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We report an investigation of anomalous-Hall resistance (AHR) and spin-Hall magnetoresistance (SMR) in Pt/Ir20Mn80/Y3Fe5O12 (Pt/IrMn/YIG) heterostructures. The AHR of Pt/IrMn/YIG heterostructures with an antiferromagnetic inserted layer is dramatically enhanced as compared to that of the Pt/YIG bilayer. The temperature dependent AHR behavior is nontrivial, while the IrMn thickness dependent AHR displays a peak at an IrMn thickness of 3 nm. The observed SMR in the temperature range of 10-300 K indicates that the spin current generated in the Pt layer can penetrate the IrMn layer (≤3 nm) to interact with the ferromagnetic YIG layer. The lack of conventional anisotropic magnetoresistance (AMR) implies that the insertion of the IrMn layer between Pt and YIG could efficiently suppress the magnetic proximity effect (MPE) on induced Pt moments by YIG. [ABSTRACT FROM AUTHOR]

Wind gust characteristics at wind turbine relevant height are closely tied with wind turbine design and wind power generation, however, they have not been detailed and documented. In this study, high-resolution wind data recorded by 3D sonic anemometers at a tall meteorological tower were analyzed to determine 12 descriptors of wind gusts and to identify the parent distributions that best fit these parameters. The main statistics were estimated using wind data from the 160 m height. It is found that the log-logistic distribution is most appropriate for a 10-min mean wind speed, gust magnitude, gust factor, and turbulence intensity; the gamma distribution appears to best fit peak factor, rise magnitude, lapse magnitude, lapse time, and gust length scale, while gust amplitude, rise time, and gust asymmetric factor are typically log-normally distributed. Gust factors tend to decrease with mean wind speed but increase as a function of turbulence intensity. The results also indicate that these wind gust descriptive parameters are height-dependent in which the 10-min mean wind speed, gust magnitude, gust length scale, rise time, and lapse time usually possess larger values at higher heights, whereas the remaining parameters exhibit negative correlation with height. [ABSTRACT FROM AUTHOR]

The anomalous Nernst effect (ANE) in disordered Fe0.5(PtxPd1-x)0.5 alloy films is investigated at room temperature. The spin orbit coupling (SOC) strength is continuously tuned by changing the composition of Pt and Pd in Fe0.5(PtxPd1-x)0.5 alloy films. It was found that the ANE voltage VANE increases with the increase of Pt composition. Meanwhile, the νN factor, which indirectly represents the anomalous Nernst efficiency, also increases with raising the composition of Pt. The enhancement of VANE and νN at larger x can be attributed to the increasing of SOC strength, which mainly comes from heavy Pt atoms. The present results will facilitate the theoretical studies of ANE and provide means of manipulating ANE for technological application. [ABSTRACT FROM AUTHOR]

The anomalous Nernst effect (ANE) is investigated experimentally in epitaxial fcc FexNi1-x (0≤x≤0.55) alloy thin films and bcc Fe thin film grown on MgO (001) substrates. The ANE measurements were performed at room temperature for various temperature gradients perpendicular to the film plane. The anomalous Nernst efficiency was indirectly characterized by the factor νN. It is found that both the ANE voltage VANE and the factor νN increase with raising the composition of Fe from 0 to 0.55, due to the presence of more abundant band structures. Moreover, the VANE and νN factor in bcc Fe thin film change sign and decrease sharply in magnitude compared to that of fcc FexNi1-x thin films, indicating that the tuning effects of the band filling near Fermi surface on ANE. The present results will facilitate the theoretical studies of ANE and provide means of manipulating ANE for technological application. [ABSTRACT FROM AUTHOR]

Stochastic phenomena in magnetic nanowires based on domain wall (DW) motion is scientifically important thus to understand and control such behaviors are very meaningful. Here we report on the investigation of pinning and depinning of DWs in permalloy nanowires with six types of longitudinally asymmetric notches using focused magneto-optic Kerr effect (FMOKE) magnetometer and magnetic force microscopy (MFM). The hysteresis loops obtained by FMOKE indicate the generation of one or two distinct depinning fields by creating one notch close to the edge of the nanowires, in comparison multiple depinning processes occur in the nanowires with two identical notches symmetrically placed along the transverse direction, indicating more remarkable stochastic DW depinning phenomena. The MFM images verify the existence of DW in each type of nanowires and the DW sizes in the latter kind of nanowires are generally larger than those in the former ones. These observations can be explained by considering the thermal perturbation and edge or surface roughness effects in nanowires. [ABSTRACT FROM AUTHOR]

