超低温环境下光纤布里渊频移特性研究

针对高温差和超低温广泛存在的空间环境，了解航天器材料及结构的热应变稳定性对于保障航天环境模拟地面试验的可靠性具有重要意义。布里渊光时域分析（BOTDA）技术能够同时检测温度和应变，且具有高精度、长传感距离、抗电磁干扰及低成本等优势，但作为传感元件的光纤能否适应空间冷黑环境还未可知。文章首先利用BOTDA解调仪获取了2种典型标准单模光纤在超低温下的布里渊增益谱（BGS），然后通过实验数据分析光纤的超低温性能，最终标定了2种光纤的温度和应变系数。结果表明，受试光纤在超低温下仍能形成洛伦兹形状的BGS，且实际频移量与低温对应的理论频移量一致，满足超低温空间环境下BOTDA传感器的测温范围要求。     

Space optical payloads, new application area for high temperature composites

High temperature composites have been extensively developed in order to produce thermal protection systems of reusable re-entry vehicles and launchers. This development effort covers all aspects including sizing, design, manufacturing processes characterization, non destructive inspection, and all industrial facilities which have also been installed. Strong interest recently appeared for these materials to meet requirements for different space applications. In particularly, for more stringent optical payloads, new materials with high performance requirements have appeared. In the field of high dimensionally stable structures for telescopes, materials have to meet severe requirements, such as low coefficients of thermal expansion, good specific modulus, long-term stability (moisture and chemical insensitivity), etc. Carbon/carbon (C/C) composites can meet these specifications. To demonstrate this capability a structure has been designed, manufactured and will be submitted for complete testing (work supported by ESA/ESTEC). The main available results (part feasibility, characterizations, analysis and stability performance budgets) are presented. For future telescope mirrors, silicon carbide is already known as a good candidate. However, an innovative concept based on silicon carbide sandwich honeycomb technology, which allows optimized design, has been developed. The first characterization results and manufacturing capabilities are presented.     

光纤光栅光谱异常模式判别和自适应分段拟合在温度标定中的应用

针对空间真空和温度交变环境下光纤光栅（fiber Bragg grating, FBG）反射光谱工作模式识别困难以及测温精度不足的问题,提出一种FBG反射光谱异常模式判别方法,并对所获取的波长?温度曲线进行自适应分段拟合。实验结果表明:在大气常温与高真空热环境下,该方法对于FBG反射光谱异常模式的识别准确;波长?温度自适应分段拟合残差分别为0.052 126和0.017 083,满足空间真空热环境下FBG传感器的测温精度要求。     

Analysis of a crossed Bragg cell acousto-optical spectrometer for SETI

The search for radio signals from extraterrestrial intelligent beings (SETI) requires the use of large instantaneous bandwidth (500 MHz) and high resolution (20 Hz) spectrometers. Digital systems with a high degree of modularity can be used to provide this capability, and this method has been widely discussed. Another technique for meeting the SETI requirement is to use a crossed Bragg cell spectrometer as described by Psaltis and Casasent. This technique makes use of the Folded Spectrum concept, introduced by Thomas. The Folded Spectrum is a 2-D Fourier Transform of a raster scanned 1-D signal. It is directly related to the long 1-D spectrum of the original signal and is ideally suited for optical signal processing. The folded spectrum technique has received little attention to date, primarily because early systems made use of photographic film which are unsuitable for the real time data analysis and voluminous data requirements of SETI. An analysis of the crossed Bragg cell spectrometer is presented as a method to achieve the spectral processing requirements for SETI. Systematic noise contributions unique to the Bragg cell system will be discussed.     

空间伸展臂热应变与热变形光纤监测技术

针对空间伸展臂在热载荷作用下承载特性与形态变化的监测需求,提出了一种基于分布式光纤传感器的伸展臂结构温度、热应变以及热变形集成监测技术。借助ANSYS Workbench有限元分析软件,构建了单端热载荷作用下铝合金空间伸展臂结构热-力模型,分别得到不同局部热载荷下伸展臂轴向温度、热应变以及热变形分布与变化规律。在此基础上,提出了基于有限元分析与热传导理论的两类伸展臂轴向热变形计算方法。构建了分布式光纤传感监测系统,实时监测伸展臂若干关键位置的温度值与应变值,进而反演出结构轴向温度场、应变场连续变化信息。研究表明:采用有限元拟合法与热传导解析法计算所得伸展臂轴向热变形误差分别为5.256%与3.556%。相关成果能够为未来航天器在轨服役状态监测与辨识提供技术支撑。     

复合材料压力容器在航天领域的应用研究

综述了复合材料压力容器在航天领域的最新应用进展,列举了国外空间系统应用的几个典型实例,从金属内衬、纤维材料及树脂基体方面给出了比较重要的技术信息.论述了低温复合材料压力容器的研发与应用趋势,金属内衬和缠绕纤维在低温环境下的性能表现优异及低温环境下树脂基体的选择.探讨了复合材料压力容器无损检测方法的研究现状及展望.未来复合材料压力容器无损检测技术将向着高效实时、精确定位、定量分析及由局部缺陷检测向整体缺陷检测的方向发展.     

