载人火星任务带电粒子辐射探测方案与应用技术研究

为确保载人火星任务中航天员的安全,有必要搭载辐射探测器对舱内的辐射环境进行实时监测。在对载人火星任务辐射环境分析的基础上,确定了辐射探测器的测量指标并完成了基于两片硅传感器探头的探测器方案设计,包括探头设计和可变采样快门时间的采样设计。另外,针对人体组织与探测材料不同,测量数据无法直接用于航天员辐射损伤预估的问题,将人体组织近似为水,分别给出了辐射剂量、传能线密度在硅和水间的转换关系。     

载人登月航天员辐射剂量分析与防护建议

针对载人登月航天员任务全周期中可能遭受空间粒子辐射损伤的问题,从航天器辐射防护设计流程出发,梳理了国际现行航天员辐射防护要求。通过蒙特卡罗模拟程序Geant4构建皮肤、眼晶体、造血器官等效人体组织模型,并对典型载人登月任务航天员受到的辐射剂量开展量化分析。从任务设计和辐射防护设计2个层面,对我国载人登月航天员辐射防护提出建议:在不超过20天的载人登月任务期内,5 g/cm~2铝材料屏蔽下的剂量即可比NASA剂量限值小一个数量级;而如果遭遇极端太阳粒子事件,航天员防护材料可选用聚乙烯等富氢材料作为保护层,屏蔽厚度需要约30 g/cm~2。     

载人航天废弃物的空间辐射防护性能研究

针对载人深空探索中的空间辐射,特别是大规模太阳粒子事件对航天员的威胁,需要在载人航天器内建立空间辐射应急防护区,为航天员在遭遇太阳粒子事件的时候提供必要的保护。考虑热融化压实技术在降低废弃物的空间占用率、高温杀菌和回收水分的同时能在不增加额外载荷的情况下为航天员空间辐射应急防护区的建设提供材料,在载人航天废弃物模型的基础上,利用Monte Carlo方法对其热融化压实产物的质子防护能力进行了计算,结合太阳粒子事件能谱和组织器官剂量计算转换因子,对不同屏蔽条件下太阳粒子事件造成航天员组织器官剂量的变化进行了研究。结果表明,在10 g/cm~2屏蔽厚度下,皮肤、脑、心脏以及红骨髓的辐射剂量都大大降低,均在剂量限值之下;除了需要对眼采取额外的局部防护措施以外,5 g/cm~2铝屏蔽+5 g/cm~2载人航天废弃物热融化压实产物基本上可以满足对太阳粒子事件的防护需求。     

火星大气高温光谱建模与非平衡辐射热流预测

火星科学实验室成功着陆后的热环境重构数据表明，气动辐射加热在火星进入防热设计中具有不同于以往认识的重要影响，未知机制和模型不确定性等问题有待进一步研究。探测器高速进入火星大气产生极高温非平衡气动环境，造成火星气动辐射与常规CO₂红外辐射研究显著不同。针对火星大气高温光谱和辐射热流预测，首先，建立适用于火星大气的高温非平衡光谱辐射模型，获得典型高温条件CO₂光谱结构和辐射强度，与NASA和JAXA试验结果对比，结果显示符合较好。其次，依靠激波管和发射光谱测量技术，开展典型进入条件的辐射强度测量试验，数值结果、试验值和NASA试验结果相互符合较好，验证了光谱模型。最后，对探路者号进行气动辐射加热分析，完成典型进入条件下的非平衡流动和辐射特性计算，基于光线法得到光谱辐射强度沿驻点线的变化，表明高速与低速条件的气动辐射机制存在显著差异；基于有限体积法获得进入器表面辐射热流分布，结果显示辐射热流的分布及变化规律与地球再入显著不同，进入速度6 km/s以下时辐射热流随进入速度增加而减小，同时进入器锥身及肩部的辐射热流高于驻点区域。     

铝球超高速撞击铝板反溅碎片云团辐射特性研究

通过超高速撞击试验,获得了铝球撞击铝板反溅粒子云团在250～340nm波段的辐射特征光谱。在该波段辨认出铝原子的六条特征谱线,并对其伴线进行了解耦。根据所测光谱数据,使用多谱线法测量出不同撞击条件下的超高速撞击反溅粒子云团的温度,发现超高速撞击反溅粒子云团温度随弹丸直径和撞击速度的增加而增加;相较弹丸直径,反溅粒子云团温度对撞击速度更加敏感;最后拟合出反溅粒子云团温度与撞击参数之间的经验公式。对每条谱线波峰和整个波段分别进行了积分,研究发现谱线波峰积分强度、整个波段积分强度均与弹丸动能呈线性关系,并获得了谱线波峰积分强度与撞击动能之间的斜率系数,该系数可以表征在超高速撞击条件下该峰值的辐射效率。最后结合所得超高速撞击反溅粒子云团温度经验公式推导出基态原子数与撞击参数之间的关系,在此基础上探讨了超高速撞击反溅粒子云团原子离化率、气化率与撞击参数的关系。     

