The Synthetic Aperture Radar (SAR) is expected to use various application for monitoring ground terrain. In 1990s, some space-borne SARs had been launched and showed their validity. These space-borne SARs had been functioned with single band and single polarization of about 30m resolution. On the other hand, airborne SAR and shuttle-borne SARs have conducted the advanced technologies, such as Interferometry and Polarimetry. As interferometry by space-borne-SAR were tried using the repeat-pass data, the functions will be included to the next generation SAR in spite of their limited conditions. Multi-polarization and multi-band observations were investigated by using combination of different satellite data. More sophisticated multi-band polarimetry has been investigated by airborne and Shuttle data, and also expected to be functioned on the next satellites. In this article, the recent and future trend of SAR system is overviewed.

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Fragmentation using pulsed power discharges in water seems one of promising methods for recycling of refuse circuit boards in electrical appliances. The Marx generator, which provides voltage of up to 480 kV and energy of up to 7.7 kJ, was employed to produce the electrical discharges in water. Refuse circuit boards were successfully broken into small pieces, and the circuit elements were separated from the boards after several tens of discharges. The amount of fragmentation is dependent on energy supplied from the Marx generator. Also the fracturing mechanism of circuit boards is described.

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This study was done for the purpose of achieving the higher removal rate of NO which was exhausted from a diesel engine. The validity of superimposing surface and silent discharge has been discussed. In this experiment, the reactor has four electrodes and consists of double coaxial cylinders. This discharge reactor generated multiple barrier discharges simultaneously in the same space. As a result, the NO removal rate for superimposing discharges mode is higher than that for single discharge mode at the same applied voltage, for the reason of spreading discharge generating area. The NO removal rate for superimposing discharges mode is also higher than that for single surface and silent discharge at the same discharge power. There are two reasons. First, the discharge area spread out into the gap space. Second, the electron is accelerated as the higher electric field.

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Magnetic reconnection of two merging toroids was used to accelerate and heat plasma particles in TS-3 device. External application of electric field by ohmic heating coil, which is located along the center axis of this device, to the the reconnection area was found useful to vary the ion speed from zero to 20km/sec and the ion heating from 10 to 90eV. The preferential ion acceleration / heating of reconnection enable us to produce new processing plasma with arbitrary ion temperature.

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A compact coplanar discharge ozonizer, of which electrodes were set on stacked and water-cooled aluminum die-cast plates, was developed. We obtained 1 kg/h ozone gas production and over 300 g/Nm³ (20wt%) saturation concentration of ozone at the pressure of 0.17 MPa. The efficiency was 100g/kWh at 180g/Nm³ when 93% oxygen contents (PSA gas) were used. Moreover, we clarified the effects of gas pressure, feed oxygen gas concentration and gas gap on the ozonizer.

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Recently, bulk-type high T_c superconductors having a characteristic of critical current density over 10⁴ A/cm² in liquid nitrogen temperature (77K) on 1T, can be produced. They are promising for many practical applications such as a magnetic bearing, a magnetic levitation, a flywheel, a magnetic shielding and others. In this research, we propose a magnetic circuit that is able to use for the magnetic shield of plural superconductors as an application of bulk-type high T_c superconductors. It is a closed magnetic circuit by means of a toroidal core. Characteristics of the magnetic circuit surrounded with superconductors are evaluated and the possibility is examined. As the magnetic circuit of the ferrite core is surrounded with superconductors, the magnetic flux is shielded even if it leaked from the ferrite core.

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With the development of miniaturization and high accumulation of electrical devices, the demand for insulation reliability of printed wiring boards that are installed in these electric and electronic parts is rising. In recent years, there is an increasing need for electrical devices in various complex field environments, which include magnetic field and electrical field. Accordingly, it is necessary to investigate the influence of complex fields on surface insulation breakdown of printed wiring board. In this paper, surface dielectric breakdown phenomena of contaminated printed wiring board under dc magnetic fields were investigated. We employed a dc magnetic field which was made at 100mT, 200mT, 300mT and then up to 500mT according to the laboratory target. The relationship between the number of electrolyte drops to insulation breakdown and relative angle between magnetic field and electrical field was examined. The relative angle between magnetic field and electrical field was 0, 90 and 270 degrees. Loading electrolyte drops between the two electrodes on the sample surface made humid conditions. The study revealed that leakage current increases with 270 degree and decreases with 90 degree under 300mT. The number of drops to breakdown decreased with 270 degree and increases with 90 degree with increasing magnetic fields. Discharge current characteristics under different magnetic field conditions were discussed by using a wavelet transform. The results indicated that the scintillation discharge energy showed a tendency toward increase with 270 degree and decrease with 90 degree when applied magnetic field was applied under 200mT. It is considered that the area of scintillation discharges occurrence was changed by application of electromagnetic force.

