电脱插应用中的问题及解决方案

主要介绍了利用电脱落插头作为弹地分离设备时的发射时序以及其在使用过程中容易出现的问题。文中所述的两个案例均为产品应用的典型案例,作者对故障产生的机理进行了详细地分析并提出了问题的解决方案,为后续利用电脱落插头作为战略技术武器系统或航天运载系统弹地分离设备的流程设计提供了有效的方案借鉴。     

稳态消谐法在零序电阻消除铁磁谐振分析中的应用

唯一稳态消谐法是近年出现的消除非线性系统谐振新的分析方法。该方法的基本思想是如果非线性系统存在一个非谐振的正常解,并且该系统具有唯一的稳态,则此时对应的条件就是系统不发生谐振的条件。将这一方法应用在中性点接地电力系统铁磁谐振的分析中,以向量比较原理为工具,得到相应的消谐条件。结果表明,消除谐振的条件可以用一个常数矩阵的HURWITZ条件来决定,并用数值模拟进行验证,表明结果是正确的,同时也说明唯一稳态消谐法的有效性。     

毛细管放电型脉冲等离子体推力器输出特性分析

为了研究毛细管放电型脉冲等离子体推力器输出特性,借助电学诊断手段展开实验研究,获得了推力器典型放电波形,系统研究了不同毛细管内径和施加电压对等离子体等效阻抗、沉积能量效率的影响规律。利用微冲量测量台架,测试了不同参数下毛细管推力器输出元冲量,并通过计算获得了推力器比冲、总体效率的变化规律。实验结果表明,当毛细管内径不断增大时,能量沉积效率不断下降,元冲量下降,比冲降低。主电容电压增大时,放电能量不断增大,能量沉积效率降低,元冲量和单次等效烧蚀质量不断增大,但推力器比冲和总体效率均先增加并趋于稳定。当毛细管腔体长度为16mm,内径3mm,主电容2.5μF,充电电压为2kV时,输出元冲量350.79±7.50μN?s,比冲531s,总体效率可达18.3%。     

Effect of the Interplanetary Electric Field on the Magnetopause From Global MHD Simulations

The north-south component B_z of the Interplanetary Magnetic Field (IMF) and solar wind dynamic pressure P_d are generally treated as the two main factors in the solar wind that determine the geometry of the magnetosphere. By using the 3D global MHD simulations, we investigate the effect of the Interplanetary Electric Field (IEF) on the size and shape of magnetopause quantitatively. Our numerical experiments confirm that the geometry of the magnetopause are mainly determined by P_dB_z, as expected. However, the dawn-dusk IEFs have great impact on the magnetopause erosion because of the magnetic reconnection, thus affecting the size and shape of the magnetopause. Higher solar wind speed with the same B_z will lead to bigger dawn-dusk IEFs, which means the higher reconnection rate, and then results in more magnetic flux removal from the dayside. Consequently, the dayside magnetopause moves inward and flank magnetopause moves outward.      

混合推进最省燃料轨道设计方法

使用混合推进方式设计地-月圆型限制性三体模型下的最省燃料转移轨道。将化学发动机以及电推进发动机的燃料消耗总和作为目标函数进行优化,推导一阶必要条件和雅可比矩阵。选择从近地圆轨道出发到达地-月L1附近Halo轨道的转移轨道为例测试上述方法。仿真结果表明,相比发射脉冲固定的情况,混合推进方式进一步降低了燃料消耗,而且给出了飞行时间和燃料消耗不同的组合方式,给予任务设计更大的灵活性。     

地球轨道卫星电推进变轨控制方法

针对地球同步轨道（GEO）卫星,采用电推进系统完成转移轨道变轨。采用基于Lyapunov函数的反馈控制方法确定时间最短变轨策略。首先在开普勒模型下研究变轨过程,然后在开普勒模型的基础上考虑地球J2项摄动和地球阴影,最后在全引力模型下研究变轨过程,即在开普勒模型的基础上考虑地球非球形引力摄动、日月第三体引力摄动、太阳光压摄动和地球阴影。仿真结果显示在变轨过程中摄动项不可忽略,除地球J2项摄动外还应该考虑日月第三体引力摄动和太阳光压摄动。对比上述三组仿真结果,发现考虑摄动后轨道转移时间的增加比燃料消耗的增加更为明显。数值仿真结果表明本文研究对未来的全电推进任务具有良好的通用性和应用参考价值。     

