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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Design Studies and Optimization of High-Field Nb$_3$Sn Dipole Magnets for a Future Very High Energy PP Collider

High filed accelerator magnets with operating fields of 15-16 T based on the $Nb_3Sn$ superconductor are being considered for the LHC energy upgrade or a future Very High Energy pp Collider. Magnet design studies are being conducted in the U.S., Europe and Asia to explore the limits of the $Nb_3Sn$ accelerator magnet technology while optimizing the magnet design and performance parame-ters, and reducing magnet cost. The first results of these studies performed at Fermilab in the framework of the US-MDP are reported in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Radiative rates and electron impact excitation rate coefficients for Ne-like selenium, Se XXV

In this article we report calculations of energy levels, radiative rates, electron impact collision strengths, and effective collision strengths for transitions among the 241 fine-structure levels arising from 2l{sup 8} and 2l{sup 7}n{sup '}l{sup '} (n{sup '{<=}}6 and l{sup '{<=}}n{sup '}-1) configurations of Ne-like Se XXV using the Flexible Atomic Code. Energy levels and radiative rates are calculated within the relativistic configuration-interaction method. Direct excitation collision strengths are calculated using the relativistic distorted-wave approximation and high-energy collision strengths are obtained in the relativistic plane-wave approximation. Resonance contributions through the relevant Na-like doubly-excited configurations 2l{sup 7}n'l'n''l'' (3{<=}n'{<=}7, l'{<=}n'-1, n'{<=}n''{<=}50, and l''{<=}8) are explicitly taken into account via the independent-process and isolated-resonance approximation using distorted waves. Resonant stabilizing transitions and possibly important radiative decays from the resonances toward low-lying autoionizing levels are considered. In addition, the resonance contributions from Na-like 2l{sup 6}3l'3l'''n''' (n'''=3-6) configurations are included and found to be predominant for many transitions among the singly-excited states in Ne-like Se XXV. We present the radiative rates, oscillator strengths, and line strengths for all electric dipole, magnetic dipole, electric quadrupole, magnetic quadrupole, electric octopole, and magnetic octopole transitions among the 241 levels. The effective collision strengths are reported for all 28920 transitions among the 241 levels over a wide temperature range up to 10 keV. To assess the reliability and accuracy of the present collisional data, we have performed a 27-state close-coupling calculation, employing the Dirac R-matrix theory. The results from the close-coupling calculation and the independent-process calculation for the identical target states are found to be in good agreement. - Highlights: {yields} Radiative and collisional atomic data are presented for the lowest 241 fine-structure levels in Ne-like Se. {yields} Calculations are performed using the FAC package. {yields} Resonances enhance significantly a large amount of transitions. {yields} Radiative damping effects are significant for many transitions. {yields} Close-coupling effects are small in Ne-like Se.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Energies, E1, M1, and E2 transition rates, hyperfine structures, and Lande g{sub J} factors for states of the 2s{sup 2}2p{sup 2}, 2s2p{sup 3}, and 2p{sup 4} configurations in carbon-like ions between F IV and Ni XXIII

Energies, electric dipole, magnetic dipole, and electric quadrupole transition rates, hyperfine structures, and Lande g{sub J} factors from relativistic configuration interaction calculations are reported for the states of the (1s{sup 2})2s{sup 2}2p{sup 2}, 2s2p{sup 3}, and 2p{sup 4} configurations in all carbon-like ions between F IV and Ni XXIII. Valence, core-valence, and core-core correlation effects were accounted for through single/double-excitation-multireference expansions to increasing sets of active orbitals. The calculated energy levels generally agree within a few hundred cm{sup -1} with the experimentally compiled results, and the Babushkin (length), and Coulomb (velocity) forms of transition rates agree within less than 1% for a majority of the allowed transitions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

SYSTEMATIC CALCULATIONS OF ENERGY LEVELS AND TRANSITION RATES OF C-LIKE IONS WITH Z = 13-36

Based on systematic calculations using a combined relativistic configuration interaction and a many-body perturbation theory (MBPT) approach, we provide a complete and consistent data set for 46 levels belonging to the 2s {sup 2}2p {sup 2}, 2s2p {sup 3}, 2p {sup 4}, 2s {sup 2}2p3s, 2s {sup 2}2p3p, and 2s {sup 2}2p3d configurations in C-like ions with 13 ≤ Z ≤ 36. The data set includes energy levels as well as electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transition properties. Extensive comparisons with available observed and calculated results are made and indicate that the present MBPT calculations are highly accurate. The present data set can be used reliably for many purposes, such as the line identification of observed spectra, and modeling and diagnostics of astrophysical and fusion plasmas.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Energy levels, lifetimes and radiative rates for transitions in the bromine isoelectronic sequence La XXIII-Dy XXXII, W XL

