Since the invention of solar cells in 1954, efforts have been made towards improving the manufacturing process to increase the yield of solar cells with high conversion efficiency, and recenly to produce solar cells of light weight, large area and high reliability at low cost, especially from requirements as power source for space vehicles. However, silicon solar cells made from single crystal have limitations. They are too expensive for terrestial use, they are small in area, yet require a gerat number of interconnection to make an array. Fortunately, recent flexible, light weight- and large area-thin film solar cells now in the development stage promise to over-come most of the limitations. Successfull thin film solar cells would find wide scale terrestial applications.
The blur of images in layer radiography is analyzed in the spatial frequency domain in which many problems of radiographic system are treated. The types of layer radiography treated here are Tomography, Planigraphy and Circus Tomography. In each case, single and multi-layer radio-graphies are studied. The line or point spread intensity distributions, on layer radiographs, from the focus of X-ray tube and their Fourier transforms are studied theoretically and experimentally. Further the optical transfer functions of image intensifying screens and films in the case of oblique incident X-ray are investigated. From these experimental results, the author suggests a few im-provements both in the part of X-ray sources and in the part of intensifying screens and films.
Etch pattern, X-ray diffraction, infrared transmission and specific gravity of polycrystalline silicon epitaxially grown from SiH4 are observed before and after a heat treatment at 1300°C. The as-grown samples of polycrystalline silicon obtanied from SiH4 have dendritic structure which are composed of grains of 1_??_10μ in length, and contain internal stresses and various kinds of void. On the other hand, the heat-treated samples have granuler structure whose grains are 1_??_10μ in diameter. The large internal stresses and the void vanish together in the latter samples.
A scintillation response of a NaI (Tl) crystal to positrons has been studied using a two-crystal NaI (Tl) scintillation spectrometer. The scintillation response of the crystal to positron-electron pairs induced by gamma rays in the crystal was accurately measured. To make clear the diffe-rence in responses to positrons and to electrons, gamma spectra were also measured by use of the same device, and the response to electrons was obtained. The scintillation response to positrons was evaluated from the experimental response to positron-electron pairs and to electrons with the aid of theoretical positron spectra in the crystal. The response to positrons is larger by about 4% that to electrons at 100 KeV. The difference in scintillation response is negligible small at energies above 0.5 MeV.
The shock response of nonlinear single-degree-of-freedom systems is analytically obtained by straight-line-segments approximation. The initial conditions of the n' th phase are equal to the boundary conditions of the (n-1)'th phase at the refracting point, and the n'th phase solution is similarly obtained to the (n-1)' th one's. It is better to determine the suitable line-segments by Ergin's method (E. I. Ergin: J. Appl. Mech. 23 (1956) 635), but is not necessary for the rough approximation. The calculated values of displacement and its time duration to the maximum response for polyurethane foam are rather greater (about 10%) than the experimental values. Damping gives a severe influence upon appearing spring constant at high speed testing.
Some of the transmission phenomena of electrons in the energy range 2-17 keV through thin aluminum films with thicknesses 500_??_6, 000Å are measured carefully. The reliability of the obtained data are enough to know the physical properties of the phenomena by planning out a new experimental method, though the rather simple apparatus are used. The experimental results concerned with the electron transmission rate, the practical range and the transmitting slow secondary electrons are described and compared with the some theoretical or experimental results by others. It is confirmed in the energy range of these measurements that the transmis-sion rate and the practical range are prescribed fairly well by Whiddington's law and Bethe's average energy loss theory, respectively. On the characteristics of transmitting slow secondary electrons, few works have been reported, so authors' results can be hardly compared with the others. But the results are rearranged and discussed together with the emission mechanism.