A strange and peculiar phenomenon was found in which pulse discharge inception voltage of a small gap decreased considerably by using an electrode with a dielectric. The dielectric was contact with an edge of the electrode which position was far isolated from the gap. The discharge inception voltage decreased with increasing permittivity of the dielectric and with reducing distance between the discharge position and the electrode edge with the dielectric. Residual charge on the dielectric was observed after application of high pulse voltage enough to discharge the gap. Potential of the dielectric was adjusted by resistive connection between conductive paint on the dielectric surface and the electrode, and was shown to influence the discharge inception voltage of the gap. A light shield between the electrode edge with the dielectric and the gap also influenced the discharge inception voltage of the gap definitely. These phenomena can be explained by pre-ionized self-triggering discharge. A peculiar point is that this electrode has no adjacent third electrode for triggering the discharge. The discharge is concluded to be triggered by UV ray from pre-ionization at a far isolated edge of its own electrode, stress of which is enhanced by adding a dielectric.
The paper proposes a method of eddy current analysis which can accurately calculate characteristics of electrical machines including several moving conductors at different velocities. In the formulation of the presented method, different moving coordinate systems are used separately in each conductor region for the purpose of setting relative velocities to be zero between every conductor and the coordinate system. The method can avoid numerical disadvantages of fixed coordinate system which has relative velocity to the conductors. Firstly, the paper discuses the difference of definitions between electromagnetic potentials introduced in moving coordinate system and potentials introduced in fixed coordinate system in order to reveal theoretical background of the proposed method. Potentials introduced in each coordinate system can be same value introducing appropriate gauge conditions. Secondarily, it shows results of numerical tests which clarify the consideration. Finally advantages of the proposed method are discussed through the practical analysis of a canned motor.
A novel type of ozone generator has been developed. In the apparatus, an extremely short gap length around 0.1mm can be constructed with a high precision. Setting the gap length to be shorter, the gas temperature in the discharge gap can be limited to be sufficiently low, moreover the dissociation rate of produced ozone by electron impacts is thought to be limited to be low. In the gap length of 0.1mm, the ozone concentration as high as 305g/Nm3 is obtained under a high power density of 1W/cm2 and the temperature of a cooling water of 15°C.
The low-aspect-ratio tokamak is expected to realize a compact and economical fusion reactor. This paper presents a equilibrium study of low-aspect-ratio tokamaks for the basis of both of Magnetohydrodynamic (MHD) analysis and cylindrical approximation model. Since its external toroidal field coil does not have enough surrounding space for the installation of neutron shielding material, it should be made of a normal conductor, whose current density and the resistive power loss should be estimated. On the basis of the cylindrical approximation model, the relationships are derived between the resistive power loss and various plasma parameters as aspect ratio, elongation, safety factor at the edge, and total beta value. The resistive power loss can be decreased by decreasing aspect ratio, however, neutron wall loading and the total beta increase. It is found that they can be in the reasonable quantitative range by the appropriate selections of the plasma parameters. The evaluation is made of the applicability of the model by comparing the results with those of the numerical MHD analysis.
Two types of thermal control materials based on polyimide film UPILEX-R are designed. One of thermal control material R/Al is coated with Al on the back surface. The other of thermal control material TCC/R/Al is coated with transparent conductive coating on the front surface and is coated with Al on the back surface. The solar absorptance is measured spectroscopically with an integrating sphere in the wavelength region of 0.26-2.50μm and the total hemispherical emittance is measured calorimetrically in the temperature range of -100-+100°C for the present thermal control materials. To evaluate the space degradation of optical properties (refractive index, extinction coefficient, absorption coefficient) on UPILEX-R film and solar absorptance on thermal control materials, space environment simulation tests are performed on the ground with independent radiation and combined radiation by UV, electrons, and protons. An onboard simultaneous measurement experiment with TCC/R/Al material have been carried out with a scientific satellite AKEBONO. The degradation of the ratio of solar absorptance to total hemispherical emittance have been obtained about 3 years in a space environment. The main degradation of absorption coefficient for UPILEX-R film was obtained upon proton irradiations. For the present materials, solar absorptance was increased, and total hemispherical emittance was unaffected.
Surface morphology and the electrical properties of LB films of binary mixtures of BEDO-TTF and C15-TCNQ were examined. The surface morphology of these LB films was observed by Atomic Force Microscopy (AFM). Surfaces of C15-TCNQ LB films were very smooth. Surfaces of BEDO-TTF+C15-TCNQ LB films were smooth, containing of small projections of BEDO-TTF crystals. The size and number of projections increased with increasing the composition of BEDO-TTF, and increasing the surface pressure at preparation condition. The value of conductivity of BEDO-TTF+C15-TCNQ LB films increased with increasing the composition of BEDO-TTF. The maximum conductivity was about 200S/m. The value of the conductivity of BEDO-TTF+C15-TCNQ LB films decreased with decreasing the temperature like semiconductors, however, the films (BEDO-TTF: C15-TCNQ=2:1) showed metaric behavior in the temperature range of 250-300K.
