Pulsed power technology has been used in pulsed wire discharge and pulsed ion-beam evaporation for preparation of various thin films and nanosized powders. Recently, these methods enabled us to synthesize novel materials including nanosized powders of Si and Ni-Fe-O which exhibited blue light emission in air for more than a year and abnormal resistivity change, respectively. In this review, we describe details of the synthesis of the materials and focus on the uniqueness of these methods.

抄録全体を表示

The effects of tensile stress and strain on magnetization and magnetic domains in silicon steel sheets were investigated. The magnetization of elastic deformation regions decreased with increase of strain and the strain-magnetization properties of plastic deformation regions under stress showed peculiar characteristics. The magnetization increased with decreasing strain. We observed Lancet and other domains in a sample, especially around the boundary of crystal, after removing stress applied to a plastic deformation region. This phenomenon can be explained by changes in the domain structures, which were partly observed. This results obtained in this investigation can be applied to the nondestructive detection of fatigue in metallic magnetic materials.

抄録全体を表示

Magnetostriction was measured in a 3% Si-Fe grain oriented single sheet of 100×500mm under non-uniform temperature distribution of 5-10°C difference in the sheet. The temperature difference of 0.2°C/mm in the sheet increased magnetostriction three to four times larger than that of uniformly elevated temperature. Compressive stress induced by non-uniform thermal expansion enhances magnetostriction tremendously that is analyzed by experiment and computer simulation.

抄録全体を表示

Power losses in electrical steel sheets have been measured with magnetic-flux wave forms composed of the superimposition of 50 Hz sinusoidal and one of its odd higher harmonics of low order: the 3rd, 5th, 7th, and 9th. We have discussed the dependence of losses on superimposing phase and the loss superimposing effect, which means the ratio of losses between the fundamental and the harmonic component.

抄録全体を表示

This paper has investigated iron loss characteristics of amorphous magnetic materials under the non-sinusoidal wave magnetic flux. The iron loss characteristics of amorphous magnetic materials have been compared with grain-oriented magnetic steel sheet. The measurement of the iron loss has been carried out with SST. As a result, it is found that the increase ratio of the iron loss of the amorphous magnetic material under the excitation of distorted waveforms and symmetric PWM-waveforms is less than that of the grain-oriented magnetic steel sheet. On the other hand, it is found that the increase ratio of the iron loss of the amorphous magnetic material under the excitation of asymmetric PWM-waveforms is larger than that of the grain-oriented magnetic steel sheet.

抄録全体を表示

In this research, a measurement technique of magnetostriction with laser displacement meter on the market has been compared with the other optical method using laser Doppler vibrometer. It examined whether or not it was possible for the laser displacement meter to measure. The specimen is fixed in one end of the flux density uniform area and make the other end freedom. It is shown that the λp-p characteristic and λ waveforms measured by laser displacement meter have good agreement with the other method.

抄録全体を表示

The effects of short circuits between laminated steels in lamination cores, caused by clinching or welding, are discussed in this paper. A short circuit between laminated steels increase a core loss. A short-circuit resistance r₁due to clinching is more affected by contact resistance than by the electrical resistivity of core material and it is inversely as the third order of the thickness of core material. In the case of welding, r₁ is influenced by the resistivity of core material and it is inversely as the second order of core material thickness, if the width and depth of welding, such as laser welding, are proportional to the thickness. The short-circuit resistance of welding is generally smaller than that of clinching, and then the short-circuit loss caused by welded core will be larger than that by clinching. According to theoretical calculation, the short-circuit losses are possibly larger than iron losses due to core materials in actual cores and more than two times in the case of segment motor cores, because the number of clinch-ing or welding is large. As the method to reduce the short-circuit losses or to avoid the short circuits, it is necessary to use thin electrical steel sheets with high electrical resistivity as core materials, or to fix laminated steels by means of adhesion or molding.

抄録全体を表示

The magnetic properties of the magnetic core under ac excition are dependent on the magnetizing conditions. In order to obtain reproducible magnetic properties, it is necessary to use measurement circuit which satisfy magnetizing conditions. This paper describes the circuit conditions for measurement of magnetic properties of the magnetic core under sinusoidal flux wave-form condition considering nonlinearity of the magnetization characteristics and eddy current. In carrying out the analysis, harmonic balance method in which magnetization characteristics are approximated by a Fourier-series and it is assumed that the eddy current factor is proportional to the rate of change of the flux was adopted. From the results obtaind by numerical analysis, the influence of circuit constants and magnetization characteristics for the flux wave-form is shown. Circuit conditions which satisfy sinusoidal flux wave-form condition are also obtained. The results of the analysis were confirmed by the experiments.

