This paper describes the electrical characteristics of the multilayered transformer which is composed of Mn-Zn ferrite core, primary and secondary conductors positioned alternately not only in the vertical direction but also in the horizontal direction. In order to clarify the operation characteristics of the two types of transformers, one had the conventional planar winding structure and the other had the new winding structure mentioned above, two dimensional finite element method which took account of two conditions, constant input voltage and load current, was introduced. The coupling coefficient of the conventional multilayered transformer degraded with increasing load current. On the other hand, the proposed multilayered transformer had independent coupling coefficient on the load current. The forward type DC-DC converter using the new multilayered transformer had higher efficiency than the converter using the conventional multilayered transformer.

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An electromagnetic conveyer which can convey micro-parts in two dimensions was fabricated. The conveyer mainly comprises a pallet made of a NdFeB magnet with yokes and eight coil-diode modules consisting of planar coil arrays and rectifying diode arrays. Fabrication of the coil-diode modules consisted of the following processes steps: sputtering, photosensitive polyimide lithography, electroless-plating, electroplating and joining. The pallet can move in two dimensions on the conveyance stage made of coil-diode modules without using a special support mechanism such as linear bearings or linear guides and stop with an accuracy of within ±20μ m by using air absorption with a V-block. Positioning accuracy on the conveyance stage is 1mm of the coil pitch. The maximumum conveyable mass of 1.2g and the output thrust of 31mN were obtained at an applied current of 1.2A/5coil. The maximum conveyer speed when unloaded was 28mm/sec.
This paper describes the conveyance properties when a circular mover is used, the cuircuit construction and fabrication of a coildiode modules to realize two-dimensional conveyance.

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Recently voltage regulators in portable electronic equipment have been required small, thin and low power dissipation, and some regulators with a planar inductor have been reported. We have developed a 1W class DC/DC converter which integrated a new power IC, including a PWM control IC and MOSFETs, with a planar inductor. This paper describes about a design of DC/DC converter, simulation of a planer inductor, a fabrication process and properties of a planar inductor on a power IC and property of the DC/DC converter module. The power IC is 4mm×5mm in area and a planar inductor is 4mm×4mm in area. The planer inductor is fabricated by a process consisting of the steps of RF sputtering, photosensitive polyimide lithography and copper electro-plating on the power IC. The DC/DC converter module, which is consisted of the power IC with a planar inductor, diode and capacitors, is 12×12×2mm and achieved efficiency of about 80% at a switching frequency of 3MHz.

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Recently, electromagnetically driven microactuators have attracted interest because of their availability. We have been studying magnetically driven actuators. This time, a magnetically driven linear microactuator using microsystem fabrication techniques has newly developed. The microactuator is composed of a mobile microplatform (mover) with some permanent magnets and a stator with a large number of planar coils. The planar coils of the stator are made by using photolithography technique and electroless plating technique. In this paper, static and dynamic characteristics of the magnetically driven linear microactuator are discussed. The mobile microplatform of the microactuator can moves at speeds higher than 75 mm/s. The microplatform carries loads more than 0.1 g. As a result of the experiments, the magnetically driven microactuator is found to be useful for a new type positioning mechanism.

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We have proposed a new electromagnetic micro-motor, in which a vibration excited on a magnet is converted into a rotary movement through a frictional force. This paper describes its basic properties and a trial fabrication for improvement of the torque. First, we fabricated and tested a motor whose stator was an air coil. The revolution speed showed a strong dependence of the excitation frequency. The starting torque was as small as 1.3×10^-5Nm. Next, we tried to increase the torque by increasing the attractive force of the rotor. An improved motor using a ferrite core exhibited the maximum torque of 2.5×10^-4Nm.

