This study presents a new theoretical model for describing a rectilinearly channeled negative surface discharge, sometimes called a guided discharge. The discharge consists of a passive region in the channel in plasma state and an active region at the channel tip in ionized state, the channel tip moving at a propagation speed. In the former region, a nonlinear diffusion equation holds valid under the assumption that the current in the channel consists of moving electrons supplied from the electrode. The boundary conditions at the channel tip are the current continuity condition and the condition that the propagation speed of the channel tip is proportional to the gradient of second power of the potential of the channel at the tip. From these boundary conditions it follows that the potential at the tip is held constant. By means of appropriate scaling of relevant quantities, a one-parameter family of general solutions of the equations is shown to be uniquely determined. This study presents how to apply the experimental data to the theoretical solution. It becomes clear in accordance with the discussion that the potential at the channel tip and the mobility will be essentially important. Moreover we discussed in relation to applied voltage and mobility based on the previously obtained experimental data.

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There have been quite a number of theoretical as well as experimental studies concerning discharge phenomena, but the results (or partial results) are complicated mathematically as well as physically. The main subject of the present paper is traced back nearly twenty years ago when the second author began experiments with an exquisite mechanism he devised. The discharge phenomenon was like the famous Stephan problem, where two different phases of one and the same substance, i.e., ice and water, coexist at a free moving boundary between them. The mathematical model consists of a diffusion-type nonlinear partial differential equation with initial and boundary conditions. In particular, one of the boundaries is given fixed condition, whereas the other is moving with a little subtle physical assumption on the speed of the propagation of discharge. Therefore, the nonlinear diffusion equation is difficult to solve by a usual method. Assuming that the applied voltage is constant and that there exists a unique solution, the original initial- and boundary-value problem is reduced to the initial-value problem of an ordinary differential equation. This latter problem allows us to define a one-parameter family of new functions. Details of the derivation of the solution of the fundamental equations and the physical meaning of the propagation condition and the analytical solution for a rectilinearly channelled negative surface discharge are discussed.

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Non-thermal plasma processes at atmospheric pressure have been considered to be an effective method for NOx removal. In this study, a packed-bed reactor for NOx removal from air steam was developed using the BaTiO₃ pellets prepared by ourselves. The reactor consists of the glass tube with the inner diameter of 17.5mm and two mesh electrodes. BaTiO₃ pellets were packed between two mesh electrodes in the glass tube. In order to investigate effects of the sintering temperature of BaTiO₃ pellets used in the reactor on NOx removal, we prepared BaTiO₃ pellets sintered at the temperatures in the range from 100°C to 1300°C. As a result, maximum NOx (=NO+NO₂) removal rate was 85% using the BaTiO₃ pellets sintered at 600°C.In this case N₂O of about 10ppm was generated for the voltage at which maximum NOx removal rate was obtained and O₃ was not detected. On the other hand, using the BaTiO₃ pellets sintered at the temperatures over 1000°C, concentrations of NO and NO₂ were increased with increasing the applied voltage compared to their initial concentrations. Properties of BaTiO₃ pellets, which significantly affect NOx removal characteristics, depend on the sintering temperatures.

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We planned to develop a small and inexpensive measurement device with which one could determine a molecular concentration. The analysis process operates by superimposing a magnetic field with a rotating electric field. When the strength and the frequency of the rotating electric field and the mass and the speed of the ion are decided, the rotating radius of the ion is fixed. We used a computer simulation to estimate ion movement in the electric field. It is possible to calculate the rotational movement of the ion in the rotating electric field, and then calculate the circular movement in the superimposed state in the rotating electric field and the magnetic field. Here, resolution ability is decided by the size of the analysis machine. The definition of resolution is the amount of separation divided by the distance of the attainment point. The fluctuation of resolution improves gradually at first, and then raises up even to over 20 times. We think that the theory of the ion movement in the rotating electric field and the magnetic field could make a small and inexpensive analysis machine.

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The authors have studied on generation processes of N₂(C³Π_u) in discharge of high E/n region. In this investigation, the spatial distribution of N₂ Second Positive Bands was measured and was compared with the calculated results obtained by the Monte-Carlo method. From the results, it is suggested that N₂(C³Π_u) was generated by any processes including direct excitation from the ground state. To confirm the generation process except the direct one, time after glow method was used. As a result, slow decay component on intensity of N₂ Second Positive Bands was detected. Its relaxation time was about 0.5ms. The relaxation time is similar to the effective life time of N₂(A³Σ_u⁺). Then, in discharge of high E/n region, it is shown that the rate of N₂(C³Π_u, υ'=3, 4) generated by re-excitation process of N₂(A³Σ_u⁺) mutual collision is high.

