A comparative analysis of the sensitivity of CsI (Tl), ZnO(Ga), and YAG(Ce) scintillators to the plasma background radiation under operating conditions of the ITER tokamak reactor

Problems related to neutral particle flux measurements on the ITER tokamak reactor under intense plasma background radiation conditions are considered. The results of measuring a background sensitivity with respect to neutron and γ-radiation for the scintillation detector, which is based on three different crystals (CsI (Tl), ZnO(Ga), and YAG(Ce)), are presented. The scintillators are compared and conclusions about the possibility of their applications in detectors of neutral particle analyzers currently created at the Ioffe Institute for the ITER tokamak reactor, are drawn.     

基于虚拟仪器技术的彩电白平衡测试系统

虚拟仪器是当今仪器仪表发展的趋势 ,根据硬件结构、总线结构、开发平台的不同 ,虚拟仪器系统有一套典型开发步骤和系统构建方式。介绍了基于虚拟仪器技术的彩电白平衡测试系统的设计 ,给出了它的硬件构成原理 ,用 VC+ + 作为软件开发平台的设计方法及此系统的特点。     

液压伺服式减振器试验台测控系统设计与开发

为提高油压减振器的制造与检修质量,研制开发新型油压减振器,迫切需要稳定性好、精度高的新型油压减振器试验台。该文简单介绍了新研制的液压伺服式减振器试验台,并结合此类试验台重点介绍了测控系统的原理、硬件设计、软件开发,对在WINDOWS系统中如何精确定时、数字滤波等问题进行了深入研究,解决了如何基于WINDOWS开发实时系统的关键问题。     

Digital-signal-processor-based dynamic imaging system for optical tomography

In this article, we introduce a dynamic optical tomography system that is, unlike currently available analog instrumentation, based on digital data acquisition and filtering techniques. At the core of this continuous wave instrument is a digital signal processor (DSP) that collects, collates, processes, and filters the digitized data set. The processor is also responsible for managing system timing and the imaging routines which can acquire real-time data at rates as high as 150 Hz. Many of the synchronously timed processes are controlled by a complex programmable logic device that is also used in conjunction with the DSP to orchestrate data flow. The operation of the system is implemented through a comprehensive graphical user interface designed with LABVIEW software which integrates automated calibration, data acquisition, data organization, and signal postprocessing. Performance analysis demonstrates very low system noise (approximately 1 pW rms noise equivalent power), excellent signal precision (<0.04%-0.2%) and long term system stability (<1% over 40 min). A large dynamic range (approximately 190 dB) accommodates a wide scope of measurement geometries and tissue types. First experiments on tissue phantoms show that dynamic behavior is accurately captured and spatial location can be correctly tracked using this system.     

激光数字化仿形测量与加工系统

简要阐述激光数字化仿型测量与加工系统的基本原理以及在数控加工中心上的实现方法,探讨实现激光数字化仿型测量系统的软硬件条件、部分硬件电路以及集成方式。实践表明,激光数字化仿型测量与加工系统在机械制造领域有着良好的应用前景。     

A conceptual project for a divertor monitor of the neutron yield in the ITER

The operating conditions of a neutron diagnostic system responsible for measuring the neutron yield in the ITER tokamak reactor are analyzed. Based on results of physical calculations and analysis of suitable methods for measuring the neutron yield, an original concept of a system for measuring neutron fluxed in the divertor zone of the ITER is proposed. The design for the neutron flux monitor located in the divertor zone of the tokamak is selected in view of the requirements specified for the neutron diagnostic system of the ITER and its operating conditions. Four fission chambers with different sensitivities and radiator materials are used as sensitive elements of the monitor. This system is capable of measuring neutron fluxes over the entire dynamic range of the neutron yield in the ITER with an error of ≤10% and a time resolution of 1 ms that are necessary for studying the physical mechanism of thermonuclear plasma ignition and burning. Several possible variants for housing the detector unit inside the divertor assembly and integrating it in the existing project are proposed. The problems of carrying out efficiency calibration of the divertor neutron monitor with the aim of determining the absolute value of the neutron yield in the ITER tokamak reactor are discussed.     

Tritium plasma experiment: parameters and potentials for fusion plasma-wall interaction studies

The tritium plasma experiment (TPE) is a unique facility devoted to experiments on the behavior of deuterium/tritium in toxic (e.g., beryllium) and radioactive materials for fusion plasma-wall interaction studies. A Langmuir probe was added to the system to characterize the plasma conditions in TPE. With this new diagnostic, we found the achievable electron temperature ranged from 5.0 to 10.0 eV, the electron density varied from 5.0 × 10(16) to 2.5 × 10(18) m(-3), and the ion flux density varied between 5.0 × 10(20) to 2.5 × 10(22) m(-2) s(-1) along the centerline of the plasma. A comparison of these plasma parameters with the conditions expected for the plasma facing components (PFCs) in ITER shows that TPE is capable of achieving most (～800 m(2) of 850 m(2) total PFCs area) of the expected ion flux density and electron density conditions.     

