The improved confinement has been recently observed in reversed-field pinch (RFP) plasmas using the pulsed poloidal current drive (PPCD) technique. The record highest τ_E =10 ms in RFP, has been achieved in the Madison Symmetric Torus using PPCD. The article explains general characteristics of RFP configuration, present status of confinement properties in RFPs under the standard operating conditions, and the principle and the main results of the PPCD experiments in RFPs. The improved confinement observed in PPCD provides a hint to obtain confinement improvement in magnetic confined fusion plasmas.

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Using a scanning Hall-sensor microscope with an active area 25µm×25µm, we measured the magnetic field distributions due to spontaneous magnetization on flat surfaces of low carbon steel SM400B with a yield point of 326N/mm² and a pulling strength of 469N/mm² under a static condition of terrestrial magnetism. Referring to the stress-strain curve, we applied a uniaxial stress to the sample and increased the stress level following the pre-scheduled experimental run, while measuring the magnetic profiles both for the stress state and after its release. The magnetic profile in the elastic stress nearly agrees with that after the release, and also agrees with that for the virgin state. However, as the stress level increases beyond the yield point and gives the residual strain after the stress release, there appear marked changes only in the results after the release compared to the others, which are attributed to the occurrence of Lüders bands. The positions with such changes in the magnetic profile move along a length direction of the sample, with extension of the Lüders bands to the whole part. The study shows the possibility to obtain information on a degree of strain progress in steels using magnetic images and to open up a practical way for non-destructive testing.

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One of industrial applications using pulsed power technologies is water treatment by streamer discharges. Streamer discharges in liquid generate high electric fields at the tip of streamers, as well as high-energy electrons, ozone, chemically active species, ultraviolet rays and shock waves. All of these may be utilized to sterilize microorganisms and to decompose molecules and materials. Large volume streamer discharges in water have been produced in order to realize industrial applications. A wire to plane electrode has been used. The influences of applied voltage, electrode separation, electrode geometry on streamer discharges in water are described.

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In order to prevent cardiac pacemakers from malfunctioning caused by electromagnetic (EM) wave, as one of the solutions to the problem of pacemaker malfunctioning, we can use a shielding material to decrease the EM wave intensity. For the effective suppression of the EM wave including a complicated enclosure or a human body, it is desirable to solve for the EM wave propagation by using numerical analysis. We introduce the transmission coefficient when an EM wave is incident into a multi-layered material with an arbitrary direction into the FDTD method. This realizes three-dimensional numerical analysis of a thin shielding material as a method to solve the EM wave transmission problem, which has been conventionally considered difficult. We use a phantom model, a dummy model of a cardiac pacemaker wearer, to analyze the EM wave shielding effectiveness of the shielding clothes. The analytical result agrees fairly well with the experimental result, which verifies the validity of the developed method. As for the effect of the aperture of the shielding clothes, the EM wave coming around from the apertures is found to be larger in amount than the EM wave transmitted through the clothes, which suggests that the aperture causes the SE to decrease largely.

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When a reduction of the waste and dissolution of the iron are carried out by using a high temperature medium, the radiant power emitted from it should be suppressed. On the contrary, it is useful for lighting and treatment of hazardous waste because it has a highly intense radiant energy. In this paper, we tried to calculate the number density and radiant power density under consideration of absorptive length emitted from atmospheric high temperature air mixed with tungsten vapor to know the basic theory about the effect of absorptive length for the development of the plasma treatment by using radiant power. The mixture ratio of W:N₂:O₂ is considered as 0, 2.5, 5%:80, 78, 76%:20, 19.5, 19%. The W is dominant in the radiant power density from 6, 000K to 10, 000K, which is calculated under consideration of absorptive length, L=0-1m. There is little absorption in this temperature range at the radiant power from W. The W is still dominant in the radiant power density even if under consideration with absorption.

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Equilibrium composition of high-temperature argon contaminated with fly-ash was theoretically obtained in consideration of phase transformation of fly-ash including some metals : Na, Mg, Al, K, Ca and Fe. The calculation was performed in a temperature range from 300 to 30000 K at a pressure of 0.1 MPa. The result revealed that as the temperature decreases, first, iron and aluminum in gas phase transform into condensed phase around 2000 K and that further reduction in the temperature causes calcium, magnesium, sodium and kalium to transform into condensed phase. From the obtained equilibrium composition, thermodynamic and transport properties were also derived.