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These days, a quiet induction motor is strongly demanded. Electromagnetic factor is main cause of vibration and acoustic noise of small induction motor. Electromagnetic forces and magnetostrictive forces are considered of origin of electromagnetic vibration and noise. In this paper, magnetostrictive vibration of ring of electrical steel sheets was simulated by mechanical Finite Element Method. Magnetostriction was assumed as external forces and they were added at each node of meshed ring. Resonant frequency and mode of ring were calculated. In steel sheet ring excited by PWM voltage source inverter, frequency spectrum of vibration of ring was measured and compared with calculated results. It was confirmed that these procedure simulated magnetostriction behavior of electrical steel sheets. Furthermore, electromagnetic forces of small induction motor was calculated and compared with magnetostriction data. It became clear that electromagnetic vibration was affected by the magnetostriction of steel. These results will be useful to reduce the acoustic noise and to develop quiet motors.

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Surface modification of austenitic stainless steel by plasma-based ion implantation at elevated temperatures below 450 °C has been studied experimentally. The nitrogen depth profile at room temperature was similar to that obtained by TRIM code simulation, but the depth of nitrogen penetration increases with target temperature and reaches to a few µm at the treatment condition of 450 °C and the implantation time of 2 h. High-dose nitrogen implantation more than 10¹⁸ cm^-2 at the temperature above 350 °C results in the formation of expanded austenite phase (supersaturated f. c. c. phase) with little CrN precipitation, leading to remarkable enhancement of surface hardness without loss of corrosion resistance.

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Experiments were carried out to investigate the magnetic properties of Sm-Fe-Co-W-Cr system nitriding compounds with TbCu7-type structure. Sm₁₀(Fe_0.95Co_0.05)_89.7-xW_0.3Cr_x (x =0-0.7) alloy ribbons were prepared by the single roller rapid-quenching method, and the effects of alloy composition, and conditions of heat-treatment and nitrogenation, were examined with regards to their magnetic properties. The optimum preparation conditions of the compounds are as follows. Composition: {Sm₁₀(Fe_0.95Co_0.05)89.4W_0.3Cr_0.3}_85.0N_15.0, roller velocity: 50m/s, heat treatment: 675 °C×60 min in high-purity Ar gas, and nitriding condition: 420 °C×10 h in high-purity N₂ gas. Typical magnetic properties of the obtained compound powders areσ_r =123.7×10^-6 Wb·m/kg, H_cJ =706.0 kA/m, (BH)_max =139.4 kJ/m³ (17.4 MGOe), and T_c =508 °C. It was found that this sample was an exchange spring magnet from TEM photographs and recoil loops of the hysteresis curve. The value of (BH)_max for the compression molding isotropic bonded magnet prepared from the {Sm₁₀(Fe_0.95Co_0.05)_89.4W_0.3Cr_0.3}_85.0N_15.0 powder is 102.9 kJ/m³ (12.9 MGOe), when the density of bonded magnet is 6.1 Mg/m³. And the reversible temperature coefficient of J_r is α(J_r) =-0.07 %/°C, the temperature coefficient of H_cJ in the range from 25 °C to 125 °C obtained by a linear extrapolation is α(H_cJ) =-0.44 %/°C.

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This paper describes the results of time-frequency analysis of pressure waves caused by an electrical tree from a point electrode in a polyethylene subjected to ac voltages. Experiments were done in two cases. In the first case, the applied voltage was raised with 5 kV step at 5 minutes intervals. When a tree growth was started from the point electrode at 15kV, a high frequency pressure wave of about 8MHz was propagated from the tree. When the tree became large and more bushy, the high frequency pressure wave from the tree tip was followed by a lower frequency pressure wave from the tree stems. In the second case, a constant voltage of 25 kV was applied to the sample for 4 hours. Both the high frequency pressure wave and the following lower frequency pressure wave became larger at the first stage. However, the lower frequency pressure wave disappeared when the treeing degradation was attained to a critical level. This was because the carbonization of the tree wall was caused by the partial discharges. These results demonstrated that the time-frequency characteristics of the pressure waves were directly related to the partial discharge behavior in tree.

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Critical current properties of a YBCO coated conductor have been studied as a function of temperature and magnetic field under high magnetic fields up to 27T. The value of critical current, I_c, for 1cm wide tape was 85A at 77K in self-field. Detailed electric field vs. current density (E-J) characteristics were measured using 100 µm wide and 1mm long bridge patterned in the tape. Critical current densities, J_c, increased drastically at low temperature, e. g., J_c retained high value more than 0.4MA/cm² in 27T at 30K. Statistic parameters of the distribution of critical current density were extracted from the E-J characteristics. Then the pinning parameters were also determined by a scaling analysis. It had been confirmed that the calculation results agree well with measurements. The errors of J_c were held less than 10% at wide range of temperature and magnetic field.

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We have already reported on reconstructions of symmetrical and nonsymmmetrical electric field vector distribution using Kerr electrooptic effect and our unique reconstruction method modified computed tomography technique. This reconstruction technique gives electric field map, i. e., the strength and the direction of electric field vector, on any plane. If electric field distribution is obtained continuously with time, the measutement of electric field distribution is more useful. So we try time series measurement of electric field distribution.

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