行星际电场与Dst指数

利用ACE卫星的太阳风及行星际磁场观测数据和相应时期的Dst指数，分析了行星际电场的Dst指数的相关关系，讨论了行星际电场作为研究磁层和太阳风相互作用的良好参数的物理机制。结果表明：行星际电场与Dst指数有很好的相关性，并且在强和中等地磁活动基间，存在显著的突变特征曲线；相对于V、V^2Bz、VB^2和ε，行星际电场的突变特征曲线更易识别；弱的扰动磁层背景状况和行星际磁场南向分量及电场晨昏分量的较大波动影响着磁暴的发展，使磁暴主相有多个发展阶段，从而增加磁暴的强度；对主相有多个发展阶段磁暴的研究有待进一步改善。     

磁壳参数L与磁暴Dst指数和行星际条件的关系

用磁坐标L-/A来描述地球近地空间粒子特性和卫星位置是近年来空间物理探测研究和数据分析中的一个新趋势.利用T96磁场模型计算了L值,并比较了在地球磁层剧烈活动期间和不同行星际条件下,用偶极子模型,国际参照磁场(IGRF)模型,和T96磁场模型这三种方式计算得到的地球表面L-A磁坐标之间的区别.在地磁纬度大于30°时偶极子近似和IGRF磁场模型计算得到的L值差别开始增大.在地磁纬度大于50°时,用IGRF磁场模型和T96磁场模型计算得到的L值差别开始增大.由于T96磁场模型引入了行星际磁场南北和东西分量,计算的L值包含了行星际条件的影响,并具有了随地方时变化的特性.本工作对于辐射带粒子动态模式的建立,以及正确理解卫星磁坐标位置等具有重要意义.     

Effects of the position of the solar wind termination shock and the heliopause on the heliospheric modulation of cosmic rays

The effects of changing the position of the solar wind termination shock and the position of the heliopause, and therefore the extent of the heliosheath, on the modulation of cosmic ray protons are illustrated. An improved numerical model with diffusive termination shock acceleration, a heliosheath and drifts is used. The modulation is computed in the equatorial plane and at 35 heliolatitude using recently derived diffusion coefficients applicable to a number of cosmic ray species during both magnetic polarity cycles of the Sun. It was found that qualitatively the modulation results for the different heliopause positions are similar although they differ quantitatively, e.g., clearly different radial gradients are predicted for the regions beyond the termination shock compared to inside the shock. The difference between the modulation for the two solar polarity cycles are less significant at a heliolatitude of 35° than in the equatorial plane. We found that moving the termination shock from 90 to 100 AU, with the heliopause fixed at 120 AU, caused only quantitative differences so that the exact position of the TS in the outer heliosphere seems not crucially important to global modulation. Moving the heliopause outwards, to represent the modulation in the tail region of the heliosphere, causes overall decreases in the cosmic ray intensities but not linearly as a function of energy, e.g., at 1 GeV the effect is insignificant. We conclude from this modelling that the modulation of protons in the heliospheric nose and tail regions are qualitatively similar although, clear quantitative and interesting differences occur.     

关于IMF北向分量特强时的太阳风－磁层－电离层耦合

关于ＩＭＦ北向分量特强时的太阳风－磁层－电离层耦合沈长寿，资民筠（北京大学地球物理系，１００８７１）（中国艺术研究院，北京）关键词行星际磁场，太阳风－磁层能量耦合函数为检验Ａｋａｓｏｆｕ提出的能量融合函数“’在ＢＺ强北向时能否反映太阳风与磁层扰动间的...     

黄道面内行星际激波相互碰撞作用过程研究—能量效应

本文用两维半MHD数值模型,数值模拟研究了两邻近扰动源所产生的激波在行星际空间黄道面内不同能量时的相互碰撞过程。在内边界(18R_s)两扰动中心的间距取为36°。结果表明:两弱激波(速度在500km/s左右以下)不会产生汇合,而是各自独立地传播;两中等强度激波(速度在1000km/s左右)将发生汇合,但在IAU尚可分辨;两强激波(速度在2000km/s以上)则在1AU以内已发生汇合,汇合后形成一个新激波,其磁场结构与单激波明显不同。激波能量越大,两激波汇合的越快。     

Coupling of the interstellar and interplanetary magnetic fields at the heliospheric interface: The effect of neutral hydrogen atoms