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A known signal with random noise was analyzed by the theory of natural observation method, the just new technique of waveform analysis which noticed instantaneous characteristics of a signal. And, as the important characteristic of natural observation method, it is mentioned that this method is a real-time analysis. It was shown that the minute fluctuation signal in noise could detect clearly by natural observation transform. As an application example, an atmospheric electricity variation signal was analyzed by natural observation transform to clarify atmospheric electricity minute fluctuation signal with seismic wave propagation. As a result, it was shown that applying the natural observation method to observation signals of electromagnetic phenomenon with the earthquake was very useful.

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The purpose of this study is use of a three dimension (3D) measuring system that can automatically measure surface condition. We applied the WDT method that is one of the migration acceleration testing methods, to calculate the spatial variation of the electrodes of ion immigration on a glass epoxy printed wiring board. We also investigated the spatial shape and its variation of dendrite after short circuit for the cases of uniform and nonuniform field strength. As a result the phenomenon of immigration peak of separated matter from cathode to anode due to nonuniform was reported.The moving of the peak of the separated matter is supposed to be due to Cu(OH)₂'s change in accumulation status. Under the nonuniform and uniform situation, the behavior of separated matter will change after occurring short circuit between the electrodes. Therefore in order to avoid the progress of ion immigration, it is necessary to pay attention to the field strength in hardwiring and the curvature so that the field strength of the wiring pattern cannot be very high.

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The application possibility of an optical diagnosis was examined as simple and non-destructive technique for diagnosing the degree of thermal deterioration of molded transformers. The optical diagnosis is the technology of estimating the degree of the thermal deterioration of organic insulating resins from the reflective absorbance difference between two wavelengths containing near-infrared light, and life prediction is also possible by using chemical kinetics. First, as a result of investigating the correlation with the glass transition temperature related to the degree of the thermal deterioration of epoxy resins obtained from the dynamic viscoelastic characteristics and the reflective absorbance difference which was a diagnostic parameter, with the correlation coefficient of 0.9 or more it was theoretically judged that an optical diagnosis was applicable. Then, the diagnostic master curve was obtained from the accelerated thermal degradation examination using model samples. Next, the optical fiber cable and the probe of a portable optical diagnostic apparatus were improved using bundle fibers. As a result of evaluating six sets of operating transformers using the improved diagnostic apparatus, it has confirmed that the residual life could be estimated.

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The effects of temperature and electrode materials on space charge distributions of Linear Low-Density Polyethylene (LLDPE) polymerized with Ziegler catalyst were measured with the pulsed electro-acoustic (PEA) method. The thickness of a sample was about 100 µm. Positive space charge was dominant and it changed from homo to hetero space charge with temperature. The mobility of positive charge was 8.1×10^-15 m²V^-1s^-1 at 23°C and 1.0×10^-14 m²V^-1s^-1 at 30°C. On the other hand, the mobility of negative charge was 3.7×10^-15 m²V^-1s^-1 at 30°C. The positive space charge accumulating near the cathode enhanced the electron injection and, as a result, the charging current. The electrode materials used were aluminum and semi-conductive polymer. The space charge distribution and the charge injection depended on electrode conditions.

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The electrical breakdown of insulating materials is strongly affected by the formation of space charge in the bulk of materials. Many researchers have attempted to study the relationship between the space charge and the breakdown, but it has not been clarified yet. Although the pulsed electroacoustic (PEA) method has been widely used to observe the space charge profiles, few works show clear evidence of the influence of space charge on the breakdown. We have developed a new PEA system with an interval of sub-millisecond for observing the space charge distribution continuously. We succeeded to observe the space charge dynamics at the breakdown. In this paper we clarify the space charge behavior of LDPE films throughout the breakdown period.

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Polymer/polymer composite insulating systems have been widely used in high-voltage equipment and power cables. Such composite insulating systems always have an interface between two polymeric insulating materials. This interface may cause partial discharge and electrical treeing under high electric stresses. The electrical properties of this polymer/polymer interface have not yet been fully understood. It has been shown in previous studies that the propagation characteristics of electrical trees in polymer/polymer composite insulating materials considerably vary depending on the combination of polymers. It has also been suggested that the 3-dimensional tree simulation based on a DBM model considering growth probability is valid. In this study, we will investigate the 3-dimensional simulated tree considering a composite insulator interface based on a DBM model with growth probability.

