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We fabricated multiwalled carbon-nanotube/cellulose composite papers and measured their temperature dependences of electrical conductivity. The dependences were described with the Sheng’s fluctuation-induced tunneling (FIT) model. A possible mechanism of the electrical conduction in the composite paper was discussed in the context of the FIT model.

Combination of two dimensional graphene and semi-conducting molybdenum disulfide (MoS2) is of great interest for various electronic device applications. Here, we demonstrate fabrication of a hybridized structure with the chemical vapor deposited graphene and MoS2 crystals to configure a memory device. Elongated hexagonal and rhombus shaped MoS2 crystals are synthesized by sulfurization of thermally evaporated molybdenum oxide (MoO3) thin film. Scanning transmission electron microscope studies reveal atomic level structure of the synthesized high quality MoS2 crystals. In the prospect of a memory device fabrication, poly(methyl methacrylate) (PMMA) is used as an insulating dielectric material as well as a supporting layer to transfer the MoS2 crystals. In the fabricated device, PMMA-MoS2 and graphene layers act as the functional and electrode materials, respectively. Distinctive bistable electrical switching and nonvolatile rewritable memory effect is observed in the fabricated PMMA-MoS2/graphene heterostructure. The developed material system and demonstrated memory device fabrication can be significant for next generation data storage applications.

The computing industry is rapidly moving from a programming to a learning area, with the reign of the von Neumann architecture starting to fade, after many years of dominance. The new computing paradigms of non-von Neumann architectures have started leading to the development of emerging artificial neural network (ANN)-based analog electronic artificial intelligence (AI) chipsets with remarkable energy efficiency. However, the size and energy advantages of electronic processing elements are naturally counteracted by the speed and power limits of the electronic interconnects inside the circuits due to resistor-capacitor (RC) parasitic effects. Neuromorphic photonics has come forward as a new research field, which aims to transfer the well-known high-bandwidth and low-energy interconnect credentials of photonic circuitry in the area of neuromorphic platforms. The high potential of neuromorphic photonics and their well-established promise for fJ/Multiply-ACcumulate energy efficiencies at orders of magnitudes higher neuron densities require a number of breakthroughs along the entire technology stack, being confronted with a major advancement in the selection of the best-in-class photonic material platforms for weighting and activation functions and their transformation into co-integrated photonic computational engines. With this paper, we analyze the current status in neuromorphic computing and in available photonic integrated technologies and propose a novel three-dimensional computational unit which, with its compactness, ultrahigh efficiency, and lossless interconnectivity, is foreseen to allow scalable computation AI chipsets that outperform electronics in computational speed and energy efficiency to shape the future of neuromorphic computing.

http://jap.aip.org/; International audience; The randomness in the structure of two-component dense composite materials influences the scalar effective dielectric constant, in the quasistatic limit. A numerical analysis of this property is developed in this paper. The computer-simulation models used are based on both the finite element method and the boundary integral equation method for two- and three-dimensional structures, respectively. Owing to possible anisotropy the orientation of spatially fixed inhomogeneities of permittivity epsilon(1), embedded in a matrix of permittivity epsilon(2), affects the effective permittivity of the composite material sample. The primary goal of this paper is to analyze this orientation dependence. Second, the effect of the components geometry on the dielectric properties of the medium is studied. Third the effect of inhomogeneities randomly distributed within a matrix is investigated. Changing these three parameters provides a diverse array of behaviors useful to understand the dielectric properties of random composite materials. Finally, the data obtained from this numerical simulation are compared to the results of previous analytical work.

