Search

We present laboratory spectra of dielectronic recombination (DR) satellite transitions attached to the He-like and H-like iron resonance lines obtained with the NASA Goddard Space Flight Center X-ray calorimeter and produced by a thermal plasma simulation technique on the EBIT-I electron beam ion trap at the Lawrence Livermore National Laboratory. We demonstrate that the calorimeter has sufficient spectral resolution in the 6-9 keV range to provide reliable measurements not only of standard DR satellite to resonance line intensities but also of DR satellite to DR satellite ratios that can be used to diagnose nonthermal electron distributions. Electron temperatures derived from the measured line intensities are consistent with the temperature of the simulated plasma. Temperature measurements based on DR satellite transitions have significant advantages over those based on collisional ionization equilibrium or continuum shape. Thus, successful demonstration of this method with the X-ray calorimeter is an important step for its application in X-ray astronomy. PACS Nos: 32.30.Rj, 32.70.Fw, 95.30.Ky, 95.55.Ka Nous presentons des spectres en laboratoire de transitions satellites a recombinaison dielectronique (DR), reliees aux raies de resonance dans le fer de types He et H obtenus a l'aide du calorimetre a rayon-X du Goddard Space Flight Center de la NASA et produits par technique de simulation de plasma thermique a l'aide du piege ionique a faisceau d'electrons EBIT-1 au Lawrence Livermore National Laboratory. Nous demontrons que le calorimetre a suffisamment de resolution spectrale dans le domaine 6-9 keV pour fournir des mesures fiables, non seulement des intensites de raie, de satellites DR a resonance, mais aussi des rapports de satellite DR a satellite DR, qui peuvent etre utilises dans les diagnostiques de distributions electroniques non thermalisees. Les temperatures electroniques obtenues a partir des intensites de raie mesurees sont coherentes avec la temperature du plasma de simulation. Les mesures de temperature basees sur les transitions satellites DR ont un avantage significatif sur celles basees sur l'equilibre de l'ionisation par collision ou la forme du continu. Ainsi, la demonstration reussie de cette methode avec le calorimetre a rayon-X est une etape importante pour son application en astronomie dans le domaine des rayons-X. [Traduit par la Redaction], 1. Introduction The electron temperature, or the electron energy distribution in general, is an important property of laboratory plasmas, but is an even more important property of astrophysical plasmas. For [...]

Surface-enhanced infrared absorption spectroscopy (SEIRAS) in attenuated total reflection (ATR) configuration has been extended to the Fe electrode/electrolyte interface in neutral and weakly acidic solutions for the first time. The SEIRA-active Fe film electrode was obtained through a potenfiostatic electrodeposition of a virtually pinhole-free 40 nm-thick Fe overfilm onto a 60 nm-thick Au underfilm chemically predeposited on the reflecting plane of an ATR Si prism. The infrared absorption for CO adlayer at the Fe film electrode measured with ATR-SEIRAS was enhanced by a factor of larger than 34, as compared to that at a Fe bulk electrode with external infrared absorption spectroscopy in the literature. More importantly, the unipolar band shape enabled the reliable determination of the Stark tuning rates of CO adlayer at Fe electrode. In situ ATR-SEIRAS was also applied to study the electrosorption of a typical corrosion inhibitor benzotriazole (BTAH) on Fe electrode as a function of potential, providing additional spectral information at positive potentials in support of the formation of a polymer-like surface complex [Fe.sup.II.sub.m][(BTA).sub.n], as the corrosion-resistant layer. 10.1021/ac1002323

A novel iron loss calculation method is proposed based on an iron loss map for an ac filter inductor used in a pulsewidth-modulation (PWM) inverter. The iron loss map, previously reported by the authors, is created by measuring the dynamic minor loop on the B-H plane, and this is used for the calculation of inductor iron loss in the dc chopper circuit. However, in the case of an ac filter inductor used in a PWM inverter, the iron loss map cannot be directory applied to the iron loss calculation. In this paper, an iron loss calculation for an ac filter inductor is presented by expanding the loss map method. We describe the principle of expansion and the practical procedure for the calculation, which utilizes the loss map and a conventional circuit simulator. Iron loss for the ac filter inductor under some typical modulation methods of the PWM inverter are calculated and discussed with regard to the relation between the modulation methods and iron loss. The calculated results are verified using experimental results from a 500-W inverter setup. The inductor loss and conversion efficiency of the PWM inverter are measured for each modulation method. Index Terms--AC filter inductor loss, pulsewidth-modulation (PWM) inverters.

The article presents a new approach that can be used for an improved analysis of the periodic permanent magnet (PPM) focusing structure for the linear beam tubes. The approach is shown to include the effects of the magnetic saturation in the iron pole pieces as well and hence is extremely accurate.

The results of the magnetic field measurement of the J-PARC RCS sextupole magnets have satisfied the requirements of the chromaticity correction schemes. Eddy currents in the end plate have caused an undesirable temperature rise and the eddy currents in the thin-layered iron are considered because the longitudinal component of the magnetic field near the end would be large.

Spectroelectrochemical sensing a metal in two different oxidation states, both of which are weakly absorbing in the visible wavelength range, was demonstrated with ferrous and ferric ion. The sensor consisted of an indium tin oxide optically transparent electrode (ITO OTE) coated with a thin film of Nafion preloaded with the ligand 2,2'bipyridine (bipy). [Fe.sub.2+] in the sample partitioned into the film where it reacted with bipy to form Fe[(bipy).sup.2+.sun.3], which absorbs strongly at 520 nm. The change in absorbance ([DELTA]A) at 520 nm associated with the accumulation of Fe[(bipy).sup.2+.sub.3] complex in the film was measured by attenuated total reflectance spectroscopy and was proportional to the concentration of [Fe.sup.2+] in the sample. Iron in the [Fe.sup.3+] form can also be determined, but it has a more complex coordination chemistry involving formation of [[Fe.sub.2] [(bipy).sub.4]O[([H.sub.2]O).sub.2]].sup.4+] as well as Fe[(bipy).sup.3+.sub.3] in the film. [Fe.sup.3+] was detected indirectly by reducing the nonabsorbing [Fe.sup.3+]bipy complexes that accumulated in the film to absorbing Fe[(bipy).sup.2+.sub.3] and monitoring [DELTA]A at 520 nm. The effects of film thickness and ligand concentration in the film on sensor sensitivity and response time for [Fe.sup.2+] were evaluated. Detection limits of 0.6 x [10.sup.-6] M for [Fe.sup.2+] and 2 x [10.sup.-6] M for [Fe.sup.3+] were obtained with 300 nm thick films after 30 min of exposure to a quiescent sample. Careful manipulation of the potential applied with simultaneous optical detection enables [Fe.sup.2+] to be distinguished from [Fe.sup.3+], which is the first step in developing a sensor for speciating the two oxidation states in a mixture.

The methods based on the magneto-optical Kerr effect are described for imaging the nonequilibrium spin polarization of electrons in Fe/GaAs spin transport devices. These methods have suggested routes for all-electrical studies of spin-dependent transport in hybrid ferromagnet-semiconductor structures.

A three-dimensional model is described that has computed the magnetic behavior of an iron grain under a varying applied field starting from its microscopic material parameters. The model can be used to determine the quantitative relations between the different microscopic parameters and their influence on the magnetic properties of the ferromagnetic grains.