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1993年, 第2卷, 第4期　刊出日期：1993-04-20 上一期    下一期

GENERAL

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ASYMPTOTIC EXPANSION OF GREEN FUNCTION OR HEAT KERNEL IN SPACE WITH TORSION 许殿彦, 许晓风 1993 (4):  241-247.  doi: 10.1088/1004-423X/2/4/001 摘要 ( 0 )   PDF(113KB) ([an error occurred while processing this directive])   An algorithm for asymptotic expansion of Green function or heat kemel in space with torsion is proposed. The De Witt-Seeley-Gilkey coeffcient E2(x) is calculated. 相关文章 | 计量指标

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A DEMONSTRATION OF 1×8 LINEAR ARRAY YBCO TRANSITION EDGE IR BOLOMETER 刘心田, 石保安, 杨德嘉, 陈兆甲 1993 (4):  248-251.  doi: 10.1088/1004-423X/2/4/002 摘要 ( 0 )   PDF(91KB) ([an error occurred while processing this directive])   A high-Tc superconducting array microbolometer has been fabricated by using a YBCO film. Optical measurements gave moderate performance as individual detector, but singnificant improverment appears possible. 相关文章 | 计量指标

CLASSICAL AREAS OF PHENOMENOLOGY

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ATOMIC-COHERENCE-INDUCED ENHANCEMENT OF REFRACTIVE INDEX 罗振飞, 徐至展, 周骄阳 1993 (4):  252-259.  doi: 10.1088/1004-423X/2/4/003 摘要 ( 0 )   PDF(180KB) ([an error occurred while processing this directive])   The influences of lower-level coherence in atomic medium of Ξ-type energy-level scheme on the absorption and dispersion are studied in dressed states. It is found that a weak probe light of a certain fre-quency can be free of atomic absorption, and at the same time has a large index of refraction. 相关文章 | 计量指标

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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RESISTIVE EFFECT ON ION FISHBONE MODE IN TOKAMAK PLASMA 石秉仁, J.W.VANDAM, R.CARRERA, Y.Z.ZHANG 1993 (4):  260-269.  doi: 10.1088/1004-423X/2/4/004 摘要 ( 0 )   PDF(221KB) ([an error occurred while processing this directive])   A consistent theoretical description of the resistive internal mode is presented to discuss the effect of resistivity on fishbone mode for different parameter regimes of bulk and hot components. We find that the ideal fishbone mode theory ceases to be correct for the low frequency fishbone branch, the so-called ion fishbone mode, which has a real frequency very dose to ω*i (the diamagnetic frequency) in marginal state. The stability domain analysis in (βh,γmhd) space based on the resistive dispersion relation shows that the transition between the stable and unstable regions is much more complicated than predicted by the ideal limit theory. Another salient feature of the resistive fishbone mode is the existence of a weakly unstable regime. For high frequency fishbone with ω≈ωdm (the toroidal precession frequency of the hot ions), resistivity has negligible effect and the ideal theory is correct. 相关文章 | 计量指标

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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STUDIES ON THE RELATIONSHIPS BETWEEN THE STRUCTURE AND THE LOCALIZED ENERGY STATES OF POLY (ETHYLENE TEREPHTHALATE) ELECTRETS 张兴元, 周漪琴 1993 (4):  270-279.  doi: 10.1088/1004-423X/2/4/005 摘要 ( 0 )   PDF(302KB) ([an error occurred while processing this directive])   A series of poly(ethytene terephthalate) (PET) films with different degrees of planar orientation [Δ(xy)z], crystallinity (Xc) and molecular weights were prepared by drawing biaxially, annealing at 110℃ and γ-imadiation of 0.5-4MGy. The peaks of localized energy states were separated from the detrapping cur-rent curves by means of poling temperature scanning method of themally stimulated current. The depth of localized energy levels enlarged with the rise of Δ(xy)z, Xc and γ-inadiation dose. The kinds of structural defects increased because of the changes of orientation structure of chains, crystalline structure and molecular chain structure, which caused the number of localized states to increase from 2 to 6 and the distribution width of the depth of localized levels to broaden. 相关文章 | 计量指标