Adachi K., Ogi H., Takeuchi N., et al. "Unusual elasticity of monoclinic β-Ga2O3", Journal of Applied Physics, 124(8), 085102 (2018) https://doi.org/10.1063/1.5047017., This paper determines all the 13 elastic constants Cij of monoclinic β-Ga2O3, which has never been achieved since the discovery of this crystal about 100 years ago. We used resonant ultrasound spectroscopy with laser-Doppler interferometry, where the resonant-mode identification was unambiguously made by comparing measured and calculated displacement distributions on the vibrating specimen surface. Using more than 110 resonance frequencies, we inversely determined the Cij: C11 = 242.8 ± 2.9, C22 = 343.8 ± 3.8, C33 = 347.4 ± 2.5, C44 = 47.8 ± 0.2, C55 = 88.6 ± 0.5, C66 = 104.0 ± 0.5, C12 = 128 ± 0.1, C13 = 160 ± 1.5, C23 = 70.9 ± 2.1, C15 =-1.62 ± 0.05, C25 = 0.36 ± 0.01, C35 = 0.97 ± 0.03, and C46 = 5.59 ± 0.69 GPa. We also performed a density-functional-theory calculation and found that the local density approximation yields both the lattice parameters and Cij closer to the measurements than the generalized gradient approximation. Strong elastic-stiffness anisotropy is found in the diagonal elastic constants: C11 is smaller than C22 and C33 by ∼30%, and the difference between C44 and C66 exceeds 50%. Our measurements also reveal anomalous Poisson's ratios: ν21 and ν31 exceed 0.5, and ν23 and ν32 are almost zero. We explain these unusual elastic properties with the truss-like deformation of the tetrahedra-octahedra network and confirm this view with the ab-initio calculation.

Mechanical failure resulting from subcritical crack growth in the SiN x inorganic barrier layer applied on a flexible multilayer structure was studied by an electro-mechanical two-point bending method. A 10¿nm conducting tin-doped indium oxide layer was sputtered as an electrical probe to monitor the subcritical crack growth in the 150¿nm dielectric SiN x layer carried by a polyethylene naphthalate substrate. In the electro-mechanical two-point bending test, dynamic and static loads were applied to investigate the crack propagation in the barrier layer. As consequence of using two loading modes, the characteristic failure strain and failure time could be determined. The failure probability distribution of strain and lifetime under each loading condition was described by Weibull statistics. In this study, results from the tests in dynamic and static loading modes were linked by a power law description to determine the critical failure over a range of conditions. The fatigue parameter n from the power law reduces greatly from 70 to 31 upon correcting for internal strain. The testing method and analysis tool as described in the paper can be used to understand the limit of thin-film barriers in terms of their mechanical properties.

This paper describes performance characteristics of a bridge‐connected magnetic circuit with single output winding in dc control. The difference between positive and negative amplitudes of output current changes with the dc control current. An application of the bridge‐connected magnetic circuit to a dc current detector is presented in this paper.

Recently, we reported on the appearance of a double peak in the switching current during the reverse poling. In the present paper, the switching current measurements have been carried out on a soft lead zirconate titanate as a function of grain size. While in small grains only a small single switching peak is observed, large grains, however, showed double peak switching, as commonly observed in this material. The pyroelectric coefficient curves show a consistent trend with the switching curves. This behavior is attributed to non-180° domain switching during the reversed poling case as a result of residual stresses developed during forward poling. ©2007 American Institute of Physics

This paper discusses the effects of eddy currents induced in an electrically conducting plate which is placed in the airgap of a linear synchronous actuator with moving permanent magnets. The eddy currents induced in this plate, which is part of a controlled atmosphere chamber, cause not only damping but also deteriorate the actuator performance by disturbing the position measurement with Hall sensors. Furthermore, feed-forward controllers are less effective due to the suppression of high frequent armature fields. These effects are analyzed with an analytical model and verified with finite element simulations and measurements.

The effects of a thermal cycle annealing (TCA) process on the defects in GaAs and AlxGa1-xAs solar cells on Si substrates are described in this paper. The defect density is reduced and the solar cell efficiency is improved by TCA. The defect density and the solar cell efficiency are evaluated in detail with respect to TCA temperature and Al composition. The problems involved in the fabrication of a high efficiency AlGaAs solar cell on a Si substrate are discussed.

