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Vol. 32, No. 2 (1983)

1983-01-20
CONTENT
A GENERALIZED FORMULA OF THE THIRD ORDER ELECTRICAL DEFLECTION ABERRATION COEFFICIENTS AND THEIR RELATION WITH THE RASTER PATTERN
DING SHOU-QIAN
1983, 32 (2): 145-155. doi: 10.7498/aps.32.145
Abstract +
This paper deals with the generalization of the theory of third order aberrations of an electrical deflection system under the situation as the electron beam is originally immersed in an electric field. The formulae of third order electrical deflection aberration coefficients in an arbitrary plane have been derived. It can be applied to either sequential deflection systems or superimposed deflection yokes. By means of mathematical manoeuvres, the formulae are simplified and made easy for calculation. In order to obtain high precision, the first and second order derivatives of the field E0(z) have been eliminated. In accordance with our previous work, the nomenclature and calculating procedure are kept the same as before, so we can adopt the same computing scheme.Finally, we have described the relations between the patterns of the raster distortion, astigmatism, field curvature, coma, and the corresponding deflection aberration coefficients for a small electron beam which is initially point-focused on the image screen. These relations may also be applied to the third order magnetic deflection aberrations.
ON THE BRAGG-DIFFRACTION OF SURFACE ACOUSTIC WAVES BY ACOUSTIC GRATING
WANG ZOU-QING, ZHOU SU-HUA, WANG CHENG-HAO
1983, 32 (2): 156-167. doi: 10.7498/aps.32.156
Abstract +
The surface acoustic wave diffraction phenomena on acoustic gratings in Bragg regime have been explored.The modal approach has been used to treat this problem under strong Bragg condition. Some results, including the eigen-modes in the grating, the equation of the deflected angles, and the analytical expression of deflection efficiency which depends on the operation frequency and the grating parameters, have been obtained.Experimentally, the image of the diffraction acoustic fields on acoustic grating which was composed of some aluminium film stripes on y-cut LiNbO3 crystals have been visualized by means of Schlieren method. Some excellent photographs of diffraction fields have been obtained, and the deflection angles and deflection efficiency at different frequency have been measured by using optical method. The comparison between the theoretical and the experimental results shows that the agreement is satisfactory.
INVESTIGATION OF MAGNETIC PROPERTIES AND M?SSBAUER SPECTRA OF LaxBa1-xFe12-xZnxO19 FERRITES
DU YOU-WEI, LU HUAI-XIAN, ZHANG YU-CHANG, HUI LI-REN, WANG TING-XIANG
1983, 32 (2): 168-175. doi: 10.7498/aps.32.168
Abstract +
The hexagonal ferrites LaxBa1-xFe12-xZnxO19 were prepared by oxalate eopreci-pitation method. The ferrites with magnet oplumbite structure were found to be formed for xf and the magnetic crystal anisotropy constant k decreases with increasing x. M?ssbauer spectra have revealed that Zn2+ ion tends to occupy 4f2 site.
GENERATION AND ANNIHILATION OF VERTICAL BLOCH LINES IN STRIP DOMAIN WALLS
MAO TING-DE, LI JING-YUAN, FAN SHE-YONG, LIU YING-LIE
1983, 32 (2): 176-181. doi: 10.7498/aps.32.176
Abstract +
Magnetic domains in a magnetic bubble film have been observed in different bias fields after application of pulsed bias fields. The experimental results indicate that the formation of multifingered domains during the rapid expansion of bubbles is usually accompanied by the generation of a large amount of vertical Bloch lines (VBL). The sign of the VBL has a definite relation to the strength of the bias fields applied. On application of a series of bias pulses which are not very strong, the motion of strip domain heads leads to the generation of a large amount of VBL in the domain walls. The VBL will disappear when the pulsed bias fields are strong enough.
CRACKING DUE TO A PLATE-FORM INCLUSION OF SHEAR TYPE
ZHE XIAO-LI, ZHANG HONG-TU
1983, 32 (2): 182-190. doi: 10.7498/aps.32.182
Abstract +
Plate-form inclusions of shear type represent the mechanical aspect of many important processes, such as the formation of slip bands, twin bands and martensitc plates in crystalline materials. All these processes connect closely with fracture of materials. Analytical expressions for stress intensity factors of the crack near the inclusion have been derived by using dislocation theoretical method. Using the results of this paper, some aspects of the cracking due to a plate-form inclusion are discussed. The Hall-Petch relation of twin-fracture stresses can be obtained from the inclusion model, and the theoretical results are in good agreement with experiments.
