays an important role in the plasma electron density measurement.     

Plasma Shape and Current Control Simulation of HT-7U Tokamak

This paper describoes the discharge simulation of HT-7U tokamak plasma equilibrium and plasma current by solving MHD equations and surface average transport equations using an equilibrium evolution code. The simulated result shows the evolution of plasma parameter versus time .The simulated result can play an important role in the design of the plasma equilibrium and control system of a tokamak.     

Plasma production and preliminary results from the ADITYA Upgrade tokamak

The Ohmically heated circular limiter tokamak ADITYA (R0 =75 cm,a =25 cm) has been upgraded to a tokamak named the ADITYA Upgrade (ADITYA-U) with an open divertor configuration with divertor plates.The main goal of ADITYA-U is to carry out dedicated experiments relevant for bigger fusion machines including ITER,such as the generation and control of runaway electrons,disruption prediction,and mitigation studies,along with an improvement in confinement with shaped plasma.The ADITYA tokamak was dismantled and the assembly of ADITYA-U was completed in March 2016.Integration of subsystems like data acquisition and remote operation along with plasma production and preliminary plasma characterization of ADITYA-U plasmas are presented in this paper.     

ISTTOK plasma control with the tomography diagnostic

The presently available processing power in generic processing units (GPU) combined with state-of-the-art programmable logic devices enables the implementation of complex algorithms for plasma diagnostics in a real-time scenario.A tomography diagnostic based on three linear pin-hole cameras each with eight lines of sight has been developed for the ISTTOK tokamak. The plasma emissivity in a poloidal cross-section is computed locally on a sub-millisecond time scale, using a variant of the Fourier-Bessel algorithm. The output signals are then used for active plasma position control.The data acquisition and reconstruction system is based on ATCA technology and consists of one acquisition board with integrated FPGA capabilities and a dual-core Intel module running RTAI Linux.In this paper, the tomographic algorithm and some preliminary results of the real-time plasma position control are presented with a performance benchmarking against other available positioning diagnostics. The algorithm has shown to be accurate and the system has successfully controlled the plasma position during a plasma current reversal.     

Development of the simulation platform between EAST plasma control system and the tokamak simulation code based on Simulink

Plasma control system (PCS),mainly developed for real-time feedback control calculation,plays a significant part during normal discharges in a magnetic fusion device,while the tokamak simulation code (TSC) is a nonlinear numerical model that studies the time evolution of an axisymmetric magnetized tokamak plasma.The motivation to combine these two codes for an integrated simulation is specified by the facts that the control system module in TSC is relatively simple compared to PCS,and meanwhile,newly-implemented control algorithms in PCS,before applied to experimental validations,require numerical validations against a tokamak plasma simulator that TSC can act as.In this paper,details of establishment of the integrated simulation framework between the EAST PCS and TSC are generically presented,and the poloidal power supply model and data acquisition model that have been implemented in this framework are described as well.In addition,the correctness of data interactions among the EAST PCS,Simulink and TSC is clearly confirmed during an interface test,and in a simulation test,the RZIP control scheme in the EAST PCS is numerically validated using this simulation platform.     

Development of a fast electron bremsstrahlung diagnostic system based on LYSO and silicon photomultipliers during lower hybrid current drive for tokamak

A novel real time fast electron bremsstrahlung (FEB) diagnostic system based on the lutetium yttrium oxyorthosilicate scintillators (LYSO) and silicon photomultipliers (SiPM) has been developed for tokamak. The diagnostic system is dedicated to study the FEB emission in the hard x-ray (HXR) energy range between 10 and 200 keV during the lower hybrid current drive. The system consists of a detection module and three data acquisition and processing (DAP) boards. The detection module consists of annulus LYSO-SiPM detector array and a 12-channel preamplifier module. The DAP boards upload the data to the host computer for displaying and storing through PXI bus. The time and space resolutions of the system are 10 ms and 4cm, respectively. The experimental results can show the evolution over time and the spatial distribution of FEB. This paper presents the system performance and typical discharge results.     

快电子对快离子损失诊断测量的影响

基于闪烁体原理的快离子损失探针(Fast Ion Loss Detector,FILD),可以同时测量损失快离子的能量和pitch-angle的值,是核聚变装置中对高能粒子诊断的重要方式。根据先进实验超导托卡马克(Experimental Advanced Superconducting Tokamak,EAST)的发展需求,为了更好地对损失快离子行为进行研究,设计并安装了快离子损失诊断,且探测到在中性束加热条件下产生的损失快离子。同时,探测到在放电中产生的逃逸电子,以及低杂波注入时快电子产生X射线对快离子损失背景信号的影响。并且在H-mode放电时边界扰动也对快离子损失信号产生影响,这些探测到的现象都为不断升级损失诊断系统提供依据。     

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.     

Real-Time Bonner Sphere Spectrometry on the HL-2A Tokamak

Real-time Bonner sphere spectrometry(BSS)at the HL-2A tokamak for the neutron spectrum diagnostic is described.The spectrometer consists of eight different size Bonner spheres made of polyethylene and with a ~3helium-filled detector in the center,pre-amplifiers,and parallelprocessing data acquisition system(DAQ).Dynamic neutrons from plasma discharges of the HL-2A tokamak were measured and the real-time neutron spectrum was presented.     

