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Search Publications by: Yuri Ralchenko (Fed)

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Displaying 51 - 75 of 97

Transition Energies of the D-lines in Na-like Ions

June 5, 2013
Author(s)
John D. Gillaspy, Dmitry D. Osin, Yuri Ralchenko, Joseph Reader, S A. Blundell
The NIST electron beam ion trap (EBIT) was used to measure the D1 (3s-3p1/2) and D2 (3s-3p3/2) transitions in Na-like ions of xenon, barium, samarium, gadolinium, dysprosium, erbium, tungsten, platinum, and bismuth. New relativistic many-body perturbation

Testing the Reliability of Non-LTE Spectroscopic Models for Complex Ions

May 11, 2013
Author(s)
Yuri Ralchenko, S Hansen, S. Bastiani-Ceccotti, C. Bowen, H.-K. Chung, J. Colgan, F. de Gaufridy de Dortan, C. J. Fontes, F. Gilleron, J.-C. Marques, R. Piron, O. Peyrusse, M. Poirier, A. Sasaki, E. Stambulchik, F. Thais
Collisional-radiative atomic models are widely used to help diagnose experimental plasma conditions through fitting and interpreting measured spectra. Here we present the results of a code comparison in which a variety of models determined plasma

Collisional-Radiative Modeling for Highly-Charged Ions of Tungsten

April 23, 2013
Author(s)
Yuri Ralchenko
We present an overview of the recent advances in collisional-radiative modeling of highly-charged ions of tungsten that are relevant to fusion research. The status of spectroscopic data for W ions is briefly discussed as well. Strategies and peculiarities

EUV magnetic-dipole lines from highly-charged high-Z ions with an open $3d$ shell

November 27, 2012
Author(s)
Yuri Ralchenko, John D. Gillaspy, Joseph Reader, Dmitry D. Osin
The electron beam ion trap (EBIT) at the National Institute of Standards and Technology was used to produce highly-charged ions of hafnium, tantalum and gold with an open $3d$ shell. The extreme-ultraviolet (EUV) spectra from these ions were recorded with

EUV spectra of Rb-like to Cu-like gadolinium ions in an electron beam ion trap

October 8, 2012
Author(s)
Yuri Ralchenko, Deirdre Kilbane, G. O'Sullivan, John D. Gillaspy, Joseph Reader
Measurements of extreme ultraviolet radiation from highly-charged gadolinium ions were made at the National Institute of Standards and Technology. The ions were produced and confined in an electron beam ion trap (EBIT) and the spectra were recorded with a

Non-statistical population distributions for hydrogen beam in fusion plasmas

July 27, 2012
Author(s)
O. Marchuk, Yuri Ralchenko, D. R. Schultz
Most atomic models for a neutral hydrogen beam in fusion plasmas assume statistical (Boltzmann) distribution of populations for excited states with the same principal quantum number n. Here we analyze population distributions for the excited magnetic

Populations of excited parabolic states of hydrogen beam in fusion plasmas

January 1, 2012
Author(s)
Oleksandr Marchuk, Yuri Ralchenko
The injection of a neutral beam into the core of magnetically confined plasmas is a foundation for various plasma diagnostics, including charge-exchange recombination spectroscopy, beam-emission spectroscopy and motional Stark effect diagnostics. We review

EUV Spectral Lines of Highly-Charged Hf, Ta and Au Ions Observed with an Electron Beam Ion Trap

January 12, 2011
Author(s)
Ilija Draganic, Yuri Ralchenko, Joseph Reader, John D. Gillaspy, Joseph N. Tan, Joshua M. Pomeroy, Samuel M. Brewer, Dmitry D. Osin
Extreme ultraviolet spectra of highly charged hafnium, tantalum, and gold were produced with an electron beam ion trap (EBIT) at the National Institute of Standards and Technology (NIST) and recorded with a flat-field grazing-incidence spectrometer in the

Consistency of atomic data for the interpretation of beam emission spectra

November 8, 2010
Author(s)
E. Delabie, M. Brix, R. J. Jasper, C. Giroud, O. Marchuk, M. G. O'Mullane, Yuri Ralchenko, E Surrey, M. G. von Hellermann, K. Zastrow, JET-EFDA Contributors
Several collisional-radiative (CR) models \citeanderson,hutchinson,marchuk:htpd} have been developed to calculate the attenuation and the population of excited states of hydrogen or deuterium beams injected into tokamak plasmas. The datasets generated by

Atomic Spectroscopic Databases at NIST

October 28, 2010
Author(s)
Joseph Reader, Alexander Kramida, Yuri Ralchenko
We present recent work at NIST to develop and maintain databases for spectra, transition probabilities, and energy levels of atoms that are astrophysically important. We also describe our programs to critically compile these data as well as the recently

Measurement of the D Line Doublet in High-Z Highly-Charged Sodium-like Ions

July 8, 2009
Author(s)
John D. Gillaspy, Ilija Draganic, Yuri Ralchenko, Joseph Reader, Joseph N. Tan, Joshua M. Pomeroy, Samuel M. Brewer
We report a direct observation of the D line doublet of sodium-like ions with Z≥72. Spectra in the 1 nm to 9 nm spectral range are presented showing the widely split doublet for Hf61+, Ta62+, W63+,and Au68+. The ions were produced and confined in an

Large-scale MCHF Calculation of the Li I 4d-4f Energy Separation

November 1, 2007
Author(s)
Yuri Ralchenko, Charlotte Fischer
The calculational methods in atomic structure are currently capable of providing the level of accuracy close to that of the most precise experiments. The multiconfiguration Hartree-Fock method is applied to calculation of the 4d--4f energy difference in Li

Spectra of W 39+ -W 47+ in the 12 nm to 20 nm Region Observed With an EBIT Light Source

October 14, 2007
Author(s)
Yuri Ralchenko, Joseph Reader, Joshua M. Pomeroy, Joseph N. Tan, John D. Gillaspy
We observed spectra of highly ionized tungsten in the extreme ultraviolet with an electron beam ion trap (EBIT) and a grazing incidence spectrometer at the National Institute of Standards and Technology. Stages of ionization were distinguished by varying

Density Dependence of the Forbidden Lines Ni-Like Tungsten

June 14, 2007
Author(s)
Yuri Ralchenko
The magnetic-octupole (M3) and electric-quadrupole (E2) transitions between theground state $3d^{10}~^1S_0$ and the lowest excited $3d^94s$ $(5/2,1/2)$ J = 3and J = 2 states in the Ni-like tungsten are shown to exhibit a strongdependence on electron

Is There a High Energy Particle Population in the Quiet Solar Corona?

December 6, 2006
Author(s)
Yuri Ralchenko, Uri Feldman, G. A. Doschek
A study of spectra emitted by the quiet solar corona indicates that the majority of line intensities originating in low-lying levels are consistent with isothermal plasma of ~1.3 106 K. Nevertheless, a number of line intensities and in particular those