The surface wave plasma (SWP) processing apparatus has been permitted to generate high-density and uniform plasmas via 2.45GHz microwave without external magnetic fields. To enlarge the processing area of the SWP apparatus, special configuration was investigated for a rectangular-type surface wave plasma apparatus that is equipped with multi dielectric-windows. The experimental investigation of the discharge characteristics of this apparatus with four windows (each size with 10cm × 10cm) has been carried out. To improve electron density uniformity, two methods have been surveyed. One is to insert quartz plates between metallic window frames of the chamber to make the boundary surface between plasma flat, and the other is to place parallel conductor plates on the window surface. The combination of these methods permits the reduction of nonuniformity of the spatial distribution of the electron density less than ± 6%.

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Using a modified loop antenna, RF plasmas are formed under high vacuum without collisions between neutral atoms and a test piece or a target (Si) is mounted in the plasma.
By applying a negative high voltage to the target, carbon ions are implanted into the target by the three-dimensional ion implantation method. Films thus formed have been identified as DLC (diamond-like carbon) by Raman spectra, X-ray diffractometry and Rutherford back scattering. In the case of a target of WC with 10% Co, it has been found that the sticking force of film is 60N and the friction coefficient 0.13.

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The purpose of this study is to improve NOx removal by combining surface discharge and TiO₂. Especially, this paper was discussed about the effect of TiO₂ to NOx removal in case of mixing oxygen. The reactor had structure that luminescence of surface discharge was irradiated to TiO₂. Therefore it was expected that TiO₂ was activated by UV rays included in luminescence of surface discharge. TiO₂ was used in the form of porous sheet mixed particle of Teflon and TiO₂. The experiment was carried out to measure NOx concentration in case of changing discharge power and O₂ concentration. As a result, NOx removal performance was improved by using TiO₂. From this matter, it was found that TiO₂ was activated by luminescence of surface discharge. In the effect of oxygen to TiO₂, NOx removal of TiO₂ increased with increasing O₂ concentration. The reason is that the amount of O₂- generated on TiO₂ surface increases. From the point of by-product, NO₂ was not generated in case of using TiO₂. It was considered that generated NO₂ by discharge was adsorbed to inside of TiO₂ sheet that had porous structure.

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Voltage-current characteristics and plasma parameters of high-current nitrogen glow discharge for various gap lengths and gas pressures are described in this article. The transient glow discharge was produced with high-current larger than 100 A by static breakdown in nitrogen gas. Damping resistor was used to control the glow discharge current and was altered in order to obtain the voltage-current characteristics. The voltage-current characteristics of the normal glow phase and the abnormal glow phase were obtained in a wide current range from 50 mA to 100 A. The experimental results show that the current at phase transition of a normal to abnormal glow increases with increasing the gas pressure. The current at the phase transition is independent of the gap length. The electron density and temperature in positive column of the glow discharge were estimated using the voltage-current characteristics. The electron density and temperature increased with increasing the glow current and these values were 10¹⁰-10¹² cm^-3 and a few eV, respectively. The number densities of ions, metastable molecules and atomic radical particles in plasma were also estimated based on the each voltage-current characteristics. Metastable molecules density was 2-3 orders higher than electron density. Especially, the N₂(A) metastable molecule density was 3 orders higher than the other metastable molecule densities.

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The corona discharge air ionizer is one of the most important equipment for controlling electrostatic charges in the manufacture of semiconductor devices. However, the conventional air ionizer generates various kinds of contaminations, including particles. The dual jet ionizer that has a jet emitter in a nozzle has been proposed for reducing contamination from an emitter. Ions are generated in a nitrogen atmosphere in the dual jet ionizer because of nitrogen gas flow in both the emitter and the nozzle. The characteristics of ion generation and ozone generation were investigated for both the dual jet ionizer and the non-jet air ionizer. The characteristics of the dual jet ionizer depended strongly on the flow rates of nitrogen gas in the emitter and the nozzle. The number of particles generated by the dual jet ionizer under the optimum operating conditions was approximately four times smaller than that by the non-jet air ionizer.

