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As part of the basic research for the improvement of the electromagnetic environment, the present study has developed a ferrite plate having orientation characteristics. To exhibit the orientation characteristics of a plane wave, a slit was cut on the surface of the ferrite plate. The values of the radio frequency (RF) magnetic shielding degree SDHH when holding the slit horizontal to the ground, in the frequency region of 1 MHz (43 dB) to 200 MHz (8 dB), decreased with frequency. The value of RF magnetic shielding degree SDHP when holding the slit perpendicular indicated an average value of 20 dB in this frequency region. Namely, the values of the difference, SDHH - SDHP, indicated an average value of 13 dB as the orientation characteristics. The orientation characteristics of the ferrite plate, however, displayed no orientation characteristics in the frequency region of 200 MHz to 3 GHz. Therefore, in order to improve the orientation characteristics in this frequency region, a compound plate was formed by the superposition of a slit carbon plate over the slit ferrite plate. The values of the difference, SDHH - SDHP, for the compound plate were then improved by approximately 35 dB in the frequency region from 1 MHz to 3 GHz. Experimental results revealed several orientation characteristics of the compound, slit ferrite and carbon plates. [ABSTRACT FROM AUTHOR]

Recently, there has been an increased need for the development of a highly sensitive magnetic sensor for gathering new magnetic information. As one of the basic areas of research for the development of a highly sensitive magnetic sensor, the present authors have constructed a bulk Bi-Pb-Sr-Ca-Cu-O (BPSCCO) magnetic sensor by the shock compaction method as a new fabrication technique of the bulk high-critical temperature superconductor (HTS). Values of the shock compaction pressure P are systematically changed between 1 and 9 GPa to investigate the magnetic sensitivity S of the sensor. It was found that the value of S was related to the value of P. The magnetic sensitivity reached optimum values when maintaining a pressure of! GPa, being approximately 11%/(104 T), and about 11 times that of a giant magnetoresistance (GMR) sensor. The voltage fluctuation of a bulk BPSCCO sensor, when changing the value of P, under a constant current density J, was previously unknown. To help clarify this, systematic measurements were taken of the voltage noise power (VNP) spectrum of the sensor. The results lead to an important criterion for use in the design of a highly reliable and sensitive magnetic sensor. [ABSTRACT FROM AUTHOR]

\REBa2\Cu3\Ox (REBCO, RE = rare earth) coated conductors are expected to show high performance for superconducting applications because of their high current density and high mechanical strength. Fujikura has developed REBCO coated conductor over 570 A/cm width at 77 K, self field with over 800 m length. In addition, we have succeeded in developing a 5 T cryocooled REBCO magnet with a stored energy of 426 kJ. The magnet is composed of 24 pancake coils with an inner diameter of 260 mm, and the total length of the REBCO coated conductors is approximately 7.2 km. We confirmed that the REBCO magnet could be excited up to 5 T for 720 min 9 months after the fabrication of the magnet. It is important to validate the long-term operation test results of the REBCO magnets with larger diameters in order to use these conductors in practical superconducting applications. On the other hand, we have fabricated and evaluated a model magnet before we fabricated a 426 kJ cryocooled magnet. The model magnet is composed of 6 REBCO pancake coils and 18 “dummy coils” with an inner diameter of 260 mm and an outer diameter of 515 mm. The model magnet is about the same size and shape as the 426 kJ cryocooled magnet. We have confirmed that the calculated critical current (Ic) of the top pancake coil of the model magnet was in good agreement with the measured coil Ic from 30 to 77 K under the conduction-cooled conditions. In addition, we have evaluated the thermal runaway behavior of the model magnet under the conduction-cooled conditions. As a result, we have confirmed that the model magnet with a 0.3-mm-thick copper stabilizer had sufficient time to ramp down without degradation at 361 A transport current after the detected normal transition. [ABSTRACT FROM PUBLISHER]

REBCO coated conductors are expected high performance in superconducting applications because of their high current density and high mechanical strength. However, in order to use these conductors in superconducting applications, a technique is required for fabricating impregnated REBCO coils without degradation.In this work, we fabricated six pancake coils without degradation using wounded REBCO coated conductors. These conductors were laminated with a copper tape as a stabilizer, and were fabricated by the IBAD/PLD method. In addition, we evaluated the V-I characteristics and n-values of the coils in liquid nitrogen and compared the calculated and measured values for the critical current (Ic) of the REBCO coated conductors. The measured Ic of the coils were in good agreement with the calculated ones. Furthermore, we fabricated a stacked coil using an approximately 190 m long REBCO coated conductor and evaluated the stability of the stacked coil at 77, 60 and 50 K under conduction-cooled condition. The thermal runaway current of the stacked coil was 166.4 A, and the central magnetic field was 1.27 T at 50 K. [ABSTRACT FROM PUBLISHER]

