电感耦合等离子体发射光谱法测定钛铁矿中主、微量元素

采用氢氟酸-盐酸-硝酸-硫酸四酸溶矿,建立了电感耦合等离子体发射光谱仪法(ICP-AES)同时测定钒钛磁铁矿、钛铁矿中铝、钙、镁、钾、钠、锰、钛、铬、锶、锌和钒11种元素的方法。对最佳仪器条件及分析谱线进行了优化筛选,并探讨了4种消解方法及酸度对测定的影响。实验结果表明:ICP-AES法测定钒钛磁铁矿、钛铁矿中铝、钙、镁、钾、钠等元素,与原子吸收光谱法、分光光度法、滴定法、重量法等单一元素测定方法相比较,具有检出限低、灵敏度高、测量范围宽、操作简便,适合大批量样品测定等突出优点。方法准确度(RE)小于10%,元素精密度(RSD,n=12)为0.68%~5%。采用国家一级标准物质进行了方法验证,取得了令人满意的结果。     

电感耦合等离子体质谱法测定饮用水中微量元素

采用电感耦合等离子体质谱法快速测定饮用水中的微量元素,样品处理简便,检出限低,重现性好,分析速度快。方法检出限为0．007～0．911μg／L,精密度达到0．73％～4．87％。     

六极杆碰撞池-电感耦合等离子体质谱法测定海洋沉积物中的钒和铬

采用带六极杆碰撞池技术(CCT)的电感耦合等离子体质谱(ICP-MS)测定了海洋沉积物中的钒和铬。在六极杆碰撞池中引入He/NH3(99/1)混合气,有效地减轻了多原子离子(ClO+,ClN+,ClOH+,ClNH+等)对钒、铬测定的干扰,降低了方法的检出限。对He/NH3混合气的流量及ICP-MS的测定条件进行了最佳化选择。方法对钒和铬的检出限(3σ)分别为0.035μg·g-1和0.083μg·g-1(稀释因子1000),12份样品测定的相对标准偏差均小于5%。方法经海洋沉积物国家一级标准物质验证,测定值与标准推荐值吻合。     

斜入射分层线性各向异性等离子体电磁散射时域有限差分方法分析

提出了斜入射分层线性各向异性等离子体电磁散射的时域有限差分(FDTD)方法,通过将二维麦克斯韦方程等价地转换为一维麦克斯韦方程,避免了用二维时域有限差分方法分析该散射问题,极大地提高了计算效率.分析推导了TE_z和TM_z波斜入射线性分层各向异性等离子体电磁散射的FDTD方法,然后通过该方法计算不同入射角的各向异性等离子板的电磁波反射系数,并与其解析解进行比较,结果表明该方法的准确性和有效性.最后,将该算法应用于计算涂覆分层各向异性等离子     

Tailored Blast Wave Production Pertaining to Supernova Remnants

We report on the first production of “tailored” blast waves in cluster media using a 1 ps laser pulse focused to 2×10¹⁶ W/cm². This new technique allows cylindrical blast waves to be produced with a strong axial modulation of variable spatial frequency, as a seed for instability growth. Energy deposition is modified by changing the cluster density whilst keeping the atomic density of the target constant. Electron density maps show the production of strongly modulated blast waves and the development of a thin shell structure in H at late times, and the trajectories show blast waves forming in H, and Ar. In Xe, a blast wave does not form on the timescales studied. Analysis of astrophysical similarity parameters suggests that a hydrodynamically similar situation is created in H, and that further evolution would create a regime where radiative effects may be influential in Ar and Xe.     

