一种全息滤波用于粒子场层析的方法

本文介绍用4F傅里叶透镜系统和全息滤波器对粒子场分布作全息记录的原理和方法。理论和实验结果表明,这种记录方法能同时准确记录位于输入平面和在其前、后相同距离平面上的粒子分布,并能根据清晰的粒子像直接判读出粒子尺寸和空间位置。若应用不同的全息滤波器,就能在输出平面上记录与滤波器相匹配的三个层次平面上的粒子分布。这种用4F系统的全息滤波记录方法,实质上是用全息术测量粒子场分布的层析法。文中还介绍了制作这种全息滤波器的原理和方法。     

Investigation of PMSE dependence on high energy particle precipitation during their simultaneous occurrence

This paper is based on the observations of Polar Mesosphere Summer Echoes (PMSE) with the EISCAT VHF 224?MHz radar during the summer month 08–12 July 2013. The effect of high energy particle precipitation on PMSE intensity, particularly during their simultaneous occurrence for longer time interval (longer than or equal to 3-h) has been investigated. The correlation between the two phenomena has been computed using the Spearman rank and Pearson linear correlation coefficient. The variations in high energy particle precipitation reaching down to altitude of 91?km and PMSE intensity in the altitude range of 80–90?km are positively correlated. The electron density irregularity due to ionization caused by precipitating particles might be one of the possible reasons for this positive correlation. Moreover, some other background parameters i.e. K-indices (proxy of high energy particle precipitation) and electron fluxes during the simultaneous occurrence of the two phenomena also support one of the possible reasons given for explanation of the observed positive correlation. The X-rays and proton fluxes have no noticeable effect on PMSE echoes in this study.     

行星际尘粒中锂同位素丰度与太阳星云演化的关系

1引言构成太阳系的大多数元素都经历过恒星演化过程,但3种轻元素Li,Be和B极为脆弱,在绝大多数恒星内部的高温、高密度和剧烈变动的条件下,很快就会分解．太阳系的早期阶段,太阳星云可能是由大爆炸产生的1H、2H、3He、4He和7Li及附近超新星爆发产生的C、N、O等构成[1],而6Li、Be、B是以后由宇宙射线粒子轰击附近星际和行星际的C、N、O等的核产生[2]．因为Li的同位素丰度的一部分是由大爆炸生成,一部分是由宇宙射线与星际介质核反应产生,因此它的丰度与宇宙射线暴露时间有关．1991年,文献间报导过在行星际尘粒中发现Li、Be和…     

硼粒子直径对点火位置及燃烧效率的影响研究

采用颗粒轨道模型对非壅塞固冲发动机补燃室内不同直径硼粒子的点火及燃烧进行了数值模拟。其中,气相反应简化为一种等效气体的燃烧,硼粒子与O2的燃烧反应模型采用涡耗散模型。硼粒子的点火过程采用King模型,燃烧过程采用化学动力学控制的燃烧模型。结果表明,直径较小的硼粒子能够在补燃室头部点火,且能随气流旋转,驻留时间较长,燃烧较为充分,直径较大的硼粒子与此相反。     

Reverse shock acceleration of electrons and protons at mid-heliolatitudes from 5.3-3.8 AU

We examine the intensity, anisotropy and energy spectrum of 480–966 keV protons and 38–315 keV electrons observed by the HI-SCALE instrument on Ulysses associated with Corotating Interaction Regions (CIR) from mid-1992 to early 1994. The particle events are most clearly ordered by the reverse shocks bounding the CIRs. The bulk of the ion fluxes appear either straddling, or with their maximum intensity following, the reverse shock. The electron intensities rise sharply to their maximum upon the passage of the reverse shock, and are delayed with respect to the protons. We believe that following acceleration at the reverse shock the electrons re-enter the inner heliosphere and mirror, to return to the reverse shock for repeated acceleration. This process is more effective for electrons (vc/2) than for ions, and also favours the higher velocity electrons, which accounts for the observed spectral hardening with latitude.     

Polarization of Light Scattered by Cometary Dust Particles: Observations and Tentative Interpretations

Analysis of the polarization of light scattered by cometary particles reveals similarities amongst the phase curves, together with some clear differences: i) comets with a strong silicate emission feature present a high maximum in polarization, ii) the polarization is always slightly lower than the average in inner comae and stronger in jet-like structures. These results are in excellent agreement with the Greenberg model of dust particles built up of fluffy aggregates of much smaller grains. Also, they suggest the existence of different regions of formation, and of different stages of evolution for the scattering particles inside a given cometary coma. This revised version was published online in June 2006 with corrections to the Cover Date.