Neutron analysis of the ITER vertical neutron camera

The neutron fields in the collimators of a new design for the vertical neutron camera (VNC) of the ITER have been calculated for a standard isotropic bulk DT neutron source. The neutron and gamma-ray spectra and flux densities at the neutron detector sites have been calculated. The signal-to-background ratio of VNC detectors (²³⁸U-based fission chambers and diamond detectors) has been estimated. The signal-to-background ratios versus the threshold energy were calculated for the diamond detectors operating in the threshold counter mode. The effect of background Γ-ray radiation on the performance of the diamond detectors in the VNC environment has been estimated. The radiation heating of the VNC structural components has been calculated. The serviceability of the VNC with the proposed design has been demonstrated.     

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.     

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.     

Progress toward the development and testing of source reconstruction methods for NIF neutron imaging

Development of analysis techniques for neutron imaging at the National Ignition Facility is an important and difficult task for the detailed understanding of high-neutron yield inertial confinement fusion implosions. Once developed, these methods must provide accurate images of the hot and cold fuels so that information about the implosion, such as symmetry and areal density, can be extracted. One method under development involves the numerical inversion of the pinhole image using knowledge of neutron transport through the pinhole aperture from Monte Carlo simulations. In this article we present results of source reconstructions based on simulated images that test the methods effectiveness with regard to pinhole misalignment.     

Application of the trial-and-error method for solving the inverse radon problem for ITER neutron tomography

A method for solving the inverse 2D Radon problem for a single temporal cross section as applied to the two-aspect-angle ITER neutron tomographic detection system is described. This method allows reduction of the calculation time owing to the formation of the reconstructed image described by models that are as simple as possible in the case of a single plasma filament (a spatial density distribution of the plateau, hill, crater, and banana type). These models are reduced to the approximation of the solution in the form of a superposition of two elliptic Gaussian curves (or the sum of an arbitrary number of circular Gaussian curves).     

Irradiation tests of ITER candidate Hall sensors using two types of neutron spectra

We report on irradiation tests of InSb based Hall sensors at two irradiation facilities with two distinct types of neutron spectra. One was a fission reactor neutron spectrum with a significant presence of thermal neutrons, while another one was purely fast neutron field. Total neutron fluence of the order of 10(16)?cm(-2) was accumulated in both cases, leading to significant drop of Hall sensor sensitivity in case of fission reactor spectrum, while stable performance was observed at purely fast neutron spectrum. This finding suggests that performance of this particular type of Hall sensors is governed dominantly by transmutation. Additionally, it further stresses the need to test ITER candidate Hall sensors under neutron flux with ITER relevant spectrum.     

基于模块化设计的ITER真空室中子屏蔽结构组件数字化

ITER真空室中子屏蔽结构为多组件结构体.根据真空室双层壳体之间的空间结构和平面结构特征,运用模块化设计概念和相关的CAD设计软件,提出了基于位置特征和结构特征的零件标签设定方法,并将设计信息库、屏蔽组件实体库及其结构仿真形成一个完整的数字化设计系统,并发展了虚拟装配技术.结果,建立了可供编辑管理的数据信息库和实体模型库.实现了设计过程的信息化和设计结果的数字化,为今后其他大型、复杂装置的多零件系统产品数字化提供了一个很好的范例.     

中子照相技术及其应用

本文简述中子照相的原理、方法和特征。包括中子源 ,中子转换屏 ,中子成像技术等关键技术。给出在 4 5MV静电加速器上快中子照相的结果。并概述中子照相技术的一些应用实例     

客车车身结构概念设计中的优化分析

通过对客车车身概念开发阶段有限元优化分析的作用和特点的研究,可以利用参数化分析模型进行早期结构方案优化分析,并针对实例客车概念开发,以提高整车刚度、降低车身骨架自重为目的,进行优化分析的应用研究.优化结果对于客车概念开发阶段的方案确定及后续车身结构详细设计具有重要参考.     

中子衍射应力谱仪垂直聚焦单色器的优化设计

为提高应力谱仪样品处的中子注量率,对垂直聚焦单色器进行了优化设计.应用蒙特卡罗模拟程序MCSTAS对中子衍射应力谱仪的垂直聚焦Ge(511)单色器进行优化计算,得到了垂直聚焦单色器的高度与单晶片之间的倾角等参数的最佳值.然后,对比分析了在垂直聚焦单色器与平板单色器两种情况下样品处的中子注量率.最后,讨论了单色器起飞角对谱仪分辨率的影响.计算结果表明:单色器尺寸为50 mm×150 mm;垂直单色器在样品台中心位置的中子注入量是平板单色器的4.99倍,表明利用垂直单色器可以显著提高应力谱仪样品处的中子注量率.     

