The effect of barrier between a needle electrode and plane one in (N₂/SF₆)gas mixture on creeping flashover was investigated using a μs pulse voltage. The content of SF₆ gas was varied from 0 to 100%, and gas pressurre was varied from 0.1 to 0.3MPa. The flashover voltage increased with increasing the content of SF6 for a positive needle electrode. For a negative needle electrode, excepting the total pressure 0.1MPa in which similar flashover characteristics was obtained as positive one, considerable decrease in flashover voltage was found in the case of the mixture of a few percentage of SF₆ in (N₂/SF₆) gas mixture at elevated total pressures. The corona behavior on the barrier in (N₂/SF₆) gas mixture was investigated utilizing an ultrahigh-speed digital framing camera.

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Analysis of NOx removal by a discharge plasma is made with an equivalent circuit. The used NOx reduction system consists of a neon transformer and a plasma reactor based on a dielectric barrier discharge. Impedance of the neon transformer has been determined experimentally, The equivalent circuit based on a series connection of two capacitors is used for the plasma reactor. The capacitances are obtained from experimental V-Q Lissajous diagram. Comparison with experimental data of consumed energy and the dependence of NO removal on gap length is successfully done.

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Current-voltage characteristics of the droplet shield plate (aluminum, 100mmφ) in the shielded vacuum arc apparatus was measured in order to probe the possibility of ion control. Arc current was 50 A and pres-sure was 0.5 Pa with Ar or N₂ gas flow. At negative voltage region, the current was almost constant at around 1A. However, even at lower positive voltage region, the current rapidly increased more than 10 A. Such large current was found to be a part of arc current, resulting the shield plate act as an anode. These re-sults indicate that the higher positive voltage cannot be applied to the shield plate and thus it is difficult to reflect the ions with few tens electronvolts, which are emitted from cathode.
Next, in order to clarify the disturbance of the droplet shield to the plasma, the plasma parameters were measured by using Langmuir probe. It was found that the electron and ion densities drastically decreased behind the shield plate. Furthermore, the plasma parameters were derived from the current-voltage char-acteristics of the shield plate, assuming the plate was a large electrostatic probe, and compared with those obtained from Langmuir probe measurement. The result indicates that the shield plate could be used for rough evaluation of electron energy and ion density.

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In present research, experiments using a diffuse glow discharge, which is one of non-thermal plasma, were carried out to remove NO_x. To generate diffuse glow discharge a double discharge method was used and it was consisted of two discharges, pre-discharge and main discharge. The pre-discharge produces many initial electrons around cathode and generates the main discharge easily at atmospheric pressure.
The experiments employed two kinds of sample gas, NO/N₂ mixture and NO/N₂/O₂ mixture gas, with several different NO concentrations for removing N_Ox, and adjusted at 1.25 [l/min] for all measurements. Using NO/N₂ mixture gas a reduction rate of NO decreased with increasing initial NO concentration. Thus the present NO_x reactor can remove efficiently at the region of low NO_x concentration. Nevertheless, an energy yield of NO removal improved and reached 8.82 [mg/Wh] at initial NO value of 186 [ppm] which is about 5 or 6 times comparing to conventional discharge methods. Steepness of main voltage was important factor for removing NO_x. With NO/N₂/O₂ mixture gas the reduction rate of NO reached 100 [%] at O₂ mixture rate of 20[%] because NO oxidation was accelerated drastically by generated ozone together with O atoms. The energy yield of NO removal was 21.9 [mg/Wh] which is about 2.5 times higher than one of NO/N₂ mixture gas.

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In order to design the driving electric circuits of PDPs, it is necessary to know how to treat the discharge as an electric circuit element. We have constructed a simple and novel discharge model which can be applied to general silent discharge phenomena. In this model, we treat the discharge as a resistor whose conductance changes with time. Using this macro-discharge model for silent discharges, not only we can know the electrical characteristics of PDP, but also we can understand the physical meaning of a PDP discharge, and general silent discharge phenomena systematically.

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Triple-Probe measurement of the short duration arc plasma generated by melting down the thin wire fuse element under the atmospheric pressure has been carried out. The time depending electron temperature as well as the electron density of the plasma were successfully obtained by carefully reducing the noises into the probe circuit using an optical isolation amplifier. Experimental results show that:
(1)The electron temperature shows about 30000 [K] immediately after generation of the arc plasma and decreases to approximately 10000[K] after 1.5 [ms] of the discharge. This value of 10000[K] was the same irrespective of the values of initially applied voltages and currents for melting the fuse element.
(2)The electron density shows about 10₁₆ [cm^-3] immediately after the generation of the arc plasma and also decreases to approximately a constant value of 10¹⁵ [cm^-3] after 1 [ms] of the discharge. The radius of the arc plasma column first expands to about5 [mm] at beginning of the discharge and then shrinks to about 3 [mm] before disappearing. All data are presented and discussed.