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We have been studying the breakdown characteristics of the low-density polyethylene films (LDPE) caused by the partial discharge in the air gap. The purpose of this study is to clarify the effect of the sample temperature rise on breakdown mechanism of LDPE films under the repetition rectangle wave pulses. The large change appears in the pulse number up to breakdown (N_BD) near 250Hz (4ms) in the N_BD dependence of frequency. From these thermograph results, the temperature rises at the diameter 1mm under the electrode needle show in high frequency region. The sample temperature rise shows a correlation to the decrease of N_BD at a frequency. The surface and center temperature of sample are estimated using the heat equivalent circuit. The sample temperature increases by the heat pulses due to the discharge and it decreases by the heat constant (4ms) of this insulation system. If the repetition period of applied voltage is shorter than the heat constant (4ms), the sample temperature increases and the insulation system leads to breakdown at a few numbers of the applied pulses. From these results of the heat image, there are good agreements between the measured sample temperature rise and the estimation value by the heat equivalent circuit.

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Both electric and electronic apparatus have recently been improving in size and performance with increasing heat quantity from inside and have large and important subjects to diffuse the heat efficiently in their design. Although resins are mainly used for insulating materials, they have quite low thermal conductivities, usually 1 - 3 orders lower than those of ceramics and metals, to greatly prevent the heat from diffusing. In this paper, we suggested a novel strategy to afford high thermal conductive thermosetting resins and confirmed it. We used several kinds of epoxy resin monomers with mesogens, and cured them with aromatic diamine curing agents. The thermal conductivities of epoxy resins containing biphenyl groups were 0.22 - 0.33 W/m·K that were a maximum 1.7 times higher than the conventional epoxy resin of 0.19 W/m·K, but the values were considered to be a limit in this system. To further improve the thermal conductivity, we made epoxy resins from the monomers containing two phenyl benzoate groups as mesogens. These epoxy resins had quite excellent thermal conductivities of 0.85 - 0.96 W/m·K that would be highest of all isotropic insulating resins. We also carried out the confirmations of high order structures of resins by TEM observation.

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The pulsed electro-acoustic (PEA) method has been developed to measure space charge phenomena in dielectric materials. This method is widely used for the space charge measurement not only on polymer, but also on other dielectric materials. It is considered that the difference in acoustic characteristics of the electrode and specimen can make error in the space charge measurement. This error used to be examined by the theoretical formula on transmission and reflection using acoustic impedance. However, it was difficult to analyze simultaneously both of spatial and transient phenomena in generation and propagation of acoustic wave in the space charge measurement by this formula. In this paper, a new numerical model is proposed on the generation and propagation of acoustic wave in order to discuss the error factors in space charge measurement.

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The pulsed electro-acoustic (PEA) method has been developed to measure space charge phenomena in dielectric materials. This method is widely used for the space charge measurement not only on polymer, but also on other dielectric materials. It is considered that the difference of acoustic characteristics of each dielectric material can make measurement error in the 2-layer dielectric. This error used to be examined by the theoretical formula on transmission and reflection using acoustic impedance. However, it was difficult to analyze simultaneously both spatial and transient phenomena in generation and propagation of acoustic wave in the space charge measurement by this formula. So, we have proposed the numerical analysis model for generation and propagation of acoustic wave in order to discuss the error factors in space charge measurement. In this paper, the numerical analysis of experimental results in 2-layer dielectric has probed that the effects of the acoustic characteristics of electrode and 2-layer dielectric and the difference of dielectric constant of samples on the results of space charge measurement can be caused.

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The aim of this paper examine the realization of a single-layer type rubber sheet wave absorber at X and V bands using carbon micro-coils paid attention as a new industrial material. First, a complex permittivity of a dielectric material with carbon micro-coils was measured at X band under change of a content and a length of the carbon micro-coil. And then the new wave absorber at X band was fabricated based on these measured results. It was confirmed that the absorption of the absorber of 20dB or more was obtained under the frequency between 9.4 and 10.7GHz and the incident angle ranging from 0 to 40degrees. From the measured result of the absrober at V band, it was also shown that the millimeter-wave absorber with the absorption of 20dB or more was realized under the frequency between 56.0 and 60.0GHz and the incident angle ranging from 10 to 35degrees.

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