For miniaturization of magnetic devices, it is necessary to increase the operating frequency. We have studied thin-film micro-inductors to realize a high operating frequency and reduce the iron loss. In this paper, we propose a thin-film micro-transformer with high operating frequency achieved by application of a multilayered magnetic film to the core. The magnetic core is made of amorphous CoFeSiB monolayer film or a CoFeSiB/SiO₂ multilayered film. The induced magnetic anisotropy is controlled so that the exciting direction of the coil is along the hard axis. The total thickness of the magnetic layer is 3μm and the size of the core is 0.6 mm × 2.3 mm. The experimental transformers show that a multilayered core is useful for improving the transmission loss of transformers at high operating frequency. A thin-film transformer whose transmission loss is 2.7 dB from 100 MHz to 250 MHz has been developed. This value is smaller than the 5.3 dB of the monolayer core.

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This paper proposes a new method for shielding an ambient magnetic field in CRTs. The key to this method is the use of U-shaped magnetic sheets arranged around the frames of the CRTs. The sheets are magnetized by the ambient field, and set up a demagnetizing field to cancel the field perpendicular to the screen. They are effective in reducing miss-landing. For example, miss-landings at the corner of the screen were reduced to one-fourth of the number that occurred without the sheets. On the other hand, there are no shielding effects on the field parallel to the screen.

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It is well known that, in a color CRT, color change occurs as a result of the magnetization of the shadow mask and frame in the enviromental magnetic field. In order to clarify the influence of the mask and frame quantitatively, We analyzed the magnetization by integral equation method when a shadow mask and frame were subjected to an ambient field.
We calculated the electron beam trajectories by using the derived magnetic field distributions, and computed the miss-landing to evaluate the color change quantitatively. The results of the numerical analysis agree well with experiment, and aid in relating the shielding to the miss-landing.

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MFM images of a magnetic head and a recording medium obtained by using electrodeposited FeNi, Co, and FeCo tips show quite different features. These differences are explained by the saturation magnetization and the coercive force of the magnetic thin films electrodeposited on the W wires, In addition, we attempted to observe the magnetic structure of the tip by using magnetotactic bacteria that swim along the lines of the magnetic field originating from the poles on the tip.

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In conventional magnetic measurements, magnetization characteristics are measured under a single directed excitation condition, and consequently the results represent magnetization characteristics in the measured direction. However, these characteristics cannot be applied to analysis in a rotating magnetic field. In order to anlyze fields, We measured magnetization characteristics as vector values by using a two-dimensional magnetic measurement apparatus. This paper presents a magnetic reluctivity tensor expression for two-dimensional magnetization characterisitcs in finite element analysis. We show that this expression is quite effective for the analysis of rotating magnetic fields.

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In conventional magnetic measurement, only the same components of the magnetic flux density B and the magnetic field intensity H in the excited direction are measured. In short, the measured values are dealt with as scalars. Since it is well known that B and H have a phase difference in space, the values should be dealt with as vectors. We have used a two-dimensional magnetic measurement apparatus to understand the magnetization process of B and H precisely. In the conventional method, when the excited direction does not correspond to the rolling direction, the locus of the vectors of B is not an alternating flux; that is, it becomes a loop. Therefore, the iron loss in the conventional method is different from that in the two-dimensional measurement method.

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The influence on electromagnetic force analysis of the difference between the magnetization characteristic used for calculation and the real characteristic is evaluated in this paper. The electro magnetic force is calculated by Maxwell's stress tensor method and the virtual magneitc charge method. The magnetic field used in these methods is analyzed by the FEM, using a magnetization characteristic. Comparison of the results calculated by using a magnetization characteristic and those calculated by using its transformed characteristics shows that the influence of the magnetization characteristics is small at low reluctivity, and is independent of the fineness of the mesh in the FEM. In addition, there is little difference between the methods of calculating the electromagnetic force with regard to the influence of the magnetization characteristic.

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We developed a helmet-sized superconducting magnetic shield for a high-T_c Bi-Pb-Sr-Ca-Cu-O superconductor. The shield is 32 cm in diameter, 60 cm in depth, and 2.5 cm in thickness. It was experimentally confirmed that the container can reduce a Weak magnetic field to -100 dB or 1/100000. The shielding effect of the superconducting container does not decrease even at frequencies as low as 0.2 Hz.
Using equipment consisting of a superconducting container, a cryostat to keep the container at liquid nitrogen temperature, and an rf SQUID gradiometer, we successfully detected the magnetic fields of a human brain. We detected somatosensory magnetic fields by stimulating the tibial nerves of the patient with current pulses.

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This study focuses on the properties of nerve excitation elicited by time-varying magnetic fields. We analyzed the effects of trapezoidal magnetic fields on the nerve transmembrane potential. Nerve excitation processes were simulated while changing the rise-time, the duration of the plateau, and the falltime of the trapezoid. The results show that the exciting point and the threshold for nerve excitation change with the time course of the magnetic fields, even if the stimulating intensity remains the same.

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This study focuses on the electrical brain activities during sleep, particularly on K-complexes in normal subjects during sleep stage 2. We investigated the relationship between the sources of K-complexes and the sources of auditory evoked responses. We analyzed these waveforms the basis of on both topographic electroencephalographic (EEG) and magnetoencephalographic (MEG) maps. The components of magnetic fields perpendicular to the surface of the head were measured by using a 1ch dc-SQUID with a second order gradiometer or a 7ch dc-SQUID with a first order gradiometer, and electric potentials were simultaneously recorded at 14 electrodes. On the basis of the results of the MEG measurements, the source of K-complexes can be modeled by two current dipoles. The dipoles are estimated at a position 10 mm superior to the sources of N100 components of the auditory evoked responses estimated from the evoked potentials and magnetic fields. This result suggests that the mechanism of K-complexes is closely related to that of auditory evoked responses.

