A pellet injector of the HL-2A tokamak

A variable-cross-section extruder, in which rheological properties of solid-state hydrogen isotopes are used for manufacturing ice suitable for forming fuel pellets of thermonuclear facilities, was for the first time designed. The fuel injector for fueling the HL-2A tokamak (SWIP, China) by deuterium pellets with a 1.3-mm diameter, a length of 1.3–1.7 mm, a velocity of 100–450 m/s, and a frequency up to 33 Hz has been designed based on it.     

The development of Thomson scattering system on HL-2A tokamak

A new Thomson scattering diagnostic system is successfully developed to measure core plasma electron temperature (Te) and density (ne) of HL-2A tokamak (major radius R=165 cm, minor radius a=40 cm). In this system, a standard lamp-monochromator combination is utilized for the calibration of spectral responses. By sweeping in the range of 750-1200 nm with a step of 2 nm, the work can be done automatically for one-point calibration and then for other. Electronic gain calibration and gain monitoring are done by pulsed light emitting diode light. By utilizing an intense Nd:YAG laser of pulse energy up to 4 J and employing good quality interference filters in the five-channel filter polychromator to surpress greatly the stray light, the TS system can be routinely used to make measurements with good quality data. After each HL-2A plasma discharge, the measured Te and ne data are transferred to HL-2A database for lookup and analyses.     

Measurements of the fast electron bremsstrahlung emission during electron cyclotron resonance heating in the HL-2A tokamak

A fast electron bremsstrahlung (FEB) diagnostic technique based on cadmium telluride (CdTe) detector has been developed recently in the HL-2A tokamak for measurements of the temporal evolution of FEB emission in the energy range of 10-200 keV. With a perpendicular viewing into the plasma on the equatorial plane, the hard x-ray spectra with eight different energy channels are measured. The discrimination of the spectra is implemented by an accurate spectrometry. The system also makes use of fast digitization and software signal processing technology. An ambient environment of neutrons, gammas, and magnetic disturbance requires careful shielding. During electron cyclotron resonance heating, the generation of fast electrons and the oscillations of electron fishbone (e-fishbone) have been found. Using the FEB measurement system, it has been experimentally identified that the mode strongly correlates with the electron cyclotron resonance heating produced fast electrons with 30-70 keV.     

A synthetic diagnostic for the evaluation of new microwave imaging reflectometry diagnostics for DIII-D and KSTAR

The first microwave imaging reflectometry (MIR) system for characterization of fluctuating plasma density has been implemented for the TEXTOR tokamak [H. Park et al., Rev. Sci. Instrum. 75, 3787 (2004)]; an improved MIR system will be installed on DIII-D and KSTAR. The central issue remains in preserving phase information by addressing antenna coupling between the reflection layer and the detector array in the presence of plasma turbulence. A synthetic diagnostic making use of coupled full-wave diffractive codes has been developed in geometries and applied to a variety of optical arrangements. The effectiveness of each scheme is quantitatively compared with respect to the fluctuation levels accessible in the simulation.     

Multiband reflectometry system for density profile measurement with high temporal resolution on JET tokamak

A new system has been installed on the JET tokamak consisting of six independent fast-sweeping reflectometers covering four bands between 44 and 150 GHz and using orthogonal polarizations. It has been designed to measure density profiles from the plasma edge to the center, launching microwaves through 40 m of oversized corrugated waveguides. It has routinely produced density profiles with a maximum repetition rate of one profile every 15?μs and up to 100,000 profiles per pulse.     

The dependence of extracted current on discharge gas pressure in neutral beam ion sources on HL-2A tokamak

The discharge gas pressure is a key factor to influence the extracted current of ion source. In this paper, the dependence of extracted current on discharge gas pressure was investigated in detail at different arc discharge currents. The discharge gas pressure with a very broad range (0.1 Pa-2.7 Pa) was scanned for the first time. It is turned out that, with the increasing of discharge gas pressure, the extracted current increases and the arc voltage decreases at different arc currents; however, when the discharge gas pressure exceeds a certain value, the extracted current decreases. For the same discharge gas pressure, the higher the arc current, the higher the arc voltage and the extracted current are. The arc efficiency was also calculated, and its dependence on gas pressure was almost the same with the dependence of extracted current on gas pressure, but at the same discharge gas pressure, the lower the arc current, the higher the arc efficiency is and the lower the extracted current is.     

