霍尔推力器电磁辐射测量方案研究

电磁辐射特性的检测与评估是电推进系统与航天器系统间电磁兼容性研究的重要组成部分。电推进放电室和电子电路间电压、电流振荡引起强电磁辐射干扰,可能会对卫星平台及载荷运行产生不良影响,开展电推进电磁兼容性能测试试验十分必要。介绍了霍尔推力器电磁辐射测试系统研制方案,为优化霍尔电推进系统性能设计提供参考。     

基于STL文件和有限元法的在轨航天器关键部件热计算

针对STL(stereo lithography)文件在传递复杂几何实体模型信息方面具有精度高的特点,提出了一种基于STL文件计算复杂结构角系数和外热流的方法.根据单元和节点的拓扑关系识别六面体网格边界单元并进行辐射换热计算.详细阐述了基于STL文件和有限元法进行复杂结构的角系数和外热流的计算方法.研究了导热-辐射耦合计算的有限元方法.最后利用有限元法计算航天器关键部件在轨的三维瞬态温度场.      

SRAM单粒子效应检测方法研究

采用中国科学院近代物理研究所的回旋加速器HIRFL产生不同LET值的重离子,以模拟空间辐射环境,检测了两种国产SRAM器件抗单粒子翻转和单粒子锁定的能力。试验中采用了两套单粒子效应检测系统,结合试验检测过程和最终结果,讨论了两套检测系统各自的优缺点,总结了试验中需要注意的其他问题。本研究为今后构建其他器件的单粒子效应检测系统提供了参考。     

热化学非平衡流动红外辐射计算分析

首先通过求解热化学非平衡N-S方程的数值模拟方法,获得高焓风洞钝锥体模型的绕流及近尾的高温流场参数.然后从辐射传输方程出发,采用带辐射模型,并利用所获得的流场参数,计算分析了高温流场在λ=3μm-6μm红外波段的辐射,计算和测量结果具有较好的一致性.该项研究为今后进一步研究高温非平衡气体辐射特性奠定了基础.     

卫星舱内两类剂量计测量结果的比较

本文利用1994年和1996年两次返回式卫星的搭载条件对舱内辐射剂量进行了对比测量．通过对比测量,研究不同掺杂、不同厚度LiF剂量计测量空间辐射剂量的特点;研究GM计数管计数和LiF剂量间的转换系数以及转换系数随屏蔽状况的变化;由剂量和GM计数研究粒子平均碰撞阻止本领的估计方法．结果表明,不同掺杂、不同厚度的LiF剂量计测量结果间无显著差异,而转换系数几乎不受舱内位置和屏蔽状态的影响．不同厚度LiF剂量计,不同屏蔽状态的GM计数管计数和剂量—计数转换系数的比较研究以及对粒子平均碰撞阻止本领的估计表明,舱内辐射剂量起决定作用的是高能粒子成分,其平均碰撞阻止本领估计约为5MeV／cm．     

钛合金切削挤压复合攻丝研究

将切削挤压复合攻丝新方法成功地用于高强度钛合金内螺纹的加工,这种方法不仅可以减小挤压扭矩而且能够强化螺纹根部。加工的挤压螺纹表面有一层纤维沿其牙形连续分布。利用云纹干涉法测得牙根处的最大残余压应力为120MPa左右。疲劳对比试验结果表明,在相同应力水平下,经挤压强化螺纹的疲劳寿命大约是未强化螺纹的３倍,这主要归因于挤压螺纹表面高的残余压应力,高的纤维密度和低的粗糙度。     

Space-radiation-induced photon luminescence of the Moon

We report on the results of a continuing study of the photon luminescence of the Moon induced by Galactic Cosmic Rays (GCRs) and space radiation from the Sun, using the Monte Carlo program FLUKA. Understanding the space radiation environment is critical to future exploration of the Moon, and this includes photons. The model of the lunar surface is taken to be the chemical composition of soils found at various landing sites during the Apollo and Luna programs, averaged over all such sites to define a generic regolith for the present analysis. This surface model then becomes the target that is bombarded by Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) or Solar Particle Events (SPEs) above 1 keV in FLUKA to determine the photon fluence albedo produced by the Moon’s surface when there is no sunlight and Earthshine. The result is to be distinguished from the gamma-ray spectrum produced by the radioactive decay of radiogenic constituents lying in the surface and interior of the Moon. From the photon fluence we derive the spectrum which can be utilized to examine existing lunar spectral data and to aid future orbiting instrumentation in the measurement of various components of the space-radiation-induced photon luminescence present on the Moon.     

Artificial equilibrium points and bi-impulsive maneuvers to observe 243 Ida

In the restricted three-body problem, the traditional Lagrange points L₁ and L₂ are the only equilibrium points near the asteroid 243 Ida. The thrust generated by a solar sail over a spacecraft enables the existence of new artificial equilibrium points, which depend on the position of the spacecraft with respect to the asteroid and the attitude of the solar sail. Such equilibrium points generate new spots to observe the body from above or below the plane of motion. Such points are very good observational locations due to their stationary condition. This work provides a preliminary analysis to observe Ida through the use of artificial equilibrium points as spots combined with transfer maneuvers between them. Such combination can be used to observe the asteroid from more different points of view in comparison to fixed ones. The analyses are made for a spacecraft equipped with a solar sail and capable of performing bi-impulsive maneuvers. The solar radiation pressure is used both to maintain the equilibrium condition and to reduce the costs of the transfers and/or to create transfers with longer duration. This is a new aspect of the present research, because it combines the continuous thrust with initial and final small impulses, which are feasible for most of the spacecraft, because the magnitudes of the impulses are very low. These combined maneuvers may reduce the transfer times of the maneuvers in most of the cases, compared with the maneuvers based only on continuous thrust. Several options involved in these transfers are shown, like to minimize the fuel spent ($\mathrm{\Delta }\mathit{v}$) as a function of the transfer time or to extend the duration of the travel between the points. Extended transfer times can be useful when observations are required during the transfers.     

一个控制超强电离辐射抗性开关基因的研究进展

电离辐射广泛存在于地球和空间,会引起生物体内的DNA损伤,导致机体突变甚至死亡.生物体的DNA损伤响应对于稳定基因组的完整性至关重要.耐辐射奇球菌因其超强的DNA修复能力成为研究DNA损伤修复的模式生物之一.PprI-DdrO系统是近年来发现的一种新型且高效的损伤响应途径,PprI作为响应损伤的重要开关蛋白,通过酶切D...     

辐射及化学非平衡流耦合场计算方法

把一种新的三维热辐射计算方法应用到高超声速非平衡流场的数值模拟过程中:在非结构网格上对高超声速化学非平衡流场的数值模拟过程中,耦合了辐射输运方程来求解辐射热流。控制方程为含有化学反应源项和辐射源项的三维N-S方程,数值离散格式采用了Jam eson有限体积法,辐射输运方程采用有限体积法求解。化学反应模型为7组元7反应模型,并采用了化学反应特征时间步长。本文分别对RAM C-Ⅱ和MU SES-C模型进行了计算,计算结果与参考文献的结果吻合。