Single crystals of LuAG doped with Pr3+ ions (0.2 mol%) are grown by the micro-pulling-down (μ-PD) method with an RF heating system. The as-grown crystals are confirmed to be of garnet-type structure with the space group of Ia3d (230). The emission-excitation spectra and luminescence decay kinetics are measured in the temperature range of 5-310 K by using synchrotron radiation as an exciting light source. The intrinsic luminescence is observed at 250 nm at low temperatures. Four emission bands at 308, 325, 360, and 380 nm are ascribed to the 5d- > 4f transitions of Pr 3+ ions. From the decay kinetics measurements, it is pointed out that there exist two kinds of energy transfer mechanisms from the host LuAG lattice to the Pr 3+ ions. The mechanisms of energy transfer are discussed in connection with the formation of substitution-type defects. [ABSTRACT FROM AUTHOR]

CeF3 single crystals heavily doped with Sr2+ ions are grown by the micro-pulling-down (μ-PD) method. The deviation of the composition in as-grown crystals is found to be entirely negligible. Three dimensional emission-excitation spectra are measured in a wide temperature range of 5-300 K by using synchrotron radiation as an exciting light source. Two intense emission bands are observed at around 320 and 400 nm. The origin of these bands is discussed on the basis of the perturbation effects introduced by Sr doping. It is pointed out that the energy transfer takes place from Ce3+ sites to defect sites when the crystal is warmed from 5 to 300 K. [ABSTRACT FROM AUTHOR]

In order to improve the electromagnetic environment associated with the widespread use of electronic devices for communication, computation, automation, among other purposes, the present paper has developed a carbon plate that exhibits polarization characteristics. To achieve polarization characteristics in the far field, slits were cut into the surface of a carbon plate; termed the slit carbon plate. The value of the RF magnetic shielding degree SDHP when holding the slits of the carbon plate perpendicular to the ground, in the frequency region of 140 MHz to 700 MHz, increased with frequency, and displayed a value of 35 dB at 700 MHz. It was also shown that the value of SDHH, when aligning the slits horizontal to the ground, increased with frequency, and recorded a value of 5 dB at 700 MHz. Namely, the difference in the shielding degrees of the slit carbon plate for the orientation of the slits indicated polarization characteristics. In present research, the polarization characteristics of the slit carbon plate were improved, in the frequency region of 1 MHz to 800 MHz, by the superposition of slit ferrite and copper plates over the slit carbon plate; termed compound plate. For example, the difference between the values of SDHP and SDHH for the compound plate at 30 MHz was found to be improved by approximately 50 dB. In addition, important criteria are discussed for the design of a plate having polarization characteristics, for effective RF magnetic shielding. [ABSTRACT FROM AUTHOR]

With rapid development in the field of information technology, there has been increased interest for electromagnetic shielding in the radio frequency (RF) region. An excellent RF magnetic shielding material can be realized by the use of bincho-charcoal, a high quality charcoal found in Japan, due to its very large value of relative permittivity in the RF region. The present paper has improved the RF magnetic shielding characteristics of a bincho-charcoal plate to realize a broadband frequency by the superposition of a ferrite plate over the bincho-charcoal plate. This configuration is termed the compound plate. The RF magnetic shielding effects of the compound plate have been examined, including the characteristics of the RF magnetic effect against both the frequency and the RF magnetic power. In addition, RF electric shielding effects have been examined as functions of the frequency and the RF electric power. [ABSTRACT FROM AUTHOR]

A c-axis oriented epitaxial REBa2Cu3Oy (RE 123) thin film performs excellent superconducting properties in magnetic field. Recently, we reported that a critical current density (Jc) in the RE123 thin film was improved by a deliberate composition control. A Sm1+xBa2-xCu3Oy (Sm123) thin film with a small amount of Sm/Ba substitution x showed the great Jc ∼ 0.17 MA/cm² in 5 T at 77.3 K, while the Jc in (Yb1-xNdx)Ba2Cu3Oy (Yb/Nd123) thin films depended on an amount of mixed crystal ratio z. In this report, we studied Jc as a function of magnetic field and field orientation with respect to a b-planes. In low magnetic field, the Jc of Sm123 thin film was almost independent of the applied angle of the field. In the case of Yb/Nd 123 thin film, extremely high Jc were observed when the magnetic field was aligned parallel or perpendicular to the surface of the film. Because compositional fluctuations in RE 123 thin films were observed by transmission electron microscopy, we found that the pinning centers in RE 123 thin films are strongly affected by the composition in the thin films. [ABSTRACT FROM AUTHOR]

In the present study, the authors describe a system using optical and magnetic sensors to measure the thickness of polymer sheets accurately. A newly developed planar error correction method used in the manufacturing process of the sheet is also presented. The system was drastically improved for the precision of measurement of the polymer sheet, resulting in a precision of ±1% or less. As a result, we have succeeded to produce sheets with thickness of 300 μm at a manufacturing process speed of approximately 30 m/min. [ABSTRACT FROM AUTHOR]