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ORDER ALLOY IN GexSi1-x/Si(100) STRAINED-LAYER SUPERLATFICES 余是东, 李齐, 冯端, 俞鸣人, 褚一鸣 1993 (4):  280-285.  doi: 10.1088/1004-423X/2/4/006 摘要 ( 0 )   PDF(206KB) ([an error occurred while processing this directive])   The GexSi1-x/Si(100) strained-layer superlattices have been investigated by means of the transmission electron microscopy of the cross-sectional specimen (XTEM) and the high resolution electron microscopy (HREM), The order alloy with a period of modulation twice as large as the lattice constant along <100> zone axis has been found in the alloy layers of the superlattices with x≈0.4-0.5. This order struc-ture makes the superlattices inhomogeneously strained. The result of the compuler simulation shows that the order alloy exhibits an altemating stack of 2 monolayers of Ge atoms and 2 monolayers of Si atoms along the <100> zone axis. Thc calculated elastic strain energy of the disorder alloy reported in the litera-ture is very close to that of the order alloy along <100> zone axis. Thus, during the MBE growth of the alloy layers, both the disorder and order alloys can be formed along <100> zone axis. 相关文章 | 计量指标

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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PROPERTIES OF PROPAGATION OF GUIDED ELECTRON WAVES IN COUPLED ASYMMETRIC QUANTUM WELLS 袁世齐, 顾本源 1993 (4):  286-299.  doi: 10.1088/1004-423X/2/4/007 摘要 ( 0 )   PDF(411KB) ([an error occurred while processing this directive])   In this article we investigate the properties of the propagation of guided electron waves in the coupled asymmetric quantum wells. By decomposing the eigenfunctions of electron in the coupled double quantum wells in terms of the basis eigenfunctions of the individual wells, the expression of the mode amplitude func-tions for various bare states in wells has been given. By setting up appropriate boundary conditions one can simulate different injecting manners of electron into the system and study how the electron waves trans-fer among various states. The major electron wave transfer happens between the matching bare states in wells. The particular pattern of the transfer depends on the injecting manner and the energy of the inci-dent electron. We also show the influence of the presence of the multimodes on the variatinn of the mode amplitude functions. It leads to producing some oscillations imposed on the original sinusoidal-like func-tions and causing incomplete transfer between a pair of states in channels due to the beating frequency effect or the interference among various modes. 相关文章 | 计量指标

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SIZE EFFECT OF INNER RADIUS ON CIRCULARLY SYMMETRIC SOLITON STATES IN ANNULAR JOSEPHSON JUNCTIONS 徐昆明, 陆道芳, 姚希贤 1993 (4):  300-310.  doi: 10.1088/1004-423X/2/4/008 摘要 ( 0 )   PDF(295KB) ([an error occurred while processing this directive])   The effect of the inner radius of an annular Josephson junetion on the excitation 0f circularly symmetric soliton states is explored by direct numerical simulation. In a circularly symmetric annular Josephson junction (CSAJJ hereafter), the phase difference in the order parameters Φ across the junction bar-rier obeys the modified sine-Gordon equation (SGE) in which there is a perturbation term Φp/ρ inversely proportional to the radial coordinate ρ. and this term does not appear in the case of a 1D in-line junc-tion. The effect of the Φp/ρ term becomes prominent when ρ is small. It turns out that for junctions of grven dissipation and annular width, there is a lower limit of the inner radii for the junctions to support stable soliton motion, while the lower limit depends strongly on the dissipation coefficient α. For example, for a CSAJJ with inner radius 5λJ, outer radius 10λJ, no stable soliton states would exist when α=0.01 or α=0.02. However, for 0.06≥α≥0.03, there are ring-shaped solitary wave solutions, presumably because the dissipation suppresses the effect of the Φp/ρ term. Finally, the behaviour of the seliton states and the rele-vant I-V characteristics are also disscussed. 相关文章 | 计量指标