Vol. 30, No. 11 (1981)
1981-06-05
CONTENT
1981, 30 (11): 145-147.
doi: 10.7498/aps.30.145
Abstract +
In this paper, it has been shown that in the near field of parametric sound array, the Fresnel's approximation proposed by Berktay is inappropriate.
1981, 30 (11): 148-150.
doi: 10.7498/aps.30.148
Abstract +
A U1-bundle formalism for the Born-Infeld electrodynamics is proposed and the equation of motion for a test particle in the Born-Infeld electromagnetic field is given. There are two forces acting on the test particle, one corresponds to the Lorentz force and the other the Poincaré stress.
1981, 30 (11): 151-154.
doi: 10.7498/aps.30.151
Abstract +
By using the perturbative expansions of 〈j⊥· E⊥〉 it was proved that the coherent renormalization theory acquired the energy conservation of non-linear drift waves within the sixth order.
1981, 30 (11): 1415-1422.
doi: 10.7498/aps.30.1415
Abstract +
It is well known that, in the bremsstrahlung formula derived by Birmingham and Dawson, the screening effects of ions on the fields were discarded. It is unapt to do so. In this paper a corrected formula, including the polarization effects of ionic fields, is derived. In many cases, the screening effects of ions can considerably reduce the energy of the bremsstrahlung.
1981, 30 (11): 1423-1437.
doi: 10.7498/aps.30.1423
Abstract +
On the basis of Vlasov equation, we extend the results of our previous work [10] and obtain the general coupling equations for the electrons, ions of plasmas and the electromagnetic radiation. We have solved these coupling equations, and obtaind the threshold powers and growth rates of the stimulated scattering and harmonic radiation. Finally, we propose a successive generating mechanism of the harmanics and sub-harmonics, such a mechanism is in agreement with the experimental results in the literatures.
1981, 30 (11): 1438-1447.
doi: 10.7498/aps.30.1438
Abstract +
We consider the nonlinear saturation of a fast x mode instability near the electron cyclotron frequency due to electron population inversion. A quasilinear theory is discussed. The corresponding saturation time, amplitudes as well as the temporal evolution of the electron distribution functions are also studied.
1981, 30 (11): 1448-1455.
doi: 10.7498/aps.30.1448
Abstract +
Under a quite general condition, we show that a very strong high frequency pump can only excite the OTSI-like absolute instabilities in either uniform or nonuniform plasmas.Such property can be extended to magnetized plasmas as well.
1981, 30 (11): 1456-1463.
doi: 10.7498/aps.30.1456
Abstract +
The absorption spectrum of the vibrational excited state in BC13 has been obtained by means of a infrared double resonance technique. A variety of relaxation processes and energy transfer processes were observed. The relationship PτV-V(11BCl3)= 3μs·torr has been obtained. A radial sound modulation was observed on the double resonance signal. The sound velocity is 2×104cm/sec and it agrees with the calculated value.
1981, 30 (11): 1464-1478.
doi: 10.7498/aps.30.1464
Abstract +
The dependences of OAO fluorescence on space and time are investigated by using a time and space resolved method. The notable effect of the geometrical shape of the sample cell on OAO fluorescence is observed. A pulse acoustic wave and its relationship with OAO flurescence are recorded. It shows that the excited BC13 molecules are excited again becase of the action of the pulse acoustic wave By using of a simple model, the generation of OAO fluorescence and its axial shift are analysed. The calculated results are in agreement with the experimental data.
1981, 30 (11): 1479-1487.
doi: 10.7498/aps.30.1479
Abstract +
Atechnique for analytic evaluation of one-dimension Huygens' integral is proposed. The sound fields of the parametric line array can be analysed by it. Firstly, the point-source function is expanded into an operator on a plane wave function. Putting it into above mentioned integral and calculating it, it is shown that if we make an operation of this operator on the far-field solution, a general expression of radiation from parametric line array can be obtained. Secondly, both Fraunhofer's far-field approximation expression and Fresnel's, nearfield approximation expression are derived from it, but the latter approximation make a appreciable contribution on the radiation only outside the range of half-width angle.Furthermore; the radiation of a truncated parametric line array whose length is R1 is caleucated. We find that the beam pattern of this array becomes more narrow as decreasing the range. And a prediction can be made that the radiation field of a real parametric array will depend on following three parameters: kR sin2θ, βR, R1. Finally, basing on this theory, it appears to the author that the inconsistencies in ap-pearenee for some published experiments can be consistent with each other.