金沢大学理工研究域電子情報学系, This paper presents theoretical evaluation of the digital modulation performance of semiconductor lasers in digital communication systems with gigabit rates. The study is based on numerical integration of the rate equations augmented by a nonreturn-to-zero (NRZ) bit generator. For solitary semiconductor lasers, the performance is evaluated in terms of the eye diagram, turn-on delay jitter (TOJ), and signal-to-noise ratio. In communication systems, the performance is evaluated by the bit error rate (BER) and power penalty induced by the laser noise. Contributions of both the intrinsic fluctuations and bit pattern to the TOJ and BER are assessed. The results show that when the modulation current is low and the semiconductor laser is biased relatively above threshold, the power penalty decreases although the eye diagram is not well open. When the modulation current is high enough, biasing the semiconductor laser far-above threshold achieves both lower power penalty and higher eye-diagram quality. © 2008 American Institute of Physics.

Phosphorus (P) or boron (B) atoms can be doped at temperatures as low as 80 to 350 °C, when crystalline silicon (c-Si) is exposed only for a few minutes to species generated by catalytic cracking reaction of phosphine (PH_3) or diborane (B_2H_6) with heated tungsten (W) catalyzer. This paper is to investigate systematically this novel doping method, “Cat-doping”, in detail. The electrical properties of P or B doped layers are studied by the Van der Pauw method based on the Hall effects measurement. The profiles of P or B atoms in c-Si are observed by secondary ion mass spectrometry mainly from back side of samples to eliminate knock-on effects. It is confirmed that the surface of p-type c-Si is converted to n-type by P Cat-doping at 80 °C, and similarly, that of n-type c-Si is to p-type by B Cat-doping. The doping depth is as shallow as 5 nm or less and the electrically activated doping concentration is 10^ to 10^ cm^ for both P and B doping. It is also found that the surface potential of c-Si is controlled by the shallow Cat-doping and that the surface recombination velocity of minority carriers in c-Si can be enormously lowered by this potential control.

We present the density functional theory calculations of the binding energy of the Phosphorus (P) donor electrons in extremely downscaled single P-doped Silicon (Si) nanorods. In past studies, the binding energy of donor electrons was evaluated for the Si nanostructures as the difference between the ionization energy for the single P-doped Si nanostructures and the electron affinity for the un-doped Si nanostructures. This definition does not take into account the strong interaction of donor electron states and Si electron states explicitly at the conductive states and results in a monotonous increase in the binding energy by reducing the nanostructure's dimensions. In this paper, we introduce a new approach to evaluate the binding energy of donor electrons by combining the projected density of states (PDOS) analysis and three-dimensional analysis of associated electron wavefunctions. This enables us to clarify a gradual change of the spatial distribution of the 3D electron wavefunctions (3DWFs) from the donor electron ground state, which is fully localized around the P donor site to the first conductive state, which spreads over the outer Si nanorods contributing to current conduction. We found that the energy of the first conductive state is capped near the top of the atomistic effective potential at the donor site with respect to the surrounding Si atoms in nanorods smaller than about 27 a0. This results in the binding energy of approximately 1.5 eV, which is virtually independent on the nanorod's dimensions. This fact signifies a good tolerance of the binding energy, which governs the operating temperature of the single dopant-based transistors in practice. We also conducted the computationally heavy transmission calculations of the single P-doped Si nanorods connected to the source and drain electrodes. The calculated transmission spectra are discussed in comparison with the atomistic effective potential distributions and the PDOS-3DWFs method.

This paper discusses two new kinds of micromagnetoelastic devices made on silicon wafer whose function is to control the permeability of magnetostrictive soft magnetic thin films by voltage-controlled elastic strain. One is piezoelectric type and the other is electrostatic type. Structure, fabrication process, characteristics, and maximum possible output are discussed. The feasibility of these devices has been clarified although the rate of obtained permeability change was less than 1%. These device characteristics could be improved to 11% for piezoelectric type and to 80% for electrostatic type by the optimization of device dimensions and reduction of process damage to the magnetic film.

