Phase conjugation has recently represented a new technique for optical measurement. However, the optical intensity of phase conjugate images is weak because the phase conjugate generation efficiency of photorefractive media is relatively low. In this paper, we have proposed a new method for enhancing the phase conjugate image, and have discussed the quality of output images both experimentally and theoretically, based on diffraction and propagation theories. The successful application of the presented method to surface defect detection demonstrates the effectiveness and applicability of this new technique in this field.

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In this paper, the theoretical and experimental examinations of a transparent wave absorber is carried out so as to realize the large absorption under TE and TM wave polarizations in X-band. The wave absorber is analyzed on the basic of an equivalent circuit using a distributed line. The proposed wave absorber is made of Glass and PC(Polycarbonate) plate which is deposited with ITO(Indium Tin Oxide). The calculation model is partly fabricated by the glass(glass-glass-glass) or PC(PC-glass-glass) for the surface of the absorber. The design charts including the variation of thickness and complex permittivity of used materials are also provided. It has been confirmed that the transparent wave absorber for TE and TM polarization waves is realized.

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Harmful organic air pollution matter influences ecology system. DIOXINS are main matters. The Ministry of Environment says the hazardous waste should be burned at 1, 200°C or more. This content means a benzen circle chlorine will be cut from the benzen circle. But it cann’t break benzen circles. Benzen circles can recombine chlorines. Therefore benzen circles should be broken. This research tried to destroy benzen circles by arc. In the first experiment biphenyl was treated by arc. In the second experiment a benzen gas and a chlorobenzen gas were treated by arc. The first one broke the biphenyl by 99.9965%. In the second the benzen gas was treated by 45.92% and the chlorobenzen gas by 89.95%.

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This paper describes partial discharge (PD) characteristics in such a defect shaped as a needle-like void or a foil-like crack in epoxy resin filled with air of SF₆. AC voltage up to about 6 kV/mm as field strength were applied. PD appears at a lower electric field and discharge quantity is higher for a deeper and wider defect. PD quantity mainly depends on the depth and width of a defect, almost independently of its cross sectional area. SF₆-filled defects show the PD characteristics similar to those of gaseous discharge in a gas gap. These results were compared with the numerical calculation by the boundary element method.

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This paper describes the degradation process caused by partial discharge (PD) inside a defect filled with air or SF₆ in epoxy resin. In the case of air at atmospheric pressure, PD shows a significant change with voltage application from initial PD patterns to the occurrence of treeing, and ultimately to puncture. On the other hand, SF₆-filled cracks generate PD moving from place to place inside a crack with a nearly constant charge. The V-t characteristics have been measured and compared between needle-like and foil-like defects as well as between filled gas of air and SF₆.

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The cylindrical cavity resonator method based on the perturbation method, is a popular method for measuring the complex permittivity and the complex permeability by using perturbation formula. It is assumed here that the electromagnetic field in the resonator has no change distribution before and after we have inserted the sample. It is, however, well known that the measurement error increases, when a sample with large size, high complex permittivity and high complex permeability is chosen. In this paper, we calculate the resonant frequency and quality factor using finite difference time domain (FDTD) method with rotationally symmetric geometries on condition that a circular rod sample is inserted into the TM₀₁₀ mode cylindrical cavity resonator. Consequently, the measurement error included in the real and imaginary parts of the complex permittivity was estimated quantitatively by the perturbation formula under the variation of the size and complex permittivity of the sample.

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The measurements and the comparative study have been performed on electron density profiles focusing on the electron density gradient near the magnetic separatrix in various kinds of plasma confinements such as ST, spheromak and RFP in the TS-3 device. A CO₂ laser interferometer using a glass tube to clear the path for the laser was introduced to measure the electron density profile with time resolution. It was shown that ST with a high q value at the plasma edge (q:safety factor) has a larger electron density gradient than that of low q plasma confinements such as spheromak and RFP. Especially, the ST with edge q value greater than about 2 showed a large electron density gradient at the edge. The idea that the j×B force profile of the higher q ST could sustain the higher thermal pressure supports these results.

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The plasma merging is expected as one of innovative methods of initial heating for spherical tokamak (ST) plasmas. Detailed measurements of time evolution of electron density profiles during plasma merging processes in TS-3 device were performed using CO₂ laser interferometer with time and spatial resolution. The experimental observations show that the electrons are confined inside the magnetic separatrix firmly in the moving plasma during the merging process. It has been found that the plasma particles are not outpoured from confinement region throughout the magnetic reconnection event though the magnetic structure of plasma is changed drastically. Furthermore, it is shown that the electron density profile becomes hollow after the plasma merging. These results indicate that the plasma merging is effective not only as a method of initial heating of ST but also as a way for a particle supply to ST.

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Capacitance C and dielectric dissipation factor tan δ of a water-treed XLPE sheet sample have been measured under the application of 100 V or 1 kV at 60 Hz. The values of C and tan δ at 1 kV are much larger than those at 100 V. The value of tan δ gradually decreases with the exposure time to the voltage of 1 kV. On the other hand, C is almost constant for the exposure time. The results have been discussed based on a model where filling of water into channels interconnecting voids is taken into account. It has been found that the increase of C and tan δ is caused by the growth of water-filled channel region by the application of voltage. The gradual decrease in tan δ with the exposure time is explained by an increase in the conductivity of water-filled channel region through which the relaxation time shifts to higher frequencies.