1981, 30 (11): 1488-1497.
doi: 10.7498/aps.30.1488
Abstract +
The computer method of indexing Debye-Scherrer photographs has been extended to the case of orthorhombic crystals. Any observed diffraction line may be represented by an equation of a plane hi2A+ki2B+li2C=sin2θi in the A-B-C three dimensional space, where A, B, and C are related to the translational vectors a, b, and c by A = λ2/4a2. B = λ2/4b2, and C = λ2/4c2 respectively. Since the indices (hi, ki, li) are unknown at the outset, these planes are only conditional planes. It is seen that the intersection of three conditional planes, representing respectively three low angle lines with simple indices, will determine a point in the space which might indicate the dimensions of the unit cell. To guard against accidental coincidences, a series of equiatomic curved surfaces is introduced, representing in each case an integral number of configuration units contained in the unit cell. The equation of the equiatomic curved surface is ABC = (pλ3/8Mm0)2 (l/Z2), where p is the density of the crystal, M the formula weight of the configuration unit, m0 the mass of the atom of unit atomic weight, and Z the number of configuraunits contained therein, Z being a parameter. It is seen that if the point determined by the intersection of conditional planes is a physical point, this point must lie on one of the equiatomic surfaces.As a further discrimination, a fourth observed line may be used, to see whether a triplet (h, k, l) of the coefficients may be fitted into the conditional equation to form a plane that will pass through the proposed point.In fact, the whole geometrical problem is reduced to that all planes represented by their respective proper triplets will intersect at one point which passes through an equiatomic surface.The programme is written in Fortran and will be indicated by POWDBX-OR.
1981, 30 (11): 1498-1507.
doi: 10.7498/aps.30.1498
Abstract +
As Debye chiracteristic temperature denotes the average vibration energy of atoms or ions in a costal, while different atoms in the crystal may have different vibration modes, or the same atom in a noncubie crystal may have different vibration modes along different directions, there arises the problem of inhomogeneity and anisotropy of characteristic temperatures.It is discussed in this paper the methods of investigating the inhomogeneity and anisotropy of characteristic temperatures in crystals.If there are two kinds of atoms (a) and (b) in a crystal, then the diffraction lines in the Debye-Scherrer photograph may be classified into two categories: in one of them the structure factor is the sum of the structure factors of respective atoms, F5= mFa + nFb, while in the other, the structure factor is the difference of the structure factors of respective atoms, F = gFa - qFd. Owing to the fact that both Fsobs and Fdobs are functions of sin θ/λ, so, if observed values of Fsobs and Fdobs are plotted against sin θ/λ, two smooth curves should be obtained, where Fobs= KFcalc. In the calculated structure factors, Fa= fa exp(-Ba sin2 θ/λ2) and Fb= fbexp(-Bb sin2θ/λ2), where fa and fb are the atomic scattering factors of the respective atoms, while Ba and Bb are Debye parameters of the respective atoms in the crystal. It is seen that from the two curves one can find the corresponding values of Fobsd or Fobss at the same abscissas as Fobss or Fobsd. If corresponding pairs of values are multiplied by proper coefficients and then be added or subtracted, a series of values of Fobs+ and obs- can be obtained which are now pure functions of Fa and Fb. Then if log (fa/Fobs+) and log (fb/Fobs-) are plotted agains sin2θ respectively, two straight lines can be obtained which should intercept at the same point on the ordinate axis, the slopes of which represent respectively Ba log e/λ2 and Bb log e/λ2, whence one can obtain Ba and Bb. For anisotropic crystals, a series of (h, k, 0) reflexions should be singled out. Just as in the case of isotropic crystals, one may plot log(Icalc/Iobs) against sin2θ, a straight line should be obtained, the slope of which gives 2B⊥ log e/λ2. Then single out another series of (0, 0, 1) reflexions. If one plots log (Icatc/Iobs) against sin2θ, then another straight line should be obtained, the slope of which gives 2B‖ log e/λ2. The two straight lines should intercept at the same point on the ordinate axis. Here B‖ and B⊥ represent the Debye parameters parallel and perpendicular to the principal axis respectively.Having datermined Debye parameters, characteristic temperatures can be obtained in the same way as we have described in our previous paper.The characteristic temperatures of CaF2 have been determined. It is shown that the characteristic temperature of Ca2+ ion in CaF2 crystals is 400K, while that of F-ion is 476K, the difference being 76K.