We present numerical results showing the effect of neutral hydrogen atoms on the solar wind (SW) interaction with the local interstellar medium (LISM), where the interstellar magnetic field (ISMF) is coupled to the interplanetary magnetic field (IMF) at the surface of the heliopause. The IMF on the inner boundary surrounding the Sun is specified in the form of a Parker spiral and self-consistently develops in accordance with the SW motion inside the heliopause. The model of the SW–LISM interaction involves both plasma and neutral components which are treated as fluids. The configuration is chosen where the ISMF is orthogonal to the LISM velocity and tilted 60° to the ecliptic plane. This orientation of the magnetic field is a possible explanation of the 2–3 kHz emission data which is believed to originate ahead of the heliopause. It is shown that the topology of the heliospheric current sheet is substantially affected by the ISMF. The interaction pattern dependence on the neutral hydrogen density is analyzed.     

空间尘埃的充电过程及与等离子体参数的关系

考虑了地球附近的彗星、行星环、行星际介质等空间尘埃等离子体环境中尘埃颗粒的充电问题．应用典型的空间尘埃等离子体参数，计算了不同种类的尘埃颗粒，以及不同等离子体成分下等离子体中尘粒的平衡电势，得到了尘埃颗粒的平衡电势与尘埃等离子体成分、温度，及其他等离子体参数之间的相互关系．     

Substorm activity during the main phase of magnetic storms induced by the CIR and ICME events

In this work, the relation of high-latitude indices of geomagnetic activity (AE, Kp) with the rate of storm development and a solar wind electric field during the main phase of magnetic storm induced by the CIR and ICME events is investigated. 72 magnetic storms induced by CIR and ICME events have been selected. It is shown that for the CIR and ICME events the increase of average value of the Kp index (Kp_aver) is observed with the growth of rate of storm development. The value of Kp_aver index correlates with the magnitude of minimum value of Dst index (|Dst_min|) only for the ICME events. The analysis of average values of AE and Kp indices during the main phase of magnetic storm depending on the SW electric field has shown that for the CIR events, unlike the ICME events, the value of AE_aver increases with the growth of average value of the electric field (Esw_aver). The value of Kp_aver correlates with the Esw_aver only for the ICME events. The relation between geomagnetic indices and the maximum value of SW electric field (Esw_max) is weak. However, for the ICME events Kp_aver correlates with Esw_max.     

A synchrotron-based facility for the in-situ location,chemical and mineralogical characterization of ∼10 μm particles captured in aerogel

NASA’s Stardust mission collected dust from the coma of Comet Wild-2 on January 2nd, 2004, by direct capture into aerogel cells that flew through the dust coma at ∼6 km/s. Stardust collected several hundred comet particles >10 μm in size. These comet samples were delivered to Earth on January 15th, 2006. We developed a facility at the National Synchrotron Light Source at Brookhaven National Laboratory (Upton, NY, USA) for the in-situ characterization of ∼10 μm particles collected in aerogel. These analytical instruments allow us to perform extensive chemical, mineralogical, and size-frequency characterization of particles captured in aerogel. These analyses are conducted without any invasive extraction, minimizing the possibility of contamination or particle loss during preparation. This facility was used to determine the chemical composition, the oxidation state, the mineralogy and to provide an indication of the grain size of the Wild-2 particles before they were removed from the aerogel. This information provides a catalog of particle types, allowing a more reasoned allocation of the particles to subsequent investigators based on a relatively detailed knowledge of the chemical composition and mineralogy of each particle. These measurements allowed a comparison of the chemical and mineralogical properties of the Wild-2 particles with other types of extraterrestrial materials, including interplanetary dust particles and meteorites. The success of in-situ analysis for Wild 2 particles demonstrates that synchrotron-based facilities will be important for the analysis of particles collected in aerogel on future earth-orbiting satellites and spacecraft.     

行星际南向磁场事件与强磁暴

利用１９７８－１９８８年期间的太阳风和地磁资料对行星际磁场（ＩＭＦ）南向分量Ｂｓ事件（即Ｂｓ〉１０ｎＴ及其所驱动的错向电场ＶＢｓ〉５ｍＶ／ｍ、持续时间△Ｔ〉３ｈ的事件）与弱磁暴（Ｄｓｔ≤－１００ｎＴ）关系进行了分析。结果表明,１００％的Ｂｓ事件能能引起磁暴的发生,但其中只有８４％为强磁暴;强磁暴的发生都与较强的ＩＭＦ Ｂｓ活动密切相关,但只有６８％的强磁共伴随Ｂｓ事件而发生;Ｂｓ事件与强磁暴并不是