Table of contents

15 April 2000, Volume 9 Issue 4 Previous issue    Next issue

GENERAL

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THE RELATIVISTIC COVARIANCE OF ONNES EQUATION Liu Ze-wen (刘泽文), Zhu Zhen-long (朱镇龙), Meng Xiang-jun (孟祥君) Chinese Physics, 2000, 9 (4):  241-243.  DOI: 10.1088/1009-1963/9/4/001 Abstract ( 885 )   PDF (171KB) ( 334 )   On the assumption that Onnes equations meet the requirements of the relativistic covariance, virial coefficients as functions of temperature are derived by using the transformations between thermodynamic variables provided by the vector theory of relativistic thermodynamics, and result in agreement with those obtained from cluster expansions in statistics. This breaks, to some extent, the traditional ideas that the thermodynamic theory is not able to derive equations of state at all and presents a possibly simple and new way of finding theoretically the equation of state.

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USING OPTIMAL FEEDBACK CONTROL FOR CHAOS TARGETING Peng Zhao-wang (彭召旺), Zhong Ting-xiu (钟廷修) Chinese Physics, 2000, 9 (4):  244-249.  DOI: 10.1088/1009-1963/9/4/002 Abstract ( 1045 )   PDF (146KB) ( 379 )   Since the conventional open-loop optimal targeting of chaos is very sensitive to noise, a close-loop optimal targeting method is proposed to improve the targeting performance under noise. The present optimal targeting model takes into consideration both precision and speed of the targeting procedure. The parameters, rather than the output, of the targeting controller, are directly optimized to obtain optimal chaos targeting. Analysis regarding the mechanism is given from physics aspect and numerical experiment on the Hénon map is carried out to compare the targeting performance under noise between the close-loop and the open-loop methods.

CLASSICAL AREAS OF PHENOMENOLOGY

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RESONANT INTERACTION BETWEEN A PAUL-TRAPPED ION AND A STANDING WAVE LASER Feng Mang (冯芒), Hai Wen-hua (海文华), Zhu Xi-wen (朱熙文), Gao Ke-lin (高克林), Shi Lei (施磊) Chinese Physics, 2000, 9 (4):  250-258.  DOI: 10.1088/1009-1963/9/4/003 Abstract ( 1041 )   PDF (321KB) ( 372 )   An ultracold two-level ion experiencing the standing wave of a resonant laser in a Paul trap is investigated in the Lamb-Dicke limit and weak excitation regime, with full consideration of the time-dependence of the trapping potential. The analytical forms of the wave functions of the system can be described with our approach, and the time evolution of the pseudo-energy of the system as well as the squeezing property of the quadrature components is studied in comparison with the treatment of harmonic oscillator model.

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QUANTUM LANGEVIN THEORY OF WHISPERING-GALLERY-MODE MICROSPHERE LASER Chai Jin-hua (柴金华), Lu Yi-qun (路轶群), Leung Pui-tang (梁培) Chinese Physics, 2000, 9 (4):  259-273.  DOI: 10.1088/1009-1963/9/4/004 Abstract ( 1372 )   PDF (324KB) ( 454 )   A quantum Langevin theory of whispering-gallery-mode microsphere laser theory is developed. The linear and nonlinear analysis are made for laser operation below and above the threshold. In these analysis, corresponding to the specific property of microsphere, the effect of inversion fluctuation is treated. The coherence functions of laser field are calculated, and the intensity, the amplitude fluctuation and the linewidth of the field are obtained, which are connected with the enhancement factor of whispering-gallery-mode microsphere. It is shown that the strong couple and strong pumping are useful for the amplification of intensity and the decrease of linewidth below the threshold. It is also shown that, for the laser action above threshold, the variances of photon number and the linewidth of internal field are related to the enhancement factor and the square of the enhancement factor, respectively.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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DISPERSION RELATION OF A MAGNETIZED PLASMA-FILLED BACKWARD WAVE OSCILLATOR Gao Hong (高宏), Liu Sheng-gang (刘盛纲) Chinese Physics, 2000, 9 (4):  274-278.  DOI: 10.1088/1009-1963/9/4/005 Abstract ( 1049 )   PDF (109KB) ( 523 )   A linear theory and a more general dispersion relation of electromagnetic radiation from a magnetized plasma-filled backward wave oscillator with sinusoidally corrugated slow-wave structure driven by a solid intense relativistic electron beam have been given. The comparisons show good agreement with the previous works when B0→$\infty$ and $\omega_b$ = 0 from this dispersion relation.

