Vol. 29, No. 3 (1980)
1980-02-05
CONTENT
1980, 29 (3): 273-285.
doi: 10.7498/aps.29.273
Abstract +
The present paper describes a graphic method of determining the drift constants in Debye-Scherrer photographs and discusses the various methods in the evaluation of lattice constants. By the method proposed by the author, the accuracy of lattice spacings determined reaches 1 part in 500,000.
1980, 29 (3): 286-295.
doi: 10.7498/aps.29.286
Abstract +
This paper describes a method of calibrating the absolute spectral sensitivity of silicon photovoltaic cell. The cell was used for measuring minute radiant power, irradiance and radiant intensity of radiations, ranging from 0.4 μm to 1.1 μm. It was also used for measuring the external quantum efficiency of electroluminescent devices. The sensitivity of the system is higher than that of the conventional thermopile by three orders of magnitude. By incorporating with an integral sphere, it is very convenient to measure the radiant power, ranging from 6.3 nW to 310 mW, of any uniformly or non-uniformly distributed source.The maximum spectral efficiency Km was determined by using this system, and the accuracy of radiometrie system and photometric system was discussed. Finally, the measured optical parameters of some light-emitting diodes were examined.
1980, 29 (3): 296-304.
doi: 10.7498/aps.29.296
Abstract +
In this paper we analyzed the uniformity of the illumination-distribution on the window of an integrating sphere and obtained the distribution function determined by the geometrical parameters of the sphere. On the basis of this result, we discussed the condition of existence of the equi-illumination circle and also such problems as the calculation of the blind region.
1980, 29 (3): 305-310.
doi: 10.7498/aps.29.305
Abstract +
In this paper, the first experiment of generating the phase conjugated backward wave by degenerate four-wave mixing in chlorophyll solution is reported. It is demonstrated that the efficiency converting the incident object beam into the phase conjugated backward wave with interaction length 5mm long has approached 22%. This is a four-level system having a high conversion efficiency. The intensity of the complex conjugate reflected wave is proportional to that of the incident object wave as we kept the pumping beam intensity constant. The phase conjugate behaviours of the backward wave have been demonstrated. By using the phase conjugate nature of the reflected wave, good quality reconstructed images of a grid are obtained through a phase distorting media.
1980, 29 (3): 311-319.
doi: 10.7498/aps.29.311
Abstract +
The critical velocity of runaway electrons in a magnetized plasma is investigated from a kinetic theoretical approach. The results of numerical calculation are obtained for the parameter regions of tokamaks. The frictional force along the magnetic field encountered by the higher velocity runaway electrons is greater than that in a field free plasma. This means a higher critical velocity in a magnetized plasma. For an electron with large longitudinal velocity, the transverse velocity enhances the dynamic friction. This gives rise to the results of a higher critical velocity for the electrons with larger transverse velocity.
1980, 29 (3): 320-329.
doi: 10.7498/aps.29.320
Abstract +
This article discusses the distribution of α particles in fusion reactor. We divide these particles into two parts: i.e., a high energy part and a thermolized part, and introduce the concept of slowing down density. A set of slowing down-diffusion equations satisfied by distribution function of α particles are then obtained. For the parameters of typical tokamak fusion reactor, the set of equations are solved analytically with simplified conditions. Thus the distribution of a particles and the rate of self heating are obtained. Finally,, the results computed by using different diffusion coeffecients are compared.
1980, 29 (3): 330-340.
doi: 10.7498/aps.29.330
Abstract +
The ion optical properties of the crossed toroidal electric and inhomogeneous magnetic fields as a mass spectrometer are discussed. By means of Fermat's principle, the equations of ion trajectory are derived. The second order aberration are calculated for the crossed fields mass spectrometer.
1980, 29 (3): 341-353.
doi: 10.7498/aps.29.341
Abstract +
Dislocations and stacking faults in silicon webs were observed and analysed by means of X-ray projection topographic method. Large area stacking faults parallel to the web surface have been found in as-grown specimens. In addition to the edge-, screw-, and 60°-type total dislocations with Burgers vector 1/2, and edge-type Shockley partial dislocations with Burgers vector 1/6, 30°- and 60°-type Shockley partial dislocations with Burgers vector 1/6 have also been discovered in the webs. These total dislocations move during heat treating at high temperatures and interact with other ones to form nearly hexagonal dislocation networks. Several dislocation reactions in a single slip plane have been found. The configuration and contrast of stacking faults in as-grown webs were changed by high temperature annealing. That can be explained by the moving of extended dislocation pairs, and the overlapping of stacking faults with each other in different layers. The extinction rule of image of Shockley partial dislocations was invalidated by the presence of impurity segregations. Dislocations within the stacking fault image were also observed. The experimentally observed results were analysed and discussed briefly.