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A new algorithm for 2-D ion temperature measurement was developed by including to the Gaussian-fitting process of Doppler broadened spectrum line in tomography reconstruction. A modified Bessel function model and squared cosine function model were used to satisfy both of annular boundary conditions in space and gaussian profile of spectrum line in wavelength. This method was found much more robust against projection signal errors than the conventional Gaussian-fitting method at each wavelength.

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Diamond-Like Carbon films were deposited by the ion beam plating method using negative pulse bias on silicon wafer substrates. Benzene (C₆H₆) gas was used as a working gas for plasma. Direct current ion source was used to produce a glow discharge plasma. Negative pulses were applied to a substrate holder to accelerate ions from plasma. The DLC films were analyzed using Raman Spectroscopy, X-ray Photoelectron Spectroscopy and Electron Energy Loss Spectroscopy. The result of the mechanical property of DLC films using negative pulse bias was as follows. Adhesion power was 81 N, durability was 933 minutes and average of hardness was 21 GPa. As compared negative pulse bias with direct-current bias, adhesion power of the DLC films increased by 2.7 times, durability of the DLC films has been improved about 85 times and hardness of the DLC films can be controled broadly.

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The profile optimization of an insulator such as a spacer is very important in reducing the cost of power equipment. This paper describes the profile optimization of a disk-type spacer utilized in coaxial cylindrical power equipment. The optimization is based on making the electric field distribution as uniform as possible on the surface of a spacer. The Charge Simulation Method was used to calculate the electric field and the Marquardt Method was used as an optimization technique.
The following optimization conditions were set on the spacer surface.
a) Constant tangential component of the electric field(E_t)
b) Constant total electric field(E_a)
In the case of b), profile optimization was achieved, where the total field strength diminished to about 60% of the maximum value in the corresponding coaxial cylindrical arrangement without a spacer.

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The thermodynamic and transport properties of an argon-alumina mixture were calculated assuming local thermodynamic equilibrium for a temperature range of 4, 000 to 20, 000K with the pressure of 10⁵Pa. The main effects of alumina injection into argon are summarized below. Specific enthalpy and specific heat increase because of dissociation of AlO molecules and ionization of Al and O atoms. Electrical conductivity dramatically increases below 15, 000K because of low ionization energy of Al atoms. Thermal conductivity increases below 11, 000K because of dissociation of AlO molecules and of ionization of Al atoms. Viscosity decreases below 14, 000K because of relatively large cross section of Al⁺ ions.

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Computer simulation was carried out to obtain a better understanding of the discharge characteristics of a plasma display panel (PDP). We calculated the characteristics of the microdischarge in a DC-type cell filled with a mixture of He and Xe gases using a time-dependent and one-dimensional fluid model simulation including the back-diffusion effect of secondary electrons from the cathode due to collisions with gas molecules. The simulation was conducted under local field approximation (LFA) for electrons, four kinds of ions, and seven kinds of excited species, with consideration of the absorption and reemission of imprisoned resonant radiation, and the wall loss at the barrier ribs. Under the conventional conditions of the cell, the sparking voltage was 276V with secondary electron yield γ in vacuum which increased to 294V corresponding to the decrease of yield γ' in gas. The peak currents with γ and γ' in the pulse discharge were 104μA and 72μA, respectively. The characteristics of vacuum ultra-violet (VUV) rays and the luminous efficiency were also investigated.

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Removal of NO_x has been successfully demonstrated using an intense, pulsed relativistic electron beam (IREB). The elongate gas chamber (1.8 m long) is filled up with dry-N₂-balanced or dry-N₂/O₂-balanced NO gas mixture with the pressure of 120 kPa, and is irradiated by the IREB. The kinetic energy, current and pulse width of the IREB are ∼2 MeV, ∼2.2 kA and ∼90 ns (full width at half maximum), respectively. With the initial NO concentration of 100 ppm in N₂-balanced NO gas mixture, ∼96 % of NO_x is removed by firing 10 shots of the IREB. We have obtained the energy efficiency of NO_x removal of ∼220 nmol/J in N₂-balanced NO gas mixture with the initial NO concentration of 880 ppm. The energy efficiency of NO_x removal increases with increasing the initial NO concentration. In N₂/O₂-balanced NO gas mixture, NO_x is removed if the initial NO concentration is less than 200 ppm. However, the NO₂ is also generated by the irradiation of the IREB. The theoretical calculation on the half-life time of NO shows that the NO₂ is generated by the oxidation of NO by O or O₃.