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THE EFFECT OF MESH ANODE ON CATHODIC ARC IN FOCUSING MAGNETIC FIELD Zhang Tao (张涛), Hou Jun-da (侯君达), Tang Bao-yin (汤宝寅), T. K. Kwok, Zeng Zhao-ming (曾照明), I. G. Brown, Paul K. Chu Chinese Physics, 2000, 9 (4):  279-283.  DOI: 10.1088/1009-1963/9/4/006 Abstract ( 1157 )   PDF (129KB) ( 452 )   The performance and characteristics of a cathodic arc deposition apparatus consisting of a titanium cathode, an anode with and without a tungsten mesh, and a coil producing a focusing magnetic field between the anode and cathode are investigated. The arc voltage Va is measured with a fixed arc current. The relationship between Va and the magnetic field B with and without a mesh is obtained. In addition, the relationship between the arc current Ia and Vc, the voltage to which the artificial transmission line was charged, is measured with and without the mesh to determine the minimum ignition voltage for the arc. The arc resistance increases with the focusing magnetic strength B and decreases when using the mesh. Our results indicate that the high transparency and large area of the mesh allows a high plasma flux to penetrate the anode from the cathodic arc. The mesh also stabilizes the cathodic arc and gives better performance when used in concert with a focusing magnetic field.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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CHARACTERIZATION OF POLYCRYSTALLINE GRADIENT THIN FILM BY X-RAY DIFFRACTION METHOD Li Bin (李彬), Tao Kun (陶琨), Liu Xing-tao (刘兴涛), Miao Wei (苗伟), Feng Tao (冯涛), Yang Ning (杨宁), Liu Bai-xin (柳百新) Chinese Physics, 2000, 9 (4):  284-289.  DOI: 10.1088/1009-1963/9/4/007 Abstract ( 1154 )   PDF (239KB) ( 337 )   A direct method is proposed to quantitatively characterize the structural depth profiles emerged in the polycrystalline thin films based on the information obtained by X-ray diffraction (XRD) with various incident angles and treated by a numerical procedure known as the constrained linear inversion. It should be noted that the proposed method was neither sensitive to the random noise appearing in experiment nor to the error originated from the measured thickness of the specimen. To testify the validity of the method, XRD measurements were carried out on a specially designed Pd/Ag bilayer sample, which was annealed at 490℃ for 20 min, and the depth profiles were accordingly calculated through resolving the obtained XRD patterns. The elemental concentration depth profile of the Pd/Ag bilayer sample was in turn calculated from the resolved patterns, which was in good agreement with those obtained by Auger electron analysis on the annealed sample.

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ELECTRON PARAMAGNETIC RESONANCE STUDIES OF DIMENSIONALITY OF POLYANILINE FILMS Jiang Zhi-jie (蒋志洁), Mo Dang (莫党) Chinese Physics, 2000, 9 (4):  290-293.  DOI: 10.1088/1009-1963/9/4/008 Abstract ( 1053 )   PDF (98KB) ( 370 )   The line shape analysis of electron paramagnetic resonance (EPR) spectra for low-dimensional solids are calculated. A comparison is carried out between the experimental EPR results of polyaniline samples and theoretical calculation. The dimension evolution of the samples from nonconducting to conducting states is obtained. It is found that the dimensional properties determined by EPR are in good accordance with those obtained using previous ellipsometric methods.

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AXISYMMETRIC ELASTICITY PROBLEM OF CUBIC QUASICRYSTAL Zhou Wang-min (周旺民), Fan Tian-you (范天佑) Chinese Physics, 2000, 9 (4):  294-303.  DOI: 10.1088/1009-1963/9/4/009 Abstract ( 1047 )   PDF (121KB) ( 536 )   A method for analyzing the elasticity problem of cubic quasicrystal is developed. The axisymmetric elasticity problem of cubic quasicrystal is reduced to a single higher-order partial differential equation by introducing a displacement function. As an example, the solutions of elastic field of cubic quasicrystal with a penny-shaped crack are obtained, and the stress intensity factor and strain energy release rate are determined.

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

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MAGNETIC PROPERTIES OF BALL MILLED FexCu1-x (x=0.4, 0.5) ALLOY Li Yu-zhi (李玉芝), Lin lei (林磊), Wang Wang-chen (王汪陈), Xiong Cao-shui (熊曹水), Shen Bao-gen (沈保根) Chinese Physics, 2000, 9 (4):  304-308.  DOI: 10.1088/1009-1963/9/4/010 Abstract ( 1226 )   PDF (143KB) ( 412 )   The samples Fe0.4Cu0.6 and Fe0.5Cu0.5 ball milled for 50 h are investigated by X-ray diffraction, M$\ddot{\rm o}$ssbauer spectra, as well as magnetic measurement. The experiments show that the structure of the samples is fcc, with lattice constant 0.361 nm and there are fcc Fe-rich phase and fcc Cu-rich phase in the samples. Most of Fe atoms (91%) are in the fcc Fe-rich phase, which is a ferromagnetic phase. The M-H curve at 1.5 K shows the saturation magnetization of the samples are 80.5 emu/g and 101.6 emu/g for Fe0.4Cu0.6 and Fe0.5Cu0.5 respectively. The average magnetic moment of Fe atoms is deduced to be 2.40 $\mu_{\rm B}$. Compared with theoretical predication, the Fe atoms in the fcc phase are in high spin state.

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MICROSTRUCTURE OF SiOx:H FILMS PREPARED BY PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION Ma Zhi-xun (马智训), Liao Xian-bo (廖显伯), Kong Guang-lin (孔光临), Chu Jun-hao (褚君浩) Chinese Physics, 2000, 9 (4):  309-312.  DOI: 10.1088/1009-1963/9/4/011 Abstract ( 984 )   PDF (117KB) ( 508 )   The micro-Raman spectroscopy and infrared (IR) spectroscopy have been performed for the study of the microstructure of amorphous hydrogenated oxidized silicon (a-SiOx:H) films prepared by Plasma Enhanced Chemical Vapor Deposition technique. It is found that a-SiOx:H consists of two phases: an amorphous silicon-rich phase and an oxygen-rich phase mainly comprised of HSi-SiO2 and HSi-O3. The Raman scattering results exhibit that the frequency of TO-like mode of amorphous silicon red-shifts with decreasing size of silicon-rich region. This is related to the quantum confinement effects, similar to the nanocrystalline silicon.