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MEG measurements can detect brain sources that are difficult to detect with EEG measurements. The purpose of this study is to make models of sleep spindles in which both MEG and EEG activities are recorded simultaneously. The components of magnetic fields perpendicular to the surface of the head were measured by using a dc SQUID with a firstderivative gradiometer. We propose three models of spindles. In the first, the source is sliding into the shallow area of the head so as to be perpendicular to the surface of the head. Here, the power spectrum of the MEG is decreasing. In the second, the source is sliding into the deep area, so that it is perpendicular to the surface. Here, the power spectra of both the MEG and the EEG are decreasing. The last model is perpendicular to the surface, which is leaning and sliding into the deep area. Here, the power spectrum of the EEG is decreasing but that of the MEG is not.

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The magnetic and electrical sources of the gustatory responses in the human brain were analyzed using magnetoencephalography (MEG) and electroencephalography (EEG) methods. We stimulated a human tongue with NaCl, acetic acid, and distilled water. Gustatory evoked potentials were measured at 14 points on the surface of the head, and gustatory evoked magnetic fields were measured with a dc SQUID system over the left hemisphere of the subject's brain. Slow electrical responses dominant in the frontal region were observed as responses to the taste stimuli. Gustatory evoked magnetic fields similar to gustatory evoked potentials were observed in the left temporal region. On the basis of these experimental results, dipole models for the magnetic and electrical gustatory responses were proposed.

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Fibrin polymers are diamagnetic materials that are Oriented in a magnetic field. Fibrinogen is changed to fibrin monomer by the action of protease thrombin, and fibrin monomers are polymerized. When a strong magnetic field is applied to the polymerization process of fibrin, the fibrin fibers are oriented parallel to the magnetic fields. The present study focuses on the role of ferromagnetic particles in the magnetic orientation of fibrin polymers. Fine magnetic particles were mixed into a solution of fibrinogen. The polymerization process of fibrin was exposed to magnetic fields up to 8.0 T created by using a superconducting magnet. Magnetic particles were agglomerated to form chains of clusters oriented parallel to the magnetic fields. The chains of magnetic particles themselves agglomerated and polymerized to a large fiber. We observed no oriented fibrin near the chains. In contrast, oriented fibrins were observed in the large fibers of chains.

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We have observed a phenomenon in which candle flames are pressed down by magnetic fields of high intensities. We have also observed a phenomenon in which flow of gases such as carbon dioxide and oxygen is blocked by magnetic fields. A model called a “magnetic curtain” has been introduced to explain these phenomena. It is assumed that the magnetic curtain is a wall of air caused dy magnetic fields. We have demonstrated that a candle flame can be quenched by a magnetic field, since a magnetic curtain intercepts oxygen.
This study focuses on the mechanism of the magnetic curtain. A collision gas model based on molecular dynamics is proposed. Computer simulation Shows magnetic fields blocking the gas flow.
To verify the validity of the model, a magnetic curtain was produced by means of an 8-T superconducting magnet, and the gas pressure in the bore of the magnet was measured by using a manometer.

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A study of clinical hyperthermia based on the soft heating method is discussed. A heating device made of temperature-sensitive amorphous metal flakes consisting of Fe-P-C-Cr was prepared and implanted in an gar phantom and in vivo. We measured the temperature distribution established in a phantom and the heating characteristics in vivo. In an animal experiment, a rabbit and a VX-2 tumor were used. The VX-2 tumor was transplanted into the rabbit's liver. The results of the experiment reveal that the heating device sufficiently heats the tumor when the temperature is up to 43°C under blood flow. This method has potential applications in clinical uses.

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We present the measured resistivity, Hall coefficient, and magnetization in three kinds of Bi₂Sr₂CaCu₂O_8+δ ceramics subjected to various heat treatments. The Hall effect shows that the carriers have the hole characteristic in this system. The hole number varies according to the heat treament. It increases and T_c decreases as a result of oxidation. In spite of the atmosphere of the heat treatment, the density of the flux pinning is increased by quenching. The Hall mobility is independent of the heat treatments for Bi₂Sr₂CaCu₂O_8+δ This result indicates that oxygens enter and leave sites on a plain other than the CuO₂ plain in Bi₂Sr₂CaCu₂O_8+δ.

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The flux density distributions in sintered Bi₂Sr₂CaCu₂O_x high T_c superconducting specimens Were observed by means of a magneto-optical method using iron garnet films. The samples were formed to the disks with the thickness of 60∼600μm and the diameter of 1.5 mm. SEM image showed that the specimen consists of the grains with the diameters of about 300μm. Flux penetrated inhomogeneously for the specimens with smaller thickness than the diameter of the grain. However, it penetrated homogeneous as increasing the thickness. Preferential flux penetration at grain boundaries was not observed for all specimens. The values of the critical current density, that was estimated from the flux penetration distance by using Bean's model applied to disk-shaped specimens, was about 10⁴ A/cm² at 30 K, Which was nearly equal to the Value estimated from magnetization assuming that the shielding current flows uniformly through the entire specimen.

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