scholarly journals Determination of Atomic Data Pertinent to the Fusion Energy Program

2013 ◽  
Author(s):  
J. Reader
Keyword(s):  
Fusion Energy ◽  
Atomic Data

scholarly journals Determination of atomic data pertinent to the Fusion Energy Science Program

2014 ◽  
Author(s):  
Yuri Ralchenko ◽  
Alexander Kramida ◽  
John D. Gillaspy ◽  
Joseph Reader ◽  
Charlotte Froese Fischer
Keyword(s):  
Fusion Energy ◽  
Atomic Data ◽  
Science Program ◽  
Energy Science ◽  
Fusion Energy Science

scholarly journals The Abundance of Boron in Disk-Metallicity Stars

2000 ◽  
Vol 198 ◽  
pp. 415-424
Author(s):  
Katia Cunha
Keyword(s):  
Linear Trend ◽  
Solar Spectrum ◽  
Atomic Data ◽  
Solar Photosphere ◽  
Halo Stars ◽  
Orion Association ◽  
Solar Metallicity ◽  
Solar Analysis ◽  
Solar Ratio

Although the behavior of boron versus metallicity has been probed in a fairly large sample of halo dwarfs with HST, it is only very recently that boron abundances have been derived systematically in solar metallicity dwarfs. This effort began with a re-analysis of the solar spectrum with modern atomic data and model atmospheres so that the Sun could be adopted as a standard for the calibration of a line list in the region of the B I transition at 2497 Â. The solar analysis indicates that boron is not depleted in the solar photosphere. From a subsequent study of a sample of 14 field F/G-dwarfs with roughly solar metallicities, it is found that the behavior of boron versus [Fe/H] follows the linear trend that is observed for the halo stars. The average B/Be obtained for solar metallicity stars is 27±5 compared to the solar ratio of 23. The determination of boron abundances in the young B-type and G-type stars of the Orion association reveals a behavior of boron and oxygen in Orion that is opposite of the positive correlation which is observed for the field stars: the boron and oxygen abundances are anticorrelated.

scholarly journals Atomic Data Needed for X-ray and EUV Astronomy

1992 ◽  
Vol 9 ◽  
pp. 573-574
Author(s):  
John C. Raymond
Keyword(s):  
Spectral Resolution ◽  
Atomic Data ◽  
Ionization State ◽  
Crystal Spectrometer ◽  
X Ray ◽  
Transmission Grating ◽  
Elemental Abundances ◽  
The Past ◽  
Accurate Temperature

AbstractThe astronomical X-ray and EUV satellites of the past generally had low enough spectral resolution that atomic data of modest quality was sufficient for most interpretation of the data. Typical proportional counter resolution Δ E/E ~ 1 permits a determination of the spectral shape sufficient for an estimate of the temperature of the emitting gas, but only the Fe K feature at 6.7 keV stands out as a distinct emission line. The higher spectral resolution Einstein Transmission Grating, Solid State Spectrometer, and Focal Plane Crystal Spectrometer instruments measured a score of emission lines or line blends, permitting determinations of the elemental abundances, temperature, and ionization state of the emitting gas. The higher spectral resolution and throughput of the BBXRT aboard the ASTRO mission and the instruments planned for EUVE, ASTRO-D, AXAF, and XMM will make possible a far more detailed analysis of the data. It should be possible to derive better abundances for more elements, accurate temperature distributions, electron densities, and accurate ionization states.

scholarly journals Wind models and synthetic UV spectra for O-type stars

2003 ◽  
Vol 212 ◽  
pp. 206-207
Author(s):  
Tadziu L. Hoffmann ◽  
Adalbert W.A. Pauldrach ◽  
Joachim Puls
Keyword(s):  
Uv Spectra ◽  
Atomic Data ◽  
Atmospheric Models ◽  
Adequate Model ◽  
Model Code ◽  
Synthetic Spectra ◽  
Realistic Description ◽  
Rigorous Treatment ◽  
Adequate Representation

Spectral analysis of hot stars requires adequate model atmospheres, which take into account the effects of non-LTE and radiation-driven winds properly. Here we present significant improvements of our approach in constructing detailed atmospheric models and synthetic spectra for O-type stars (model code wm-basic; see Pauldrach, Hoffmann & Lennon 2001). The most important ingredients of these models with regard to a realistic description of stationary winds are: (i) a rigorous treatment of line blocking and blanketing; (ii) a consistent determination of the radiative line acceleration; (iii) a considerably improved and enhanced atomic data archive providing the basis for a detailed multilevel non-LTE treatment and an adequate representation of the radiative line driving; and (iv) the inclusion of EUV and X-ray radiation produced by cooling zones originating from shock-heated matter. This new tool not only allows to constrain the properties of stellar winds, the stellar parameters, and the abundances via a comparison of observed and synthetic spectra, but also provides the astrophysically important information about the ionizing fluxes of these stars. We use this new method to compute selfconsistent wind parameters for a series of Galactic stars analyzed in the optical and verify the theoretically predicted dependence of the wind momentum on metallicity.

