Vol. 33, No. 10 (1984)
1984, 33 (10): 1341-1349. doi: 10.7498/aps.33.1341
The linear behavior of the double tearing mode driven by anomolous electron viscosity effects associated with magnetic braiding is investigated within the framework of MHD. A two-space-scale analysis is performed and the result is used to obtain an approximate dispersion relation for the mode. If the seperation of the rational surfaces at x =±xs is sufficiently small, xs/ αyα)-11/15R-1/15, the growth rate is predicted to scale as R-1/15. With increa-sing seperation the mode makes a transition to R-1/3 scaling, where R = τv/τH. The R-1/5 scaling is shown to be correlated with violation of the constant-φ approximation.
1984, 33 (10): 1350-1358. doi: 10.7498/aps.33.1350
In the slab model the so-called universal modes are absolutly stable. How about the cylindrical plasma? The main difference is that instead of the out-going boundary condition in the slab mode, in the cylindrical plasma there is not any wave energy outgoing at r=0 and r=∞. This may change the stabilities of the modes effectively.Assuming exponential plasma density and current profiles, the integral eigen-equa-tion of drift wave has been derived. In the ease of slow radial variation, it can be converted into a second order differential equation. The equation has been solved numerically. The results show that the unstable modes do exist. The comparison between the two models (cylindrical one and slab one) has been made.
1984, 33 (10): 1359-1367. doi: 10.7498/aps.33.1359
The variations of magnetization- and strain-induced anisotropy in metallic glasses (Fe1-xCox)78Si10B12 with composition and temperature have been studied. The magnetization- and the irreversible strain-induced anisotropy constants, Kam and Kusi, have positive values, the maximums of which occur at x=0.7 and 0.5 respectively. The reversible strain-induced anisotropy constant Kusr has a negative value except for x>0.975, the magnitude of which exhibits a maximum at x=0.7. As to the temperature dependence of Ku, a common relation Ku(T)=kMsα(T) is followed, in which a is a constant between 3.4 and 7.5 depending on the composition and the annealing condition used. Some of the experimental results are explained by using the concept of short range ordering.
1984, 33 (10): 1368-1376. doi: 10.7498/aps.33.1368
In this paper, the multiplicativity of the partially polarized image-plane speckle noise is considered. After deriving the n-th order moment of the intensity of the speckled image, the multiplicative model of speckle noise is justified. The mean squared error of the model for partially polarized case is discussed. Finally, the validity of the multiplicative model for the incoherent superposition of n independent linearly polarized speckled images formed with identical illumination is treated.
THE QUANTUM GRAVITY WITH TORSION AND GHOST-FREE DE SITTER GRAVITY (Ⅰ)——GRAVITATIONAL FIELD WITH HOESION UNDER LINEAR COVARIANT GAUGE CONDITION
1984, 33 (10): 1377-1385. doi: 10.7498/aps.33.1377
Under a general linear covariant gauge condition, the propagators are calculated in a gravitational theory with torsion containing 17 parameters. It is showed that there are three terms in the Lagrangian having no contributions to the particle content of the theory. Jp=l- particle is a gauge-dependent non-physical particle, which does not effect whether the original Lagrangian is ghost-free and tachyon-free or not.
THE QUANTUM GRAVITY WITH TORSION AND GHOST-FREE DE SITTER GRAVITY (Ⅱ)——CHOST-FREE PROPERTY OF SO(3,2) DE SITTER GRAVITY
1984, 33 (10): 1386-1392. doi: 10.7498/aps.33.1386
By using the rezults of our paper (I), the particle content in de Sitter gravity are explored. It is found that the SO(3, 2) de Sitter gravitational theory is ghost-free and tachyon-free, and the SO (4, 1) theory should be excluded. There are three kinds of particles in SO (3, 2) de Sitter gravity: JP=2+, 1- with m=0, and JP=0+ with m = 21/2L-1, (L is the radius of de Sitter pseudosphere). The spontaneous symmetry breaking of the Minkowski vacuum caused by the cosmological constant is also investigated at the tree level.
