Both electrolessly-deposited CoP and CoFeB films, and electrodeposited Co films formed on rapid-quenched amorphous alloy ribbons. These polycrystalline Co-based films were obtained with different preferred orientations, surface structures, and magnetic properties, from the species of the substrates. Electrochemical characterizations by means of polarization curve clarified the catalytic activity of electrodes and the overpotential, for electroless- and electrodepositions, respectively. These electrochemical properties may affect the first stage of the deposition, to determine the structural and magnetic properties of the films.

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Effect of FRP spacers on breakdown phenomena in liquid nitrogen in the presence of bubbles is investigated with a plane-to-cylindrical electrode. The interface between FRP spacers and liquid nitrogen was arranged at shortest gaps in electrode system. Bubbles were produced by a heater mounted in the cylinder for simulation of insulation circumstance in a state of quench. The experimental results show that thermal-bubble generation site at initial stage of boiling concentrates around contacting points of FRP and cylinder, and that the concentration of bubbles reduces breakdown voltage. Even if no boiling occurs, bubble produced by previous events and trapped near the interface causes the drastic reduction in breakdown voltage.

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Xe/Ne plasmas are important for plasma display panels and VUV light sources. However, reactions between electrons and excited particles in the mixtures are so complicated that influence of the reactions on the plasma properties is not understood well. In this work, taking account of reactions through which electrons are produced, such as cumulative and Penning ionization, and of transition between excited levels, the electron and excited particle properties in Xe/Ne plasmas are calculated using the Boltzmann equation. The ionization coefficient and electron drift velocity agreed with experimental data. The influence of laser absorption in Xe/Ne plasmas on the plasma properties is also discussed.

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Flow electrification characteristics of transformer oil were investigated by applying dc field and dc/ac composite field with both bare and covered electrode systems. In the case of bare electrode system, it was found that flow electrification characteristics were almost the same between positive and negative dc voltage application and negative charges were generated for both dc voltage and dc/ac composite voltage applications at high dc field region. In the case of covered electrode system, it was found that apparent flow electrification characteristics were different between positive and negative dc voltage applications. For the former, negative charges were generated at high dc field strength for both dc voltage and dc/ac composite voltage applications and for the latter, positive charges always generated for both dc voltage and dc/ac composite voltage applications. However, negative charge generation for positive voltage application was considered to be the influence of negative charge generation at bare part of covered electrode end and it was found that fundamental charge generation characteristics of covered electrode were an increase of positive charge generation by dc voltage application and positive charge generation was accelerated by superimposed ac field.

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The authors have studied on surface treatment of PTFE by a low pressure discharge.It is deduced that excited nitrogen molecules contribute to introduce polar'components on the surface.To confirm the speculation, we tried to change population of metastable nitrogen N2(A3Σ+ u) by quenching precursor N2 (B3IIg) with hydrogen molecule.The decrease of relaxation time which indicates a change of excited molecule and measured by emission spectroscopy using a time after glow method was obtained.
As a result, the relaxation times of N2 (B3IIg) and N2 (A3Σ+ u) decreased to 55% and 20% respectively, when mixing ratio of hydrogen was 3%. It was also deduced that hydrogen atom may take a part in a quenching process of N2 (A3Σ+ u).

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This paper presents a new method which visualizes the high-speed three-dimensional images of the pre-breakdown streamers in dielectric liquids. A new optical system, having two crossed light axes to observe the needle tip from different directions was designed. The shadowgraphic images from these two directions were combined through a beam splitter and focused on the photo-cathode of image converter camera. The photograph taken by this high-speed shadowgraph system was reconstructed to the three-dimensional images using an image scanner and a computer. Using this system, the growth and the decay processes of the streamer in cyclohexane was investigated.