Diamagnetic flux measurement in Aditya tokamak

Measurements of diamagnetic flux in Aditya tokamak for different discharge conditions are reported for the first time. The measured diamagnetic flux in a typical discharge is less than 0.6 mWb and therefore it has required careful compensation for various kinds of pick-ups. The hardware and software compensations employed in this measurement are described. We introduce compensation of a pick-up due to plasma current of less than 20 kA in short duration discharges, in which plasma pressure gradient is supposed to be negligible. The flux measurement during radio frequency heating is also presented in order to validate compensation.     

An equivalent time temperature mapping system with a 320 x 256 pixels full-frame 100 kHz sampling rate

In this paper we describe a novel temperature mapping system based on a standard infrared camera with 50 Hz frame rate for the measurement of ultrafast temperature transients which, in principle, demand for a much faster acquisition rate. In particular, we base our system on the widely used equivalent time sampling concept which can be adapted to the temperature acquisition system, thanks to a very fast and sensitive camera sensor: an InSb sensor, which allows a reduced integration time of 10 micros, and a custom digital synchronization circuit. The latter has been realized by the usage of a fully programmable digital circuit, which generates all the signals needed for the synchronization of the IR camera, of the experiment, and a personal computer needed for data acquisition and storage. We show, with experiments, how this system is capable of detecting temperature transients with an equivalent bandwidth of 100 kHz full frame, far beyond the capabilities of the fastest available IR cameras.     

Strategy for the absolute neutron emission measurement on ITER

Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement subsystem, cross calibration among them, and in situ calibration are needed. Neutron transport calculation shows the suitable calibration source is a DT/DD neutron generator of source strength higher than 10(10)?n/s (neutron/second) for DT and 10(8)?n/s for DD. It will take eight weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.     

Active spectroscopic measurements using the ITER diagnostic system

Active (beam-based) spectroscopic measurements are intended to provide a number of crucial parameters for the ITER device being built in Cadarache, France. These measurements include the determination of impurity ion temperatures, absolute densities, and velocity profiles, as well as the determination of the plasma current density profile. Because ITER will be the first experiment to study long timescale (～1?h) fusion burn plasmas, of particular interest is the ability to study the profile of the thermalized helium ash resulting from the slowing down and confinement of the fusion alphas. These measurements will utilize both the 1 MeV heating neutral beams and a dedicated 100 keV hydrogen diagnostic neutral beam. A number of separate instruments are being designed and built by several of the ITER partners to meet the different spectroscopic measurement needs and to provide the maximum physics information. In this paper, we describe the planned measurements, the intended diagnostic ensemble, and we will discuss specific physics and engineering challenges for these measurements in ITER.     

Work function measurements during plasma exposition at conditions relevant in negative ion sources for the ITER neutral beam injection

Cesium seeded sources for surface generated negative hydrogen ions are major components of neutral beam injection systems in future large-scale fusion experiments such as ITER. The stability and delivered current density depend highly on the work function during vacuum and plasma phases of the ion source. One of the most important quantities that affect the source performance is the work function. A modified photocurrent method was developed to measure the temporal behavior of the work function during and after cesium evaporation. The investigation of cesium exposed Mo and MoLa samples under ITER negative hydrogen ion based neutral beam injection relevant surface and plasma conditions showed the influence of impurities which result in a fast degradation when the plasma exposure or the cesium flux onto the sample is stopped. A minimum work function close to that of bulk cesium was obtained under the influence of the plasma exposition, while a significantly higher work function was observed under ITER-like vacuum conditions.     

Charged fusion product loss measurements using nuclear activation

In ITER, α particle loss measurements will be required in order to understand the alpha particle physics. Techniques capable of operating in a fusion reactor environment need further development. Recent experimental studies on JET demonstrated the potential of nuclear activation to measure the flux of escaping MeV ions. New results from MeV ion induced activation of metallic, ceramic, and crystal samples placed near the plasma edge are reported. Activation products were measured as function of orientation with respect to the magnetic field as well as function of the distance to the plasma. Sample activity was measured using ultralow-level gamma-ray spectrometry. Distribution of 14.68 MeV fusion proton induced activation products is strongly anisotropic in agreement with simulations and falls off sharply with increasing distance to the plasma. Prospects for using the technique in ITER are discussed.     