CALCULATION OF WAVE FUNCTION OF A SINGLE IMPURITY IN A ONE DIMENSIONAL SYSTEM WITH INCOMMENSURATE LATTICE POTENTIAL
1984, 33 (10): 1393-1400. doi: 10.7498/aps.33.1393
We study the effect of a single impurity in a one dimensional system with incommensurate lattice potential. The energy level and the wavefunction of the impurity State is derived with the Green's function technique. The energy level is found to be very sensitive to the impurity position in the region where the incommensurate potential is varying rapidly. The wavefunction of the impurity state decays exponentially with small oscillation of the amplitude. We also consider the effect of the impurity on the states in the band. For a system that is symmetric about the impurity, we find a large reduction of the amplitude of the wavefunction with even parity in the vicinity. For a system that is asymmetric about the impurity, a step-wise increase in the amplitude occurs at the impurity.
The total cross section and differential cross section of high-energy electron impact excitation can be calculated with Born approximation. The differential cross section is proportional to the so called generalized oscillator strength. The target atom or ion may be excited to infinite bound states, auto-ionizing states and adjoint continuum states which can be treated in an unified manner by Multichannel Quantum Defect Theory. Thus, we can define the generalized oscillator strength density as the strength per unit excitation energy. Taking the lithium atom as an example, we present here a summary of the variations of the generalized oscillator strength density with respect to excitation energy as well as momentum transfer. Comparing with recent accurate experimental data, the validity of Born approximation is discussed.
1984, 33 (10): 1408-1417. doi: 10.7498/aps.33.1408
The contributions of sd interaction to the electrical resistivity of 1-dimensional conductor are considered in the case of single impurities and coupling impurities separately. In order to show the essence of the coupling, the 1-d RKKY interaction is derived. The qualitative discussions about the resistivity of 1-d magnetic alloy and the theoretical predictions about the resistivity-temperature curves in some eaces are made.
A simple model about transition impurities in semiconductors is proposed, and the impurity energy levels and wave functions produced by substitutional and interstitial atoms in silicon are calculated by Green's function method. It is shown that the properties of these two kinds of impurities are remarkably different. The substitutional atom can produce impurity energy level only when Vd, the atomic level of d state, is below the top of valence band. It's wave function is mainly dangling bond state, and gradually turns into bond state when the energy level approaehs the edge of conduction band. The interstitial atom can produce impurity energy level only when Vd is above the top of valence band. It's wave function is mainly d state of central atom and gradually turns into weak antibond state. Finally, the chemical trend and some experimental facts of transition impurity energy levels are qualitatively explained.
1984, 33 (10): 1427-1433. doi: 10.7498/aps.33.1427
The phase equilibrium and transition in the pseudo-binary system Ba2CaWO6-Sr2CaWO6 have been investigated by means of DTA, X-ray powder diffraction, precise measurement of lattice parameters and other methods. A continuous solid solution was formed at high temperatures (above 860℃). At room temperature, a solid solution based on the structure of Ba2CaWO6 was formed on Ba2CaWO6-rich side and a solid solution with the structure of Sr2CaWO6 on Sr2CaWO6-rich side and a phase transition point was found at 25mol. per-cent of Ba2CaWO6.As a coating material for the filaments of high voltage sodium lamp, the important characters of BaxSr2-xCaWO6, the electron emission and the rise of the lamp voltage during multiswiching, were investigated. The best performance was found at the composition of BaSrCaWO6.
1984, 33 (10): 1434-1436. doi: 10.7498/aps.33.1434
A new method of preparing superconducting PdCu alloy is ion-implanting Cu into Pd and subsequent electrolysis at room temperature, then hydrogen implanting at liquid nitrogen temperature. Thus we obtain the superconducting structure H/Pd55Cu45=0.7, which has the highest transition temperature of 17 K. The paper also gives some results of the distribution of hydrogen in the alloy and its effects on superconducting transition temperature, as well as experimental conditions, so that it provides some interesting informations about the investigation of the new method in preparing them.
1984, 33 (10): 1437-1441. doi: 10.7498/aps.33.1437
This article investigates the influence of collective effects of plasma on bremsstrah-lung. According to the theoretical results we obtained, the influences on the inverse bremsstrahlung absorption of laser light and the spectrum and total energy of spontaneous bremsstrahlung are studied numerically.