大型空间展开机构常压高低温环境模拟试验系统研制

为各类大型空间展开机构地面可靠性验证试验提供高低温环境,研制了一种常压高低温环境模拟试验系统。该系统的保温箱体结构采用内、外框架的结构形式,内、外框架之间的连接采用绝热玻璃纤维增强复合塑料杆,其目的是:在进行大温差高低温交变环境试验时,有助于结构的热边界条件稳定;合理的气流组织布局设计有助于内部高低温环境的快速建立,使温度分布更加均匀;冷热源供给系统可稳定地提供高低温环境建立所需冷量及热量;干燥氮气置换系统可实现高低温环境下的超低露点温度;基于PLC的测控系统对试验系统进行高精度测量及控制。试验表明,此大型空间展开机构常压高低温环境模拟试验系统能满足型号产品试验过程中对温度范围、变温速率、温度场均匀性及露点温度的要求。     

空间与环境探测星载高速光纤数据总线

随着空间与环境探测技术的快速发展，对空间与环境探测星载总线的信息带宽、码速率、可靠性以及容错能力等提出了很高的要求。根据国内外光纤总线技术的发展水平，研究分析了空间光纤数据总线的拓扑结构、模块功能、数据链路层特点和冗余方案。结果表明，此空间光纤数据总线数据处理速度可达到1．458Gbit／s，能够有效提高信息实时处理能力，为空间与环境探测卫星提供一种高可靠性、容错能力强的光纤总线。     

基于氢化镁的核电/核热双模共质空间核动力技术

针对未来空间任务对能源和动力日益提高的需求,提出了基于氢化镁的核电核热双模共质空间核动力技术。该技术以一种储氢密度高、热稳定性较好,能够以常温常压储存的氢化镁作为工质,通过核能加热后氢化镁分解成为核热推进可用的高压氢气和电推进可用的单质镁,并结合高效动态热电转换系统,形成大功率核电源、大功率超高比冲核电推进、高比冲氢气核热推进以及大推力镁核热推进多种工作模式。基于氢化镁的多模共质空间核动力技术解决了低温推进剂、气态工质在空间应用时的存储安全性和存储密度低的问题,其具备的多种工作模式能够针对不同任务需求提供相应的能源或者动力输出,提高核动力飞行器任务能力。     

采用MPPT技术的国外深空探测器电源系统综述

最大功率点跟踪（MPPT）技术能够最大限度利用太阳电池阵输出功率,对于光强和温度变化较大的深空探测器,具有一定的优势。对MPPT电源系统拓扑结构及其在国外深空探测领域的典型应用,如＂罗塞塔＂（Rosetta）、＂信使＂（MESSENGER）探测器电源系统等,进行了调研和综述,分析了3种MPPT拓扑结构的特点,并指出光强、温度等空间环境因素,以及负载特性、系统稳定性对电源系统的影响,可为MPPT技术在我国深空探测器电源系统设计中应用提供参考。     

Space light: space industrial enhancement of the solar option

The solar option can be enhanced significantly by space light technology. Reflectors in suitable orbits beam to Earth measured amounts of sunlight, the most versatile and bio-compatible energy source. The multitude of space light functions ranges from night illumination of rural and urban areas (by Lunetta systems) to photosynthetic production enhancement for the growth of food and of biomass for conversion to chemical fuels, local agricultural irradiation for crop drying and weather stabilization and to electric power generation by irradiating suitable photovoltaic or thermal ground receivers at night or by adding to the natural solar energy input during daytime (Soletta systems).

The Lunetta and Soletta concepts, developed by the author during the past ten years, building on the foundations laid by the great space pioneer Prof. H. Oberth (1928), are reviewed, along with their socio-economic merits. An assessment of terrestrial alternatives shows that many useful functions have no practical alternative, the major exception being electric power generation. Three systems are selected, bracketing the broad versatility of space light—Lunetta, Powersoletta and a large Biosoletta for large-scale seafood production in Antarctic and Artic waters. The systems, and several maintenance and supply requirements are described, sized and analyzed, along with suitable orbit selection for different applications. Models are developed for rural and urban area lighting, power generation at selected sites around the globe with photovoltaic and thermal ground stations and for the large-scale production of seafood at high southern and northern latitudes with ample nutrient upwell, but insufficient annual supply of solar energy. The economics of these systems is analyzed.     