抄録全体を表示

The geometry, pressure and power coupling conditions of most plasma sources for semiconductor manufacturing lend themselves to particle simulations such as Monte Carlo simulations(here after MCS). Usually the kinetics solvers are coupled to solvers for Poisson’s Equation. MCS usually employ averaging over discrete regions of parameter space. When the number of discrete regions is increased, two problems result: one is the instability of the solution because of a statistical change and the other is the increase of the calculation time. Ventzek and Kitamori (J. Appl. Phys., vol. 75, pp. 3785-3788, 1994) proposed Legendre Polynomial Weighted Sampling (here after LPWS) which aimed to optimize sampling statistics with an economy of particles. In this paper, we characterize an Ar RF parallel plate discharge using a MCS employing LPWS based on the Date’s model (T. IEE Japan, 111-A, 11, pp. 962-972, 1991). The method is shown to replicate the behavior of RF discharges with high fidelity.

抄録全体を表示

The Electro-Magnetically Accelerated Plasma Spraying (EMAPS) was developed and applied to the deposition of boron carbide (B₄C) powder, which was accelerated and heated by the pulsed high current arc plasma in a coaxial plasma gun and sprayed on the substrate. Dense deposit of crystalline B₄C with Vickers hardness of 2600 kgf/mm² was obtained on the mirror polished SUS304 substrates with high adhesion. It was supposed that the deposit was formed by the impact of B₄C particles with the velocity of more than 2.5 km/s for the powder less than 10 µm in diameter and about 2 km/s for 30±10 µm.

抄録全体を表示

This article describes the influences of circuit inductance on alumina (Al₂O₃) tile joining using explosive titanium foil. Several kAs pulse current was supplied from 8.28 µF storage capacitor to the 50 µm thickness titanium foil which was sandwiched between the Al₂O₃ tiles with pressure of 8.3 MPa. The temperature of the foil was rapidly increased owing to ohmic heating with the large current, and then the foil was liquefied and vaporized. The Al₂O₃ tiles were successfully bonded when the input energy to the titanium foil was higher than the energy required for the foil vaporization. The bonding strength increases with increasing the energy input to the foil. However, the foil explosion cracked the tiles when the input energy exceeds a critical value. Increasing the circuit inductance from 1.13 µH to 64.8 µH, the critical energy of tile cracking increase from 160 J to 507 J, respectively. the maximum bonding strength of 330 kg was obtained when the circuit inductance was 21.8 µH. An investigation of the interfacial structure of the joints using electron probe micro-analysis revealed that distinct reaction areas existed in the interlayer.

抄録全体を表示

In order to reduce fluctuations of lamp power and maintain constant power in a continuous dimmer circuit in high-pressure mercury discharge lamps, the authors propose to add a supplementary control circuit on the continuous dimmer circuit. This supplementary control circuit is equipped with a photosensor to control the levels of light. Moreover, we connect the by-pass circuit to the tap of ballast which is close to the power source side. The addition of a by-pass circuit, in which circuit constant is adjusted to reasonable value, make it possible to improve power factor and reduce harmonic current.

抄録全体を表示

The decomposition rate of benzene and its by-products are estimated a barrier discharge with 0% to 4% oxygen in nitrogen. The decomposition rate of benzene decreases with increasing amount of oxygen. By the checking of mass balances of carbon and hydrogen atoms, it is found that benzene is converted into carbon oxide, carbon dioxide and water in the presence of a sufficient amount of oxygen for reaction. As a result of the estimation of the amounts of ozone and oxides, the nitrogen atom is found to be the main reactor in the decomposition of benzene, after which, oxygen atoms react with the decomposed benzene.

抄録全体を表示

The various harmonics in a power system are typically measured with a heterodyne receiver if we are using analog methods, or by a FFT (Fast Fourier Transform) when digital methods are being used. The harmonics can be analysed over a wide range of frequencies by means of these methods. However, since the circuit configurations that are needed can become very complicated, the equipment tends to be too expensive for practical use. This paper presents a novel harmonic meter using a PLL (Phase Locked Loop) circuit. By means of the phase feedback loop, a reference sinusoidal wave is locked on to the input signal along with the harmonics that we wish to measure, and hence the corresponding harmonic component in the input signal is easily detected. The effectiveness of the proposed harmonic meter is confirmed by experiment.

抄録全体を表示

The electrostatic discharge (ESD) of charged metal objects produces electromagnetic (EM) fields having broad-band frequency spectra over the microwave region, which often gives serious EM interference (EMI) to electronic equipment. For the EMI of this kind, it has widely been accepted that the lower spark voltage ESD causes the stronger EMI to high-tech information equipment, whereas its mechanism still remains unknown. On the other hand, we previously proposed a new FDTD algorithm based on gap excitation with the time-variant conductivity and electric field of a spark channel, which enables one to predict the ESD fields due to charged metals having arbitrary shapes. In this study, the spark voltage dependence of the magnetic field due to a spark between cylindrical metals was investigated from our proposed FDTD computation and a spark experiment. As a result, it was found that the lower spark voltage produces the higher magnetic field level, while a certain spark voltage causes the highest magnetic field. This finding implies the presence of an ESD specific condition due to charged metals that gives the highest EM fields.