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The paper describes characteristics of charging on a spacer which is shape of cylider and cone. It is known that charged spacer decreases insulation strength for polarity reversal. If charging on a spacer decreases, insulation strength of a spacer will increase for polarity reversal. To prevent charge accumulation, the effects of coating on spacers and electrodes were investigated. Metal sputtering coating on spacers obtained by glow discharge in a low pressure Ar gas decreases surface resistivity. So charge accumulated on a spacer is forced to leak. Dielectric coating on electrodes prevent electron emission from the negative electrode. These coatings prevent a spacer from charging. For a conical spacer, the effects of the normal component of electric field and the electric field line from a conductor were investigated. Combinig these methods, charge accumulation becomes to be minimized.

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This paper describes the effect of acetophenone on space charge formation and dc dielectric breakdown in polyethylene film. Impulse electric strength increased in the polarity where carrier injection was much larger in the acetophenone coated film. The increase of impulse electric strength is considered to be due to the homo space charge formed by the carrier injection from acetophenone coated side electrode. With increase of voltage rise rate, dc electric strength increased in the acetophenone coated film. Space charge was formed by the carrier injection from acetophenone or benzene coated side electrode. However the amount of space charge formed in benzene coated film after short-circuiting was smaller than that in acetophenone coated film. The dc electric strength of benzene coated film was almost as same as that of non coated film. From these results, it is considered that the decrease of do electric strength in acetophenone coated film is caused by both thermal breakdown process and accumulation of space charge

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We investigated partial discharge (PD) inception characteristics in composite insulation system of liquid nitrogen (LN2) and FRP with uniform electric field under thermal bubble condition. Experimental results revealed that PD inception field strength (PDIE) decreased as the bubble rate increased, and finally reduced down to the range of the breakdown strength in nitrogen gas. Moreover, we measured PD signal and observed the behavior of thermal bubbles. It was clarified that PD took place in thermal bubbles and the PD charge had close relationship to the size of thermal bubbles.

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The materials of particles suspending in mineral oil were investigated with ferrography. The effect of particles on partial discharge characteristics in oil immersed insulating system was investigated Various particles were evaluated in density, size shape and material. The dependence of charge quantity of partial discharge on the electric field of the oil gap and the phase of partial discharge initiation were measured. These characteristics were classified into some patterns.

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The observation technique for dc prebreakdown in dielectrics was established by the use of a long image guide scope as an image delay line. We observed prebreakdown images in a silicone-oil/PET-film composite under point-cathode/plane-anode. When the photographed duration of images was set below a few nanoseconds, a faint light emission appeared near the anode which was covered by PET film. This result supports the assumption that a complete breakdown is caused by a positive streamer which propagates from the film breakdown spot to the point-cathode.

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This paper describes deterioration phenomena and mechanisms on silicone rubber housing on the polymer insulators by corona discharge. The corona discharge was observed on the trunk portion of one of the three insulators tested in a fog chamber. Nitric acid and ozone generated by the corona discharge were recognized on that trunk portion, which was discolored whitish. The discolored area was expanded with test period. Surface conditions and mechanical properties of six kinds of the silicone rubber containing Alumina trihydrate (ATH) and Calcium carbonate (CaCO3) as fillers, were investigated after immersion in 1N nitric acid for 96 hours.
As a result, larger weight loss of test pieces containing some types of filer, such as CaCO3, was recognized. Cracks were observed on the surface of two specimens containing CaCO3 filler, and not observed on that not containing CaCO3 filler. This shows the cracks on the surface due to the corona discharges are depending on the kind of the filler. The careful survey on the deterioration of the housing rubber due to the corona discharge should be done when we select the housing materials for the polymer insulators.

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A Magneto-Impedance (MI) effect was found in CoSiB/Cu/CoSiB thin film elements fabricated by RF magnetron sputtering. In these elements very large impedance change ratios were achieved when an external magnetic field was applied to the longitudinal direction. These ratios were much higher than those of any other element with MI effect. Therefore, it is useful for the high resolution direction sensing .