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A new method to separate the metal from metal-plated plastic is proposed, and experimentally its effectiveness is confirmed. The pulsed high voltage is applied between two rod electrodes covered by ceramics. The discharge electrodes are moved with a high speed by a robot. The pulsed arc discharges produce the plasmas between two electrodes and the surface of metal-plated plastic, and the shock wave is produced when a part of metal layer is vaporized. Then the plated metal comes off from plastic. Both the removed metal and the plastic can be recycled as materials.

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In this paper, the effect of discharge gap dispersion on ozone generation characteristics of a tube type ozone generator is investigated quantitably by calculation and experiment. It is clarified that off-centered electrode layout seriously affects the ozone generation characteristics. Therefore, it is extremely important for efficient and high concentration ozone generation to shape a uniform discharge space.

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We have proposed the new water treatment using the active oxygen species such as an atomic oxygen with the oxidation power that is stronger than ozone. Based on the results of simulations we designed the silent discharge type active oxygen generator with a water ejector, which is operated on the discharge conditions of low pressure of 6.6kPa. and high temperature of about 200°C. The experimental results are as follows. (1) The yield of the active oxygen increases with the increase of the discharge tube temperature and the decrease of the gas pressure. (2) The life time of active oxygen is tens msec. (3) The active oxygen oxidizes efficiently the formic acid compared with ozone. It is assumed from these results that the active oxygen species having a strong oxidation power is generated.

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The aim of this paper is to understand the statistical inception mechanism of the first corona in positive non-uniform air gaps ranging 0.3˜1.0 cm. We calculated first how the spatial distributions of negative ion density depend on the gap length, UV irradiation and the concentration of water vapor using the steady state continuity equation for ion flow states. Next the cumulative probability of the first corona inception as a function of the statistical time lags was evaluated from the critical volume model in which initial electrons are provided by collisional detachment of negative ions. Furthermore, we also measured the cumulative probability of the corona inception under similar experimental conditions.
From comparison between the numerical and experimental results and their discussions, it was found that in the short range of gap length, negative ions produced near the cathode associated with positive ion bombardment play an important role in the statistical inception mechanism of the first corona. And also, much higher probability of corona inception in the case of UV irradiation was attributed to a number of negative ion produced near the cathode through the photo emission process.

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The two-dimensional vector magnetic properties are proposed as a method to express the magnetic anisotropy and iron loss precisely by using the relationship between the flux density vector and the magnetic field strength vector. The E&S modeling⁽⁶⁾ and the E&SS modeling^(7)˜(9) have enabled to express the two-dimensional vector magnetic properties in the FEM calculation. However, the calculated flux density waveform at each element, has phase difference depending on the exciting condition. In this paper, we have improved the E&SS modeling to solve the magnetic field problems under any exciting condition.

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A polypyrrole (PPy) film electrochemically grown in a thin slab vessel consisting of poly(tetrafluoroethylene) (PTFE) walls, exhibits a notable anisotropy along the thickness. This anisotropy allows it to bend in a regular direction upon electrochemical undoping and reverts upon doping. In this paper, the size effect, i.e., the length dependence of reduction current, of the actuator has been studied. The length was changed by trimming the tip of the actuator which was initially soaked for 12 mm in the electrolyte. It has been clarified that the current saturates when the actuator exceeds a certain length. This may reflect the reduction of conductivity of PPy upon undoping, which makes the tip of actuator almost be insulated from the power source. It is also found that the width of actuator and the electrolyte do not influence on the size effect.

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The melt-spun ribbons of Didymium-Fe-Co-Nb-V-B system alloys were prepared by single roller liquid rapid-quenching method. The effects of composition, wheel velocity and heat treatment on the magnetic properties were investigated. Didymium_12.5Fe_69.5Co₁₀Nb₁V₁B₆ ribbons prepared at a wheel velocity of 17.5 m/s were crystallized by heat treatment, and the optimum heat treatment condition was found to be at 600 °C for 5 min, then the values of (BH)_max and H_cJ were 128.3 kJ/m³, 1100.0 kA/m, respectively. The temperature coefficients of J_r and H_cJ for the ribbons crystallized from the Didymium_12.5Fe_69.5Co₁₀Nb₁V₁B₆ alloy were α(J_r)_ave=-0.044 %/°C(reversible) and α(H_cJ)=-0.370 %/°C(irreversible), respectively. The value of (BH)_max for the isotropic compression molding Didymium_12.5Fe_69.5Co₁₀Nb₁V₁B₆ bonded magnet prepared by using the ribbons annealed at 600 °C for 5 min is 88.9 kJ/m³ and the density is 6.3 Mg/m³. Irreversible loss of the bonded magnet is -3.64 %/°C(at 150 °C).