A conceptual development of novel ultra-precision dimensional measurement technology

This research explores the unique physical phenomenon of electrical output versus displacement of a potentiometer with the view of nano-scope. Based on the interesting characters of the phenomenon, a novel conceptual development of ultra-precision dimensional measurement technology is carried out. As an example, a potentiometer and a stack of piezoelectric elements are adopted to build a dual-stage ultra-precision measurement instrument. The theoretical error analysis with the research demonstrates that an instrument developed with this novel ultra-precision dimensional measurement technology is able to achieve low double-digital nanometer absolute measurement accuracy over a large dimensional range.     

垂直轴风力机应用概况及其展望

水平轴风力机是当今应用最广的一种风力机,垂直轴风力机也有着自身优越的性能,并越来越被人们所重视。介绍垂直轴风力发电机与水平轴风力发电机的优缺点,以及垂直轴风力机的最新应用及其发展趋势。     

民用飞机概念设计中客舱布置的工具开发

客舱布置是民用飞机设计的重要内容,对飞机的安全性、经济性和舒适性有重要影响。根据适航条例中对客舱座椅、应急出口和过道分布等的规定,总结出了一套客舱快速布置的方法,并应用MATLAB编程技术开发了一个具有良好用户界面的设计工具。算例验证表明,该设计工具可实现快速的客舱布置方案设计,且设计结果与参考机型基本一致。     

协同概念设计中的管理技术与系统开发

概念设计是产品开发过程的一个重要环节,为支持网络环境下的协同概念计,本文在分析异地协同概念设计过程的基础上,提出了一种支持并行工程的对产品概念设计过程进行管理的软件系统框架,并对其中的用户管理、基于实例的求解过程管理以及网上协作过程的管理作了进一步的分析,初步构造了一个可行的并行化的功能驱动的概念设计过程管理机制。     

全自动立式胀管机研制

介绍了空调器换热器生产线专机全自动立式胀管机的研制,论述了这种胀管机的结构与特点及其关键部件的处理方法,并对这种胀管机的运行情况进行了分析     

夹紧功能原理方案设计目录的研究

研制了实现夹紧功能的原理方案设计目录，详细分析了该设计目录的各组成部分，并提供了应用实例。该目录为夹具设计自动化提供了辅助工具。     

Thomson scattering diagnostic systems in the ITER divertor

A diagnostic array has been developed for studying the operating modes of the divertor in the ITER tokamak-reactor using the Thomson scattering technique. The aim of this study is to measure the spatial profiles of the electron temperature and density. The structure of the diagnostic setup was selected on the basis of a classical diagnostic geometry and the high-resolution LIDAR system, which provide access to different regions of the divertor plasma. A severe radiation environment, limited access to the plasma in the ITER divertor, and a high-dust environment (the divertor plate erosion material) in the divertor volume pose many problems for performing diagnostics under unique conditions having no analogs in the tokamaks that are now in operation. Different methods for protecting optical surfaces from plasma-enriched deposition are proposed and analyzed. The efficiency of these methods has been demonstrated in bench tests. The concept of laser and detector systems and diffraction polychromators capable of operating at different electron temperatures with a lower limit of 1 eV, has been justified and approved.     

Diagnostics of the ITER neutral beam test facility

The ITER heating neutral beam (HNB) injector, based on negative ions accelerated at 1 MV, will be tested and optimized in the SPIDER source and MITICA full injector prototypes, using a set of diagnostics not available on the ITER HNB. The RF source, where the H(-)∕D(-) production is enhanced by cesium evaporation, will be monitored with thermocouples, electrostatic probes, optical emission spectroscopy, cavity ring down, and laser absorption spectroscopy. The beam is analyzed by cooling water calorimetry, a short pulse instrumented calorimeter, beam emission spectroscopy, visible tomography, and neutron imaging. Design of the diagnostic systems is presented.     

Optimization studies of the ITER low field side reflectometer

Microwave reflectometry will be used on ITER to measure the electron density profile, density fluctuations due to MHD/turbulence, edge localized mode (ELM) density transients, and as an L-H transition monitor. The ITER low field side reflectometer system will measure both core and edge quantities using multiple antenna arrays spanning frequency ranges of 15-155 GHz for the O-mode system and 55-220 GHz for the X-mode system. Optimization studies using the GENRAY ray-tracing code have been done for edge and core measurements. The reflectometer launchers will utilize the HE11 mode launched from circular corrugated waveguide. The launched beams are assumed to be Gaussian with a beam waist diameter of 0.643 times the waveguide diameter. Optimum launcher size and placement are investigated by computing the antenna coupling between launchers, assuming the launched and received beams have a Gaussian beam pattern.     

Development of in-vessel components of the microfission chamber for ITER

Microfission chambers (MFCs) will measure the total neutron source strength in ITER. The MFCs will be installed behind blanket modules in the vacuum vessel (VV). Triaxial mineral insulated (MI) cables will carry signals from the MFCs. The joint connecting triaxial MI cables in the VV must be considered because the MFCs and the MI cables will be installed separately at different times. Vacuum tight triaxial connector of the MI cable has been designed and a prototype has been constructed. Performance tests indicate that the connector can be applied to the ITER environment. A small bending-radius test of the MI cable indicates no observed damage at a curvature radius of 100 mm.