The thermally grown oxide (TGO) layer, which forms below the topcoat of thermal barrier coating (TBC), is an important factor which causes topcoat delamination, and its detection is important for health monitoring of TBC. Photoluminescence detects the emission from Cr³⁺ in the TGO layer upon laser excitation, and is an effective, nondestructive method to detect the TGO layer. In this method, the laser light and Cr³⁺ photoluminescence must transmit through the topcoat, so the topcoat transmittance is a limiting factor of the measurement sensitivity. In this report, the topcoat transmittance was measured by comparing the photoluminescence intensities from the TGO layer in the presence and absence of the topcoat. The round-trip transmittance of the topcoat of thickness 300 µm was 1.26 %, corresponding to an attenuation coefficient of 7.3 mm^-1. The sensitivity of the luminescence measurement was evaluated by placing ND filters of known attenuation in front of the TGO layer, to simulate attenuation for different topcoat thickness. The results showed that luminescence measurement is possible for a maximum topcoat thickness of about 700 µm. A method to adjust the photoluminescence intensity for different topcoat thickness is presented.

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Nitrogen gas mixtures have been studied as one of substitute for SF₆. However, it is confirmed that active species of nitrogen supply electrons in space even under high pressure condition. In order to clear the electron supply mechanism, some kind of gases were mixed in nitrogen and delay time for each discharge was measured under the repeated voltage application. NO with high de-excitation rate coefficient for active species of nitrogen and SF₆ with high electron affinity were used for mixing gases. The results showed that the number of supplied electrons against interval time showed the different tendency between that of NO and SF₆. From these results, it was deduced that SF₆ act only on attaching electrons and did not contribute on quenching processes, and electron was generated at the cathode surface by gammma effect. It was also deduced that NO quenced the activated species in space and many electrons were generated and the quenching reactions should be the many body reactions.

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The influence of the pH of aqueous solution on the decomposition of acetic acid was investigated for water treatment using a pulsed streamer discharge under atmospheric pressure. The acetic acid present as persistent organic compounds in the aqueous solution was decomposed by the pulsed streamer discharge on the water surface. Oxygen and argon were used as gases to envelope the water surface. When oxygen was used, the decomposition efficiency (the amount of decomposition of acetic acid per energy consumed) strongly depended on the pH of the solution, i.e., the higher the pH, the higher the efficiency. However, the discharge energy was unchanged in both oxygen and argon when the pH of the solution changed. It was found that the decomposition efficiency was improved when the initial pH of the aqueous solution was higher, namely, in oxygen.

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This research has been discussed a growth promoting effect for agricultural products by discharge products. Ozone and nitrogen oxide was generated by dielectric barrier discharge from oxygen or air. These discharge products were dissolved in water as the bubble rises through the water. It was thought that sterilization of water and growth of agricultural products could be promoted by using the water containing ozone and nitrate ion for hydroponics. Radish sprouts and potherb mustard were used as agricultural products. The growth of agricultural products to the ozone concentration and nitrate ion concentration of the water used for hydroponics was discussed.

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To understand the properties of the composite insulating materials, DC breakdown test and the thermal conductivity measurement of polymethylmethacrylate (PMMA) / Aluminum oxide (Alumina) composite material produced by the electrostatic adsorption method were performed. In the PMMA/Alumina sample which has an Alumina as a main particle and a PMMA as an adsorption particle, DC breakdown strength decreased with the increase of Alumina content. It was considered that the increase of the interface between an alumina particle and a PMMA particle led to the lower DC breakdown strength. The thermal conductivity in PMMA/Alumina composite material increased with the increase of Alumina content. From these results, it was suggested that the electrostatic adsorption method could produce the various structure in the material and the insulating materials with various properties like the higher thermal conductivity and the tolerable breakdown strength by using the combination like the particle size of a main particle and adsorption particles.

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Recently, a system of wireless power transfer (WPT) using the electromagnetic resonant coupling has been studying and developing for practical applications, such as wireless charge systems of automobiles and electronic devices. But, efficiency of an electromagnetic resonant coupling type WPT system with LC resonators is greatly affected by a layout of LC resonators allocated in the system. This means that there is an optimum layout of LC resonators to transferring wireless power at higher efficiency. This paper presents a new method for identifying an optimum layout of LC resonators in a WPT system. One of key ideas is that a problem of searching optimum layout is replaced to a problem of calculating equivalent current sources given into LC resonators. Amplitudes of equivalent current sources can be calculated to solve ill-posed system equations by using inverse analysis. First, the proposal method is described. And system equations to be solved are formulated by means of equivalent circuit techniques. Second, the proposal method is applied to a simplified model to identifying an optimum layout of LC resonators in a WPT system. Then, an identified result by means of the proposal method is verified by comparing a ratio of receiving powers with the identified layout and without LC resonator. Finally, in order to verify the validity of the proposal method, calculated results are compared with experiment results using same model.

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Microwave assisted magnetization switching (MAS) has been expected as one of the prominent future ultra-high density magnetic recording technologies. In this paper, we have studied the rf field dependence of the switching behavior of Co/Pt nanodot arrays with various dot diameters. While the critical frequency increases and the minimum switching field decreases with increasing the rf field, MAS behavior critically depends on the dot size. For small dots less than 130 nm in diameter, the critical frequency and the minimum switching field exhibit linear variation with the rf field. On the other hand, for the larger dots (dot diameter ≥ 230 nm), they exhibit not only profound MAS effect but also obvious change in the behavior at a certain rf field. These changes of MAS behaviors are explained as a consequence of the change of magnetization precessional mode. On the other hand, the dispersions of MAS effect exhibit no remarkable variation on the rf field.

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The electrical insulating materials in motors are exposed to higher electric field in improving their performance such as high outputs and/or miniaturizations. Especially, the motor windings have the small gap at which partial discharge (PD) may occur under the high electric field and it can lead to dielectric degradation and breakdown. The actual power equipment is used under various environmental conditions. In actual case, PD may easily occur due to charge on the surface of the insulating parts. Therefore, it is important to clarify the partial discharge inception voltage (PDIV) characteristic at the small gap of the motor windings. In this study, we investigated the influence of surface charge on DC or AC partial discharge inception voltage in the insulation-air gap composite system.

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Non-destructive, two-dimensional distribution measurement of rusting under opaque anticorrosion paint was carried out, using a terahertz camera, a quantum cascade laser, and a galvanic scanner. The measurement speed of the present method was found to be 11 times faster than the conventional raster scanning method based on time-domain spectroscopy. A signal to noise ratio exceeding 10² was confirmed for both systems, which enables detection of minor rusting.

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PTFE has the best properties as a material of high frequency PC board. However, it has low adhesion force for using cabling material. In order to improve adhesion force, we studied on surface modification of PTFE by using nitrogen ion irradiation. As a result, peel strengths of PTFE improved up to 900 N/m to amount of treatment time. On the other hand, surface energy did not increase. From here onwards, improved peel strengths on modified surface could be forecasted because of a change that is binding state of modified layer. The compositions of surface on samples after peel test were analyzed so as to prove the hypothesis. As a result, adhesive/PTFE system occurred to destruction in deep portion of modified layer. Moreover, binding of oxygen could be existed with long treatment time. Therefore, it was suggested that the brittle layer of deep modifying layer need to be modified for the improvement of adhesive strength.

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