In this paper we report the soft magnetic properties of thin films of sputtered MnZn ferrite deposited on thermally oxidized Si substrates. A high deposition temperature, 600¿°C, together with the addition of water vapor to the sputtering gas was found to improve the initial ac permeability, µ. The highest value obtained was approximately 30. For MnZn-ferrite films with much larger grain sizes, as obtained by deposition on a polycrystalline Zn-ferrite substrate, a µ of 100 was obtained. The results are discussed in terms of the so-called nonmagnetic grain boundary model.

InAs quantum dots (QDs) grown on InP substrates can be used as light emitters in the telecommunication bands. In this paper, we present optical characterization of high-density circular quantum dots (QDots) grown on InP(311)B substrates and elongated dots (QDashes) grown on InP(001) substrates. We study the charge carrier transfer and luminescence thermal quenching mechanisms of the QDots and QDashes by investigating the temperature dependence of their time-integrated and time-resolved photoluminescence properties. This results in two different contributions of the thermal activation energies. The larger activation energies are attributed to the carrier escape to the barrier layer and the wetting layer (WL) from QDots and QDashes, respectively. The smaller activation energies are found to be originated from inter-dot/dash carrier transfer via coupled excited states. The variation of the average oscillator strength associated with the carrier re-distribution is discussed. The relation of the two activation energies is also quantitatively studied with the measurements of excited-state and ground-state energy separations. Finally, we show an approach to isolate individual quantum dots or dashes in a suitable nanostructure.

The paper examines the breakdown process at 100 kHz in a changing temperature-dependent mixture of Ar and Hg and the associated transitions between breakdown regimes. Each measurement series started at 1400 K, 10 bar of Hg, and 0.05% admixture of Ar and finished by natural cooling at room temperature, 150 mbar of Ar, and 0.01% admixture of Hg. The E/N at breakdown as a function of temperature and gas composition was found to have a particular shape with a peak at 600 K, when Hg makes up for 66% of the gaseous mixture and Ar 34%. This peak was found to be an effect of the mixture itself, not the temperature effects or the possible presence of electronegative species. The analysis has shown that at this frequency both streamer and diffuse breakdown can take place, depending on the temperature and gas composition. Streamer discharges during breakdown are present at high temperatures and high Hg pressure, while at room temperature in 150 mbar of Ar the breakdown has a diffuse nature. In between those two cases, the radius of the discharges during breakdown was found to change in a monotonic manner, covering one order of magnitude from the size typical for streamer discharges to a diffuse discharge comparable to the size of the reactor.

Microwatt power oscillation devices at sub-terahertz frequency region between 0.3 and 1.0 terahertz (THz) were fabricated from high-Tc superconducting single crystalline Bi2Sr2CaCu2O8þd and used as a source of the transmission terahertz imaging system. As test examples, terahertz images of coins and a razor blade placed inside the brownish paper envelopes with the spatial resolution of 1mm are presented. The signal-to-noise ratio exceeds 130 in these images. Using a simple wedge-shaped interferometer and analysing the interference fringe pattern, the wavelength of the terahertz wave is calibrated within 0.1% accuracy. This interferometer also provides a simple method to measure the absorption coefficient of the liquid sample. Two test measurements for distilled water and ethanol are demonstrated and their absorption coefficients are obtained with 99.2% accuracy. This suggests that our terahertz imaging system can be applied to many practical applications, such as biological and biomedical imaging, environmental monitoring, microanalysis of impurities, structure and dynamical analyses of large molecules and ions in solution.

