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Vol. 26, No. 2 (1977)

1977-01-20
CONTENT
THERMALLY INDUCED BIREFRINGENCE IN YAG RODS IN THE (001) DIRECTION
LASER CRYSTALS RESEARCH GROUP
1977, 154 (2): 93-99. doi: 10.7498/aps.26.93
Abstract +
The principal axes of thermally induced birefringence in YAG laser rods generally do not possess axial symmetry because the strain-optic tensor of YAG crystals is different from that of isotropic materials A calculation is given for the (001) direction, the results of which are supported by experiments in which it was found that for CW or high repetition rate pulsed operation the transmission loss of (001) rods is lower than that of (111) rods. The polarized output of YAG lasers in which a polarizer was placed in the cavity was maximum where the transmission loss was minimum.
SOME ASPECTS IN HIGH PRESSURE HIGH TEMPERATURE TECHNOLOGY
HE SHOU-AN, LI JIA-LIN, CHENG XIANG-RONG, WANG WEN-JUN, SHEN ZHU-TONG
1977, 154 (2): 100-114. doi: 10.7498/aps.26.100
Abstract +
A brief description of the methods and results of high pressure measurement with quasihydrostatic high pressure apparatus is given. The effects of the frictional layer of the sealing padding and the size of the pyrophillite tetrahedron on the pressure generation, also the pressure dependence of the thermal and mechanical properties of the pressure-transmitting medium under high pressure have been determined and the results discussed.
THE BEHAVIOURS OF THE DIELECTRIC CONSTANT AND ELECTRICAL CONDUCTIVITY OF α-LiIO3 SINGLE CRYSTALS
ZHU YONG, ZHANG DAO-FAN, CHENG XI-MIN
1977, 154 (2): 115-123. doi: 10.7498/aps.26.115
Abstract +
The characteristic curves, measured with a 10 kHz signal of the apparent dielectric constants ε′c and ε′a were obtained for a bias electrostatic potential of various voltages applied on an α-LiIO3 single crystal z-cut plate, the potential being either in the homogeneous or in the heterogeneous direction relative to the crystal's electrical polarity. Results show that there do not exist Schottky barrier layers in the crystal. A relaxation phenomen on of ε′c as the result of application of the bias d-c field was observed similar to that which had been detected in the case of the enhancement of neutron diffraction. It was experimentally verified that the current carriers in this crystal are chiefly, if not entirely, lithium ions, and that the conductivity may be approximately described as one-dimensional along the c-axis. The characteristic curves of ρc against V+ (homogeneous direction) and V-(heterogeneous) were also obtained.
AN IONIC GROUPING THEORY OF THE ELECTRO-OPTICAI AND NON-LINEAR OPTICAL EFFECTS OF CRYSTALS (Ⅱ)——A THEORETICAL CALCULATION OF THE SECOND HARMONIC OPTICAL COEFFICIENTS OF THE LITHIUM IODATE CRYSTAL BASED ON A HIGHLY DEFORMED OXYGEN-OCTAHEDRA MODEL I
CHEN CHUANG-TIAN
1977, 154 (2): 124-132. doi: 10.7498/aps.26.124
Abstract +
A highly deformed oxygen-octahedra group (IO3)-1 such as that found in the iodate has been adapted te explain the second harmonic optical coefficients of the LiIO3 crystal. Calculations have been made on the basis of such an ionic grouping model. Calculated values are in good agreement with the experimental ones, hence the following conclusions:1) The second harmonic optical effects of the iodate crystal arise mainly from the covalent-bond contribution of the ionic grouping (IO3)-1. 2) Within this (IO3)-1 grouping it is the lone-pair electronic orbitals and the |2σ>, |2Py> orbitals of oxygen which have particulas influence on these second harmonic optical effects.
SINGLE AND DOUBLE FREQUENCY RESONANCE HEATING IN LASER-IRRADIATED PLASMAS
TAN WEI-HAN, XU ZHI-ZHAN
1977, 154 (2): 133-148. doi: 10.7498/aps.26.133
Abstract +
In this paper accurate solutions for the single frequency heating conditions have been obtained based on equations derived for laser plasma electron-ion coupling. The threshold values and rate of increase of various unstable oscillations under double frequency resonance heating conditions have also been obtained and compared with those under single frequency heating conditions.
THE STATIC STABILITY OF PLASMA
HUO YU-PING
1977, 154 (2): 149-154. doi: 10.7498/aps.26.149
Abstract +
In this article, the effects of the small magnetic field perturbation on the equilibrium of plasma are discussed (the problem of the static stability of plasma). It is pointed out that a large variation in the equilibrium configuration may take place only when the small magnetic perturbations couple with the plasma modes which are almost neutally stable. Accordingly, the effects of the main classes of the stray field in Tokamak devices are analysed.
ON SPHERICALLY SYMMETRIC SU2 GAUGE FIELDS AND MONOPOLES
GU CHAO-HAO, HU HE-SHENG
1977, 154 (2): 155-168. doi: 10.7498/aps.26.155
Abstract +
In this paper we consider some general properties of spherically symmetric SU2 gauge fields. We prove that the SU2 gauge fields which are spherically symmetric in the most general sense may be divided into three basic types only: (1) synchro-spherieally symmetric SU2 gauge fields, (2) strict-spherically symmetric SU2 gauge fields, (3) spherically symmetric SU2 gauge fields reducible to U1 gauge fields.The spherically symmetric SU2 gauge fields with a Higgs field are investigated in detail and their types are completely determined. If such a field is regarded as due to the interaction of an electromagnetic field and electrically-charged vector bosons, then the following conclusion is obtained: In the spherically symmetric case there cannot exist an electrically-charged vector boson field around an m-unit monopole except for m =± 1, 0.
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