The issues of thermal stability and quench process of Low-Temperature superconductor have been studied and used appli- cation of superconducting coil. However the normal propagation property of High-Temperature superconductor, especially experiment data about thermal and electromagnetic behavior has not been reported yet. Therefore we measured the effect of operating temperature dependence of normal-zone propagation velocity, Vq, with regard to Ag sheathed Bi-2223 superconducting single core tape. We adopted operating temperature (from 10K to 40K) and transport current (load factor It/Ic: 0.4-0.9, where It is transport current and Ic is critical current) as parameters of measurements. The operating temperature is controlled by a cryocooler. As a result, we measured that normal propagation velocities of sample are slower by the two or three orders than that of Low-Temperature superconductors. Since the normal propagation velocities are 0.5-1.5[cm/s], the dependence of operating temperature is not large enough in this study.
We examined the effect of γ-ray irradiation at different temperatures (room temperature and 250°C) and atmospheric conditions (air and N2) on the electrical and mechanical characteristics of thermoplastic polyimidc (TPI) insulated and sheathed coaxial cable which is designed for high temperature and radioactive use. It was found that the TPI insulated and sheathed coaxial cable had good radiation resistance at 250°C under N2, γ-ray irradiation of 75 MGy under air, and electron beam irradiation of about 100 MGy under Hc. It was also found that both the crosslinking and the crystallization of TPI was accelerated by the synergistic effect of heat and γ-ray irradiation.
The authors already reported that localized heat generation appears before dc breakdown of low-density polyethylene film, which shows the contribution of thermal process to the breakdown. This paper describes the further study on the localized heat generation leading to dielectric breakdown in a low-density polyethylene film and the effect of heat treatment and elongation on it. To study the effect of density of polyethylene, very-low-density polyethylene (VLDPE) and high-density polyethylene (HDPE) films were also used. It was observed that the localized heat generation was suppressed after the heat treatment but was promoted after the elongation of the film. In VLDPE film, localized heat generation and dielectric breakdown occurred at obviously lower electric field than those in LDPE film. On the other hand, the localized heating was scarcely detected in HDPE film. These results indicate that the weak point where localized heat generation and breakdown occur might be one where local density or crystallinity is lower.
Division of Electronic and Information Engineering, Tokyo University of Agriculture and Technology Tracking resistance of insulating materials has been studied by many investigators with a test method of the IEC Publ. 112. The effect of different parameters is still far from being well understood. These investigations are further enhanced due to the increasing of organic insulating materials being used in the lower atmospheric pressure and radiation environments of space and nuclear power facilities. This paper presents a study on effects of γ-rays irradiation and lower atmospheric pressure on tracking resistance of polyethylene by use of the IEC Publ. 112 method. Polyethylene samples which were irradiated in air until 1×107R and 1×108R with dose rate of 106R/hr using 60CO γ-source have been employed. The total dose effect on the tracking, namely on the weight loss and erosion depth have been studied under combined conditions. As the total doses are increased, the weight loss and maximum erosion depth decreases, and the rate of reduction increases with decreasing pressure in the investigated range of 1007hPa to 500hPa. The effects of gamma-rays irradiation are determined due to radiation-induced cross-linking. In this case, as the atmospheric pressure is reduced, the tracking resistance decreases. It is considered this is due to the increasing residual carbon on the samples surface.
According to increase a use of DC motor for various electronic instruments together with a large-scale integrated (LSI) circuit, measures against a high frequency noise and a surge voltage have been very important to protect semiconductor device from miss operation and destruction. Ceramic varistor has a large electrostatic capacity and a large non-linear coefficient between applied voltage and current at the region of a large current. Therefore, it is often used to prevent these noise and surge. However, the large electrostatic capacity often causes a series resonance together with a inductance and a resistance of a motor. It is necessary to design a ceramic varistor suitably with considering characteristics of a motor. In the present paper, the authors replaced a ceramic varistor with a simple equivalent circuit from the experimental results for frequency characteristics of capacity and dissipation factor and DC characteristics. After then analyse a noise reduction mechanism of ceramic varistor by using simulation program with integrated circuit emphasis (SPICE). In this method, it is easy to measure current which is conducted in a each part of ceramic varistor and motor. It is expected for the present method to design a ceramic varistor theoretically.