彗星穿越过境对磁层的影响及其分析讨论

对哈雷、百武和海尔-波普三颗慧星在不同时间、不同位置的情况下5次过近地点可能引起对地球磁层影响进行了资料分析和统计研究，指出，根据等离子体彗尾的特征，完全可以对磁层引起扰动，但是这种扰动有严格的制约条件，不是每次彗星过境都很容易对地球电磁环境产生影响。     

基于离子电推进系统的航天器有效载荷能力分析

为预估与提高航天器有效载荷能力,结合航天运输系统理论与离子推力器放电模型,对深空探测任务中以离子电推进系统为主要动力来源的航天器有效载荷能力进行了分析。通过理论推导,构建并揭示了有效载荷分数与深空探测任务参数和电推进系统性能参数的函数关系与潜在联系。结果表明:动力装置单位质量越小,航天器所能达到的最佳有效载荷分数越大;有效载荷分数的高低与离子引出份额、原初电子利用率参数的大小以及任务时间的长短呈正相关;当离子电推进系统可以达到更高的载荷比时,则需要更高的工质利用率作为支持。     

离子推力器放电室阳极壁面电流密度分布特性研究

为了准确掌握离子推力器放电室阳极壁面电流密度分布特性,并深入理解阳极壁面处等离子体运动特性,设计了近阳极壁面等离子体诊断的具体实施方案,并基于LIPS-200离子推力器开展了近阳极壁面处等离子体诊断试验研究,得到了主要磁极附近壁面等离子体参数,并得到阳极壁面吸收电流密度分布特性。试验结果表明：LIPS-200离子推力器阳极壁面处主要磁极附近的等离子体密度范围为,测试点的电子温度范围为,壁面电流密度范围为;柱段壁面电子温度相对锥段较低,但电流密度较大,尤其在中间极靴位置电流密度最大,约为阴极极靴处电流密度的3倍,约为屏栅极靴处电流密度的2倍,阳极电流主要在放电室中间极靴处发生损失。     

基于小孔投影面积的平面栅极间距测量方法

栅极间距是影响推力器离子束流的发散角、推力大小的关键参数,为了解决栅极组件在装配过程中栅极间距自动检测的技术难题,针对栅极孔径的特殊结构和光线传播的特性,建立了栅极间距和小孔面积的数学模型,提出了基于机器视觉的非接触式平面栅极间距检测方法并搭建试验平台。选取栅极中心孔位进行35次重复试验,该方法的标准差为12μm,具有较高的重复精度。精度验证试验结果表明,该系统精度高于±20μm,满足离子推力器装配过程中的栅极间距测量要求,在实际应用中有望替代现有人工检测方法。     

电离层离子丰度对哨声传播经度效应的影响

Iss-b卫星探测结果表明,|电离层离子丰度呈现经度变化.本文选取较真实的电离层模型参数,对130°E和114°E两个子午面内传播的低纬哨声进行了射线跟踪.我们发现,由于[O~+],[He~+]和[H~+]决定的电子浓度垂直梯度的经度变化,导致哨声传播特性的经度效应,使得130°E比114°E内传播的低纬哨声更好地满足透射条件:|μsinδ|≤1.与电子浓度的水平梯度的影响比较,离子丰度决定的电子浓度垂直梯度随经度的变化使哨声传播产生的经度效应明显得多.武昌(地理30.5°N,114.6°E;地磁19.3°N).和鹿儿岛(31.5°N,130.8°E;20.5°N)两台站观测到的哨声出现率的经度效应证实了本文的理论预言.     