On high-altitude electric fields in the auroral downward current region and their coupling to ionospheric electric fields

The downward field-aligned current region plays an active role in magnetosphere–ionosphere coupling processes associated with aurora. A quasi-static electric field structure with a downward parallel electric field forms at altitudes between 800 km and 5000 km, accelerating ionospheric electrons upward, away from the auroral ionosphere. Other phenomena including energetic ion conics, electron solitary waves, low-frequency wave activity, and plasma density cavities occur in this region, which also acts as a source region for VLF saucers. Results are presented from high-altitude Cluster observations with particular emphasis on the characteristics and dynamics of quasi-static electric field structures. These, extending up to altitudes of at least 4–5 Earth radii, appear commonly as monopolar or bipolar electric fields. The former occur at sharp boundaries, such as the polar cap boundary whereas the bipolar fields occur at softer boundaries within the plasma sheet. The temporal evolution of quasi-static electric field structures, as captured by the pearls-on-a-string configuration of the Cluster spacecraft, indicates that the formation of electric field structures and of ionospheric plasma density cavities are closely coupled processes. A related feature of the downward current is a broadening of the current sheet with time, possibly related to the depletion process. Preliminary studies of the coupling of electric fields in the downward current region, show that small-scale structures are typically decoupled from the ionosphere, similar to what has been found for the upward current region. However, exceptions are also found where small-scale electric fields couple perfectly between the ionosphere and Cluster altitudes. Recent FAST results indicate that the degree of coupling differs between sheet-like and curved structures, and that it is typically partial. The electric field coupling further depends on the current–voltage relationship, which is highly non-linear in the downward current region, and still unrevealed, as to its specific form.     

航天用电连接器的可靠性研究

电连接器的质量和可靠性直接关系到卫星、飞船、导弹等重点型号产品的成败。电连接器的设计、生产制造工艺、检测、选型、贮存和使用等环节都存在着影响质量和可靠性的因素。较详细地分析了影响航天用电连器可靠性的各种因素、并探讨了提高可靠性的主要途径。     

Magnetospheric electric field variations caused by storm-time shock fronts

On January 20, 2005 there was an X 7.1 solar flare at 0636 UT with an accompanied halo coronal mass ejection (CME). The resultant interplanetary shock impacted earth ∼36 h later. Near earth, the Advanced Composition Explorer (ACE) spacecraft observed two impulses with a staircase structure in density and pressure. The estimated earth-arrival times of these impulses were 1713 UT and 1845 UT on January 21, 2005. Three MINIature Spectrometer (MINIS) balloons were aloft on January 21st; one in the northern polar stratosphere and two in the southern polar stratosphere. MeV relativistic electron precipitation (REP) observed by all three balloons is coincident (<3 min) with the impulse arrivals and magnetospheric compression observed by both GOES 10 and 12. Balloon electric field data from the southern hemisphere show no signs of the impulse electric field directly reaching the ionosphere. Enhancement of the balloon-observed convection electric field by as much as 40 mV/m in less than 20 min during this time period is consistent with typical substorm growth. Precipitation-induced ionospheric conductivity enhancements are suggested to be (a) the result of both shock arrival and substorm activity and (b) the cause of rapid (<6 min) decreases in the observed electric field (by as much as 40 mV/m). There is poor agreement between peak cross polar cap potential in the northern hemisphere calculated from Super Dual Auroral Radar Network (SuperDARN) echoes and horizontal electric field at the MINIS balloon locations in the southern hemisphere. Possible reasons for this poor agreement include (a) a true lack of north–south conjugacy between measurement sites, (b) an invalid comparison between global (SuperDARN radar) and local (MINIS balloon) measurements and/or (c) radar absorption resulting from precipitation-induced D-region ionosphere density enhancements.     

手提电钻的噪音分析与研究

从实验和理论上研究了手提电钻在工作时产生噪音的主要噪声源及其特点,为减少其噪音提供了依据。