平面光栅的偏振特性分析

平面光栅作为一种重要的光学元件,被广泛应用于声光学,全息光学及光谱学领域,在高辐射灵敏度的光学遥感系统中,系统对偏振灵敏度的要求也很高,这就需要对光栅的衍射效率及偏振特性做详细的研究,文中利用严格耦合波分析法讨论了光栅的偏振特性,并给出了平面光栅的偏振矩阵。     

空间数据系统发展的三个阶段

提出把空间数据系统的发展历程分为三个阶段：第一阶段是面向信道传输,主要解决数据如何在空间链路上有效可靠传输;第二阶段是面向数据源,主要解决如何自适应不同数据源的传输要求。这两个阶段的技术已经成熟并应用。文章预测,空间数据系统将走上第三阶段,即面向数据用户的体制,到那时用户可以根据自己的需求,主动从空间分布式数据库中获取数据。文章重点阐述了第三阶段的新概念设想,它的第一步是云遥测,然后进一步建成支持交互的空间云数据系统。     

卫星流体回路技术的动态热模型与仿真

文章通过合理的分析与简化,建立了一个包括各热组件模型、受控对象模型以及控制系统模型的系统动态热模型,并建立了仿真程序,仿真结果表明:应用这一模型可以十分简便地计算卫星内部热源及空间外热流变化时的单相流体回路系统的温度变化趋势。该动态热模型还可用于对新型控制策略做进一步的研究,指导工程设计。     

Shuttle demonstration of large space structure fabrication and assembly

The purpose of this paper is to describe a program aimed at an early on orbit demonstration of a large space structure fabrication and assembly capability. Requirements for the demonstration concept have been formulated. The concept that has been selected to meet these requirements is a Large Space Structure Platform consisting of a triangular prism of 31.5 m length. Sensors can be mounted on this platform to perform Earth observation measurements from space. Structural elements of the platform are fabricated using an automated beam builder in the Shuttle Orbiter payload bay. Special fixtures are designed to assemble the structure with the aid of the Remote Manipulator System and two astroworkers in an EVA mode. Results are shown of the platform preliminary design in terms of a design layout with related structural, thermal, mass properties and control dynamics data. The assembly scenario is described. Estimates of the total construction time and Orbiter support requirements are also presented.     

Reliability analysis and utilization of PEMs in space application

More and more plastic encapsulated microcircuits (PEMs) are used in space missions to achieve high performance. Since PEMs are designed for use in terrestrial operating conditions, the successful usage of PEMs in space harsh environment is closely related to reliability issues, which should be considered firstly. However, there is no ready-made methodology for PEMs in space applications. This paper discusses the reliability for the usage of PEMs in space. This reliability analysis can be divided into five categories: radiation test, radiation hardness, screening test, reliability calculation and reliability assessment. One case study is also presented to illuminate the details of the process, in which a PEM part is used in a joint space program Double-Star Project between the European Space Agency (ESA) and China. The influence of environmental constrains including radiation, humidity, temperature and mechanics on the PEM part has been considered. Both Double-Star Project satellites are still running well in space now.     

基于无源光网络的高速光纤总线技术研究

随着航天遥感类载荷性能的提高,其数据量大幅增加,对高速数据传输提出了更高要求.针对航天环境的高可靠性要求,提出了一种基于命令响应式协议的新型高速光纤总线结构,即把无源光网络技术与FC-AE-1553协议相结合,采用高生存性的逆向双环的冗余拓扑结构搭建了地面演示验证系统.实验表明,新的光纤总线系统通信速率可达2.5Gbps,容易隔离失效节点,所用设备简单,可靠性高,满足航天工程应用需求,具有较强的实用价值.     

光纤法布里-珀罗传感器及其高温应用

随着航天技术不断发展，大推力运载火箭等精细化设计需求日益增加，飞行器高温工况结构及流场状态感知已成为当前研究的关键环节。基于法布里-珀罗干涉结构的光纤传感器在高温、高压、狭小空间等特殊环境展现出独特优势，被视为下一代高温原位测量工具。介绍了法布里-珀罗传感器的基本结构及原理，并分别从温度、应变和压力监测方面介绍了法布里-珀罗高温传感技术研究进展以及未来的发展趋势。基于石英光纤的法布里-珀罗传感器能够应用于1000°C以下环境，对于1000°C以上环境，需要以蓝宝石光纤作为敏感元件和传光介质。     

碳纤维复合材料贮箱内压和低温承载行为研究

碳纤维增强聚合物复合材料具有轻质高强的优异特性,是液氢液氧燃料贮箱的理想材料。然而液氢液氧燃料贮箱在服役时要承受极低温度载荷,复合材料贮箱箱体的低温结构可靠性尚未可知。开展了碳纤维/环氧复合材料缠绕贮箱结构在温度和内压载荷下的变形及损伤研究,分别进行了常温/低温抗渗漏测试,结合应变测量、声发射监测、氦质谱检漏等方法分别研究了内压以及低温工况对复合材料贮箱的应变分布及损伤泄漏状态影响机制。研究结果表明,封头与圆筒区域交界处易产生应变集中,低温载荷导致复合材料局部小幅度基体损伤及纤维/基体界面脱粘,但并未影响贮箱箱体承压性能和气密性。本研究可为未来大型航天器减质设计提供参考。     

用碳纤维复合材料制造轻型空间光学镜面

用碳纤维复合材料可以制造轻型空间光学镜面结构 ,如哈勃类空间望远镜的镜面或高带宽广播通信卫星的天线反射器等。文章根据国外几十年成型工艺的经验 ,概要介绍了空间光学镜面的要求 ,阐明了利用碳纤维复合材料通过选材设计、工艺技术控制等来满足这些要求。