载人核热火箭登陆火星方案研究

针对未来载人登陆火星任务,比较了化学推进、电推进及核推进的优缺点,指出核热推进是未来载人登陆火星的首选。简述了美国和俄罗斯在核热推进的研究进展,指出核热/发电双模式是未来载人登火的发展趋势。提出我国近地轨道5次对接、人货分离载人登陆火星构想。在此基础上,设计了单台推力15 t,比冲940 s载人核热发动机并提出我国核热火箭2016—2035年发展研究规划。     

一种基于自适应滤波器的潜艇辐射噪声仿真方法

文章提出了一种基于自适应滤波器的潜艇辐射噪声仿真方法。在对潜艇辐射噪声连续谱、线谱和调制谱的数学模型进行研究的基础上,利用Ecs型功率谱模型,基于自适应滤波器,通过傅里叶反变换对潜艇辐射噪声连续谱进行了仿真,分别叠加了线谱信号和调制谱信号之后,得到潜艇辐射噪声的仿真结果。通过对仿真结果的分析和利用仿真结果与实装进行对接测试,表明仿真的辐射噪声逼真度较高。     

固液混合火箭发动机喷焰红外辐射特性分析

为了研究固液混合火箭发动机喷焰在不同飞行状态的红外辐射特性,建立了固液两相状态下喷焰的红外辐射计算模型,获得了喷焰在2~12μm波段的红外辐射.将喷焰的温度、压力、摩尔组分等作为输入条件,米氏散射(Mie)模型计算颗粒相的散射,采用有限体积法(FVM)离散辐射传递方程,利用中分辨率大气辐射传输(MODTRAN)模型计算不同观测距离的大气透过率,编程计算得到不同飞行高度,不同观测方向下喷焰的红外辐射.结果表明喷焰红外辐射亮度与温度分布类似,在2.7~3.0μm和4.2~4.5μm波段范围内的辐射较强,高温粒子在近红外比远红外对总辐射的贡献大,太空与地面观测不同飞行高度的发动机喷焰辐射率因大气衰减的不同而有所差异,可为目标跟踪与发动机设计提供参考.      

载人登陆火星任务核热推进系统方案研究

针对载人登陆火星任务需求,基于核热推进大比冲、高能量转换效率和低风险的优点,设计了8次地面发射、5次近地轨道对接、人货分离任务构架,并提出了总推力为450 kN的核热推进总体方案;最后依据我国航天技术水平,对核热发动机及增压输送子系统系统组成和参数分配进行了详细设计,载人登火任务核热推进系统方案没有超过我国现有航天技术水平。     

民航机组人员所受宇宙辐射的剂量水平,危害及防护

宇宙辐射来自银河系,主要由具极高能量的氦核组成,一个粒子能量10~(20)eV(电子伏特)换成机械能就能把一本书上举1m。初始辐射与地球大气层作用生成次级辐射,由电离成分(μ介子、快速点子和γ线等)和中子组     

辐射发射与辐射法测温—如何接近表面真实温度

从辐射测法中辐射率变化对温度的影响，讨论了多色辐射测量法的发展与应用实践，比较了不同处理方法的优缺点。     

Nonthermal Radiation Mechanisms

In this paper we review the possible radiation mechanisms for the observed non-thermal emission in clusters of galaxies, with a primary focus on the radio and hard X-ray emission. We show that the difficulty with the non-thermal, non-relativistic Bremsstrahlung model for the hard X-ray emission, first pointed out by Petrosian (Astrophys. J. 557, 560, 2001) using a cold target approximation, is somewhat alleviated when one treats the problem more exactly by including the fact that the background plasma particle energies are on average a factor of 10 below the energy of the non-thermal particles. This increases the lifetime of the non-thermal particles, and as a result decreases the extreme energy requirement, but at most by a factor of three. We then review the synchrotron and so-called inverse Compton emission by relativistic electrons, which when compared with observations can constrain the value of the magnetic field and energy of relativistic electrons. This model requires a low value of the magnetic field which is far from the equipartition value. We briefly review the possibilities of gamma-ray emission and prospects for GLAST observations. We also present a toy model of the non-thermal electron spectra that are produced by the acceleration mechanisms discussed in an accompanying paper Petrosian and Bykov (Space Sci. Rev., 2008, this issue, Chap. 11).     

Thermal Radiation Processes

We discuss the different physical processes that are important to understand the thermal X-ray emission and absorption spectra of the diffuse gas in clusters of galaxies and the warm-hot intergalactic medium. The ionisation balance, line and continuum emission and absorption properties are reviewed and several practical examples are given that illustrate the most important diagnostic features in the X-ray spectra.     