Spatio-temporal structure of the wave packets generated by the solar terminator

Using long-term (1998--2009) total electron content (TEC) measurements from the GPS global network including dense network of GPS sites in USA and Japan, we have obtained the first data regarding the spatio-temporal structure and the statistics of medium-scale traveling wave packets (MS TWPs) excited by the solar terminator (ST). Total amount of the detected TWPs exceeds 565,000. There is no correlation between TWPs occurrence and geomagnetic and solar activity. We found that the diurnal, seasonal and spectral MS TWPs characteristics are specified by the solar terminator (ST) dynamics. MS TWPs are the chains of narrow-band TEC oscillations with single packet’s duration of about 1–2 h and oscillation periods of 10–20 min. The total duration of chain is about 4–6 h. The MS TWPs spatial structure is characterized by a high degree of anisotropy and coherence at the distance of more than 10 wavelengths. Occurrence rate of daytime MS TWPs is high in winter and during equinoxes. Occurrence rate of nighttime MS TWPs has its peak in summer. These features are consistent with previous MS travelling ionosphere disturbance (TID) statistics obtained from 630-nm airglow imaging observations in Japan. In winter, MS TWPs in the northern hemisphere are observed 3–4 h after the morning ST passage. In summer, MS TWPs are detected 1.5–2 h before the evening ST appearance at the point of observations, but at the moment of the evening ST passage in the magneto-conjugate point. The obtained results are the first experimental evidence for the hypothesis of the ST-generated ion sound waves.     

A model study of the negative chlorine ion chemistry in the Earth’s mesosphere

An ion chemistry model is used to investigate the negative chlorine ion chemistry of the mesosphere for quiet ionospheric conditions. Model results are presented for high latitudes in February as well as for the equator in Summer. For nighttime, Cl^-${\text{Cl}}^{-}$, Cl^-${\text{Cl}}^{-}$(HCl), and NO₃⁻(HCl) are the most abundant chlorine anions in the mesosphere. The concentration of ClO₃⁻ depends significantly on its stability against collision-induced dissociation. In contrast to previous model predictions, the abundance of Cl^-(_H2O)${\text{Cl}}^{-}({\mathrm{H}}_2\mathrm{O})$ is small. For daytime, photoelectron detachment and photodissociation have pronounced impact on the negative chlorine ion chemistry in the mesosphere. The abundance of all anion cluster is considerably smaller than at night. While Cl^-${\text{Cl}}^{-}$ decreases in the upper mesosphere, its abundance increases at lower altitudes.     

离子束增强沉积TiB2薄膜的耐蚀性能研究

研究了在紫铜基材上用离子束增强沉积法（ＩＢＥＤ）沉积ＴｉＢ２薄膜后，在６００，７００和８００℃的空气中氧化的动力学曲线；在ＩＮＨ２ＳＯ４溶液中，用动电位扫描法测定了其极化曲线和极化阻力，用ＳＥＭ观察了其形貌，用俄歇电子谱仪（ＡＥＳ）分析了膜的成份，用Ｘ－射线衍射仪（ＸＲＤ）研究了膜的微观结构；讨论了ＴｉＢ２薄膜具有优良耐蚀性的机理。     

Nonlinear quantum ion acoustic shock wave dynamics with exchange-correlation effects

The dynamics of linear and nonlinear electrostatic shock excitations is studied in homogeneous, unmagnetized, unbounded and dissipative quantum plasma consisting of electrons and ions. The dissipation in the system is taken into account by incorporating the ion kinematic viscosity. The system is modelled using the quantum hydrodynamic equations in which the electrons are significantly affected by the quantum forces, viz., the quantum statistical pressure, the quantum Bohm potential and electron exchange-correlations due to electron spin. In the weakly nonlinear limit, using reductive perturbation method deformed Korteweg-de Vries Burgers’s (KdVB) equation, which elegantly combines the effects of nonlinearity, dispersion and dissipation is derived. It is found that the present model predicts the existence of both nonlinear oscillatory and monotonic shock structures. The temporal evolution, stability and phase-space dynamics of nonlinear ion acoustic shocks are investigated numerically to elucidate the effects of quantum diffraction, electron exchange correlation and ion kinematic viscosity.     

基于薄膜热电堆的新型高温瞬态热流密度传感器的研制

目前针对国内薄膜瞬态热流传感器一致性较差、制备工艺不成熟等问题，提出了一种基于光刻工艺和离子束溅射镀膜工艺的制备方法，200对T型金属薄膜热电偶沉积在10mm×10mm的水冷块上，测量1μm的氧化铝热阻层温差，从而得到瞬态热流密度值。对新型高温瞬态热流密度传感器进行比对法标定，一致性误差为0.211%，即工艺的一致性约为99.79%。实验表明，研制的新型高温瞬态热流密度传感器的一致性好,制备工艺具备良好重复性和可移植性，能够满足高温瞬态热流检测需要，为热流传感器的推广应用及标准化、批量化生产提供了良好的技术支撑。