Using the multiconfiguration Dirac–Fock method, calculations for the lowest 62 levels of the ([Ar] 3d{sup 10})4s{sup 2}4p{sup 5}, ([Ar] 3d{sup 10})4s{sup 2}4p{sup 3}4d{sup 2}, ([Ar] 3d{sup 10})4s{sup 2}4p{sup 4}4d, ([Ar] 3d{sup 10})4s4p{sup 6}, and ([Ar] 3d{sup 10})4s4p{sup 5}4d configurations are performed for the bromine isoelectronic sequence La XXIII-Dy XXXII, W XL. Results of energy levels, lifetimes, wavelengths, and electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole radiative rates are presented. In order to assess the accuracy of results, independent calculations for W XL have been carried out using the many-body perturbation theory (MBPT) method. Comparisons are made with available theoretical results from other calculations and the observed values of the Atomic Spectra Database of the National Institute of Standards and Technology. Energy levels are estimated to be accurate to better than 1%, and radiative rates (and lifetimes) are accurate to better than 20% for a majority of strong transitions. These results should be useful in many applications of lanthanide ions related to broad area of research such as applied physics, laser physics and fusion science.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2016

Extended relativistic configuration interaction and many-body perturbation calculations of spectroscopic data for the N ≤ 6 configurations in Ne-like ions between Cr xv and Kr xxvii

Level energies, wavelengths, electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transition rates, oscillator strengths, and line strengths from combined relativistic configuration interaction and many-body perturbation calculations are reported for the 201 fine-structure states of the 2s{sup 2}2p{sup 6}, 2s{sup 2}2p{sup 5}3l, 2s2p{sup 6}3l, 2s{sup 2}2p{sup 5}4l, 2s2p{sup 6}4l, 2s{sup 2}2p{sup 5}5l, and 2s{sup 2}2p{sup 5}6l configurations in all Ne-like ions between Cr xv and Kr xxvii. Calculated level energies and transition data are compared with experiments from the National Institute of Standards and Technology (NIST) and CHIANTI databases, and other recent benchmark calculations. The mean energy difference with the NIST experiments is only 0.05%. The present calculations significantly increase the amount of accurate spectroscopic data for the n > 3 states in a number of Ne-like ions of astrophysical interest. A complete data set should be helpful for analyzing new observations from solar and other astrophysical sources, and is also likely to be useful for modeling and diagnosing a variety of plasmas, including astronomical and fusion plasma.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2016

CALCULATIONS WITH SPECTROSCOPIC ACCURACY: ENERGIES AND TRANSITION RATES IN THE NITROGEN ISOELECTRONIC SEQUENCE FROM Ar XII TO Zn XXIV

Combined relativistic configuration interaction and many-body perturbation calculations are performed for the 359 fine-structure levels of the 2s{sup 2} 2p{sup 3}, 2 s2p{sup 4}, 2p{sup 5}, 2s{sup 2} 2p{sup 2} 3l, 2 s2p{sup 3} 3l, 2p{sup 4} 3l, and 2s{sup 2} 2p{sup 2} 4l configurations in N-like ions from Ar xii to Zn xxiv. Complete and consistent data sets of energies, wavelengths, radiative rates, oscillator strengths, and line strengths for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 359 levels are given for each ion. The present work significantly increases the amount of accurate data for ions in the nitrogen-like sequence, and the accuracy of the energy levels is high enough to enable the identification and interpretation of observed spectra involving the n = 3, 4 levels, for which experimental values are largely scarce. Meanwhile, the results should be of great help for modeling and diagnosing astrophysical and fusion plasmas.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Systematic calculations of energy levels and transition rates of BE-like ions with Z = 10–30 using a combined configuration interaction and many-body perturbation theory approach

We report calculations of energy levels and radiative rates for transitions among the lowest 116 fine-structure levels arising from the n⩽5 configurations in Be-like ions with Z = 10–30. The wavelengths, oscillator strengths, line strengths, and radiative rates for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 116 levels have been calculated using the combined configuration interaction and many-body perturbation method. The accuracy of the results is determined through extensive comparisons with existing laboratory measurements and theoretical results. The present complete set of results should be of great help in line identification and the interpretation of spectra, as well as in the modeling and diagnostics of astrophysical and fusion plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Energy levels and radiative transition rates for Ba XLVIII

Highlights: • Lowest 431 levels of Ba XLVIII are calculated. • Radiative data for E1, E2, M1 and M2 transitions from the lowest 3 levels to 431 levels are presented. • Lifetimes for lowest 431 fine structure levels are provided. Energy levels and radiative rates are reported for transitions in F-like Ba XLVIII. Configuration interaction has been included among 27 configurations (generating 431 levels) over a wide energy range up to 618 Rydbergs, and the fully relativistic multi-configurational Dirac–Fock method adopted for the calculations. To assess the accuracy, calculations have also been performed with the flexible atomic code, FAC. Radiative rates, oscillator strengths and line strengths are reported for all electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions from the lowest 3 levels, although calculations have been performed for a much larger number of levels. We have made comparisons of our results with existing available results and a good agreement has been achieved. Additionally, lifetimes for all 431 levels are listed.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2010

Design and Analysis of a Single-Shot Longitudinal Phase Space Measurement Diagnostics at the Argonne Wakefield Accelerator

A single-shot longitudinal phase space diagnostics is currently being assembled at the Argonne Wakefield Accelerator (AWA). The diagnostics consists of mapping the longitudinal phase space coordinates to the transverse position space plane using a beamline that incorporates two magnetic dipoles arranged as a dogleg followed by an rf deflecting cavity. The deflecting cavity streaks the beam vertically while the dipole magnets bend horizontally. In this paper, we analyze analytically and via numerical simulations the performances of such diagnostics and their limitations. Simulations done in IMPACT-T shows good reconstruction of the longitudinal phase space.

43 PARTICLE ACCELERATORS↗