We investigate spin-current transport with an antiferromagnetic insulator NiO thin layer by means of the spin-Hall magnetoresistance (SMR) over a wide range of temperature in Pt/NiO/Y3Fe5O12 (Pt/NiO/YIG) heterostructures. The SMR signal is comparable to that without the NiO layer as long as the temperature is near or above the blocking temperature of the NiO, indicating that the magnetic fluctuation of the insulating NiO is essential for transmitting the spin current from the Pt to YIG layer. On the other hand, the SMR signal becomes negligibly small at low temperature, and both conventional anisotropic magnetoresistance and the anomalous Hall resistance are extremely small at any temperature, implying that the insertion of the NiO has completely suppressed the Pt magnetization induced by the YIG magnetic proximity effect (MPE). The dual roles of the thin NiO layer are, to suppress the magnetic interaction or MPE between Pt and YIG, and to maintain efficient spin current transmission at high temperature. [ABSTRACT FROM AUTHOR]

Ion temperatures can be determined from H[sub α] line broadening measured by charge exchange recombination spectroscopy on Hanbit, a mirror device. Since the H[sub α] line emission from hydrogen atoms in plasma edges is much larger than that of the charge exchange recombination emission of ions, the line shape of the latter is submerged into the former when measured by an array detector such as a CCD detector. Thus, a notching filter in front of a detector is needed to block out the central region of the emission line. An optical fiber array detector, which works as a notching filter as well as an array detector, has been developed, since the transmission characteristics of commercial notching filter are not suitable for the line-broadening measurements. The design concept of the optical fiber array detector is described, and the feasibility to determine ion temperatures from the H[sub α] line broadening measurements is estimated. [ABSTRACT FROM AUTHOR]

Provides an overview on the Korea Superconducting Tokamak Advanced Research (KSTAR) project for plasma diagnostics. Determination of plasma control, core plasma and divertor/edge plasma; Characteristics of the KSTAR diagnostics; Motional Stark effect system; Core Thomson scattering system; Machine access for diagnostics.

We report room temperature ferromagnetism in boron-doped ZnO both experimentally and theoretically. The single phase Zn1-xBxO films deposited under high oxygen pressure by pulsed laser deposition show ferromagnetic behavior at room temperature. The saturation magnetization increases monotonically from 0 to 1.5 emu/cm3 with the increasing boron component x from 0% to 6.8%. The first-principles calculations demonstrate that the ferromagnetism in the B-doped ZnO originates from the induced magnetic moment of oxygen atoms in the nearest neighbor sites to B-Zn vacancy pairs. The calculated total magnetic moment shows an increasing trend with the boron component which is consistent with experiment. [ABSTRACT FROM AUTHOR]

A piezoelectric valve, which has a flow rate of about 463 mbar l/s, has been installed to fuel the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. The valve flow rate is in situ calibrated by analyzing the pressure rise curve while fueling the vessel at a constant rate. The calibration method and results are presented. In addition to the flow rate, other vacuum system parameters, such as the pumping speed and the vessel volume, were experimentally obtained. Based on these measurements, a KSTAR vacuum system simulator was developed to calculate the valve drive signal to obtain a programmed pressure trace. An arbitrarily shaped pressure trace was successfully controlled in KSTAR with this hardware and software system. [ABSTRACT FROM AUTHOR]

A radio-frequency-driven hydrogen-ion source of the diagnostic neutral beam has been developed for the Hanbit magnetic mirror device at the Korea Basic Science Institute IS. M. Hwang et al., Trans. Fusion Technol. 35, 99 (1999)]. The three-electrode system with 37 apertures extracts the hydrogen-ion beam with 29.8 kev beam energy and 1.2 A beam current at a 9.6 cm diam. The ion source has the capability of varying the beam pulse width from 10 to 100 ms and also is capable of beam modulation at 50 Hz with a 10 ms flattop pulse width. The beam power and the ratio of the mixed ion species were measured by infrared thermography and Doppler shift spectroscopy, respectively. Most recent experimental results will be presented in this article. [ABSTRACT FROM AUTHOR]

Describes the first results of the ion bean extraction experiments conducted at Korea Basic Science Institute. Experimental setup; Results; Conclusion.

We designed a high power and ultra-wideband two-section 3 dB coaxial hybrid coupler for load resilient ion cyclotron range of frequency heating by configuring asymmetric impedance matching using a three-dimensional simulation code, hfss. By adjusting the characteristic impedances of main and coupled lines of the hybrid coupler, we realized that the bandwidth of the proposed circuit is not only wider than that of a conventional three-section coupler, but also that the bandwidth is almost twice as wide compared to the conventional two-section hybrid coupler while maintaining the identical overall size. [ABSTRACT FROM AUTHOR]

Analyzes the ion species ratios and the angular divergences of the ion beams of a radio-frequency driven multicusp ion source using a Doppler shift spectroscopy of H[sub alpha] spectral lines. Effect of extraction voltage on beam divergences; Effect of gas-target thickness on correction factors; Ion species ratios at varying source pressures.