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Search Publications by: Yuri Ralchenko (Fed)

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Displaying 26 - 50 of 97

Recommended electron-impact excitation and ionization cross sections for Be I

November 23, 2018
Author(s)
FNU Dipti, Tapasi Das, klaus Bartschat, I Bray, D Fursa, O Zatsarinny, C Ballance, H-K Chung, Yuri Ralchenko
Analytic fits to the recommended electron-impact excitation and ionization cross sections for Be I are presented. The lowest 19 terms of configurations 2snl (n 4) and 2p2 terms below the first ionization limit are considered. The fits are based on the

Measuring the difference in nuclear charge radius of Xe isotopes by EUV spectroscopy of highly charged Na-like ions

November 5, 2018
Author(s)
Roshani Silwal, A. Lapierre, John D. Gillaspy, Joan M. Dreiling, S A. Blundell, Dipti Goyal, A. Borovik, Jr., G Gwinner, A.C.C. Villari, Yuri Ralchenko, Endre Takacs
The difference in the mean-square nuclear charge radius of xenon isotopes was measured utilizing a method based on extreme ultraviolet spectroscopy of highly charged Na-like ions. The isotope shift of the Na-like D1 (3s 2S1/2 − 3p 2P1/2) transition between

Standard Reference Data Workshop Report

June 12, 2018
Author(s)
Debra L. Kaiser, Neil Alderoty, Richard R. Cavanagh, Barbara Guttman, Robert J. Hanisch, Adam G. Morey, Jeanita Pritchett, Yuri Ralchenko, Stacy S. Schuur, William E. Wallace
On October 17, 2017, the ODI sponsored a day-long Standard Reference Data Workshop. More than 120 NIST staff members and associates from four NIST laboratories and three offices registered for this workshop. The workshop format consisted of presentations

Relativistic all-order many-body calculation of energies, wavelengths, and M1 and E2 transition rates for the 3d^n configurations in tungsten ions

January 3, 2018
Author(s)
M S. Safronova, U I. Safronova, S. G. Porsev, M G. Kozlov, Yuri Ralchenko
Energy levels, wavelengths, magnetic-dipole and electric-quadrupole transition rates between the low-lying states are evaluated for W51+ to W54+ ions with 3dn (n = 2 to 5) electronic con gurations using an approach combining con guration interaction with

Infrared and visible laser spectroscopy for highly-charged Ni-like ions

April 12, 2017
Author(s)
Yuri Ralchenko
Application of visible or infrared (IR) lasers for spectroscopy of highly-charged ions (HCI) has not been particularly extensive so far due to a mismatch in typical energies. We show here that the energy difference between the two lowest levels within the

Review of the 9th NLTE code comparison workshop

February 24, 2017
Author(s)
R. Piron, F. Gilleron, Y Aglitskiy, H.-K. Chung, C. J. Fontes, S. B. Hansen, O. Marchuk, H. Scott, E. Stambulchik, Yuri Ralchenko
We review the 9th NLTE code comparison workshop, which was held in the Jussieu campus, Paris, from November 30th to December 4th, 2015. This time, the workshop was mainly focused on a systematic investigation of iron NLTE steady-state kinetics and

Multi-configuration Dirac-Hartree-Fock calculations of forbidden transitions within the 3d^k ground configurations of highly charged ions (Z = 72 - 83)

February 21, 2017
Author(s)
Z.L. Zhao, K. Wang, S. Li, R. Si, C.Y. Chen, J. Yan, Yuri Ralchenko
Extensive self-consistent multi-configuration Dirac-Hartree-Fock (MCDHF) calculations are performed for the 3s^2 3p^6 3d^k(k = 1−9) ground configurations of highly charged ions (Z = 72−83). Complete and consistent data sets of level energies,wavelengths

Validation and Verification of Collisional-Radiative Models

February 25, 2016
Author(s)
Yuri Ralchenko
Quality control is as relevant to scientific computing as to any other software. For complex collisional-radiative (CR) models that are used to calculate plasma population kinetic parameters and spectra, each computer code is expected to be thoroughly

SOLAR-WIND ION DRIVEN X-RAY EMISSION FROM COMETARY AND PLANETARY ATMOSPHERES: MEASUREMENTS AND THEORETICAL PREDICTIONS OF CHARGE- EXCHANGE CROSS SECTIONS AND EMISSION SPECTRA FOR O6+ + H2O, CO, CO2, CH4, N2, NO, N2O, AND Ar

August 15, 2015
Author(s)
J. R. Machacek, D. P. Mahapatra, David R. Schultz, Yuri Ralchenko, A. Moradmand, O. E. Ghazaly, A. Chutjian
Relevant to modeling and understanding X-ray emission from cometary and planetary atmospheres, total cross sections for 1.17 and 2.33 keV/u O6+ colliding with H2O, CO, CO2, CH4, N2, NO, N2O, and Ar have been measured for the processes of single, double

NIST program of spectroscopic data for light elements of fusion interest

January 15, 2015
Author(s)
Joseph Reader, Alexander Kramida, Yuri Ralchenko, Wolfgang L. Wiese, Jeffrey R. Fuhr
This paper summarizes work at the National Institute of Standards and Technology (NIST) in support of the IAEA Coordinated Research Project on “Light Element Atom, Molecule and Radical Behaviour in the Divertor and Edge Plasma Regions.” It includes

