After a brief recall of the main features of the laser produced plasmas and the problems involved on the production of nuclear DD reactions, we deal with the fundamental data upon heating mechanisms. The experimental results and heating limitations are then developed. We conclude by a review of present and future feasabilities both for lasers and plasma parameters.
Reversible electrical and optical memory effects in amorphous semiconductors are reviewed. General discussions of the bistable memory and switching phenomena are given by using a transition theory in a system having two energy states. The structral phase transformation of amorphous semiconductors from the amorphous to crystallized states, and behaviors of physical properties both in the individual state are demonstrated. A model for the explanation of “light induced nucleation”, which attains lowering the transition temperature and the high speed crystallization, is discussed by the influence of an excess electron-hole pair injection. Clear changes in the electrical and optical properties by the phase transition can be used for binary storage and read-out purpose in the information processing. Some current topics for this purpose in the application field are also introduced.
The radial distribution curves for As2(Se1-xTex)3 were obtained and the atomic structure and the co-ordination number was investigated on the vitreous state and on the crystallization process at 150°C. In the vitreous state for a composition range X=1/2_??_4/5, the radial distribution curves showed peaks at the following atomic distances. the first peak γ1=2.60±0.05Å the second peak γ2=3.95±0.05Å the third peak (shoulder) γ3=5.0_??_5.3Å These values were independent of the cooling conditions in the sample preparation and manifested no change on crystallization. The mean number of the nearest-neighbour anion atoms surrounding the As atom, as estimated from the area under the first peak, changed remarkably from 3.40±0.2 in the vitreous state to 3.8±0.2 after 4 hr, 4.0±0.2 after 8 hr, 4.4±0.2 after 10 hr on crystallization at 150°C. The value 4.4±0.2 was equal to the mean co-ordination number of the Te atoms surrounding the As atoms in crystalline As2Te3.
Polycrystalline films of tin oxide doped with antimony are prepared on the substrate of polished Pyrex glass plates by CVD (Chemical Vapor Deposition) method. Their electrical properties and structures are investigated in relation to the surface temperature of the substrate and of the impurity concentration in films. In the films, only SnO2 is detected as crystals, whose (200) and (301) planes are oriented parallel to the surface of the substrate and though their crystal size is influenced by the surface temperature, the impurity concentration seems to have no effect. The films are assigned to be n-type semiconductors. The range of the carrier densities lies between 2×1019 and 5×1020/cm3 and that of mobilities between 18 and 35cm2/V•sec. The carrier density depends upon the antimony content and the surface temperature at the time of making samples. It is assumed that the mobility is influenced by the amount of the scattering due to ionized antimony and the boundary of agglomerated crystals.
After effects in GM counters of organic and halogen quenched types were studied by the use of low energy X-ray bursts from a pulsed X-ray generator. From the experimental results, it is shown that the probability of an after pulse occuring in the irradiation of low energy X-ray bursts is much smaller than that obtained with_??_1 MeV X-ray bursts. It was found that after pulses are not associated directly with the main pulse, and the probability of their appea-rance depends on the intensity of the X-ray burst and the position of the irradiation. Especially when the vicinity of the cathode was irradiated, a considerable increase in the number of after pulses was observed. As for the time distribution of after pulses, the experimental results were similar to those obtained with_??_1 MeV X-ray bursts.
Electric vacuum arcs are stable in a low vacuum, whereas fine evaporated films are formed in a high vacuum. To obtain fine evaporated films two electrodes are put in a small glass chamber, into which Ar gas is leaked, and maintained at a low vacuum and the chamber is placed in a large bell jar evacuated to a high vacuum. Arcs are initiated and maintained in a mixture of Ar gas and vapour of metal evaporated continuously from the electrodes. Metal vapour jetting out through a small hole bored in the wall of the glass chamber condenses on glass plates placed in the jar. Cd and Zn arcs are stable with a small current of about 3 amperes, and produce fine speculum films on the substrate glass plates. Evaporated films of other metals are expected to be produced, when the arc current is increased to values ranging between 10 and 20 amperes.