We investigated complex magnetic domain formation on a chiral molecule-based magnet, [Cr(CN)6][Mn(R)-pnH(H2O)](H2O) (termed as R-GN), whose two-dimensional molecular network was constructed with the help of a single-handed chiral ligand ((R)-pn). There, the first- and third-harmonic magnetic responses (M1ω and M3ω) against the ac magnetic field were observed, and magnetic hysteresis in ac field of a few Oe was discussed in terms of Rayleigh loop. The diagnostics of this magnetic hysteresis clarified the complex process of magnetic domain formation against a change in temperature. For R-GN, it was reported that a giant M3ω (termed #4 in this paper) appeared just above the so-called “magnetic ordering temperature (TC)." In the present study, three M3ω responses (#1-3) were newly observed on the lower-temperature side of #4, and the ac field dependencies for all of #1-#4 were investigated. #1 also accompanied the giant M3ω, which suggests that a significant degree of magnetic fluctuation surviving below TC. This glassy behavior below TC is an attractive new phenomenon in molecule-based magnets with a single-handed chiral ligand. #2 and #3 exhibited magnetic ordering and the formation of a small magnetic domain, respectively. The M3ω responses of #1-3 were suppressed with increasing the amplitude of ac field, and the corresponding magnetic hysteresis was a normal Rayleigh loop accompanying the out-of-phase of the M1ω response. The M3ω response of #4 without the out-of-phase of M1ω was, however, enhanced with increasing the amplitude of ac field, and #4 represented a large magnetic hysteresis in the paramagnetic region, intrinsically different from those of #1-#3.

This paper deals with a numerical model of orthogonal‐core transformers for use in spice. The model was devised on the basis of the magnetic circuit of the orthogonal‐core with the saturation and hysteresis effects. Using the numerical model, the behavior of the dc‐ac converter constructed with the orthogonal‐core transformers and square‐wave transistor choppers was analyzed. The calculated values and measured ones show a good agreement. The method presented here is suitable for the circuit analysis and design optimization of the dc‐ac converter taking account of nonlinear characteristics of the orthognal‐cores and semiconductor devices used in the converter.

This paper describes the synthesis of copper/copper oxide nanoparticles via a solution plasma, in which the effect of the electrolyte and electrolysis time on the morphology of the products was mainly examined. In the experiments, a copper wire as a cathode was immersed in an electrolysis solution of a K2CO3 with the concentration from 0.001 to 0.50 M or a citrate buffer (pH = 4.8), and was melted by the local-concentration of current. The results demonstrated that by using the K2CO3 solution, we obtained CuO nanoflowers with many sharp nanorods, the size of which decreased with decreasing the concentration of the solution. Spherical particles of copper with/without pores formed when the citrate buffer was used. The pores in the copper nanoparticles appeared when the applied voltage changed from 105 V to 130 V, due to the dissolution of Cu2O.

In this paper, we study the relationship between nanoparticles’ structure/composition and the chemical nature of the molecules to be identified in surface enhanced Raman scattering (SERS) spectroscopy. Three types of nanoparticles (NPs) were synthesized, including Ag, Au, and silver coated by gold (Ag@Au), in order to study the resulting enhancement effects. When a rhodamine 6G dye molecule was used to assemble the NPs, it was found that Ag NPs exhibited the highest enhancement activity. However, when a thiol containing 3-amino-1,2,4-triazole-5-thiol molecule was used to assemble the NPs, it was found that the Ag@Au NPs exhibited high Raman activity as well as the Ag NPs. The results give insight into how the chemical properties of the molecules to be analyzed play an important role in the SERS detection. An additional parameter of the analysis reveals the relative stability of the three types of NP probes synthesized with regard to oxidation in the presence of different mediating molecules and varying salt concentrations. The results are of interest in designing and employing NP probes to detect biological molecules using colorimetric and SERS based approaches.

