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Modeling density and Anisotropy of Energetic Electrons Along Magnetic Field Lines

Plasma Science and Technology 2006年第3期8卷 279-284页

作者：肖伏良冯学尚 Department of Physics and Electronic Sciences Changsha University of Science and Technology Changsha 410076 China State Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China State Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China

The electromagnetic wave growth or damping depends basically on the number density and anisotropy of energetic particles as the resonant interaction takes place between the particles and waves in the magnetosphere. The variance of both the number density and anisotropy along the magnetic field line is evaluated systematically by modeling four typically prescribed distribution functions. It is shown that in the case of ＂the positive anisotropy＂（namely, the perpendicular temperature T⊥ exceeds the parallel temperature T｜｜）, the number density of energetic electrons always decreases with the magnetic latitude for a regular increasing magnetic field and the maximum wave growth is therefore generally confined to the equator where the resonant energy is minimum, and the number density is the largest. However, the ＂loss-cone＂ anisotropy of the electrons with a ＂pancake＂ distribution or kappa distribution keeps invariant or nearly invariant, whereas the ＂temperature＂ anisotropy with a pure bi-Maxwellian distribution or Ashour-Abdalla and Kennel＇s distributions decreases with the magnetic latitude. The results may provide a useful approach to evaluating the number density and anisotropy of the energetic electrons at latitudes where the observation information is not available.

关键词： number density anisotropy distribution function magnetic field line

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Electro-optic Properties of DR1 Doped SiO_2 Organic/inorganic Guest-host Films

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Chemical Research in Chinese Universities 2009年第5期25卷 726-732页

作者： LIU Shao-lin YANG Han JIN Ru-long YAN Zhao-xu YI Mao-bin State Key Laboratory on Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun 130012 P.R. China

We made a comprehensive investigation on the electro-optic（EO） properties of hybrid sol-gel silica film doped with Dispersed Red 1 dye（DR1/SiO2）. An important finding is that the dipoles which don＇t orient along the direction of corona poling field in the films can be instantaneously poled by alternate modulation electrical field. This instant poling effect results in the EO coefficients dependent on the frequency and intensity of alternate modulation electric field, and some experiments have proved it. We also investigated the electro-optic coefficients and thickness of films at different stir temperatures（Ts） of start solution and at different number densities of DR1. Experimentally the DR1 number density was optimized to an order of 1021/cm^3 and a large EO coefficient of γ33= 37 pm/V for DR1/SiO2 film was measured by simple reflection technique at 1 kHz frequencies of modulation electric field. These findings may benefit the practical application of DR1/SiO2 films in the field of EO modulator and EO probing.

关键词： Electro-optic DR1/SiO2 Instant poling number density Frequency

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FORMULATION OF STATISTICAL EVOLUTION OF MICROCRACKS IN SOLIDS

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Acta Mechanica Sinica 1991年第1期7卷 59-66页

作者： Bai Yilong (1) Ke Fujiu (1) Xia Mengfen (1) 1. Laboratory for Non-Linear Mechanics of Continuous Media Institute of Mechanics Chinese Academy of Sciences 100080 Beijing China

The paper presents a principal formulation of statistical evolution of microcracks, occurring in solids, subjected to external loading. In particular, the concept of ideal microcracks is elaborated, in order to describe the fundamental features of damage resulting from nucleation and extension of microcracks. Relevant average damage functions are also discussed.

关键词： micro-cracks statistical evolution number density

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An Inquiry into Two Intriguing Values of the Critical Current density of Bi-2212

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World Journal of Condensed Matter Physics 2021年第3期11卷 53-64页

作者： Gulshan Prakash Malik Vijaya Shankar Varma B-208 Sushant Lok 1 Gurugram India 180 Mall Apartments Delhi India

The empirically reported values of the critical current density (jc) of Bi-2212 as 2.4 × 105 (jc1;Sample 1) and 1.0 × 106 A/cm2 (jc2;Sample 2) are intriguing because both of them correspond to the same values of the temperature T = 4.2 K and the applied magnetic field H = 12 × 104 G. This difference is conventionally attributed to such factors—not all of which are quantifiable—as the geometry, dimensions and the nature of dopants and the manners of preparation of the samples which cause their granular structures, grain boundaries, alignment of the grains and so on to differ. Based on the premise that the chemical potential μ subsumes most of these features, given herein is a novel explanation of the said results in terms of the values of μ of the two samples. This paper revisits the problem that was originally addressed in [Malik G.P., Varma V.S. (2020) WJCMP, 10, 53-70] in the more accurate framework of a subsequent paper [Malik G.P., Varma V.S. (2021) JSNM, 34, 1551-1561]. Besides, it distinguishes between the contributions of the electro-electron (e-e) and the hole-hole (h-h) pairs to jc—a feature to which no heed was paid earlier. The essence of our findings is that the jcs of the two samples differ because they are characterized by different values of the primary variables μi and , where is the effective mass of a charge-carrier and me is the free-electron mass and i = 1 and 2 denote Sample 1 and Sample 2, respectively. In the scenario of the charge-carriers being predominantly h-h pairs, the values of these parameters are estimated to be: μ

关键词： Chemical Potential- Temperature- and Applied Magnetic Field-Dependent Critical Current density of Superconductors number density Landau Quantization Law of Equipartition of Energy Bi-2212

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