A SCALING LAW FOR THE ANOMALOUS ELECTRON TRANSPORT IN TOKAMAKS
ZHANG YANG-ZHONG
1983, 32 (2): 191-197. doi: 10.7498/aps.32.191
Abstract +
It is assumed in the paper that the dominant mechanism for the anomalous electron transport in Tokamaks is the renormalized electron magnetic drift wave driven by temperature gradient. A scaling law for the anomalous electron transport coefficient D(T) has been derived by solving self -consistently the kinetic process, it reads D(T)=(c/ωpe)2 {((ve/qR)2/2π+(vc/2)2)1/2 - vc/2} It coincides in numerical values with the Alcator scaling law given by the Tokamak's experiments, and it agrees with the Ohkawa scaling law in the collisionless limit (vc → 0). Furthermore, its deviation from the Alcator scaling law is analyzed, and the possibility of achieving the thermonuclear ignition for a high-field ohmically heating Tokamak is also discussed based on the scaling law.
SUBHARMONIC STROBOSCOPIC SAMPLING METHOD FOR STUDY OF PERIOD-DOUBLING BIFURCATION AND CHAOTIC PHENOMENA IN FORCED NONLINEAR OSCILLATORS
HAO BAI-LIN, ZHANG SHU-YU
1983, 32 (2): 198-208. doi: 10.7498/aps.32.198
Abstract +
By using subharmonic stroboscopic sampling method, very high resolution, comparable with that for discret mappings, has been reached in numerical study of periodically forced nonlinear oscillators. For the first time period-doubling bifurcation sequences up to 8192th subharmonics and corresponding sequences of chaotic bands are identified for a system, described by ordinary differential equations. Secondary and tertiary bifurcation sequences embedded in chaotic bands are shown to exist. Merits and limitations of this method as well as some precaution in using it are discussed briefly.
PHENOMENON OF WAVE-LENGTH INCREASE IN RAYLEIGH-BéNARD CONVECTION AND CRITERION OF MAXIMUM ENTROPY PRODUCTION
CHEN SHI-GANG, WANG YOU-QIN
1983, 32 (2): 209-215. doi: 10.7498/aps.32.209
Abstract +
The phenomenon of wave-length increase occurred in Rayleigh-Bénard convectiou is analysed by numerical method, and the result obtained is in good agreement with experiment. The calculations for stability and entropy production show that the criterion of maximum entropy production for relative stability of steady states is correct.
STATISTICAL FLUCTUATION PROBLEM IN PULSED RADIATION DIAGNOSTICS
Lü MIN
1983, 32 (2): 216-224. doi: 10.7498/aps.32.216
Abstract +
When the waveform of a radiation pulse is measured, a large number of radiation particles interact with the detector simultaneously. The output current waveform is proportional to the waveform of the radiation pulse. The statistical fluctuation phenomenon will appear when the radiation source is relatively weak or the sensitivity of the detector is low. In this paper, the fluctuation phenomenon are considered and mathematical expressions for fluctuation are given. We have also discussed the uncertainty due to statistical fluctuation of various pulse parameters measured, such as amplitude, width, time interval and other special parameters.
THE HAWKING RADIATION OF CHARGED DIRAC PARTICLES IN KERR-NEWMAN SPACETIME
XU DIAN-YAN
1983, 32 (2): 225-238. doi: 10.7498/aps.32.225
Abstract +
The Hawking radiation of charged Dirac particles on event horizon of Kerr-Newman black holes is studied in this paper. First, we construct the symmetrized null tetrad from which the symmetrized spin coefficients and Dirac equation are derived. Next, we solve the Dirac equation near the event horizon and get the four component ingoing and outgoing wave functions. Finally, by analytic continuation, the Hawking thermal spectrum formula of Dirac particles for arbitrary Kerr-Newman black holes is obtained.
BRIEF REPORT
DETERMINATION OF THE GENERATION LIFETIME AND SURFACE GENERATION VELOCITY BY VOLTAGE STEP METHOD
ZHANG XIU-MIAO, BAO ZONG-MING, SU JIU-LING
1983, 32 (2): 239-246. doi: 10.7498/aps.32.239
Abstract +
A simple method for determining both the generation lifetime and surface generation velocity is suggested. By this method, using the data of three points from the MOS capacitance transient response to a step voltage, both the generation lifetime and surface generation velocity can be calculated readily. The experimental results show that this method is reasonable, and indicate that neglecting surface generation velocity would result in reducing of apparent generation lifetime.
THE ATOMIC STRUCTURE AND ELECTRONIC STATES OF GaAs1-xPx (110)
XU YONG-NIAN, ZHANG KAI-MING
1983, 32 (2): 247-250. doi: 10.7498/aps.32.247
Abstract +
In this paper, the clean surface GaAs1-xPx(110) has been studied by the EHT method using a cluster model. We obtained the following results: (1) the value of the rotated relaxation angle is about 26°. (2) For x≥0.25 the empty intrinsic cation states are found in the gap near the conduction band edge.