Revisiting RV Tauri stars: first ionization potential (FIP) effect

2019 ◽  
Vol 97 (11) ◽  
pp. 1210-1220
Author(s):  
G. Yolalan ◽  
T. Şahin
Keyword(s):  
Asymptotic Giant Branch ◽  
Equilibrium Analysis ◽  
Atomic Data ◽  
Alternative Mechanism ◽  
Asymptotic Giant Branch Stars ◽  
Echelle Spectrograph ◽  
Elemental Abundances ◽  
First Time ◽  
Giant Branch Stars

We have derived elemental abundances of eight RV Tauri-type post-asymptotic giant branch stars: AR Sgr, CE Vir, DY Aql, HP Lyr, SS Gem, SZ Mon, TT Oph, and UZ Oph. The abundance analysis of these luminous stars is based on the high-resolution (R ≈ 55 000) optical echelle spectra obtained with the 2.1 m Struve reflector telescope and the CCD-equipped Sandiford Cassegrain echelle spectrograph at the McDonald Observatory. Standard 1D local thermodynamic equilibrium analysis provides a fresh determination of the atmospheric parameters and elemental abundances for 17 species including C, Na, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, and Nd. Then, the computed up-to-date abundances are used to investigate FIP in the program stars, as seen in the Sun and sun-like stars. Also, we scrutinize their behavior for dust–gas separation as an alternative mechanism to the FIP. For the first time, we provide atomic line lists with up-to-date atomic data employed in the analysis for AR Sgr, HP Lyr, SZ Mon, TT Oph, and UZ Oph.

Applications of EBIT to magnetic fusion diagnostics

2008 ◽  
Vol 86 (1) ◽  
pp. 285-290 ◽  
Author(s):  
C H Skinner
Keyword(s):  
Fusion Energy ◽  
Atomic Data ◽  
World Population ◽  
Magnetic Fusion ◽  
Spectroscopic Diagnostics ◽  
Radiation Losses ◽  
Plasma Facing Components ◽  
Burning Plasmas ◽  
Fusion Diagnostics ◽  
52.70 Kz

Fusion-energy development has reached an exciting stage with the agreement by seven nations, representing over half the world population, to build the International Thermonuclear Experimental Reactor (ITER) and demonstrate the scientific and technological feasibility of magnetic fusion. High-Z materials such as tungsten are used in plasma-facing components, and contamination of the plasma by sputtered impurities must be controlled to limit radiation losses. Spectroscopic diagnostics will be used to monitor impurity influx and EBIT has played a key role in generating the atomic data necessary to interpret the spectroscopic observations. In this paper, we focus on the key contributions that EBIT devices are uniquely positioned to make in the spectroscopic diagnostics of next-step burning plasmas such as ITER and list specific areas where new data are needed. PACS Nos.: 32.30.Jc, 32.30.Rj, 52.40.Hf, 52.55.Fa, 52.70.Kz, 52.70.La

scholarly journals Main Sequence Evolution, Abundance Anomalies and Particle Transport

2002 ◽  
Vol 12 ◽  
pp. 279-281
Author(s):  
Georges Michaud ◽  
Olivier Richard ◽  
Jacques Richer
Keyword(s):  
Stellar Evolution ◽  
Particle Transport ◽  
Main Sequence ◽  
Convection Zone ◽  
Accurate Determination ◽  
Atomic Diffusion ◽  
Atomic Data ◽  
Data Bases ◽  
Abundance Anomalies

AbstractThe availability of large atomic data bases has made it possible to calculate stellar evolution models taking into detailed account the abundance variations of all important contributors to opacity. In a first step, in addition to nuclear reactions, the atomic diffusion, radiative accelerations and opacity are continuously calculated during evolution taking the abundance changes of 28 species into account. This leads to the first self consistent main sequence stellar evolution models. In A and F stars (M≥ 1.5Mʘ) an iron peak convection zone is shown to appear at a temperature of 200000 K. The calculated surface abundance anomalies, that follow without any arbitrary parameter, are very similar to those observed in AmFm stars in open clusters except that they are larger by a factor of about 3. The second step, is then to introduce a competing hydrodynamical process. To reduce the calculated anomalies to the observed ones, turbulence has been introduced. It is found that the mixed zone must be about 5 times deeper than the iron convection zone. Detailed comparisons to a few AmFm stars have been carried out. The determination of the abundance anomalies of a large number of atomic species (20 to 30 are probably accessible) makes it possible to constrain stellar hydrodynamics. In clusters, the original abundances and age may be known and the accurate determination of surface abundances may constrain turbulence, mass loss and differential rotation when the required atomic data bases are available and used for the modeling of particle transport in stellar evolution.

scholarly journals Spectroscopy in Ne-Like Plasmas. Z-Dependence of the Atomic Data Used in a Collisional-Radiative Model

1988 ◽  
Vol 102 ◽  
pp. 95-97
Author(s):  
M. Cornille ◽  
J. Dubau ◽  
M. Loulergue ◽  
S. Jacquemot
Keyword(s):  
Radiative Decay ◽  
Dielectronic Recombination ◽  
Rate Coefficients ◽  
Atomic Data ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Structure Scheme ◽  
Distorted Waves ◽  
Laser Experiments

AbstractThe Livermore X-ray Laser experiments in 1984 have shown the existence of Ne-like 3p-3s population inversions in a collisional Se plasma (Z=34) with significant gains (5 cm-1). We have focused our efforts on the behavior of the gains along the target neon Isoelectronic sequence. This study implies the determination of the Z-dependance of the rate coefficients of all the Involved atomic processes: collisional excitation (C). radiative decay (A) and dielectronic recombination (αd). Thus we use atomic structure and electron-ion collisional codes (SUPERSTRUCTURE. Distorted Waves. AUTOLSJ and JJOM). The different calculations have been done on a large selection of ions, from Ar to Ag. They Include relatlvistic effects in a fine structure scheme. The Z-dependance of the numerical results is expressed as polynomial or rational forms.

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