HT-7 Multipoint Nd Laser Thomson Scattering Apparatus

1. IlltroductionThomson scattering diagnostic has been an important and standard method for measuring temperature and density profiles on all modern toka-maks, such as the TV Thotnson Scattering systemon TFTR [1], the LIDAR system on JET [2] and theNd:YAG laser Thomson scattering system on Dlll--D[3]. It has the attractive characteristics of not per-turbillg the plasma to be investigated and of derivingthe absolute values of electronic temperature Ti anddensity ne' From the knot'.led…     

Development of a Data Acquisition Control System for the First NBI on EAST

Neutral beam injection （NBI） heating is one of the most efficient auxiliary plasma heating methods for fusion devices. The data acquisition control system （DACS） with PXI （pe- ripheral component interconnect extensions for instrumentation） data acquisition card for the first NBI system in the experimental advanced superconducting tokamak （EAST） is presented in this paper. As an important sub-system, DACS is designed to obtain physical measurement signals in the EAST NBI system and to deal and store these data with the Lempel-Ziv-Oberhumer （LZO） lossless data compression algorithm, as well as offer convenient data call-back and access inter- faces to the user for examining and analyzing the data. Experimental results show that accurate data will ensure that researchers correctly analyze it and then properly adjust the experimental parameters or operation, so DACS should take a large step in improving experimental efficiency. Tile hardware and software sections are briefly presented in this paper, and now this system has been tested to be able to work reliably and steadily.     

Preliminary Experiment of Non-Inductive Plasma Current Startup in SUNIST Spherical Tokamak

The non-inductive plasma current startup is an important motivation in SUNIST spherical tokamak. In the recent experiment, the magnetron microwave system of 100 kW and 2.45 GHz has been used to the ECR plasma current startup. Besides the toroidal field, a vertical field was applied to generate preliminary toroidal plasma current without the action of the central solenoid. As the evidence of plasma current startup with the effect of vertical field drift, the direction of plasma current is changed when the direction of vertical field changes during the ECR plasma current startup discharge. We also observed a maximum plasma current by scanning vertical field in both directions. Additionally, we used electrode discharge to assist the ECR plasma current startup.     

Development of a real-time magnetic island reconstruction system based on PCIe platform for HL-2A tokamak

A real-time magnetic island reconstruction(MIR) system based on PCI express platform for HL-2 A tokamak is introduced. The front-end analog circuit and high performance analog-to-digital converters complete high-precision synchronous sampling of 18 channel Mirnov signals, and the application of PCIe platform and direct memory access technology enables high speed data transmission between graphics processing unit and field programmable gate array(FPGA).FPGA, as a mainstream high speed parallelizable computing tool, was used to implement the MIR algorithm, while a parameter table is established in an external double data rate SDRAM to improve the computational efficiency. The software of the MIR system is developed with Compute Unified Device Architecture 8.0 in Centos 6 system, which mainly realizes driver development, data transmission, network communication, parameter calculation and system control. This system has been tested in HL-2 A plasma discharge experiment, and the reconstructed magnetic island structure can achieve a spatial resolution of 1.02 cm while the time resolution can reach 2 ms.     

Design of neutral beam injection system for KSTAR tokamak

The neutral beam injection (NBI-1) system has been designed for providing a 300 s deuterium beam of 120 kV/65 A as an auxiliary heating and current drive system of the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak. The deuterium beam is produced from a long pulse ion source composed of a bucket-type plasma generator and a multi-aperture tetrode accelerator with the help of discharge power supplies and high voltage (HV) power supplies. The beamline components (BLCs) include a neutralizer with an optical multi-channel analyzer (OMA) section, a bending magnet (BM), an ion dump assembly, a movable calorimeter, beam scrapers, and a cryo-sorption pump system in a rectangular vacuum tank. A beam duct equipped with bellows and a voltage break is placed between the NBI vacuum tank and the KSTAR vacuum vessel. All data and parameters of the NBI system are controlled by a control and data acquisition (CODAQ) system through the EPICS based Ethernet interface.     

Measurement of Current Profile in a Tokamak Through AC Modulation

The plasma current is modulated with an alternating current （ac） component in a frequency range of 90 Hz - 900 Hz in the plateau discharge phase in the CT-6B tokamak. A plasma electric conductivity profile in a form of （1 - r^2/a^2）^α with a parameter α which is fitted with the experimental data, can be determined. The effects of magnetic shear in a tokamak field configuration on the current penetration are taken into account in the numerical simulation. The measurement method and obtained results are discussed.     

The implementation of magnetics verification in EAST plasma control system

Experimental advanced superconducting tokamak (EAST) is an experimental device aiming at steady state plasma operation for fusion research. The values of many discharge parameters, such as plasma shape, position and current must be directly acquired or indirectly evaluated from the magnetic measurements, so the accuracy of magnetic measurements plays an important role in reliable plasma control performance. A method for verifying the key magnetic measurements in real time for each shot is described in this paper. Such magnetics verification will prevent the discharge from a key magnetic signal failure and ensure the quality of a successful discharge. The diagnostics verification algorithm has been implemented in the plasma control system for the EAST. The implementation details and its application in the recent experiment are presented in this paper.