Planetary Radiation Budgets

The energy state of a planet depends fundamentally on its radiation budget. Measurements made from space over past decades have led to significant revisions of ground-based estimates, both of the reflected fraction (the Bond albedo) of solar radiative flux and of the emitted thermal infrared radiation flux, for the Earth as well as for the other planets. After a brief survey of methods and difficulties in accurately determining planetary radiation budgets, we note contradictions in existing tabulations of global parameters, in particular Bond albedo. For the Earth, such contradictions are unjustified, considering that global and annual means as well as the seasonal cycle of Earth Radiation Budget components have now been determined with high accuracy. The Earth's Bond albedo is close to 0.3. Net storage of energy in the Earth-ocean system is close to zero, with a well-established annual cycle of amplitude close to ±12 Wm⁻². Some contradictions remain for the other terrestrial planets. For the giant planets, modern reduced values of the Bond albedo imply reduced but still significant internal energy generation.     

The Engineering Radiation Monitor for the Radiation Belt Storm Probes Mission

An Engineering Radiation Monitor (ERM) has been developed as a supplementary spacecraft subsystem for NASA’s Radiation Belt Storm Probes (RBSP) mission. The ERM will monitor total dose and deep dielectric charging at each RBSP spacecraft in real time. Configured to take the place of spacecraft balance mass, the ERM contains an array of eight dosimeters and two buried conductive plates. The dosimeters are mounted under covers of varying shielding thickness to obtain a dose-depth curve and characterize the electron and proton contributions to total dose. A 3-min readout cadence coupled with an initial sensitivity of ～0.01 krad should enable dynamic measurements of dose rate throughout the 9-hr RBSP orbit. The dosimeters are Radiation-sensing Field Effect Transistors (RadFETs) and operate at zero bias to preserve their response even when powered off. The range of the RadFETs extends above 1000 krad to avoid saturation over the expected duration of the mission. Two large-area (～10 cm²) charge monitor plates set behind different thickness covers will measure the dynamic currents of weakly-penetrating electrons that can be potentially hazardous to sensitive electronic components within the spacecraft. The charge monitors can handle large events without saturating (～3000 fA/cm²) and provide sufficient sensitivity (～0.1 fA/cm²) to gauge quiescent conditions. High time-resolution (5 s) monitoring allows detection of rapid changes in flux and enables correlation of spacecraft anomalies with local space weather conditions. Although primarily intended as an engineering subsystem to monitor spacecraft radiation levels, real-time data from the ERM may also prove useful or interesting to a larger community.     

The Electron Radiation Belt

Electron radiation belts can change dramatically in a few seconds or slowly over years. Important issues in understanding such changes are: (1) What is the source of electrons in the radiation belts? (2) How important is radial diffusion compared to other radial transport mechanisms? (3) What are the detailed changes in the magnetosphere that produce radial diffusion? (4) Why is the response of the electron radiation belt to changes in the solar wind different from that of substorms and of the ring current? (5) Are processes other than radial transport, such as wave-particle interactions, important in energizing electrons in the radiation belts?     

Dynamics of Radiation Belt Particles

This paper reviews basic concepts of particle dynamics underlying theoretical aspect of radiation belt modeling and data analysis. We outline the theory of adiabatic invariants of quasiperiodic Hamiltonian systems and derive the invariants of particle motion trapped in the radiation belts. We discuss how the nonlinearity of resonant interaction of particles with small-amplitude plasma waves, ubiquitous across the inner magnetosphere, can make particle motion stochastic. Long-term evolution of a stochastic system can be described by the Fokker-Plank (diffusion) equation. We derive the kinetic equation of particle diffusion in the invariant space and discuss its limitations and associated challenges which need to be addressed in forthcoming radiation belt models and data analysis.     

任意口径天线辐射场的计算

研究了理想导体面上任意形状的波导-口径天线的辐射特性。利用波导腔和自由空间之间的场匹配技术给出了描述它们之间的耦合关系的线性方程组,通过求解线性方程组的未知系数,严格计算了口径天线在半空间的辐射场,波导内的反射场及导体板上的电流分布;并通过数值算例进行了验证。     

电磁辐射环境研究

电磁辐射环境是指设备或分系统在执行规定的任务时，可能遇到的辐射发射电平在不同频率范围内功率和时间的分布。本文对飞机飞行区域和机内的电磁辐射环境以及空中发射武器所处的电磁辐射环境进行了分析。同时还讨论了试验室内的电磁环境电平大小对电磁兼容性试验、雷达截面和天线方向图测试精度的影响。     

Radiation transmission in adverse weather

A simplified practical approach to determining the effects of weather on the transmission of radiation at visible, infrared (IR), and millimetre (mm) wavelengths, with particular reference to the aircraft landing problem, is outlined. Passive landing systems are studied. Landing categories related to visibility are defined. An extinction coefficient used to relate the effect of the atmosphere on the radiation detected by the human eye (or an imaging sensor onboard the aircraft) to the landing category and the calculation of this coefficient are discussed. The approach makes use of data from openly available literature. Results have been found useful in indicating the effects of adverse weather on imaging sensor performance for an enhanced vision aircraft-mounted landing system. As an example of the technique, the method of determining the extinction coefficients in fog for infrared radiation is outlined