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The switching time and arc-ignition probability of a sustained main discharge in laser trigger vacuum gap were measured. The third harmonic beam of Nd:YAG pulse laser(wavelength 355 nm, energy 5mJ/pulse, power density 4×10⁷ W/cm²) was used to trigger the gap. The main electrodes of 85mm diameter were made of oxygen-free copper. The gap length was 1.6mm and the experimental chamber was evacuated to about 1.3×10^-4 Pa by a turbo-molecular pump. The UV beam from the laser was focused at normal incidence onto the grounded cathode.
The switching time decreased with increasing of the applied voltage.And arc ignition probability increased with increasing of the applied voltage. The switching time was 326ns at 15kV with the circuit inductance 107μH. Its jitter was 24.8 ns. The advantageous results obtained with UV beam are compared to the previously reported data in the triggered vacuum gap.

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This paper presents the characteristics of a basic experimental model of a newly developed dehumidifier with membrane as a humidity controller to guard against high levels of moisture concentration from the outside air. The model is an active steam discharger which removes moisture from inside the box utilizing temperature variations. It also prevents the intrusion of water vapor from the outside through the use of membranes and buffer spaces. The humidity controller consists of two cylindrical chambers and three membranes made of a waterproof film that separate the chambers and allows moisture to pass freely through without a water drain tube. Experimental results have shown that the basic design of the device can be employed in practical use to dehumidify air and eliminate permeation of moisture. It is not possible to keep an appropriate moisture level using a passive device without an electric power supply. However, by using the humidity controller, we can keep the relative humidity inside the electric device housing within a low level of risk of rusting.

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The effect of a cylindrical side wall on the current-voltage (I-V) characteristic and the dc breakdown voltage were investigated using a positive needle-to-plane electrode geometry in transformer oil. Linear plots of V vs. I^1/2 were obtained for the geometries with and without the side wall. Conduction currents decreased by the presence of the side wall, and the slope of linear plots changed when V and I exceeded their critical values. The breakdown voltage increased for gaps with the side wall. These are discussed on the bases of the generation of turbulence flow and the space charge effect on the electric field strength at the needle tip.

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In this paper, we studied the resistance lattice circuits in two and three dimensions. The exact voltage distribu-tions on these circuit are obtained based on the Modified Bessel function. The combined resistance and asymptotic property of these circuits are formulated. Moreover another exact solution under the boundary condition of Kro-necker's delta is constructed.

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Surface potentials of phthalocyanine derivative Langmuir-Blodgett (LB) films on metal electrodes were studied. Two kinds of phthalocyanine derivatives (C6PcCu and CuttbPc) were examined as a function of the number of deposited layers. The distributions of spatial excess charge density and of electronic state at the metal/film interface were determined. It was found that these two distributions clearly depend on the two kinds of phthalocyanine derivatives.

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Thermodynamic properties such as enthalpy and specific heat, and viscosity of different compositions of argon-iron mixture gases are calculated under the assumption of local thermal equilibrium for a temperature range of 2, 500K to 30, 000K. The enthalpy decreases basically with increasing iron vapor content, however increases in the temperature range between 5, 000 and 14, 000K due to the ionization of iron atoms around 7, 000K. The specific heat changes complexly with temperature having several peaks corresponding to the ionization of iron and argon atoms and their ions. The viscosity decreases with increasing iron vapor content above the temperature range of 6, 000K due to the iron ions, which have a relatively large coulombic cross section. Increasing pressure causes the enthalpy to be decreased, however the viscosity to be increased. This result comes from the upward shift of temperature region in which the ionization reactions proceed efficiently.

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The authors are studying and firstly report the influence applying magnetic field during preparation on properties of vacuum-deposited organic dye thin films. In spite of weak magnetic field (0.1-0.3T), the effect of magnetic field can be observed in PL spectra, X-ray diffraction pattern or IR-RAS spectra of p-quaterphenyl (4PO) thin films. Although 4PO molecules are aligned almost normal to glass substrate, the application of magnetic field during preparation will disturb the particular molecular orientation. As a result, the intensities of X-ray diffraction peak and IR absorption decrease. The influence due to magnetic field depends on the intensity of magnetic field. It cannot be observed even if magnetic field applies to 4PO thin films after preparation. As magnetic field is weak in this paper, 4PO molecules cannot be aligned on the basis of magnetic orientation.

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This paper describes the application of a sputtered perm ally thin film to a common-mode noise filter in the 1 MHz-1 GHz frequency range. The 4-μm-thick perm alloy film exhibits high loss characteristics which are based on the eddy current loss. It is confirmed that a filter whose volume is from a quarter to a half that of a conventional filter (ferrite core) exhibits the same noise attenuation. Moreover, the noise emission from a twisted pair cable is greatly reduced without any increase in the cable volume by employing the permalloy film as a shielding material

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It has been reported in polymer insulation that the ac loss current in phase to applied voltage is distorted with developing of water trees. We have also obtained the distorted ac loss current from the water treed polyethylene sheets. In order to analyze this distorted ac loss current, we have discussed with the modified Maxwell-Wagner two layer model, in which the capacitance C₁ for the non-degraded region is connected in series to the parallel combination of the capacitance C₂ and the non-linear conductance G₂ for the water treed region. This model takes account of a non-linear dependence of conduction current through G₂ on voltage across the capacitance C₂. By numerically solving a non-linear differential equation for the electric charge on the capacitance C₂, the ac loss current was calculated. The observed wave forms were compared with the calculated ones by changing parameters of non-linear conduction.