抄録全体を表示

OH radicals are measured in a pulsed corona or a pulsed dielectric barrier discharge (DBD) using laserinduced fluorescence (LIF) method. The pulsed discharges occur in nitrogen-oxygen mixture with 2.4% water vapor at atmospheric pressure. The pulse width is 100ns and the peak voltage is 35kV. The electrode configuration is a needle to plate electrode with 16-mm gap for corona discharge, and with 5-mm gap for DBD where the barrier is 2mm thick glass plate. It is shown that OH density is approximately proportional to the energy consumed by the discharge. The OH density per the discharge energy is about 2-4×10¹⁴cm^-3/mJ for both discharges in H₂O(2.4%)/N₂ mixture. It is shown that OH density increases with oxygen content in DBD, whereas OH density reaches a maximum at 3% oxygen content in corona discharge. The existence of oxygen accelerates OH decay rate in both discharges. A trace amount of trichloroethylene (TCE) is added to the ambient gas. It is shown that the addition of 100ppm TCE to corona discharge reduces discharge current by about 50%. That leads to decrease of OH production.

抄録全体を表示

The An increase in dc breakdown strength (BDS) for LDPE film was found using the additives of polycyclic compounds: anthracene(An), perylene(Pr), 9, 10 bromo-anthracene(Br_An), 1, 7 bromo-perylene(Br_Pr). We also used an additive of p-nitorobenzene-azoresorcinol(Az_hn). The experimental results indicate that all the additives used are effective in increasing BDS. The most effective additive is Br_An. BDS for the film with this additive is about 1.6 times higher than that for the film without additive. These results are observed in the temperature range between -20°C and 20°C. The BDS characteristics indicate that the breakdown of film may be due to an electron avalanche from the cathode. The reason for the increase in BDS is studied by comparing the experimental results for the five additives. UV absorption spectra for the films with additive suggest that the increase in BDS may not result mainly from the kinetic energy absorption due to the excitement of the additive at the collision between additive and electron carrier. TSC curves indicate that the quantity of negative charge trapped in the film is increased by the existence of the additive, which may locate at the boundary between the crystalline and amorphous regions in the film. It is considered that the increase in BDS may be achieved by a trapping of the electron carrier by the additive. The electron carrier scattering due to the dipole moment of the additive is no effective factor for the increase of BDS in this study because the polycyclic compounds used have no dipole.

抄録全体を表示

In this paper, the 3-dimensional form of the dendrite generated by the WTD method was measured using the 3-dimensional form measurement system. We had also investigated about a change of the short-circuit current while changing protection resistance and the dendrite with the passage of time. Consequently, after failure, in nonuniform electric field electrode it turns out that there is more accumulation thing at the anode than the cathode. In uniform electric field, if the maximum current is less than 0.1[mA], then the accumulate thing at cathode. If the maximum current is more than 0.1[mA], then the amount of accumulation at anode is larger than of cathode. The amount of generating per unit electric charge and the protection resistance holds a linear relation. The volume of the accumulation thing per unit electric charge grows larger with the increase of protection resistance. But it decreases if the time after failure becomes longer. For a same protection resistance, it turns out that the amount of generating per unit electric charge is smaller in nonuniform electric field than the uniform electric field. The current at the field strength differs form the failure current. And the action state of the accumulation thing after failure varies with the protection resistance, the failure time is shorter in the large environment. We also consider the progress speed of the accumulation thing after failure is faster. We think that this point is important to design a circuit pattern and a circuit.

抄録全体を表示

Although diamond thin films have been mainly produced by chemical vapor deposition methods (CVD) up to now, pulsed laser deposition (PLD) have a potential for growing diamond thin films including no hydrogen at a lower substrate temperature than those of CVD. In the previous study, we could succeed in growing diamond thin film homoepitaxially in an oxygen atmosphere by pulsed laser ablation of graphite. In this report, we investigated structural change of diamond thin film for the substrate temperature and the repetition rate of laser pulses. Based on the result, we considered the growth mechanism of diamond thin film by pulsed laser deposition.

抄録全体を表示

Decomposition of organic contaminants in water is achieved using pulsed high voltage barrier discharge in atomized water in oxygen. We obtained 58% of TOC (Total Organic Carbon) reduction in 200mL water after 22 times circulation through the reactor. Energy consumption in the discharge was 5W and maximum efficiency for TOC reduction of rohdamine B was 0.33µg/J.

抄録全体を表示