磁化等离子体中静电漂移波和剪切阿耳芬波的非线性耦合

本文采用Hasegawa-Wakatani方程组研究磁化等离子体中静电漂移波和剪切阿耳芬波的非线性耦合。求得非线性方程组的偶极涡旋解。这些解属于本性电磁涡旋,对应的扰动磁场和纵向电流在涡旋边界上是连续的。 关键词：     

载流有界等离子体柱中的剪切阿尔芬波涡旋

本文采用二流体方程组，研究低β（ｍｅ／ｍｉ＜＜β＜＜１）载流有界等离子体柱中的非线性剪切阿尔芬波，求得一类新的电磁涡旋解。在这类解中，扰动电场和扰动磁场的局域结构由单极部分和多极部分组成，而扰动密度是多极涡旋结构。这些相干结构以一定的角速度整体地绕等离子体柱轴运行。对于本文所取的参数，平衡电流对扰动电磁场和密度的涡旋结构无影响。     

等离子体四波混频精确解

给出了均匀磁化等离子体介质中的简并与近简并的建党波四波混频形成反射光栅位形时的普适非线性耦俣方程组，在不作无衰减抽运近似的情况下，得到了任意复耦合系数时的方程组的精确解，其解不仅可以推广到各种等离子体形态，而且可以推广到光致折射材料中去。     

等离子体四波混频精确解反射光栅位形

给出了均匀磁化等离子体介质中的简并与近简并的寻常波四波混频形成反射光栅位形时的普适非线性耦合方程组。在不作无衰减抽运近似的情况下,得到了任意复耦合系数时的方程组的精确解。其解不仅可以推广到各种等离子体形态,而且可以推广到光致折射材料中去。对进一步理论研究四波混频相位共轭,发展新的非线性光学器件可能有所帮助。     

载流等离子体中的气球涡旋

本文研究载流等离子体中的非线性气球模。我们导出描述载流等离子体中的非线性气球模的方程组,求出该方程组的偶极涡旋解。它们属于Rossby型涡旋。结果表明,电子成份的定向运动将显著地影响涡旋的性质。     

等离子体柱中的短波漂移旋涡

本文研宄等离子体柱中短波漂移非线性波。我们推导出柱坐标系中描述该波的非线性耦合方程组,求出一类不同于在笛卡尔坐标系中得到的偶极旋涡(vortex)的新解。这类新解由轴对称和反对称两部分组成,称之为径向旋涡。     

等离子体四波混频透射放大理论

研究了寻常波在磁化等离子体中四波混频透射放大理论，得到了简并和非简并时的精确解析解，其结果适用于非磁化等离子体中的电磁波四波混频． 关键词：     

非均匀磁场中的剪切阿尔芬波涡旋

本文研究了非均匀磁场中非线性剪世阿尔芬波，研究表明，在非均匀磁场情况下，阿尔芬波通过自相互作用也可以形成避域涡旋结构。磁场的非均匀性将导致传播区的展宽。     

KT—5B托卡马克上阿尔芬波加热实验中天线阻抗的测量

一、引 言 托卡马克等离子体中的阿尔芬波加热实验研究自80年代初以来取得了许多有价值的实验结果。在阿尔芬波加热实验中,天线辐射阻抗的测量是十分重要的。天线辐射阻抗的变化不仅直接反映了阿尔芬波与等离子体之间的能量耦合情况,而且也反映了波在等离子体中传播过程的某些物理特性。例如,出现离散阿尔芬波(DAW模)或表面静电波(SEW模)便会使阻抗出现较大的峰值。因此,探索一种简便易行又能反映阻抗随放电时间变化的细微     

具有强剪切流等离子体中离子声波与涡旋的转化

研究了在具有剪切本底流的非磁化等离子体中离子声波的激发及其与涡旋的转化。从流体方程组出发，导出了描述低频静电扰动的微分方程组。采用非模方法，得到了扰动量的剪切傅里叶谐波分量随时间演化的方程组，并对方程组进行了数值分析。结果表明：在强剪切条件下，剪切旋涡可以转化为离子声波；同样地，离子声波也激发剪切旋涡。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.