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21.
Haykel Elabidi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
We present in this work energy levels, oscillator strengths, radiative decay rates and fine structure collision strengths for the Mg III and Al IV ions. The 11 configurations: (1s2) 2s22p6, 2s22p53l, 2s2p63l, 2s22p54l (l?n-1, where n is the principal quantum number), yielding the lowest 75 levels are used. The collisional data for these two ions are missing in the literature, especially the database CHIANTI, this is the principal motivation behind the present work. Calculations have been performed using the AUTOSTRUCTURE code. AUTOSTRUCTURE treats the scattering problem in the distorted wave approach. Fine structure collision strengths are calculated for a range of electron energies from 10 Ry to 240 Ry. The atomic structure data are compared to available experimental and theoretical results. 相似文献
22.
R. Stamm R. Hammami I. Hannachi H. Capes L. Godbert-Mouret M. Koubiti Y. Marandet J. Rosato 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Stochastic processes provide flexible and fast calculations for modeling dynamical interactions between an atom and charged particles. We use a stochastic renewal process for the plasma microfield being the cause of Stark broadening. The accuracy and improvement possibilities of Lyman profiles calculations with a renewal process are analyzed by comparing to ab initio simulations for ion broadening only. Stochastic processes may also be applied to out of equilibrium plasmas. We present our first results for the effect of Langmuir waves on a line broadened by electrons only, and for the changes of atomic populations submitted to strong temperature fluctuations. 相似文献
23.
原子钟的测量噪声会被引入到频率稳定度评估过程,尤其是对中短期频率稳定度的影响更大。重叠Allan方差可以克服调频闪变噪声和调频随机游走噪声随时间变化出现的非平稳问题,但由于受到测量噪声的影响,评估结果仍会出现误差。为此,本文通过对原子钟的数学模型和噪声特性进行分析,提出了原子钟频率稳定度评估的加窗平滑噪声处理方法,通过对时差观测序列合理的加窗设计和平滑处理,抑制测量噪声对评估结果的影响。实验结果表明,利用铷钟观测序列的100点平滑可以有效地提高短期频率稳定度结果(100~1 000)s的可信度。 相似文献
24.
25.
F. Ramírez-Martínez C. Lacroûte P. Rosenbusch F. Reinhard C. Deutsch T. Schneider J. Reichel 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
We present a compact atomic frequency standard based on the interrogation of magnetically trapped 87Rb atoms. Two photons, in the microwave and radiofrequency domain excite the atomic transition. At a magnetic field of 3.23 G this transition from ∣F = 1, mF = −1〉 to ∣F = 2, mF = 1〉 is 1st order insensitive to magnetic field variations. Long Ramsey interrogation times can thus be achieved, leading to a projected stability in the low 10−13 at 1 s. This makes this device a viable alternative to LITE and HORACE as a good candidate for replacing or complementing the rubidium frequency standards and passive hydrogen masers already on board of the GPS, GLONASS, and GALILEO satellites. Here we present preliminary results. We use an atom chip to cool and trap the atoms. A coplanar waveguide is integrated to the chip to carry the Ramsey interrogation signal, making the physics package potentially as small as (5 cm)3. We describe the experimental apparatus and show preliminary Ramsey fringes of 1.25 Hz linewidth. We also show a preliminary frequency stability σy = 1.5 × 10−12τ−1/2 for 10 < τ < 103 s. This represents one order of magnitude improvement with respect to previous experiments. 相似文献
26.
提出用一氧化二氮-乙炔火焰原子吸收光谱法测定热电池隔离粉中镁。介绍镁的最佳测定条件并具有良好线性范围的浓度,并对样品消化处理条件、干扰因素进行了综合考虑。该方法灵敏度高、重现性好,同时具有方法步骤简单、操作容易掌握等特点,达到了实验室分析质量控制的要求。 相似文献
27.
介绍我所研制成的一台评价原子氧对空间材料效应的高频放电氧等离子体试验装置的结构和性能.对Kapton试样的测试表明:用这种装置试验的结果与美国洛克希德公司装置的测试结果相当.其作用强度相当于200km高度轨道中原子氧作用强度的4倍以上. 相似文献
28.
利用卡尔曼滤波技术对GPS定时校频数据进行处理提高精度,是国际上近几年的最新研究课题。全面的介绍了北京无线电计量测试研究所开展该项技术的研究成果,从基本理论,滤波器模型选定、滤波器设计、仿真试验分析等方面作了论述,并给出实际应用的实验结果。对国内开发应用该技术具有参考价值。 相似文献
29.
Milan S. Dimitrijević Magdalena Christova Zoran Simić Andjelka Kovačević Sylvie Sahal-Bréchot 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Stark broadening parameters for 36 multiplets of B IV have been calculated using the semi-classical perturbation formalism. Obtained results have been used to investigate the regularities within spectral series and temperature dependence. 相似文献
30.
Rafik Hamdi Nabil Ben Nessib Sylvie Sahal-Bréchot Milan S. Dimitrijević 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Using semiclassical perturbation approach in impact approximation, we have calculated Stark widths for 32 spectral lines of doubly charged argon (Ar III). Oscillator strengths are calculated using Hartree–Fock method with relativistic correction (HFR) and an atomic model including 17 configurations. Energy levels are taken from NIST database. For perturbing levels for which the corresponding energy does not exist in NIST database, the calculated energies are used. Our widths are compared with the experimental results. The results presented here are of interest for modelling and investigation of stellar atmospheres since argon in different ionization stages is observed in many astrophysical objects. Finally, the importance of Stark broadening mechanism is studied in the atmospheric conditions of sdB stars. Electron impact Stark widths are compared to thermal Doppler widths as a function of temperature and optical depth of atmospheric layers. 相似文献