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This paper describes the novel scheme of the two-dimensional measurement of the surface magnetic flux density distribution of YBCO melt-processed bulk superconductor exposed in the alternatively changing field. It is well known that the surface flux density distribution is quite important to estimate the current density distribution inside the bulk and the position of the defect. Two-dimensional static field measurements are common and standard in these days, and one-dimensional dynamic ones are reported by many research groups. We tried to measure the two-dimensional dynamic distributions to obtain the further information on the superconducting bulk. The measurement system consists of ten Hall sensors located on straight line, which can be moved toward the perpendicular direction all together. The alternative magnetic field is applied by the external coil, and the sensors are moved in a way synchronized with the field. As the results, we obtain the two-dimensional dynamic surface flux density distribution of YBCO bulk. The specimen has several cracks on the surface, and we are able to find that some of them correspond to the irregular distribution of the results.

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In this paper, using Positive Temperature Coefficient (PTC) elements, we propose a simple repetitive high-speed PTC Current Limiter (PTC-CL) whose rated voltage is increased by using a series transformer (ST) at levels far beyond their intrinsic voltage rating. The PTC-CL consists of PTC resistors connected in series and in parallel to each winding of the ST. The PTC-CL was numerically studied by using the electro-magnetic transient program (EMTP) and the electrical equivalent model for PTC. The winding resistance effects and whether all of PTCs will trip or not under the fault current condition were studied. The experimental results in case of two PTCs, where the PTC element is rated (60V/40A), show that the sufficient voltage is applied on the non-tripped PTC even after another PTC trippd at first, and all PTCs of PTC-CL tripped within 0.2 ms where the fault current was suppressed from 1200 A to 52 A at rated voltage 120 V. But, the saturation current started to flow after 2 ms and reached above 1500 A because of the small size of the used core. In order to reduce it, RC components were proposed and the measurement results indicate that the saturation current can be eliminated adopting a suitable parameter for RC components.

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Triggering and guiding of electrical discharge using an ultra-short, high-power laser is demonstrated. Laser-induced breakdown is observed at a gap length of 2m and a voltage of -1.12MV. Breakdown voltages at a gap length of 1m are reduced by 23% and 5% of the natural breakdown voltage at negative and positive polarity, respectively. Maximum triggering effect is observed for laser pulses at 2μs after the rise of the applied high voltage pulse. Multiple filamentation is expected to allow long distance guiding effect using long distance propagation of multiple filaments.

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To achieve good visibility and eye-catching quality for LED information board under various illuminance environments, we made an attempt to know the optimum numbers of display color so that a driver can correctly recognize displayed information. Under four kinds of surrounding illuminance, we tried to determine an optimum number of display colors based on categorical color technique. The results showed that the optimum numbers of display color were ten. Our experimental results also revealed the influence on color recognition under various surrounding illuminance.

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A new reconstruction technique for Doppler spectroscopy has been developed using spatial and wavelength profiles of line spectrums. Unlike conventional deconvolution techniquies, maximum entropy method was applied to combined reconstruction of these two profiles. Our simulation and experimental results indicate its improved significantly accuracy and robustness against measurements noise.

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AE (Acoustic Emission) techniques are universally used for investigating and watching the deformation and crack of various materials because they enable the non-destructive and continuous measurement. However, it is not always easy to clarify the main cause or mechanism of AE signal generation by its analysis and an AE sensor is generally vulnerable to the noise, and therefore advanced measurement and estimation techniques of AE signal are needed. In this paper, the authors present time-frequency visualization of AE signal using the wavelet transform. The proposed method enables especially precise measurement of the frequency band and generation time of AE signal and gives a clue in advanced AE techniques.

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