NON-DESTRUCTIVE DETERMINATION OF COMPOSITION AND THICKNESS OF MULTI-COMPONENT ALLOY THIN FILMS BY X-RAY FLUORESCENCE SPECTROSCOPIC METHOD
CHENG JIAN-BANG, CHENG WAN-RONG, WANG XI-HONG, HAO GONG-ZHANG, WU ZHANG-CUN
1983, 32 (2): 251-255. doi: 10.7498/aps.32.251
Abstract +
A non-destructive method for determination of composition and thickness of ternary alloy thin film by using the technique of X-ray fluorescence spectroscopy is employed in this paper. In this method, it is not necessary to prepare any similar solid or pure elemental standards, instead, the filter disk standards are used. These disk standards can be made readily and are stable for long period of time. A set of equations relating the characteristic X-ray intensities from elements in the film and its surface densities are formulated and solved for film composition. The quantitative dependence of attenuation of characteristic X-ray intensities of elements in substrate on increasing film thickness is used to determine the thickness. This method can be used to measure the film composition and thickness simultaneously.
THE SUPERCONDUCTING-NORMAL TRANSITIONS OF FAST QUENCHED SUPERSATURATED SOLID SOLUTION Al-lat% Ge ALLOY
CHEN XI-SEN, WANG ZU-LUN, GUAN WEI-YAN
1983, 32 (2): 256-258. doi: 10.7498/aps.32.256
Abstract +
The microstructure and superconducting-normal transitions of fast quenched supersaturated solid solution Al-lat% Ge alloy have been studied. X-ray structural analysis of the sample indicated that Al-lat% Ge alloy consists of a homogeneous supersaturated α-Al(Ge) solid solution.The resistance measurement shows that for solid solution alloy α-Al(Ge) Tc≈1.44K, which is higher than that of pure Al.
INFLUENCE OF ODD PARITY CRYCTAL FIELD ON LEVEL SPLITTING OF Ce3+ IONS
YANG GUI-LIN, XU YOU, CHU DA-PING, XUE DENG-PING, ZHAI HONG-RU
1983, 32 (2): 259-266. doi: 10.7498/aps.32.259
Abstract +
In this papar, we calculated the influence of 5d-4f mixing caused by odd parity crystal field on level splitting of Ce3+ ions in CaF2 and SrF2 lattices. Results indicated that odd parity crystal field effect on level splitting may be fairly large. For lower levels in CaF2 the contribution of odd parity crystal field may amount to 15-30%. The order of 1st and 2nd excited states even reverses. On the other hand, it has been shown that configuration mixing is one of the possible mechanisms causing the extension of radial wave fanctions of ions in crystal.
THE MEAN SQUARE ERROR OF THE MULTIPLICATIVE MODEL FOR SPECKLE NOISE
QIN KE-CHENG
1983, 32 (2): 267-272. doi: 10.7498/aps.32.267
Abstract +
The mean square error of the multiplicative model for speckle noise in coherent imaging is derived. Then we obtain the condition under which the multiplicative model is valid, that is: the model holds only when the details of the object can be completely resolved by the imaging system.
MOLECULAR AND CRYSTAL STRUCTURE OF ANCAOLIA (CRYSTAL Ⅰ AND CRYSTAL Ⅱ)
LIN XIU-YUN, ZHANG SHU-DE
1983, 32 (2): 273-279. doi: 10.7498/aps.32.273
Abstract +
ANCAOLAN is a weed killer, its series product, the crystal Ⅰ(C11H16N2O4 PSCL) and crystal Ⅱ(C12H13P21/c. There are four molecules in a unit cell. The crystal parameters are: crystal Ⅰ α=8.575?, b= 26.541 ?, c= 7.063?,β= 94.744°; crystal Ⅱ α= 8.575?, b= 26.538?, c= 7.073?, β= 93.819°. For the crystals Ⅰ and Ⅱ, the three-dimensional intensity data were collected by using PW-1100 four-circle diffractometer and the numbers of independent diffractions are 3123 and 3166 respectively.Their structures were solved by direct method and refined by full matrix least-squares method. Their final .R-factors are 0.10 and 0.11 respectively.The plane of nitro is perpendicular to the plane of benzene ring.The weed killing effect of crystal Ⅱ is better than that of the crystal Ⅰ.
DETERMINATION OF CRYSTAL STRUCTURE OF α-CHLORO-N-SEC-BUTYI-CINNAMIDE
ZHENG CHAO-DE, GU YUAN-XIN
1983, 32 (2): 280-284. doi: 10.7498/aps.32.280
Abstract +
α-CHLORO-N-SEC-BUTYI-CINNAMIDE crystal (trans) belongs to orthorhombic system. The space group is D2h15-Pbca with eight molecules in a cell of dimension α= 18.842 (0.006)?, b=14.076 (0.006)?, c=10.077 (0.003)?. The intensity data were collected on RASA-IIS four-circle diffractometer. The number of independent reflexions is 929. The structure was solved by direct method (MULTAN-80). Refinement of structure parameters was achieved by block- matrix least-squares method, R =0.088.