International audience; We present computer simulation data for the effective permittivity (in the quasistatic limit) of a system composed of discrete inhomogeneities of permittivity epsilon(1), embedded in a three-dimensional homogeneous matrix of permittivity epsilon(2). The primary purpose of this paper is to study the related issue of the effect of the geometric shape of the components on the dielectric properties of the medium. The secondary purpose is to analyse how the spatial arrangement in these two-phase materials affects the effective permittivity. The structures considered are periodic lattices of inhomogeneties. The numerical method proceeds by an algorithm based upon the resolution of boundary integral equations. Finally, we compare the prediction of our numerical simulation with the effective medium approach and with results of previous analytical works and numerical experiments.

This paper reports on the evolution of an isolated electron swarm, which is experimentally observed as spatial distributions at every moment. This observation is assumed to directly correspond to the conventional time-of-flight theory. We have measured the spatial distribution of electrons using a double-shutter technique in the drift tube, where a shutter electrode to collect electrons can be slid along the field (E/N) direction in order to capture a relative electron number at a certain range of location. As a typical parameter defined by this spatial distribution, the center-of-mass drift velocity (Wr) is determined for methane gas. The result is compared with the mean-arrival-time drift velocity (Wm) defined from the arriving electron number at fixed positions. We have also performed a theoretical analysis in which a Fourier transformed Boltzmann equation is solved to deduce both of the drift velocities from a dispersion relationship. The difference between Wr and Wm at high E/Ns (above 200 Td) is clearly ascertained in the experimental and theoretical investigations, which is attributable to the occurrence of ionization events.

The soft magnetic property and the structure of the new type nanocrystalline Fe–(P,B,Si,Nb,Cu) alloy with high Fe content about 80 at. % have been investigated. In this paper Fe77.9P3B14Nb5Cu0.1 alloy has a supercooled liquid region (ΔTx) of 33 K defined by the difference between the glass transition temperature (Tg) and crystallization temperature (Tx), which would be relating to the high glass-forming ability leading a thickness of 140 μm melt-spun ribbon with a glassy phase. The Fe80.9P2B10Si2Nb5Cu0.1 alloy with the higher Fe content can be melt spun into the thick ribbon with thickness of 65 μm due to rather large amorphous-forming ability. In addition, a homogeneous nanostructure composed of α-Fe grain with around 15 nm in diameter was realized after crystallization, and the nanostructured alloy exhibits the high Bs of 1.55 T and the low coercivity (Hc) of 4.6 A/m. The Bs and the glass or amorphous-forming ability of the alloys are superior to those for typical nanocrystalline. Therefore, the miniatu...

We have found that molybdenum dioxide (MoO_2) is an excellent dopant for enhancing electrical conductivities in organic hole-transporting layers. We fabricated hole-only devices with an alpha-sexithiophene (α-6T) layer doped with MoO_2 at various concentrations to investigate how doping MoO_2 into the α-6T layers influences the hole-injection and hole-transport characteristics of these layers. We observed a marked increase in electrical conductivity as a result of the MoO_2 doping. The 30-mol % MoO_2-doped α-6T layer had a high electrical conductivity of 8.9±1.3×10^ S/cm. From the results of our visible/near-infrared absorption spectra study of these doped layers, we confirmed that this increase in electrical conductivity is caused by a charge transfer between MoO_2 and α-6T, which leads to an increase in free hole concentration in the doped layers and the formation of an ohmic contact at an electrode/α-6T interface. In the latter part of this paper, we discuss current flow and electroluminescence (EL) characteristics of organic light-emitting diodes (OLEDs) with a 30-mol % MoO_2-doped α-6T hole-transporting layer and a 30-mol % Cs-doped phenyldipyrenylphosphine oxide (POPy_2) electron-transporting layer. We achieved an extremely low driving voltage of 3.1 V required for a current density of 100 mA/cm^2 in the doped OLEDs owing to the use of the α-6T and POPy_2 layers with high carrier mobilities and the excellent p-type MoO_2 and n-type Cs dopants. We demonstrated the enhancement of power efficiencies by ≈2 times in the doped OLEDs compared with undoped OLEDs and observed bright EL at low driving voltages in the doped OLEDs, for example, 100 cd/m^2 at 2.3 V, 1000 cd/m^2 at 2.7 V, and 10 000 cd/m^2 at 3.3 V.