Small-scale magnetic structures on the Sun

Summary The Sun provides us with a unique astrophysics laboratory for exploring the fundamental processes of interaction between a turbulent, gravitationally stratified plasma and magnetic fields. Although the magnetic structures and their evolution can be observed in considerable detail through the use of the Zeeman effect in photospheric spectral lines, a major obstacle has been that all magnetic structures on the Sun, excluding sunspots, are smaller than what can be resolved by present-day instruments. This has led to the development of indirect, spectral techniques (combinations of two or more polarized spectral lines), which overcome the resolution obstacle and have revealed unexpected properties of the small-scale magnetic structures. Indirect empirical and theoretical estimates of the sizes of the flux elements indicate that they may be within reach of planned new telescopes, and that we are on the verge of a unified understanding of the diverse phenomena of solar and stellar activity.In the present review we describe the observational properties of the smallscale field structures (while indicating the diagnostic methods used), and relate these properties to the theoretical concepts of formation, equilibrium structure, and origin of the surface magnetic flux.On leave from Institute of Astronomy, ETH-Zentrum, CH-8092 Zürich, SwitzerlandThe National Center for Atmospheric Research is sponsored by the National Science Foundation     

Scaling laws and coherent structures in the solar wind

The interplanetary medium is characterized by a very high Reynolds number and is pervaded by fluctuations providing information on a wide range of scales, from fractions of second up to the solar rotation period. In the past decade or so, turbulence in the solar wind has been used as a large wind tunnel to investigate scaling laws of turbulent fluctuations and multifractal models. Moreover, new interesting insights in the theory of turbulence have been derived from the point of view which considers a turbulent flow as a complex system, a sort of benchmark for the theory of dynamical systems. Important finding like the lack of a strict self-similarity of the fluctuations with the consequent nonapplicability of strict scale invariance, the strong anisotropy of velocity and magnetic field fluctuations, the clear lack of equipartition between magnetic and kinetic fluctuations all contributed to suggest the idea that interplanetary fluctuations could possibly be due to a mixture of propagating waves and static structures convected by the wind. In this paper we further discuss this point and bring new evidence about the fact that the presence of a background magnetic field introduces not only a symmetry breaking in interplanetary space but also organizes fluctuations about its large scale orientation.     

Features of discrete VLF emissions observed at Gulmarg,India during the magnetic storm of 6–7 March, 1986

During the analysis of archived VLF data from Indian low latitude ground stations, some discrete VLF emissions recorded at the low latitude ground station Gulmarg (geomagnetic latitude 24°26′N; geomagnetic longitude 147°09′E, L = 1.28) during moderate magnetic storm activity (Σ K _P ⁻ = 32, K _P index varies from 4 to 6 during the observation period) on 6/7 March, 1986 are presented in this paper. The dynamic spectra of these discrete VLF emissions were observed along with tweeks and its harmonics, which is interesting and complex to explain. In most of the events the harmonic frequency of tweeks correlates with the starting frequency of harmonics of discrete emissions. In order to explain the observed features of discrete VLF emissions, we propose cyclotron resonance interaction between whistler mode wave and energetic electrons of inner radiation belt as possible generation mechanism. An attempt is also made to determine parallel energy, anisotropy and wave growth relevant to the generation process of VLF emissions.     

微量地质样品铼锇含量及其同位素组成的高精度测定方法

报道了采用新型IsoProbe—T热电离质谱计测定Os含量及其同位素组成和Neptune多接收器等离子体质谱仪（MC—ICPMS）测定Re含量的分析方法。样品化学处理采用Carius管溶样、小型蒸馏法分离和微蒸馏法纯化提取Os以及阴离子树脂交换分离Re的方法。采用IsoProbe—T质谱计测定Os同位素组成具有灵敏度高和精度高的特点。对溶液标样，采用多法拉第接收器系统测定Os总量低至0．2ng的样品时，平均^192Os^16O3-离子流强度可达100mV以上并可维持约20min，其^187Os／^188Os同位素比值的测定精度可优于0．1％（1RSD）。采用所建立的化学分离流程和高精度质谱测量方法，测定了铂族元素橄榄岩标样WPR-1中Re、Os含量和Os同位素组成，测定结果与文献报道值在误差范围内吻合。     

Plasma heating in a sheared magnetic field

The mechanism of spatial resonance of Alfven waves for heating a collisionless plasma is studied in the presence of a twisted magnetic field. In addition to modifying the equilibrium condition for a cylindrical plasma, the azimuthal component of the magnetic field gives extra contribution to the energy deposition rate of the Alfven waves. This new term clearly brings out the effects associated with the finite lifetime of the Alfven waves. The theoretical system considered here conforms to the solar coronal regions.