Measurement and Calculation of Absolute Single and Double Charge Exchange Cross Sections for O6+ Ions at 1.17 keV/u and 2.33 keV/u Impacting He and H2

November 10, 2014
Author(s)
J. R. Machacek, D. P. Mahapatra, D. R. Schultz, Yuri Ralchenko, A. Chutjian, J. Simcic, S. M. Madzunkov, R. J. Mawhorter
Absolute single and double charge-exchange (CE) cross sections for the astrophysically-prominent O6+ ion with the atomic and molecular targets He and H2 are reported. These collisions give rise to X-ray emissions in the interplanetary medium, planetary

EUV spectra of Rb-like to Ni-like dysprosium ions in an electron beam ion trap

August 12, 2014
Author(s)
Deirdre Kilbane, G. O'Sullivan, Yuri A. Podpaly, John D. Gillaspy, Joseph Reader, Yuri Ralchenko
Extreme ultraviolet radiation emitted from highly-charged dysprosium ions was measured at the National Institute of Standards and Technology. The ions were created, trapped, and excited in an electron beam ion trap (EBIT), and the spectra were recorded

Measurement of High-Energy (10 keV to 60 keV) X-Ray Spectral Line Widths with eV Accuracy

August 8, 2014
Author(s)
John F. Seely, Jack L. Glover, Lawrence T. Hudson, Yuri Ralchenko, Nino R. Pereira, U. Feldman, C. D. Stefan
A high resolution crystal spectrometer (HRCS) utilizing a crystal in transmission geometry has been developed and experimentally optimized to measure the line widths of emission lines in the 10 keV to 60 keV energy range with eV accuracy. The spectrometer

Extreme ultraviolet spectra and analysis of ?n=0 transitions in highly charged barium

July 4, 2014
Author(s)
Joseph Reader, John D. Gillaspy, Dmitry D. Osin, Yuri Ralchenko
Extreme ultraviolet spectra of highly charged barium atoms were produced with an electron beam ion trap (EBIT) and recorded with a flat-field grazing-incidence spectrometer. The spectra were measured in the wavelength range 4 nm to 24 nm with the beam

ATOMIC DATA AND COLLISIONAL-RADIATIVE MODEL FOR BERYLLIUM AND ITS IONS

May 2, 2014
Author(s)
D. Kondratyev, O. Marchuk, Leonid Vainshtein, Igor Bray, Dmitry Fursa, Yuri Ralchenko, D. Fursa
In this work we present a collisional-radiative model constructed for all ionization stages of beryllium. Convergent close-coupling, K-matrix and Coulomb-Born-exchange methods were applied to calculate the necessary atomic data. For neutral beryllium atom

Benchmark of collisional-radiative models for ITER beams at Alcator C-Mod tokamak

November 12, 2013
Author(s)
I. O. Bespamyatnov, W. L. Rowan, K. T. Liao, O. Marchuk, Yuri Ralchenko, R. S.
The beam-based plasma diagnostics on ITER require high accuracy and reliability which accordingly puts challenging requirements on the collisional-radiative (CR) models used for the description of excited states of high energy beam atoms. These states are

EUV spectra from N-shell ions of Gd, Dy and W

September 23, 2013
Author(s)
Deirdre Kilbane, John D. Gillaspy, Yuri Ralchenko, Joseph Reader, G. O'Sullivan
Measurements of extreme ultraviolet radiation from gadolinium, dysprosium and tungsten ions with an open n=4 shell were performed at the National Institute of Standards and Technology. The ions were produced and confined in an electron beam ion trap and

Magnetic-dipole lines in 3dn ions of high-Z elements: identification, diagnostic potential, and dielectronic resonances

September 23, 2013
Author(s)
Yuri Ralchenko, John D. Gillaspy, Joseph Reader, Dmitry D. Osin, John J. Curry, Yuri A. Podpaly
We present a review of measurements and analyses of extreme-ultraviolet magneticdipole (M1) lines in 50-60-times ionized atoms of tungsten, hafnium, tantalum, and gold with an open 3d shell. The spectra were measured with the electron beam ion trap at the

Anisotropic LMN dielectronic resonances from ratios of magnetic-dipole lines

July 13, 2013
Author(s)
Yuri Ralchenko, John D. Gillaspy
Signatures of multi-keV LMN dielectronic resonances in highly-charged 3dn ions of tungsten were detected in the intensity ratios of extreme-ultraviolet magnetic-dipole lines within ground configurations. The measurements were performed with an electron

Atomic data for beam-stimulated plasma spectroscopy in fusion plasmas

July 11, 2013
Author(s)
O. Marchuk, Yuri Ralchenko, David R. Schultz, W. Biel, T. Schlummer, TEXTOR Team
Injection of high energy atoms into a confined plasma volume is an established diagnostic technique in fusion research. This method strongly depends on the quality of atomic data for charge exchange spectroscopy (CXRS), motional Stark effect (MSE) and beam

Comparison and Analysis of Collisional-Radiative Models at the NLTE-7 Workshop

June 25, 2013
Author(s)
Yuri Ralchenko, H.-K. Chung, S Hansen, C. Bowen, C. J. Fontes
We present the main results of the 7th Non-Local Thermodynamic Equilibrium Code Comparison Workshop held in December 2011 in Vienna, Austria. More than twenty researchers from nine countries, who actively work on development of collisional-radiative codes