This paper demonstrates that the spatial distribution of electronic states of an arsenic ion implanted Si (111) substrate can be observed by using a wavelength tunable second harmonic (SH) microscope in a wide photon energy range from 2hω=1.96 to 5.19 eV. The contrast in the SH intensity images between the As-doped area and the nondoped area depends greatly on the SH photon energy. For 2hω>3 eV, optical second harmonic generation (SHG) from the nondoped area was stronger than from the doped area, and the contrast was reversed for 2hω

This paper presents the results of an experimental and numerical investigation in electric fracture behavior of composite [Pb(Zr,Ti)O3] double torsion (DT) specimens. DT tests were conducted on a commercial piezoelectric ceramic bonded between two metals. Fracture loads under different electric fields were obtained from the experiment. Nonlinear three-dimensional finite element analysis was also employed to calculate the energy release rate for DT specimens based on the exact (permeable) and approximate (impermeable) crack models. The effects of applied electric field and domain switching on the energy release rate are discussed, and the model predictions are compared with the results of the experiments.

This paper proposes a new lithography method employing focused ion beam exposure and subsequent dry development. It is shown that the O2 plasma etching or reactive ion etching rate for resists exposed to gallium ions is much lower than that for resists not exposed. A comparison is made between plasma development and reactive ion development. An improvement in the resist sensitivity and contrast value γ using a CF4+O2 mixture gas for reactive ion development is discussed. It is possible to fabricate 0.5‐μm‐width lines and spaces in 0.6‐μm‐thick PMMA film at 1×10−4‐C/cm2 gallium ion exposure.

This paper proposes a new method for noncontact measurement of the dc current. This device utilizes the skin effect of an ac current flowing in a ferromagnetic pipe with an amorphous‐tape wound structure. The dc current controls the skin depth of the ac current. This dc‐current transformer (CT) has no winding and outputs the difference between the terminal voltage of the pipe and the induced voltage in a one‐turn coil. The ac current does not affect the dc line because of axis symmetry. A linear relation between the output and dc current is obtained when an appropriate ac drive frequency is selected. Improvement of gain can be attained by reducing the diameter. It is clarified that the magnetic pipe is applicable for a dc‐CT with a small size.

This paper describes a two c‐core type orthogonal‐core made of Fe‐6.5 wt. % Si sheet and its application to power converters. The orthogonal‐core can be used in the high‐frequency region because a Fe‐6.5 wt. % Si sheet has superior soft magnetic properties including high permeability and low core loss. Using the orthogonal‐core, we constructed a parametric oscillation type dc‐ac converter. The dc‐ac converter had voltage regulation, overload protection, noise rejection, and almost sinusoidal output. Good efficiency was obtained in the frequency range from 400 Hz to 1 kHz. Furthermore, we propose a dc‐dc converter for coupling two independent dc power sources. The dc‐dc coupling converter has bilateral power transfer and ease of controlling the transferred power. The basic operation of the dc‐dc coupling converter is described.

This paper deals with the performance characteristics of a new ac high magnetic field generator based on the effect of eddy currents. We have proposed a new ac high magnetic field generator and have obtained magnetic fields up to 15 T at 60 Hz. The proposed structure consists of layers of exciting coils and conductors built in concentric circles. The eddy currents in the conductor flow close to the hole in the conductor. The magnetic flux induced by the eddy currents is concentrated within the hole, and an ac high magnetic field is produced. A procedure for estimating the optimum shape and number of layers required to increase the concentration effect, together with a design of the colling system necessary for continuous operation, is presented.