Improved time-frequency analysis of ASDEX Upgrade reflectometry data using the reassigned spectrogram technique

The spectrogram is one of the best-known time-frequency distributions suitable to analyze signals whose energy varies both in time and frequency. In reflectometry, it has been used to obtain the frequency content of FM-CW signals for density profile inversion and also to study plasma density fluctuations from swept and fixed frequency data. Being implemented via the short-time Fourier transform, the spectrogram is limited in resolution, and for that reason several methods have been developed to overcome this problem. Among those, we focus on the reassigned spectrogram technique that is both easily automated and computationally efficient requiring only the calculation of two additional spectrograms. In each time-frequency window, the technique reallocates the spectrogram coordinates to the region that most contributes to the signal energy. The application to ASDEX Upgrade reflectometry data results in better energy concentration and improved localization of the spectral content of the reflected signals. When combined with the automatic (data driven) window length spectrogram, this technique provides improved profile accuracy, in particular, in regions where frequency content varies most rapidly such as the edge pedestal shoulder.     

New signal processing technique for density profile reconstruction using reflectometry

Reflectometry profile measurement requires an accurate determination of the plasma reflected signal. Along with a good resolution and a high signal to noise ratio of the phase measurement, adequate data analysis is required. A new data processing based on time-frequency tomographic representation is used. It provides a clearer separation between multiple components and improves isolation of the relevant signals. In this paper, this data processing technique is applied to two sets of signals coming from two different reflectometer devices used on the Tore Supra tokamak. For the standard density profile reflectometry, it improves the initialization process and its reliability, providing a more accurate profile determination in the far scrape-off layer with density measurements as low as 10(16) m(-1). For a second reflectometer, which provides measurements in front of a lower hybrid launcher, this method improves the separation of the relevant plasma signal from multi-reflection processes due to the proximity of the plasma.     

自动站故障个例的分析和数据处理

文章以本站2013年5月21日遭遇雷击造成部分仪器故障、观测数据缺测的事件为例,探讨了自动气象站常见故障的排除以及气象要素数据缺测时正点上传文件的处理方法,并介绍了日常数据的维护方法。     

基于分析法的平行度误差计算机数据处理

利用计算机对误差测量数据进行处理,可以提高形状和位置误差评定精度,提高数据处理速度.提出了基于分析法的按最小包容区域准则评定直线度误差和平行度误差的设计思想和基本算法,用VC 开发了误差评定软件,给出了关键部分程序代码.通过应用实例,验证了该算法的可行性和正确性.     

A protocol for processing interfered data in facility sensor networks

Wireless sensor networks (WSNs) have recently extended application areas to numerous sectors such as industrial automation, military applications, transportation systems, building management, and environment surveillance. In particular, WSNs provide flexible, reliable, cost-effective solutions to monitor the real-time status of automated manufacturing facilities. A facility-specific WSN for reliable monitoring and efficient management of industrial facilities is called the facility sensor network (FSN). In general, industrial facilities run various electromagnetic devices causing electromagnetic interference (EMI), which disturbs wireless data communication. To obtain accurate and reliable data in such environments, the FSN needs to deal with the EMI by proper deployment of sensor nodes and their validation and fusion. This paper proposes a data processing protocol, called Interfered Sensor Data Processing Protocol (ISDPP) to handle the EMI affecting wireless communication. ISDPP is developed with a data fusion algorithm and an exponentially weighted moving average/fuzzy logic-based error detection method to obtain reliable information from the FSN. To evaluate the performance, experiments in various settings are performed in a test-bed manufacturing facility. The experimental results indicate the interfered data, and outliers can be filtered out even if unexpected interferences occur in the facility. The FSN with the ISDPP can provide efficient real-time monitoring solutions for various industrial applications.     

Simultaneous projection and detection system of four different frequencies for microwave imaging reflectometry in Large Helical Device

A simultaneous projection/detection system of four different frequencies for microwave imaging reflectometry (MIR) was developed for three-dimensional observation of electron density fluctuations in the Large Helical Device (LHD). The microwave with four frequency components at 60.410, 61.808, 63.008, and 64.610 GHz is projected in a continuous-wave mode to illuminate the target LHD plasma. A two-dimensional horn-antenna mixer array (2D HMA) receives the reflected wave from the plasma as well as the wave from the local oscillator operating at 55.800 GHz. The first intermediate frequency (IF) signals at 4.610, 6.008, 7.208, and 8.810 GHz were confirmed to be obtained by downconversion of these microwaves using the 2D HMA. Each of these first IF components is filtered from each other and downconverted again for the superheterodyne detection. It was confirmed that both the amplitudes and the phases of the detected signals reflect the fluctuations in LHD plasmas.     