基于灰度值的非对称等离子体弧形貌的三维重建

等离子体加工技术在处理各类难加工材料的成形与制备方面备受关注,其温度特性是影响加工质量的决定性因素。针对现有温度特性研究大多在弧径向对称的假设前提下间隔采样测量完成的问题,提出了一种基于灰度值的非对称等离子体弧形貌三维重建方法。首先,基于自行设计的图像采集系统,给出了CCD空间布置方案,同步获取了360°方向上加工过程中的等离子体弧数字图像;然后,对采集图像进行了灰度化、直方图均衡化、滤波去噪以及灰度等值线提取等预处理,以获得良好的视觉场和测量效果;最后,取内六层灰度等值线进行了基于立体匹配和插值重构的数值模拟,建立了与温度场存在相关性的等离子体弧形貌三维模型。研究结果定性地描述了等离子体弧温度场的分布情况,实现了等离子体弧形貌的非接触测量,得到了加工过程中等离子体弧的真实形貌。     

智能化血液粘度测试系统设计

介绍了一种基于数字图像处理的智能化血液粘度测试系统设计方法,详细分析了该测试系统的各个组成部分以及设计原理。系统采用了一体化系统设计思想,将在显微镜下的血液细胞样片通过光学系统处理后进行图像采集,经过数字图像处理后得出检测结果。并结合血液细胞采集样本特性提出了一种新的边缘检测算法,提高了系统数据分析效率。     

一种数字语音存放系统的设计

介绍了一种基于语音专用压缩硬件进行语音编解码的数字化语音存储与回放系统的设计，阐述了系统的硬件、软件设计及其功能与工作过程，适合于多个领域应用。     

Pulse-signal digitizer for high-temperature plasma diagnostic systems

A pulse-signal digitizer for laser, neutron, and gamma diagnostics of high-temperature plasma at the GOL-3 and GDL (Budker Institute of Nuclear Physics Siberian Branch, Russian Academy of Sciences) is described. The architecture of a two-channel 12-bit ADC12500PXIe digitizer with a sampling rate of 500MHz, a PXI Express interface, and a built-in reconfigurable digital signal processing unit is described. The results of ADC12500PXIe metrological tests are presented: its signal-to-noise ratio (SNR), jitter, effective number of bits, and differential and integral nonlinearities are shown. The high-temperature plasma diagnostic systems based on ADC12500PXIe are considered. The structure of the digital signal processing unit that was modified for a prototype of the ITER vertical neutron camera (Cadarache, France) is described.     

Development of two-channel prototype ITER vacuum ultraviolet spectrometer with back-illuminated charge-coupled device and microchannel plate detectors

A vacuum ultraviolet (VUV) spectrometer of a five-channel spectral system is designed for ITER main plasma impurity measurement. To develop and verify the system design, a two-channel prototype system is fabricated with No. 3 (14.4-31.8 nm) and No. 4 (29.0-60.0 nm) among the five channels. The optical system consists of a collimating mirror to collect the light from source to slit, two holographic diffraction gratings with toroidal geometry, and two different electronic detectors. For the test of the prototype system, a hollow cathode lamp is used as a light source. To find the appropriate detector for ITER VUV system, two kinds of detectors of the back-illuminated charge-coupled device and the microchannel plate electron multiplier are tested, and their performance has been investigated.     

Laser mass-spectrometry for online diagnosis of reactive plasmas with many species

The purpose of this study is to design a diagnostic system for reactive plasma environment by combining molecular-beam time-of-flight (TOF) mass spectroscopy with laser spectroscopy technique. The combination of TOF mass spectrometers and pulsed lasers is favorable in the diagnosis of intermediate species distribution since they allow the simultaneous but separate recording of the spectra of different species. In the plasma system, the intermediate species in electronic ground state or low lying excited state is pumped to higher energy level with resonant laser excitation, and then, the ionization with a second laser system is possible which can readily be detected by the TOF analyzer. The ionization itself is only used as a detection mechanism for the observation of the excitation of these states. In this manner, the population distribution of intermediate species can be determined with state-selective and mass-selective feature. Also, in this article, a flexible data acquisition and automatic control system based on LABVIEW was designed to integrate all the stand-alone measurement instruments including a TOF spectrometer, a laser system, a high performance oscilloscope, and a digital delay generator into a single personal computer-based control unit. Moreover, a virtual Boxcar integrator with hundreds of channels has been developed to enhance the signal while filtering out the random noises. Finally, the many potentials of this technique in the application of plasma diagnosis will be discussed.     

Development of laser induced fluorescence diagnostic for measuring the parameters of plasma containing rare gas species

Laser induced fluorescence (LIF) technique development activity for measurement of plasma parameters in ITER divertor plasma is described. Helium density is the task of priority, but Doppler measurement of ion (atom) temperatures is also the aim of the program. The concept of ITER scenarios includes injection of "extrinsic" impurities (Ne, Ar, and Kr). It is possible to use the species as tracing elements for measurement of T(i), T(a). The program included modeling experiments on PNX-U (a multicusp trap with microwave argon plasma). Helium was added by puffing into discharge. Temperatures T(i)(Ar(1+)) and T(a)(He(0)) have been measured by scanning laser line across absorption line of species. Summarizing of fluorescence signals provided input data for estimation of Ar(1+) and He(0) densities via interpretative collisional-radiative models. Besides, the collisional-radiative model has been used for estimation of electron density using the ratio of fluorescence signals at 388.9 and 706.5 nm helium lines.