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1996年, 第5卷, 第1期　刊出日期：1996-01-20 上一期    下一期

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DETERMINATION OF CAPTURE BARRIERS OF DEFECTS FOR GaAs ALLOYS AND TRANSIENT PHOTO-RESISTIVITY SPECTROSCOPY 王海龙, 封松林, 周洁, 杨锡震 1996 (1):  1-9.  doi: 10.1088/1004-423X/5/1/001 摘要 ( 1236 )   PDF(229KB) ( 430 )   Si-doped Ga0.7Al0.3As grown by molecular beam epitaxy (MBE) and undoped Ga0.47Al0.53As grown by chemical beam epitaxy (CBE) have been investigated using a new deep level characterization method-transient photo-resistivity spectroscopy, which we recently developed. This method measures directly the capture process of deep centers. In GaAlAs, apparent capture barrier energy EB= 0.25eV of DX center was determined and intrinasic capture barrier energy Eσ = 0.16eV was directly measured. In GaInAs, a defect with capture barier energy EB= 0.2BeV was observed. The result proved that DX centers capture electron only from band L, belonging to small lattice relaxation model. The theoretical deduction of transient photo-resistivity spectroscopy was improved. 相关文章 | 计量指标

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EXAFS STUDY OF THE LOCAL STRUCTURE NANOCRYSTALLINE FeZrB(Cu) SOFT MAGNETIC ALLOYS 胡小军, 邬秋林, 季雨, 满一军, 虞科, 凌刚, 杨国斌, 王润, 谢亚宁 1996 (1):  10-14.  doi: 10.1088/1004-423X/5/1/002 摘要 ( 1095 )   PDF(145KB) ( 465 )   The changes of local structures around Fe and Zr atoms in the nanocrystalline films of Fe85Zr9B6 and Fe84Zr9B6 Cu1 alloys during annealing process were investigated by extended X-ray absorption fine structure (EXAFS) technique. It is confirmed that Zr atoms always exist in amorphous phase and do not dissolve in the bcc α-Fe crystalline phase. The addition of 1 at% Cu lowers the crystallization temperature. 相关文章 | 计量指标

CLASSICAL AREAS OF PHENOMENOLOGY

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SUPERRADIANCE EFFECT OF THE CRYSTAL-LIKE-GAS 凌天, 郭光灿 1996 (1):  15-23.  doi: 10.1088/1004-423X/5/1/003 摘要 ( 1082 )   PDF(173KB) ( 323 )   Crystal-like-gas (CLG) is a new kind of matter in which the atoms are arranged periodically in the space and the electrons are bound to the corresponding atoms. In this paper, we study the superradiance effect of CLG and discuss some interesting new properties due to the periodic structure of CLG. The non-ideal situation is also discussed. 相关文章 | 计量指标

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ASYMMETRIC CONTROL CHARACTERISTICS OF DYE BDN ON THE TWO TRAVELLING WAVES IN A RING YAG LASER 黄茂全, 郑晋玲, 李瑞宁, 郜江瑞, 张宽收, 苏大春 1996 (1):  24-30.  doi: 10.1088/1004-423X/5/1/004 摘要 ( 1210 )   PDF(142KB) ( 360 )   It is discovered experimentally that, when placing a plate of dye BDN in a ring YAG laser cavity, the dye shows asymmetric control actions on the clockwise and counter-clockwise travelling waves. Unidirectional dye Q-switched operation is realized in a ring cavity based on this property without the use of Faraday rotator, polarizer and half-wave plate. A simplified theoretical analysis of this phenomenon is presented. 相关文章 | 计量指标

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PHASE SPACE ANALYSIS OF FREE ELECTRON LASER EFFICIENCY REDUCTION DUE TO RANDOM FIELD ERROR 胡素兴, 傅恩生 1996 (1):  31-38.  doi: 10.1088/1004-423X/5/1/005 摘要 ( 1074 )   PDF(206KB) ( 439 )   Considering the random field error of the wiggler, we deduce the equation of phase motion and calculate the phase volume of interaction in a real helical wiggler. The result was compared with the case of the ideal wiggler field. We analyze how the random field error causes the efficiency of free electron laser (FEL) to reduce, and simulate the FEL efficiency reduction effect according to the mechanisms which we present in this paper. The consequence agrees excellently with the experiment. 相关文章 | 计量指标

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EXPERIMENTAL STUDY ON THE SELF-MODE-LOCKED Ti:SAPPHIRE LASER 邢岐荣, 张伟力, 卢炜, K.M.YOO, J.LUENG 1996 (1):  39-45.  doi: 10.1088/1004-423X/5/1/006 摘要 ( 1188 )   PDF(223KB) ( 429 )   The role of gain aperture in self-mode-locked Ti:sapphire laser was verified in our experiments. The observation of self-Q switching of self-mode-locked Ti:sapphire laser is reported. And tuning pulse duration from 50fs to 14.5ps was achieved. 相关文章 | 计量指标

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THEORETICAL INVESTIGATION OF SOLID FEMTOSECOND LASER AMPLIFIER 赵应桥, 章若冰, 王清月 1996 (1):  46-57.  doi: 10.1088/1004-423X/5/1/007 摘要 ( 1207 )   PDF(355KB) ( 360 )   In this article, we present a theoretical description of the various effects on femtosecond light pulse during its propagating through a long solid gain medium on the basis of Maxwell equations and rate equations, By numerical simulation, we analyzed the variation of pulse energy, pulse duration. pulse shape and spectral distribution due to gain saturation, spectral narrowing, phase-shift induced by gain, group-velocity dispersion and self-phase modulation. 相关文章 | 计量指标

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THE DECISIVE ROLE OF m= 1 AND 2 PERTURBATIONS IN DENSITY LIMIT DISRUPTIONS ON TEXTOR 匡光力, G.WAIDMANN 1996 (1):  58-70.  doi: 10.1088/1004-423X/5/1/008 摘要 ( 1205 )   PDF(433KB) ( 373 )   The behavior of magnetohydrodynamic phenomena associated with disruptions of ohmically heated density limit discharges (qa=3.9) in the TEXTOR tokamak has been investigated in detail. A minor disruption is demonstrated to be only due to an tn = 2 mode instability, possibly due to the magnetic reconnection of an m=2 island. When the m = 2 mode oscillations cease, the internal m = 1 kink mode instability is drastically enhanced at once, twisting the plasma core considerably. If the twisting is too strong, the twisted plasma core is inevitably displaced to the outside and brings cold plasma to the central region, leading to the energy quench at a major disruption. 相关文章 | 计量指标