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According to recent research related to space charge in polymer dielectrics, the internal space charge behavior is an important factor in the evaluation of insulation. In the case of a high-voltage oil-impregnated dc cable, polypropylene laminated paper (PPLP) is used as an insulation material, however, its space charge characteristics have not been observed in detail. We measured the transient phenomena of space charge accumulation in a PPLP sample using the pulsed electroacoustic method. In this paper, we describe the space charge behavior in PPLP samples impregnated with several types of silicone oil. The results suggested that space charge accumulates at the interface between the electrode and polypropylene under dc voltage application, and decreases exponentially. The time constant depends on the type of insulation oil. Thus it is revealed that the space charge observation provides usuful information in the evaluation of dc characteristics of PPLP insulation systems.

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The tension sensor is expected for tension monitoring or control in varies fields. For the tension monitoring of contact line, we are developing a new tension sensor using magnetostrictive film. The sputtering technique was used to prepare Ni-Fe magnetostrictive films on stainless-steel shafts. The factors affecting the output characteristics of the tension sensors are studied as functions of the composition of Ni-Fe films. The sensitivity of tension sensor is proportional to the film thickness. The optimal value of the Ni content in Ni-Fe films was found theoretically and experimentally to realize a maximum sensitivity of tension sensing.

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Rare-earth-doped thin SiO₂ films were made by plasma-enhanced chemical vapor deposition using a complex containing chelating ligands and tetraethoxysilane. By this means of deposition, the film was successfully doped with terbium or erbium and the luminescence from the film was detected. Furthermore, by making a two-layered sample consisting of the terbiumdoped SiO₂ film and non-doped SiO₂ film or fluorine-doped SiO₂ film and by examining the electroluminescence intensity, it was found that the acceleration of electrons by electric field is difficult in the fluorine-doped SiO2 film.

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We have fabricated epitaxial PbZr_0.52Ti_0.48O, (PZT)/YBa₂Cu₃O_7-x (YBCO) films (ferroelectric/superconductor/heterostructures) on the single-crystal MgO substrates by a KrF pulsed laser deposition technique. The heterostructure has high electric resistivity p (at 150 kV/cm) of 4×10¹¹ Ω•cm, dielectric permittivity of 820 and loss tan δ of 0.04, remnant polarization of 32μC/cm² and coercive field of 41kV/cm. Film thickness dependence of the coercive electric field over the thickness range 0.04-1.2μm is in close agreement with prolate ellipsoid nucleus model proposed by Kay and Dunn. Switching property of the fabricated epitaxial PZT thin films corresponds to ferroelectric needle-like nucleus growth.

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Behaviors of liquid crystal molecules, 5CB, have been investigated in the thick cells having aligning layers of the polyimide (PI) Langmuir-Blodgett (LB) films on the aluminum electrodes using the attenuated total reflection (ATR) measurement method. The ATR curves strongly depended upon the AC voltages applied to the cell and upon temperatures. The resonant excitations of the surface plasmon polariton (SPP) were observed in the broad region of the incident angle in the ATR measurements. The tilt angles of the liquid crystal molecules were calculated by fitting the theoretical ATR curves to the experimental ones. The results showed that the ATR measurement method was very useful for evaluating the behaviors of liquid crystal molecules in thick cells.

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The tension sensor is expected for tension monitoring or control in varies fields. For the tension monitoring of the Shinkansen contact line, we are developing a new tension sensor using magnetostrictive film. The sputtering technique was used to prepare 90wt%Ni-Fe magnetostrictive film on stainless-steel shafts. Thermal cycling affecting the output characteristics of the tension sensors are studied as functions of the thickness or the intrinsic stress of Ni-Fe film. The optimal value of the thickness in Ni-Fe films was found to realize a minimum thermal drift of tension sensor. The intrinsic stress in Ni-Fe films decreases with increasing the sputtering target voltage. The sensor output change by the thermal cycling test decreases with decreasing the intrinsic stress. The output change in the sensor with 90wt% Ni-Fe film prepared by -525V(sputtering target voltage) is less than ±0.2% F.S.(full scale)in the 1650 cycles durability test with 258-318K temperature. The sensor detects 12-18kN tension for the Shinkansen contact line with an accuracy of ±2% F.S. in the temperature range 258-318K.

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Large amplitude oscillation was excited by strong ionization which is caused by a nonuniform field in DC-grow discharge. Electrodes were used a big disk (C: cathode) and very small needle (A: anode) for discharge. Using gas is argon, pressure is 0.18-0.19 Torr, discharge voltage is 350-640V. In these conditions, produced signal is a sine wave (frequency: 1.06MHz, amplitude: 3.9V and output power: 75mW).

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