卫星大型挠性天线弹性振动抑制的研究

论文从工程实践角度探讨了具有大尺寸（直径几米～几十米）和高精度（０．０５°）的挠性天线指向控制问题。在借鉴和改进有关抑制挠性天线弹性振动研究的基础上，初步设计了星—地回路的挠性天线指向控制方案。最后，通过分析数值仿真结果，给出了提高挠性天线指向精度的主要因素。     

Energy input for explosive events in the transition zone

It is suggested that the energy input for explosive events in the transition zone comes from precipitating ions, typically of energies of a few×10² keV/nucleon, accelerated in the high corona. The energetics of the process are discussed, together with implications for coronal heating.     

Working group 3: Coronal streamers

The working group on coronal streamers convened on the first day of the 2nd SOHO Workshop, which took place in Marciana Marina, Isola d'Elba, 27 September –1 October 1993. Recent progress in streamer observational techniques and theoretical modeling was reported. The contribution of streamers to the mass and energy supply for the solar wind was discussed. Moreover, the importance of thin electric current sheets for determining both the gross dynamical properties of streamers and the fine-scale filamentary structure within streamers, was strongly emphasized. Potential advances to our understanding of these areas of coronal physics that could be made by the contingent of instruments aboard SOHO were pointed out.     

质子耀斑活动区的再现规律

质子耀斑活动区再现规律的研究结果表明，日面上存在着经度方向漂移式的“活火山”，即质子活动复活体，“活火山”定期地复活，并爆发质子耀斑。其复活长周期为８－１１．６年，与活动周１１年周期基本一致；短周期为１．２６年，与活动周峰年时间宽度一致。在２２周峰年中，日面南北半球上各有一个强质子活动复活体，它们爆发值流量≥１００ｐｆｕ和≥１０００ｐｆｕ的质子耀斑各占周期同类耀斑总数的７０．７％和８３．３％。     

卫生捕获太阳的新方法

对卫星入轨后捕获太阳的方法进行了研究,并对一种有效的控制规律进行了分析计算,最后对卫星的运动过程进行了仿真验证。     

轴系回转轴线指向误差测量方法

回转轴线指向误差是扫描机构的重要性能指标之一,对遥感成像质量有明显影响。针对回转轴线无法直接精确测量的问题,提出了基于平面反射镜、电子自准直仪的测量系统。在详细分析平面反射镜法线与回转轴线间关系的基础上,对测得的镜面法线指向数据进行傅里叶级数展开,通过零次项去除和一次谐波分量误差分离处理,得到真实的回转轴线指向误差。利用该方法对某扫描轴系实物进行了测量,结果表明:该方法测得的回转轴线误差为39″,满足系统的指标要求,相对于常规处理方法在精度和准确度上有所提高。     

在轨地球同步卫星地球敏感器干扰及指向计算

从工程应用角度,基于太阳、月球位置和卫星轨道根数推导了太阳和月球对地球同步轨道卫星红外地球敏感器干扰的计算公式及预报方法,同时给出了安全模式下卫星Z轴跟踪太阳时星上天线指向变化的计算模型。计算结果和卫星下传遥测数据验证了方法的正确性,可用于实际卫星管理。     

Chromospheric line emission in seismically active flares

Some flares are known to drive seismic transients into the solar interior. The effects of these seismic transients are seen in helioseismic observations of the Sun’s surface thousands of km from their sources in the hour succeeding the impulsive phase of the flare. Energetic particles impinging from the corona into the chromosphere are known to drive strong, downward-propagating shocks in active region chromospheres during the impulsive phases of flares. H observations have served as an important diagnostic of these shocks, showing intense emission with characteristic transient redshifts. In most flares no detectable transients penetrate beneath the active region photosphere. In those that do, there is a strong correlation between compact white-light emission and the signature of seismic emission. This study introduces the first known H observations of acoustically active flares, centered in the core of the line. The morphology of line-core emission H in the impulsive phase of the flare is similar to that of co-spatial line-core emission in NaD₁, encompassing the site of seismic emission but more extended. The latter shows a compact red shift in the region of seismic emission, but a similar feature is known to appear in a conjugate magnetic footpoint from which no seismic emission emanates. Radiative MHD modelling based on the profiles of chromospheric line emission during the impulsive phases of flares can contribute significantly to our understanding of the mechanics of flare acoustic emission penetrating into the solar interior and the conditions under which it occurs.     

Quasi-biennial oscillations in the cross-correlation of properties of macrospicules

Jets, whatever small (e.g. spicules) or large (e.g. macrospicules) their size, may play a key role in momentum and energy transport from photosphere to chromosphere and at least to the low corona. Here, we investigate the properties of abundant, large-scale dynamic jets observable in the solar atmosphere: the macrospicules (MS). These jets are observationally more distinct phenomena than their little, and perhaps more ubiquitous, cousins, the spicules. Investigation of long-term variation of the properties of macrospicules may help to a better understanding of their underlying physics of generation and role in coronal heating. Taking advantage of the high temporal and spatial resolution of the Solar Dynamics Observatory, a new dataset, with several hundreds of macrospicules, was constructed encompassing a period of observations over six years. Here, we analyse the measured properties and relations between these properties of macrospicules as function of time during the observed time interval. We found that cross-correlations of several of these macrospicule properties display a strong oscillatory pattern. Next, wavelet analysis is used to provide more detailed information about the temporal behaviour of the various properties of MS. For coronal hole macrospicules, a significant peak is found at around 2-year period. This peak also exists partially or is shifted to longer period, in the case of quiet Sun macrospicules. These observed findings may be rooted in the underlying mechanism generating the solar magnetic field, i.e. the global solar dynamo.     

The damping of small-amplitude oscillations in quiescent prominences

The presence of small-amplitude oscillations in prominences is well-known from long time ago. These oscillations, whose exciters are still unknown, seem to be of local nature and are interpreted in terms of magnetohydrodynamic (MHD) waves. During last years, observational evidence about the damping of these oscillations has grown and several mechanisms able to damp these oscillations have been the subject of intense theoretical modelling. Among them, the most efficient seem to be radiative cooling and ion-neutral collisions. Radiative cooling is able to damp slow MHD waves efficiently, while ion-neutral collisions, in partially ionised plasmas like those of solar prominences, can also damp fast MHD waves. In this paper, we plan to summarize our current knowledge about the time and spatial damping of small-amplitude oscillations in prominences.