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We constructed a scanning Hall-sensor microscope with an active area of 50μm×50μm, which can be served as a simple tool for non-destructive evaluation for 1m lengths of Ag-sheathed Bi2223 tapes usable at 77 K. Using this equipment, we measured two-dimensional magnetic field profiles due to trapped currents in a remanent state on surfaces of the tapes with the mono-, 19-, 37- and 61-filaments of Bi2223 superconductor, and compared with the results for the distribution of critical currents (Ic) along a length direction. Except for the case of 19 filaments, all tapes were prepared by the conventional powder-in-tube method. In the case of 19 filaments, however, another kind of the tape was prepared by covering the filaments with insulating barriers from a practical point of view for AC use, and the result was compared with that for the conventional tape without barriers. The monofilamentary tape shows the inhomogeneity in magnetic field profile due to weak links, which seems to be consistent with the Ic distribution along a length direction. An increase in filament number homogenizes both the magnetic field profile and the Ic distribution, but the tape with insulating barriers still remains the inhomogeneity in both the magnetic field profile and the Ic distribution. The respective tapes show a correlation between the magnetic field profile and the Ic distribution along a length direction, independent of the number of filaments and also of whether or not insulating barriers were introduced.

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The possibility whether measurement of residual charge is usable as a tool to detect water trees in crosslinked polyethylene is discussed. The results obtained are summarized as follows. (1) Residual charge was not measured in a sheet sample because of its small electrode area. (2) Residual charge was detected in a cable sample. (3) A clear frequency dependence of the residual charge was not observed. A model of the residual charge measurement is proposed, where the charges accumulated in a water tree are oscillated by ac electric field and are diffused through the water tree path with a high conductivity.

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In Bi-2223 oxide superconductor it is important to enhance critical current density J_c at 77K for superconducting applications. Problems of weak-links among grains must be dissolved to improve J_c. For this reason high purity and also better grain alignment of Bi-2223 phase are necessary. We sintered Bi-2223 bulk at partial-melting temperature and attempted to obtain pure and well-aligned Bi-2223 phase. As varying the partial-melting state by starting cation ratio and oxygen partial pressure on sintering, sintering temperature dependences of volume fraction V_f and degree of grain alignment F for Bi-2223 phase were discussed. Compare with samples prepared by stoichiometric cation ratio as ST, samples with the ratio (Bi, Pb): Sr:Ca:Cu=(1.83, 0.34):1.91:2.03:3.06 as CL showed wide temperature range of partial melting at 7.7% oxygen partial pressure and had larger V_f at the almost same range. Also maximum V_f was obtained at near a temperature, at which gradient variance on DTA curve by partial-melting becomes maximum. Degree of grain alignment F increased with sintering temperature at the range of 820∼860°C and became larger at high temperature side of partial melting range. F and V_f of the sample with the cation ratio CL sintered in air were 47% and 82% respectively. Therefore it was found that sintering method using partial-melting is effective for realization of high volume fraction and grain alignment of Bi-2223 phase.

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The semiconducting glaze insulator shows excellent performance under contaminated conditions. Basic characteristics of the semiconducting glaze for mass-production were reported in the previous report. The 2nd report describes its long-term characteristics and study results on how to improve them. The semiconducting glaze insulator sometimes suffers from surface roughening for longterm use under voltage application, which is called electrolytic corrosion. From the test results, the electrolytic corrosion was considered due to small discharge around wetted contaminants on the surface and thermal stress caused by leakage current flowing into the glaze. In addition, it was confirmed that the electrolytic corrosion could be improved by increasing amount of metal oxides (SnO₂ and Sb₂O₃) in the semiconducting glaze and by adding small amount of the other metal oxide (Nb₂O₅). The suspension insulators produced with the improved semiconducting glaze were subjected to the acceleration laboratory test. The test results showed good performance within permissible increase in impedance and no serious damage of the glaze. The laboratory test results were compared with the field test data and it was concluded that the said semiconducting glaze insulators could have sufficient lifetime.

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Electroluminescent device (ELD) using nanocrystalline silicon (nc-Si) was fabricated by annealing of co-sputtering of Si and silicon dioxide (SiO₂) targets and subsequently hydrofluoric (HF) acid solution treatment. The HF treatment made effective electron injection into the nc-Si and the resultant decrease in resistance of the ELD. The HF treatment also made P_b-center, which act as a role of non-radiative recombination center, compensate with hydrogen atoms. From above effects of the HF treatment, the HF-treated ELD emits high efficiency red light with external quantum efficiency of 0.35% under low operating voltage of +4.5 V. Moreover, intensity of the red light emission from the HF-treated ELD is stable for continuous operation above 10 days (operating time of 15000 min).

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High-T_c superconductors Bi₂Sr₂CaCu₂O_y, with Li additions, were prepared by melt-casting process (MCP). MCP samples with nominal composition of Bi₂Sr₂CaCu₂Li_xO_y(0≤X≤0.4) were annealed at temperatures ranging 700°C and 850°C in air, and rapidly quenched into liquid nitrogen. Measurements of electrical resistance as a function of temperature for MCP samples have shown sharp drops associated with the onset of ietragranular superconductivity. The enhancement of transport properties is due to the addition of lithium carbonate(Li₂CO₃). The maximum critical temperature occurs for the MCP sample annealed at 800°C with X=0.2.

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