Generation and sustainment of rf induction thermal plasmas in atmospheric pressure range require a high voltage in the initial startup phase and a high rf power during the steady state sustainment phase. The high rf electrostatic filed induced between induction coil conductor wound around a glass discharge tube generates surface electrostatic discharges in which the discharge current flows through the dielectric glass tube. After several hundreds microseconds the electrostatic discharges grow sufficiently to transfer to a volumetric electromagnetic discharge which is maintained by the inductive electric field. During this discharge mode transition, the loading impedance of the induction coil changes significantly. This loading impedance change of the induction coil leads a deviation from a series resonance condition of the LCR output circuit including the induction coil, which strongly affects the output characteristics of a semiconductor rf inverter power supply. In this paper transient response of the induction coil impedance in the initial startup phase of the rf thermal plasma generation is studied experimentally. Dynamic interactions of the rf inverter power supply with generated rf plasmas are also investigated and strong deterioration of the inverter output efficiency is found experimentally. Preliminary frequency tracking experiments show a successful improvement of the inverter output efficiency and absorbed rf power in the generated plasma.

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Electrostatics precipitators (ESP) are used extensively for decontaminating industrial contaminated gas and for air cleaning of a highway tunnel. The collection efficiency in gas flow velocity 7m/s is usually over 80% as the performance of ESP for the tunnel. Recently, high performance ESP is used. Its gas flow velocity is 9m/s and the collection efficiency is higher than 90%. However, the collection efficiency for the size of an aggregating particle decreases due to particle re-entrainment. Suspended aggregating particles decrease a visibility index. When their particles deposit on cameras, lamp covers, walls, etc., it becomes difficult to distinguish sight at observation points of the tunnel. Therefore, it is very important to prevent particle re-entrainment. In this work, we focus on controlling re-entrainment phenomena and improving collection efficiency. The effect of the applied voltage waveform of the collecting section in the two-stage type ESP has been investigated experimentally. Consequently, when rectangular voltage is compared with DC voltage, the collection efficiency by rectangular voltage is about 10% higher than that by DC voltage. When rectangular voltage is applied, particles deposited on the downstream surface of the wall decrease and the wall contamination is improved.

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We investigated performances of triggered and guided discharges in a 1-m long gap with negative and positive voltages using femtosecond-terawatt-laser-induced plasma filaments. Discharge guiding mainly occurred from the negative electrode in both cases of negative and positive discharges. Photos taken when a breakdown didn't occur show that a leader generated from the negative electrode and that from a laser-induced plasma filament combined each other. Laser-induced breakdown occurred even when the high voltage electrode was separated from the laser beam by up to 10 cm. These experiments also show that the breakdown induced by the plasma filament needs a certain guide length.

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This paper describes a measurement method for potential distribution generated by the voltage in a PWB. In this paper, 2D potential distribution generated by the voltage applied to printed wiring is measured with high spatial resolution using electro-optic (EO) effect of a BSO single crystal, a CCD camera. In order to measure potential distribution with high resolution, it is important to control the diffusion of surface charge distribution on a insulating EO device. To realize this, the measurement method is improved by applying AC voltage whose period is shorter than the time constant of diffusion. Furthermore, to improve the sensitivity and the linearity of characteristic curve between applied AC voltage and the intensity of output light, incident light is polarized as ellipse polarization by using 1/4waveplate. Incident pulse light is synchronized with each polarity of the AC voltage, and the output light is imaged by the CCD camera. Each polarity's modulation component is synthesized by image processing. This paper describes this method, and the result that the sensitivity improved.

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It is important to measure residual magnetization value of satellite instruments before launch because that the residual magnetization may cause to perturb an attitude of satellite and give much magnetic offset to onboard instruments. In recent pre-launch EMC tests, strict obligation is required on the remaining magnetism for deep space investigation or magnetic filed observation satellites. The measurement of residual magnetization in a magnetic shield room was a hard work because of consuming much time and manpower.
We have developed a method for measuring residual magnetization of satellite instruments used by two fluxgate magnetometers and 2-axis rotational table. The resolution of measuring magnetic moment is ±0.01 [Am²] and it takes 2 minutes of detecting time for an instrument. We can measure some satellite instruments with a high accuracy of more than one order on magnetic moment and with a time consumption of less than 1/10 on working time as compared with that of past EMC test. This accuracy and the real timed data acquisition are great improved and this method is useful for pre-launch tests.