1980, 29 (3): 354-364.
doi: 10.7498/aps.29.354
Abstract +
The internal friction of Armco-iron in the process of plastic deformation was measured by a middle torsion pendulum on a modified tensile testing machine. The effects of strain rate (in the range of 0.73×10-6/sec to 50×10-6/sec), frequency (0.30/sec to 3.6/sec), annealing and carbon content on the internal friction were studied. The results showed that on the yielding plateau, the internal friction did not change with the strain, but increased linearly with the increase of strain rate and varied inversely with frequency. In comparing the data with the theoretical expression derived from the dislocation dynamic model of internal friction in the process of plastic deformation, it is shown that the dynamic model is in good agreement with the experimental results. The dislocation dynamic exponent m of Armco-Fe derived from this model is 10.8-12.3, which is reasonable.The range within which the dislocation dynamic model holds is also discussed.
1980, 29 (3): 365-373.
doi: 10.7498/aps.29.365
Abstract +
The interrelation between traditional quantum field theory and composite quantized field theory is investigated. It is found that they are compatible and interrelated in the ladder approximation, whereas beyond this approximation the interrelation is not established.
BRIEF REPORT
1980, 29 (3): 374-379.
doi: 10.7498/aps.29.374
Abstract +
Various kinds of crystal defects, such as ferroelectric domain boundaries, growth bands, dislocations, subgrain boundaries and cellular structures, etc. in Czochraski-grown ferroelectric LiNbO3 single crystals were investigated by X-ray transmission topographic technique. The defects were identified by means of invisibility conditions using different diffractions, as well as X-ray anomalous scattering effect and optical microscopy. We have discussed the formation of domain boundaries in LiNbO3 and their relation to the growth bands.
A REVISION ON RENSCH'S FINITE DIFFERENCE METHOD FOR CALCULATING THE FIELD DISTRIBUTION IN RESONATORS
1980, 29 (3): 380-382.
doi: 10.7498/aps.29.380
Abstract +
The field distribution in Gerry's GDL device was calculated with a revised Een-sch's finite difference method. The results agreed quite well with Rensch's calculation. This revised method was applied in a wider range of coupling. Thus the question, why the power output from a unstable cavity is the half of that from a stable one, can be explained more exactly by the fact that the coupling used was too large as compared with the optimum value.
1980, 29 (3): 383-388.
doi: 10.7498/aps.29.383
Abstract +
It is shown in our experiments that the threshold current of the lasers decreases with the lowering of temperature, and finally enters saturation region. This is essentially consistent with Hwang's result in the range of 300-10 K. But further lowering in temperature will increase the threshold current of the lasers. We suppose that this iucreasement is caused by the leakage of carriers. When the temperature is in the range of 2.8-6 K, the threshold current, the voltage at the junction and the dynamic electric resistance all exhibit regular structures. If the electron-hole liquid has been generated in this process, it may be explained qualitatively by Landau's phase diagram. However, we also can not exclude the possibility that this structure is due to the impurity energy band, which could play an important role in the above mentioned process.
1980, 29 (3): 389-391.
doi: 10.7498/aps.29.389
Abstract +
TGS single crystals can be grown by the method of changing solvent, i.e., adding ethyl alcohol to the aqueous solution of TGS. Ferroelectric hysteresis loop, as well as dielectric and pyroelectric properties have been measured. It is found that the properties of TGS grown by this method are similar to that grown by slowly lowering the temperature at constant supersaturation.
1980, 29 (3): 392-394.
doi: 10.7498/aps.29.392
Abstract +
On principle, the coherent light intensity in a laser cavity should be calculated according to field strength superposition of the light waves propagating back and forth in the cavity. This paper compares the calculations using the field strength superposition and that using the usual light intensity superposition. Our work indicates that the results on local saturated gain and light intensity calculations really give considerable discrepancies, but the field distribution and power output calculations agree quite well.
1980, 29 (3): 395-399.
doi: 10.7498/aps.29.395
Abstract +
In the 5-dimensional principal U1-bundle theory unifying gravitation and electro-magnetism, which is a new version of the old Kaluza theory, the radius of the closed, space-like fifth dimension is determined to be Planck length times 2α-1/2 (α-the fine-structure constant). This explains why the fifth dimension has not been apparently observed yet.
1980, 29 (3): 400-405.
doi: 10.7498/aps.29.400
Abstract +
The correctness of the thermodynamic treatment of the internal bias field of the TGS crystal is demonstrated experimentally. The causes of the difference between the Eb-T relations of irradiated pure TGS and LATGS crystals are analyzed. The annealing effects on the improved properties of irradiated TGS crystals are also discussed.
1980, 29 (3): 406-408.
doi: 10.7498/aps.29.406
Abstract +
The noncollinear SHG method has been used to measure the pulse width of passively mode-locked Nd: YAG laser. The nonlinear ADP crystal is oriented in such a way that phase matched SHG is produced only when both incident beams are present as ordinary rays. The angle between the two beams is 25°50′. Phase-matched SHG as an extra-ordinary occurs at an angle bisecting the two beams. The correlation width obtained with passively mode-locked Nd: YAG corresponds to a pulse width of 24 ps.