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The effects of superposing a DC magnetic field on core loss of Mn-Zn ferrites were investigated. The core losses at 3MHz are reduced to 56% by superposing a magnetic field of 2kOe perpendicularly to the magnetic path. The reduction of the core losses is mainly resulting from the decrease of the residual loss, which occupies a large part of the core loss at 3MHz. The magnetization of the samples becomes about 80% of the saturation magnetization by applying a magnetic field of 2kOe perpendicularly to the magnetic path. The decrease of the residual losses can be explained by the change of magnetization process from the domain wall displacement to the rotation magnetization with increasing the superposed DC magnetic field.

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We have investigated a clock generated from a wobbled groove for higher density magneto-optical disk. Neither the readout signal nor the recording signal needs to include a clock element, because a clock derived from the wobbled groove is used for recording and readout. Therefore this clock does not depend on the quality of the readout signal. For this reason, a clock generated from the wobbled groove is effective for higher density recording.

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The Editorial Affairs Committee of the Institute of Electrical Engineers of Japan concluded that this letter should be retracted due to going against the rule for submission.

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The relationship between the piezoelectric properties of a cylindrical vibrator and performance of a vibratory gyroscope was examined using an equivalent circuit model. The temperature stability of the gyroscope depended mainly on temperature variation of mechanical quality factor Qm. The temperature dependence of Qm at-40°C-+80°C was investigated for the PbTiO3-PbZrO3Pb(Mn1/3Sb2/3)O3 and the binary PZT with acceptor additives. It was found that Qm peaked at a certain temperature. With decrease in Pb(Mn1 3Sb2/3)O3 or acceptor additives, the Qm peak shifted toward higher temperature and was reduced. The sharp transient variation in Qm with stepwise temperature change, which is termed as thermal shock in the present study, was exaggerated as temperature approached the Qm peak temperature. The thermal shock of Qm was mainly due to that of resonant resistance R1.

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Since a metal-base printed wiring board (PWB) with superior thermal conductivity has been widely used in power electronics products, high reliability is required at high electric field. Many reports have already covered surface' copper ionic migrations on PWBs which occur short-circuits on the board. The migration growing into the depth direction of a insulation layer has been clearly observed recently, and it is revealed that the growth depends on the ionic impurities of the resin.
We measured space charge behaviour in the insulation layer to know the relationship between the internal space charge and the ionic migration. The results suggest that internal negative charges are generated at high temperature with high humidity, and that a conductive region is formed near a copper electrode under dc electric field.

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Optical sensors with a Pockels crystal have been applied to the space charge measurement in electrical discharge. By using the techniques, the distribution of potential and electric field in surface discharge can be directly measured.
A new method for measuring the transient potential distribution of surface dishcharge is developed. The measuring system consists of a BGO Pockels crystal, an Ar ion laser, a beam expander, a streak camera and a CCD camera. The potential profile of a surface discharge along a linear path of 50mm in length is measured with high space and time resolution: 0.1mm and 2ns in minimum resolution. Electric fields near the tip of a negative surface streamer is over 30kV/cm. The developing velocity of the streamer initially reaches 10₈-10₉cm/s just after its inception and decreases down to 3×10₆ cm/s while propagating.

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New sensitive and quick response magnetic vector sensor is constituted using an amorphous-wire MI microsensor. A small sized three axial head is composed with three 2-mm long amorphous wires for detection of a small magnet position assuming a magnetic dipole. The sensor circuit is constructed using five inverters in a C-MOS IC chip; two inverters are for a multivibrator and three are for pulse current amplification. Some two-demensional movements of a small magnet were precisely detected comparing with the theoretical characteristics.

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Stable speed and torque control systems for IM are constructed using feedback of secondary current (I2) and secondary flux (Φ2) detected with MI micro field sensors. The secondary current is detected near the end of the motor shaft, while the secondary flux is near the motor body cover.

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