The diffraction pattern of an arbitrary single aberration is evaluated when the aberration func-tion is expressed by the circle polynomials as alnmσ2l+mRnm(r)cosmφ. In this paper, it is shown that the diffraction pattern in general either with one single aberration term or with several aberration terms can be integrated if the aberration function is expressed in the form of Σclnmσ2l+mrncosmφ. The intensity decrease at the Gaussian image point due to aberration is calculated and the importance of the amount of this decrease is explained.
Doubly doped NPN grown junction crystal for high frequency transistor has been studied. Germanium NPN grown junction transistors have been manufactured by double doped method or rate grown method. Each of these method has inherent limitations of characteristics such as low alpha cut-off frequency and high base spreading resistance. The low cut-off frequency of germanium NPN grown type crystal is mainly ascribed to the change of resistivity in the base region near the emitter junction by solid diffusion of N type (Sb or As) emitter impurities during the growth of crystal. The new NPN grown junction crystal has the emitter junction of steep gradient and has a heavily doped emitter region with phosphorus instead of Sb or As. When phosphorus is used as the emitter dopant, diffusion of the emitter element to the base region decreases remarkably because of the smallness of diffusion constant of phosphorus in germanium. This diffusion constant was smaller than expected; it was found to be 1.3×10-11cm2/sec at 900°C. The alpha cut-off frequency rose remarkably to about 20mc by the use of bars of about 20μ base width. This base width is comparable to the conventional double doped crystal of 5mc alpha cut-off frequency. Power gains greater than 40db at 455kc were easily obtained. Base spreading, resistance was reduced to a low value in triode type in spite of the high alpha cut-off frequency. Because the bonded gold wire for base lead spreads over the collector, base and the nearly metallic emitter region, sometimes the breakdown voltage dropped to a low value after bonding. So it is important to determine the allowable maximum emitter phosphorus concentration to prevent unusual breakdown and also to investigate the behavior of heavily doped PN junction. The discovery by L. Esaki of the tunnel effect of narrow PN junction was made during these experiments.
Servomechanism is applied to improve the automatized operation of equipotential line plotter furnished with an electrolytic tank. The working principle is that the speed of the probe in x-direction on xy-plane of plot is made to become inversely proportional to the deviation between reference and probe potentials that causes the probe to move in y-direction. The speed of the probe in x-direction is thus slowed down when steep curves are plotted with no fear of the y-control servomotor being saturated. The above device enabled correct plotting to be made with the speed much faster than ever reported. The gain of pre-amplifier is controlled by the potential gradient detected by a sub-probe, by which means the operation of y-motor control system becomes optimal and a high accuracy comparable to that of maps calculated by conformal representation is attained. A relay system operated by limit switches effects automatic plotting of successive equipotential lines to be made within a desired area. Theoretical analysis, detail of circuits, comparison of results with theoretical computation and examples of application are given.
When Ge diodes are kept in a vessel containing a trace of water vapor, electric characteristics of the diode deteriorate rapidly. Passivation of Ge diode against water vapor is effected by leaving Ge in dry oxygen gas and, baking it in oxygen atmosphere. Resistant and stable surface was successfully grown on Ge by baking at 120°C for 4 hours or at 140°C for 1 hour. This can be explained by the formation on Ge surface a broad energy gap surface state suggested by Kingston's model.
Photoconductivity of near-infrared irradiated sintered CdSe layer has been measured. Photosensitivity of this layer is as high as that of Ge phototransistor, PbS and PbTe films etc. which are generally used for infrared work except that the peak of sensitivity of the former lies at a shorter wavelength region of 7000_??_8000Å. Two types of samples were examined: one was of pure CdSe, the other was of Cu-activated CdSe, the activation being by 0.05 atom percentage., The following are some of the results obtained. 1. Photosensitivity increases with Cu density, this impurity Cu acting as recombination center. 2. Above the room temperature, the sensitivity drops with the rise of temperature. 3. In some conditions, the relation of light intensity to photocurrent is super-linear. 4. Time constant is small in comsarison with US cell.
Data on temperature dependence of photoelectric properties, signal and noise response of two, different types of lead sulphide photoconductive cells-high impedance type and low impedance type-have been obtained. From these data, concentration of majority carriers (holes) and their mobility are calculated at five different temperatures, Activation energy is obtained from the equation for semiconductors σ=σ0exp (-EG/2kT) where σ is the conductivity, k the Boltzmann constant and EG the activation energy. Activation energy of a typical high impedance cell and a typical low impedance cell is found 0, 38eV and 0.18eV respectively. The low impedance cell, which was prepared by “roasting oxidation process” is ascertained to have a shallow trapping center. As to photoelectric sensitivity, the high impedance cell had its peak near 240°K, became almost insensitive, while the low impedance cell was fair at high temperature (below 353°K), very high at liquid nitrogen temperature. Current noise of both cells decreased as the temperature dropped; non-current noise showed the same tendency but to a certain temperature, below which it became unaffected.
Photographic plates are widely used for electron diffraction and electron microscope work-Electron beam and visible rays of light affects photographic plates in very different ways, the cause of which is explained. For visible light, ten or more photons are needed to render one silver halide grain to become developable while for electron beam only one electron suffices. Furthermore, transmission of photographic emulsion is very large for electrons than for visible light. The above led to the explanation of the characteristics of photographic plates for electron beam-D-E characteristic, reciprocal law, energy dependence of sensitivity, resolving power etc.
The effect of physical adsorption of water vapour on production of high vacuum is discussed. As the life time of water molecules adsorbed on lead borosilicate glass at 10-6 Torr, 0_??_50°C, is about 5_??_10×10-4 sec, the adsorption very rapidly reaches an equilibrium state. Henry's law holds in the pressure region of 10-6 Torr where Henry's canstants k at 0°C and 25°C are 15_??_20 and 4_??_7 respectively. For evacuation of a vessel of volume V, actual volume becomes V+kA because of the adsorption of water vapour where A is the true surface area of inner walls of the vessel.
Electroforming of copper disk loaded waveguides for a 6MeV linear electron accelerator to be used as the injector of 1BeV electron synchrotron is described. The method used enables circular waveguides of complicated structure to be made en bloc securing good electrical contact and vacuum-tightness. In particular, this method facilitates the making of buncher which varies in dimensions along its axis. The usual difficulties met with in electroforming-difficulty of obtaining correct alignment of disks because of the assembling done in water; possible deformation caused by chemical dissolution, polishing, difference in thermal dilatation of consisting parts, all affecting dimensional correctness. -are removed, and highly accurate accelerator waveguides are made.