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Amorphous FeCoSiB films with high magnetomechanical coupling factors were studied to determine their strain sensitivities. In terms of the application of the magnetoelastic strain sensor element, we prepared the meander patterns of the films utilizing the photolithography and ion milling processes. The impedance change of the patterned films by a strain was measured in the frequency range from 1MHz to 1GHz. The film patterns were subjected to a strain by bending of their substrates, which caused the change in the magnetic anisotropy of films via magnetoelastic coupling. Reflecting the excellent magnetomechanical coupling properties, the high frequency impedance of films were changed considerably: the change in impedance of 110% was observed at 500MHz by strain. The film patterns exhibited the figure of merit F=(ΔZ/Z)/ε (change in film impedance Z per unit strain ε) of 2.6×10⁵. It is also demonstrated that, utilizing the strain-dependent impedance, a small strain of 1×10^-7 can be detected with the film pattern.

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To move the magnetic micro-machine to an objective area, it is required to control its running direction. It was demonstrated that swimming direction of the spiral-type magnetic micro-machine could be controlled by changing the direction of the rotation plane of the external rotational field. The swimming direction of the machine turned to the direction of perpendicular to the rotation plane. The radius of the bend depended on the kinematic viscosity of the fluid and on the frequency of the external rotational field.

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A new type of magnetic microprobe is presented by which surface anomalies of magnetic or conductive materials is detected with enhanced spatial resolution and sensitivity. The probe is fabricated using a pair of thin amorphous wires bent in a U-shape, on each of which two identical copper wire coils are wound. The four identical coils are connected so as to make a bridge circuit, where two coils on the same wire core are placed at opposing sides with the mutual coupling positive. Characteristics of the new probe are investigated including point spread function (PSF), spatial resolution and senstivity with reference to those of a Dahle type microprobe which is realized with the same assembly but changing connections of the four coils.

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This paper describes a new miniature thin-film coil whose area is down to 25μm x 110μm to sense magnetic near field from PCBs (Printed Circuit Boards) or ICs. The proposed coil has multi-layer planar shielded loop structure and it is insensitive to electric field. Spatial resolution of 300μm was obtained using the coil at 800MHz. This value is 4.3 times better than the PCB-made type we have already presented. Magnetic field distribution near the LSI packaged on PCB has been demonstrated.

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A novel temperature sensor with a very high sensitivity has been developed. The sensor consists of a thin metallic film and a set of coils. The coils are used to induce and detect eddy current in the thin film. Eddy current in the thin film, which is attached on an object or directed toward a radiative heat source, is used as an indicative of temperatures of the object. A very high sensitivity has been achieved because of (1) a good heat isolation due to no electrical wiring to the thin film and (2) very small heat capacity of the thin film. Temperatures of objects in a non-metallic container can also be measured by a separating configuration; the sensing thin film is attached inside the container and the other components are attached outside. The no-feed-through configuration inherently prevents the sensor from leakage and malfunctioning due to exposure of sensitive elements in tough environments.

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The highest detection resolution of a magnetic field sensor using a magnetic core is dependent on the noise of the magnetic core and the electronic circuits. Sensor sensitivity cannot be discussed without attention to these points. This paper describes the optimum excitation parameters for improvement of the dc biased-type differential magnetic field sensor resolution. Investigation of optimum excitation conditions, so that the ratio of magnetic core noise to detection sensitivity is minimum, showed that the resolution can be improved by operating at a deeper bias with a higher excitation frequency. It was possible to reduce the sensor noise level to 1×10^-13T/√Hz.

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Ti_1-xCr_xN films having a corrosion resistance superior to TiN were prepared by a dynamic ion mixing apparatus with two electron beam evaporation sources. The film composition was changed by an independent control of the respective Ti and Cr evaporation rates. The films consisted of a constant N concentration of 30 at.% by the N2⁺ ion beam irradiation at a current density of 100μA/cm² with an energy of 10keV. Electrochemical properties of the films in an HCI solution(1mol/dm³) were measured by the AC impedance method using a fast Fourie transform analyzer. The measured board diagram was interpreted by the typical equivalent circuit, which was constituted with the parallel circuit of the interfacial resistance Rt and the electric double layer capacity Cd. The Rt exhibits the corrosion resistance behavior of the films, and the Cd has influence on a variation of the surface morphology. The Ti and Cr composition ratio with the large corrosion resistance was Ti_0.57Cr_0.43N(x=0.43) having the highest Rt.