Residual gas analysis for long-pulse, advanced tokamak operation

A shielded residual gas analyzer (RGA) system on Tore Supra can function during plasma operation and is set up to monitor the composition of the neutral gas in one of the pumping ducts of the toroidal pumped limited. This "diagnostic RGA" has been used in long-pulse (up to 6 min) discharges for continuous monitoring of up to 15 masses simultaneously. Comparison of the RGA-measured evolution of the H(2)/D(2) isotopic ratio in the exhaust gas to that measured by an energetic neutral particle analyzer in the plasma core provides a way to monitor the evolution of particle balance. RGA monitoring of corrective H(2) injection to maintain proper minority heating is providing a database for improved ion cyclotron resonance heating, potentially with RGA-base feedback control. In very long pulses (>4?min) absence of significant changes in the RGA-monitored, hydrocarbon particle pressures is an indication of proper operation of the actively cooled, carbon-based plasma facing components. Also H(2) could increase due to thermodesorption of overheated plasma facing components.     

A new multichannel interferometer system on HL-2A

A new multichannel HCN interferometer has been developed on HL-2A tokamak, which is characterized by two techniques: (1) the wave-guide HCN laser with cavity length of 6 m to increase the optical resource power and (2) high response room temperature waveguide Schottky diode detectors to obtain good beat signal. The space resolution is 7 cm by the use of focusing metal mirrors mounted on the vacuum chamber and a compensated optical system. In the 2006 experiment campaign, this new interferometer has been applied for plasma density profile and density sawtooth measurement.     

电磁机构三维动态特性测试及数据处理与分析

为寻求电器电磁机构动态过程的规律,提出一种单相机三维测试新方法,将单台高速摄像机和光学成像系统相结合,对电磁机构进行了三维动态特性测试,通过图像处理得到电磁机构三维动态特性曲线.对三维动态特性测试数据样本函数的最佳估计值和不确定度等重要特征量进行分析,研究了测试引起的不确定度与测试次数的关系,根据不确定度的变化趋势确定了样本容量.利用数理统计的方法对多组三维动态特性测试数据进行了处理,分析了电磁机构的三维动态特性.研究结果表明利用三维动态特性测试和数据处理方法,能够有效地分析电磁机构三维运动过程和机构运动分散性,为电器产品的优化设计和工艺改进提供依据.     

A general-purpose microcomputer program for stereological data collection and processing

The paper describes a program, written in BASIC and designed to run on a microcomputer, to collect and process point-counting stereological data. It allows flexible equation construction using basic stereological formulae.     

A pneumatic injector of deuterium pellets for the TORE-SUPRA tokamak

A pneumatic injector for periodic injection of fuel—solid-deuterium pellets—into the plasma of the TORE-SUPRA tokamak in a steady-state mode is described. Injection of deuterium pellets with an unlimited duration is ensured by a screw extruder in which gaseous deuterium is frozen and squeezed outwards in the form of a rod with a rectangular cross section. A cutter installed on the injector’s barrel cuts a cylinder with a diameter of 2 mm and a length of 1.0–3.5 mm out from this rod. The movement of the cutter is controlled by a pulsed electromagnetic drive at a pulse repetition rate of 10 Hz. In the injector’s barrel, a compressed gas accelerates a deuterium pellet to a velocity of 100–650 m/s.     

A prototype of the centrifugal pellet injector for the ITER tokamak

A continuous action injector of solid hydrogen pellets with a centrifugal accelerator and a screw extruder is described. Over a long period of time (>3 h), the injector is capable of continuously forming with a 1-Hz frequency solid hydrogen pellets ～2.5 mm in diameter and accelerating them to a velocity of 100–500 m/s with a reliability of >95%. The characteristics of the injector meet the requirements to the ITER tokamak.     

A system for measuring the electromagnetic characteristics of the KTM tokamak

A system for measuring electromagnetic characteristics of the KTM tokamak physical setup with the magnetic thermal insulation of plasmas includes primary signal-processing modules, interface converters, and data recording unit. When the input signal varies from ?300 to +300 V in a 0-to 500-kHz frequency band, the reduced error of channels measuring signals from sensors is 1.5%. The system uses a channel-by-channel galvanic decoupling for protecting the equipment. The throughput of the digital data transmission channels is 100 Mbit/s per channel. The system is intended for operation with 160 measuring channels.     

Application of principal component analysis in dynamic thermal testing data processing

The principles and features of the application of statistical principal component analysis (PCA) in active thermal testing are considered. A comparison between PCA and Fourier analysis in finding defects in composite materials, detecting corrosion in aluminum, and determining moisture content in construction materials is performed. It is concluded that, generally, images of principal components increase the signal-to-noise ratio and are close in performance to phase diagrams; nevertheless, the results of this method are poorly predictable and require further analysis.