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In this paper, the FDTD method has been applied to analyze the site attenuation of an anechoic chamber at 100 MHz or less where the ray tracing method is not applicable. To calculate site attenuation by a personal computer, the dipole antenna and the EM absorber were modeled by the large-cell which was larger than the diameter of antenna element and the thickness of EM absorber. The equivalent diameter of the antenna element was determined so that the calculated site attenuation in free space agreed with that by the method of moment, and the equivalent dielectric constant and permeability of the absorber were determined so that the reflection coefficient agreed with that by the transmission theory. The site attenuation of the compact anechoic chamber was calculated for frequencies from 30 MHz to 100 MHz and compared with the measured one to confirm the validity of the proposed modeling method. The results indicated that the deviation between the calculated values and the measured ones was within 2 dB.

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We measured the degree of unbalance to ground and the leaked electric field from a power line in the high frequency band, to obtain its radiation emission characteristics. We also constructed a calculation model for the power line and compared the results from this with measured values. It was constructed using four port network theory, which has the circuit constant as the chain matrix of the distributed constant on a transmission line. The structural unbalance of a power line was imitated by adjusting the additive distributed constant of a power line so that the calculated and measured values agreed with each other for Transverse Conversion Transfer Loss (TCTL) in the no grounding model. In calculating the leaked electric field, we assumed the power line was a conductor flowing common mode current, and calculated the leaked electric field by integrating radiated emissions from the common mode current in each minute section at the observation point. The calculated value for TCTL was mostly in agreement with the measured value confirming the validity of the calculation methods for TCTL. The leaked electric field increased about 20dB by grounding one wire on the line. The calculated value for the leaked electric field with no grounding almost agreed with the measured one. In near and far grounding, the calculated value almost agreed with the one measured.

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We have been studying a multi-point charge measurement method using an electrostatic probe. In this technique, charge densities x must be estimated from the probe outputs b by an inverse calculation based on an equation Ax = b. The matrix A is obtained by applying a numerical field calculation technique. When the matrix A is in ill-condition, the solution often makes no sense, including extremely large errors. Therefore, we apply the Regularized Least Squares Method (RLS) with a penalty term to perform the inverse calculation stably for the ill-conditioned matrix. The penalty term imposes some constraints on the solutions.
In this paper, firstly, we have analyzed the accuracy of the charge distribution estimated by the inverse calculation. Although the perturbation bound of the solution errors has been already proposed for the Least Squares Method, it has not yet been given for the RLS. We have derived the equations that express the perturbation bound of the solution errors in applying the RLS to evaluate the estimation accuracy. Secondly, we have applied the above equations to an experimental result for a cylindrical dielectric solid, and estimated the charge distribution represented by 10140 unknowns. We have utilized an iteration technique and the symmetric configuration of the measured arrangement so as to reduce the amount of operations and memory capacity required for the inverse calculation.

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Despite of extensive researches conducted so far on the surface flashover phenomena in vacuum, the knowledge about surface charging under AC voltage excitation is limited. This paper focuses on charging process and characteristics of the accumulated charge on an insulating spacer exposed to AC voltage in vacuum. We employed an electrostatic probe technique that allowed online measurement of electric field on the grounded electrode and thus the surface charge. The insulator specimen was made of PMMA, and was in the shape of a right cylinder with 10 mm in thickness. The side surface was polished to have an average roughness of sub microns, or roughened up to several microns. As a result, we have found that the charging is characterized by three different states; Initiation, Quasi-stable state and Stable state. With comparatively smooth surface the charging takes place at every voltage phase, accompanied by current pulses, when the applied voltage peak exceeds several kilo volts. The charge, of which polarity is positive irrespective of the voltage phase, increases in amount for a short period of time. After passing the period, the charging reaches Quasi-stable state, where the probe signal consists of DC and periodical components. Within several minutes after the Quasi-stable state has been established the charging turns into Stable state, where the periodical component disappears and only the DC component remains. At the Stable state current pulses also disappears, meaning that the charging activities are suspended until higher voltages are applied. At near the triple junction on the grounded electrode, the DC component almost equals to or can be higher than the applied one. Correspondingly to our previous results with DC voltage excitations, roughening the insulator surface results in decrease in charge magnitude, thus increase in the insulation strength.

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The rust is generated on a metal electrode when the oxygen-fed ozonizer with a short gap is driven in a high discharge density. The ozonizer consists of a metal electrode and glass one, and the rust on a metal electrode disperses to a glass electrode. We found that the ozone yield efficiency improves about 20% in some condition when the rust adheres on the glass electrode. The rust is the oxidized chemical compounds of Fe, Ni, Cr, Mo which are a materials of a metal electrode(SUS304). We examined the characteristics of ozone generation using the glass electrode painting various kinds of the oxidized chemical compounds including above materials. As a result, the same characteristic in case of generation of rust is obtained when CrO₃ is painted. We conclude that the change of characteristics is caused by the Cr in the rust.