1984, 33 (10): 1442-1447. doi: 10.7498/aps.33.1442
Our Calculation indicates that even though without introducing the approximation of local linearization of the density Profile, Various parameters can still he derived, they characterize the plasma density profile more completely and accurately. Therefore, our results may describe the modification of the density profile by the ponderma-tive force near Critical density more realistically.
1984, 33 (10): 1448-1453. doi: 10.7498/aps.33.1448
High pressure effect on the crystallization processes of amorphous Fe82Si4B14 alloy were investigated and the T-T-T diagram at lbar and 77kbar were obtained. Results indicated that the pressure derivative of crystallization temperature of this amorphous alloy changes with the change of annealing duration during which the crystallization take place. Bcc-Fe(Si) solid solution crystalize preferentially at normal pressure while at high pressure DOe type Fe3B and bcc-Fe(Si) will form simultaneously.
1984, 33 (10): 1454-1458. doi: 10.7498/aps.33.1454
Low-field magnetic susceptibility of the diluted magnetic semiconductors Zn1-xMnxSe was measured between 4.2 and 30 K for the Mn concentration range 0.1≤x≤0.50 using SQUID magnetometer. When x≥0.30, the system shows a spin-glass transition in the above temperature range, as evidenced by a somewhat rounded cusp in the susceptibility. The transition temperature of spin-glass is as follow: x=0.30, Tf=10.5 K; x=0.40, Tf=16.0 K; x=0.50, Tf=19.5 K. The phase diagrams for the boundary of the paramagnetic and the spin-glass phases are obtained for this system. The difference of spin-glass transition temperature between Zn1-xMnx Se and Cd1-xMnxSe is discussed. It is found that for any given Mn concentration x the spin-glass transition temperature Tf of Zn1-xMnxSe is higher than that of Cd1-xMnxSe.
1984, 33 (10): 1459-1465. doi: 10.7498/aps.33.1459
In lattice gauge theory some alternative actions without fermions were proposed, which obey Wilson's conditions for lattice action and were related with usually adopted actions. The Schwinger-Dyson equation obeyed by Wilson loop amplitude with the alternative actions was derivated. We verified that, in large N limit in E-K reduced model, the same Schwinger-Dyson equation exists as in the standard model.
1984, 33 (10): 1466-1471. doi: 10.7498/aps.33.1466
The Coulomb coupling、the Kazama-Yang coupling-кqβ∑·r/2Mr3 and the coupling iкzzde2γ·r/2Mr3 between a charged spin-1/2 fermion and a Dirac dyon are considered simultaneously. It is shown that for all the angular momentum states the fermion's radial wave functions have the physically reasonable asymptotic behavior at the origin. The bound state condition is qualitatively analysed. We show that, in the fixed dyon field when the extra magnetic moment к→0, the bound states of fermion exist, but in the fixed monopole field when к→0, the bound states of fermion do not exist.
1984, 33 (10): 1472-1474. doi: 10.7498/aps.33.1472
This paper presents the dependence of the hydrogen contents and the Si-H bonding structure on crystallization in a-Si: H films. The hydrogen contents decreases dramatically and the bonding from transforms from Si-H to Si-H2 obviously when the grain size increases to about 200±50?. We suggest that the 200±50? is a phase transition point corresponds to transformation from mirco-crystalline-Si: H to poly- crystalline-like modification.
1984, 33 (10): 1475-1479. doi: 10.7498/aps.33.1475
The surface potential of the sample was changed by the irradiation of energetic electrons. The energy spectra of varieties of sputtered ion species were measured with different surface potential. It was found that under conventional condition, particularly when there was oxygen enhanced emission, the resonant electron tunneling would not reduce the savival probability of sputtered ions. The energy spectra were also used to investigate the dynamic aspect of the ion emmission. The dynamic parameters indicated that the surface potential which the ion yield depended on was highly localized. In addition, the electron irradiation could be helpful in improving the quatitative analysis of the SIMS even for metals.
The electronic structure of NiSi2 was calculated by using the self-consistent LMTO method. Our result was found to be in resonable agreement with the results of AEUPS photoemission experiment and other calculations. The change in the Ni electron configuration was found to be responsible for the Ni3p3/2 core level binding energy shift; the decrease of Ni3d electrons weakened the screening effect for the Ni3p electrons. The result of calculation showed that the ionicity plays a minor role in chemical bond.