1981, 30 (11): 1508-1519.
doi: 10.7498/aps.30.1508
Abstract +
It has been proved in this paper that in general the horizons in 4-dimensional static Riemann spacetime will produce Hawking radiations and the radiative temperature is proportional to the surface gravity k of the horizon.This work is extended to the state that there exist electromagnetic fields. We point out that the static electric potential which effects Hawking radiative spectrum may originate from the electrie charge inside the hos,izoii as well as outside the hosizon.The Rindler radiations in uniform accelerated frames and the Hawking radiations from Schwarzsehild B. H., Keissner-Nordstrom B. H. as wall as Schwarzschild-de Sitter universe horizons are the special cases of our present general theory.It is pointed out that the equivalence principle Is still effective and Rindlerradiations do originate from the horizons of the Rindler frames of reference. Hawkingradiation only has relation with dynamic effect K near the horizon, but has no relation with curvature of the spaeetime.
BRIEF REPORT
1981, 30 (11): 1520-1527.
doi: 10.7498/aps.30.1520
Abstract +
Some formulae of the empirical coefficient method in fluorescent X-ray spectrometric analysis are discussed theoretically and a general formula is obtained thereupon. The physical significance of the coefficients used is explained. A formula based upon the calculation of relative intensity of fluorescent X-ray is derived and it is relatively simple in application.
1981, 30 (11): 1528-1532.
doi: 10.7498/aps.30.1528
Abstract +
This paper discusses Takagi equation by means of perturbation methods. A perturbative solution of diffraction amplitude in slightly deformation crystal is obtained for the spherical incident wave.
1981, 30 (11): 1533-1538.
doi: 10.7498/aps.30.1533
Abstract +
A new indexing method on the spots of high order Lane zone in electron diffraction pattern has been developed. The first spot indices of high order Laue zone are determined immediately by means of measuring the distances between the bright dif-feraction spots and a vector composition procedure the indices of the spot closest to the centre and other spots are then derived.
1981, 30 (11): 1539-1542.
doi: 10.7498/aps.30.1539
Abstract +
Difference structures are structures subjected to certain mathematical processing, they are introduced for the convenience of solving heavy-atom-containing structures by direct methods. Information about the arrangement of light atoms can be obtained by solving the corresponding difference structure. However the existing methods of solving difference structures have not yet made full use of the angular parts of the heavy-atom contribution. In this paper an improved method is given in this respect.
1981, 30 (11): 1543-1547.
doi: 10.7498/aps.30.1543
Abstract +
The growth and characterization of BNN crystals had been investigated and the large BNN crystals with SH output power level greater than 1 watt (the highest output being 2.5 watt) had been grown successfully.
1981, 30 (11): 1548-1553.
doi: 10.7498/aps.30.1548
Abstract +
The Raman spectra of LiTaO3 have been studied from 20℃ to 800℃. No softening of ferroelectric mode has been detected. The striking feature of our results is that the Raman spectra of the ferroelectric phase merge into the paraelectric phase without any appreciable discontinuity at the phase transition. On the basis of these new experimental results and the crystal structure data in literature, we suggest that the ferroelectric phase transition in LiTaO3 may have an order-disorder character.
1981, 30 (11): 1554-1558.
doi: 10.7498/aps.30.1554
Abstract +
Polar Kerr rotation (PKR) spectra of Bi-substituted YIG monocrystals, grown by flux method, were measured in the wave length region of 0.4 to 0.8 μm at room temperature. The natural grown surfaces, as well as surfaces newly cut across different parts of the crystals were all taken under examination. The variations in the height of the same characterizing peak near 2.7 eV reveal the imhomogeneity of the content of Bi ions, entering the dodecahedral site of the lattice. Our work demonstrates the possibility of PKR spectra as a tool of surface layer analysis, applicable in the investigation of such processes as ionic distribution, diffusion or surface segregation.
1981, 30 (11): 1559-1561.
doi: 10.7498/aps.30.1559
Abstract +
In this paper, it has been shown that in the near field of parametric sound array, the Fresnel's approximation proposed by Berktay is inappropriate.
1981, 30 (11): 1562-1564.
doi: 10.7498/aps.30.1562
Abstract +
A U1-bundle formalism for the Born-Infeld electrodynamics is proposed and the equation of motion for a test particle in the Born-Infeld electromagnetic field is given. There are two forces acting on the test particle, one corresponds to the Lorentz force and the other the Poincaré stress.
1981, 30 (11): 1565-1568.
doi: 10.7498/aps.30.1565
Abstract +
By using the perturbative expansions of 〈j⊥· E⊥〉 it was proved that the coherent renormalization theory acquired the energy conservation of non-linear drift waves within the sixth order.