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The gas temperature in ozonizer affects the characteristics of the ozone generation greatly. We examined the gas temperature at outlet of discharge space theoretically and experimentally using the tubular type ozonizer by which both electrodes are cooled. It is clear that the gas temperature obtained from the experiments is about 60% of one from calculation, and the difference of gas temperature between experiment and calculation increases as the gas pressure and the discharge gap length are larger. It is considered that these differences are due to the non-homogeneity of discharge power in gap. We obtain the experimental equation of gas temperature as the function of gap length, gas pressure, discharge power density and cooling water temperature.

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Bow-tie tree(BTT) generated from contaminant, e.g., metal, carbon, amber(over cured resin) or void is a deterioration factor of XLPE cable. In particular, BTT in contact with inner or outer semi-conductive shield could significantly lower residual AC breakdown voltage of HV power cable. To evaluate influence of water and ion diffusion on generation and progress of BTT, we investigated relationship between water content of XLPE and the generation of BTT by various accelerated aging. The number of BTT in XLPE samples with accelerated aging under open condition, involving evaporation of water in which samples were immersed, was very large compared with closed condition. Furthermore, when samples were intermittently immersed in water, the number of BTT in samples was large compared with samples immersed continuously. In these experiments the generation of BTT seemed to have nothing to do with changes in water content before and after accelerated aging. Therefore, it was suggested that diffusion of ions rather than water in XLPE played an important role in the generation of BTT.

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The alternating magnetic flux leakage testing is used for the detection of cracks on the surface in steel plate. Generally, the permeability and conductivity in steel are non-uniform. As a result, the detection signal of the electromagnetic inspection method may not be uniform. In this paper, an efficient detecting technique of plural cracks using the amplitude and phase angle of flux density of horizontal (x) coil is proposed. The detecting property of plural cracks in non-uniform steel is investigated using 3-D edge-based hexahedral FEM considering the hysteresis and the non-uniformity of permeability and conductivity in steel. The possibility of the detection of plural cracks using the amplitude and phase angle of the horizontal (x) component is illustrated.

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In the case of an optical recording disk, system information such as address is recorded on a disk as an emboss signal, like wobble signal. Since this wobble signal has a polarized component, in a system using polarization property as is used in magnetic optical disks, if signals are recorded in the wobbled area, RF signal may be subject to modulation caused by the polarized component. Up until now, in order to ensure the quality of recorded signal, different ways have been adopted, such as separating the wobbled area and recording area or separating the frequency bands for wobble signal and recorded signal. For the purpose of improving efficiency of recorded signal within an optical recording disk and increasing recording density, the possibility of increasing density by recording RF signal in a wobble track was explored. The results show that when using an optical system with a laser spot diameter of 0.96 μm and applying the NRZIplus modulation method for wobble signal, it is possible to do wobble recording at a recording line density of 0.96 μm/bit, considering the limit of read-out resolution of the read-out system.

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It is well known that a lot of neutral active species such as N atom and metastable molecules are generated by discharge. It is also well known that some of those species have a long life time and have a high potential energy. Accordingly various influences on dielectric properties are observed in the case that neutral active species remain and accumulate in space. This letter presents that neutral active species make the breakdown probability and its time lag decrease in nitrogen gas.

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This paper describes the application of Co-based amorphous alloy ribbons with various thicknesses to a noise filter in the MHz-GHz frequency range. The impedance per unit volume increased with increasing thickness in as-prepared ribbons. In contrast, the noise attenuation per unit volume and impedance per unit volume increased with decreasing ribbon thickness in annealed ribbons. We considered that when the ribbon was thin, annealing had a marked stress relief effect. In contrast, when the ribbon was thick, the initial internal stress was small and annealing had little effect.

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The coefficient of viscosity η is one of the major parameters to govern the movement of particles in alumina/epoxy mixtures during the centrifugal process. During the centrifugal process, the particle fraction and corresponding values of η at a certain point varies spatiotemporally. In the present contribution, theoretical consideration to explain dependency of η_b of bimodal alumina/epoxy mixtures on particle fractions is conducted. It is found that η_b can be estimated as a function of two η's obtained for the unimodal mixtures that contain the fine and coarse particles, respectively. A modification about the definition of the coarse particle fraction from the conventional method was successfully introduced, resulting in better approximation of η_b under the conditions of high particle fractions.

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This paper proposes a simple mathematical B-H loop model capable of quantitatively representing B-H loops of various sizes, using only 11 parameters. In the proposed model, the differential permeability is represented as a normal distribution function for the magnetic flux density. The coefficients of the function are approximated as quadratic and cubic curves with respect to the applied maximum magnetic flux density. The B-H loops of a sample Ni-Zn ferrite core, in sizes ranging from small to large, are successfully demonstrated by using the proposed model with a circuit simulator.

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