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In the bulk of crosslinked polyethylene insulated cables, there remain chemicals such as acetophenone, α-methylstyrene, and cumylalcohol. We have examined the effects of these remaining chemicals on the space charge evolution in low-density polyethylene (LDPE). A two-layered specimen consisting of a non-treated sheet and a sheet soaked into the chemical was examined. As an important conclusion obtained, it becomes clear that cumylalcohol traps charge carriers at the surface of LDPE, while neither acetophenone nor α-methylstyrene has this effect. The latter two chemicals assist carrier transport. It seems that the hydroxyl group of cumylalcohol has an important role to the carrier trapping in the LDPE in which cumylalcohol is present.

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In the present paper, an approach for identifying currents in signal lines of a printed circuit board (PCB) from measured magnetic field distribution have been proposed. Key of the approach is that spatial characteristic of magnetic field probe is utilized to calculate currents from measured magnetic fields. Simulations have verified validity of our approach. Experimental examinations have demonstrated that 10MHz pulse currents in parallel lines with 2.1mm intervals can be identified.

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We investigated the space charge behavior near the interface between different low-density polyethylenes (LDPE). Charge carriers were mainly injected from the semiconductive (SC) electrode in a specimen of AI/LDPE/LDPE/SC and they moved through the interface towards the counter AI electrode. Charge carriers moving from a lower density LDPE to a higher density one were accumulated near the LDPE/LDPE interface to form space charge, while there was no space charge accumulation at the interface caused by carriers moving in the opposite direction. The mobilities of charge carriers were estimated from the change in space charge profile with time. Charge carriers were more mobile in the lower density LDPE than in the higher density one. Positive carriers were more mobile than negative ones in each LDPE. The interface between different LDPE’s greatly affected space charge behavior and discharging currents.

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A space charge distribution in a low-density polyethylene (LDPE) film is considered to change when the electric field becomes as high as its breakdown field. Since the space charge profiles measured at a few seconds interval did not show any noticeable change, we have developed a short time interval space charge measurement system. To investigate the relationship between the electrical breakdown and space charge behavior at high temperature region, the measurement system is designed to use at 90°C. The experimental results using a 100μm thick LDPE film show a large amount of positive charge was injected from anode at 3MV/cm just before the breakdown. To clarify the relationship between the positive charge injection and electrical breakdown phenomena, acetophenone-coated LDPE film samples at either anode or cathode surface were prepared. In the acetophenone-coated sample at anode surface, a significant packet-like positive charge appeared just before the electrical breakdown at 3 MV/cm. Although a negative packet-like charge appeared in acetophenone-coated sample at cathode surface at 3 MV/cm, the electrical breakdown did not occur. Based on the experimental results, it is clear that the breakdown phenomena in the LDPE film at 90°C in influenced by space charge behavior, i.e. a large amount of positive charge injection from the anode.

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The orientation of liquid-crystal directors in the vicinity of an interface between a glass plate and a liquid-crystal layer is studied under shear horizontal (SH) wave propgation. Propagation characteristics of SH wave in a trilayer structure composed of a liquid-crystal layer sandwiched between two glass plates are numerically analyzed in the form of taking into account the anisotropy of the viscous tensor. The dependence of the acoustic phase delay change on the applied voltage to the liquid crystal layer is numerically related to the liquid-crystal director-angle. The applied voltage dependence of the director-angle is evaluated under the propagation of the 0th and 1st modes of SH wave, when the two modes have the different displacement distributions in the vicinity of the interface with the glass plate. The present technique is promising for evaluating the orientation of liquid-crystal directors without requiring a complicated experiment setup and valid for real-time measurement.

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For medical equipment such as catheter or endoscope, it is required to bend its end to select the way at blanches inside of the body. We proposed a method to bend the end of the catheter using magnetic torque. By using magnetic torque we can apply the torque for bending to the magnet attached at the end of the catheter. In the experiment we used a medical guide-wire which is used to insert the endoscope. By attaching a NdFeB magnet of 0.7mm-diameter and 4.7mm-length, the guide wire bend in the curvature radius of 33mm in the field of 23.9kA/m. The bending direction and angle were controlled by 2D coils and a control system. Using this system, we could control the bending of the guide wire by stick-type controller. The obtained system is simple and wireless, obtains large enough bending, and have quick response. These properties are the most suitable point for application for medical equipment.

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The horizontal position of a small Tokamak plasma can be simply measured by a pair of optical fibers mounted over a torus vacuum vessel without being affected by the electromagnetic noises as in the case of the measurement by magnetic probes. The horizontal position H_o is given by H_o=0.3ln(F_o/F_i) from the optoelectrically transformed outputs of the fibers. Unless the plasma changes violently, the measurement by the fibers is accurate and coincident well with the measurement by magnetic porbes.

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