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Chrysotile, an asbestos, and insulating materials containing chrysotile were melted by plasma, and the material properties of the slags obtained by melting were examined for their recycling potential. The asbestos wastes were melted in a graphite crucible by changing the waste compositions and also melted in an alumina crucible simultaneously with other waste materials such as carbon steel and concrete. Chrysotile decomposed completely by melting and asbestos fibers disappeared in the melted slag under all melting conditions. The slags have good material properties such as homogeneity and chemical stability satisfying the leaching guideline of the Environmental Agency (Notification No. 46) for recycling and can be used erials. Crystalline hard slag, which is easy to be used for construction materials, could be obtained by controlling the slag compositions or the melting conditions. These results show that a plasma melting method is appropriate for rendering asbestos waste harmless and converting it into usable products.

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We have numerically studied the transient behavior of the evolution of Field Reversed Configuration (FRC) plasma with a rotating magnetic field(RMF). We consider the evolution of the plasma formed by a field reversed theta pinch by increasing the internal magnetic flux with an RMF and by regulating the axial magnetic field. The dynamic responses of a plasma pressure, separatrix radius and length are obtained by solving the radial force balance and the energy balance on the assumption that a current profile is preserved. We have studied the conditions for a successful evolution on the initial plasma parameters, the time variations of the RMF angular frequency and the axial magnetic field. It has been shown that the internal magnetic flux can be increased by applying an RMF with time-varying frequency and controlling the axial magnetic field appropriately

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Measurement of negative ion mobilities is carried out in O₂ at atmospheric pressure. This high pressure condition gives extremely low electric field intensity compared with the other swarm experiments. In this paper, we describe the results of experimental values of O₂^- mobility in O₂ varying with the drift length from 1.5cm to 9.4cm. The experiments were performed from 0.007 to 4.5V/cm? Torr in reduced electric field intensity. Mobility of O₂^- against the reduced electric field intensity are almost agreed within 3.5cm in drift length. Obtained zero field mobility of O₂^- is 2.13cm²/V•s and this value agree with the values of other researchers. But if the drift length is longer than 3.5cm, the zero field mobility of O₂^- become small with increase the ion drift length. This fact suggests that O₂^- changes to another ion species by ion-molecule collisions during the flight through the drift space.

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A thermionic electric power generation is one of the direct energy converter technologies. Although the thermionic energy converter has many advantages, it is not practically used yet. The thermionic energy converter generally works at high emitter temperature and high operating temperature might cause the shortening of emitter's life and the problem of stability. To slove these problems the laser light is irradiated to the thermionic energy converter at lower emitter temperature. A dye laser was used to study the output characteristics of the thermionic converter irradiated by the light. As a result of the experiment, it is found that the output current of the irradiated thermionic converter increases at the relatively lower emitter temperature at about 618nm and 630nm wavelength of the light. This result will be effective, when the sunlight is used both for a light source and a heat source.

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An electron cyclotron resonance (ECR) ion source for a large area uniform ion beam with multipolar magnetic field is being developed. Hot electrons heated at the localized ECR region in the source ionize a large volume of gas in the discharge chamber, where a large area plasma is generated and the plasma loss is suppressed with the multipolar magnetic field. The electron energy and current distributions are measured with Langmuir probes to confirm the above plasma generation scheme.

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Estimation of induced current inside a human body exposed to ELF (extremely low frequency) magnetic field are still remaining as an important issue. There are many computational studies reporting the relationship between outer magnetic filed and induced current inside the human body. In addition, there are some limit values regarding human exposure to magnetic field based on the induced current density. Here, we investigated and compared the relationship between magnetic field and induced current among existing literatures and guidelines. The result showed that each estimated value of magnetically induced current varied widely.

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