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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Transport of 12 GeV positron beams at Ce+BAF

Jefferson Lab (JLab) is developing a concept to upgrade the Continuous Electron Beam Accelerator Facility (CEBAF) to additionally deliver spin-polarized continuous-wave positron beams for its nuclear physics program users (Ce+BAF 12 GeV). The concept involves repurposing the Low Energy Recirculator Facility (LERF) at JLab as a dual injector, first producing 100-300 MeV spin-polarized electron beams which are subsequently used for the generation and formation of 123 MeV continuous-wave positron beams. The positron beams are transported to CEBAF and injected for acceleration up to 12 GeV, tailored to the requirements of its four experimental halls. Given the higher emittance of the secondary positron beams, the CEBAF optics are optimized for low dispersion and low beta functions to enhance transmission within the Ce+BAF acceptance limits and with an R56 to manage the positron beams bunch length and energy spread. Potential bottlenecks are being investigated through both optical modeling and measurements using an electron beam, as well as degraded electron beams, to map the 6d acceptance of CEBAF as it is today. This presentation shares preliminary results from multi-particle tracking simulations of the positron beam up to 12 GeV, including spatial, momentum, and spin characteristics, and explores the feasibility of delivering beams simultaneously to multiple experimental halls via extraction optics.

Accelerator Physics↗
DOE OSTI2025

Polarized positrons at Ce\(^+\)BAF

A baseline concept for a continuous wave (CW) polarized positron injector was developed for the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab [1]. This concept is based on positron beam generation by a high current polarized electron beam (1 mA, 120 MeV, >85% polarization) irradiating a 4 mm thick rotating water-cooled tungsten target or liquid metal target. The update on the development of the Ce+BAF injector concept including the polarized electron source, the development of high power targets, simulations of positron capture, the design of the transport line from the positron injector to the CEBAF North Linac and the planned experiment to measure the upper limits of transverse and longitudinal emittances accepted by the 12 GeV CEBAF optics are presented. [1] J. Grames et al., "Positron beams at Ce+BAF", in Proc. 14th Int. Particle Accelerator Conf. (IPAC’23), Venice, Italy, MOPL152, pp. 896–899 (2023). doi:10.18429/JACoW-IPAC2023-MOPL152

Ushakov, Andriy↗
DOE OSTI2024

Rare Earth Carbide (Nd-C and Ce-C) Synthesis and Characterization to Inform Phase Equilibrium in Advanced Nuclear Fuels

As advances are being made regarding the performance of nuclear fuels, uranium carbides, and composites, such as (U,Zr)C and UO2 + UCx, have recently gained significant interest for deployment in nuclear space propulsion and high temperature gas-cooled reactors, respectively. However, the phase equilibria of several fission products in carbide systems remain unknown and may impact the overall fuel performance, specifically for particle nuclear fuels that are designed for commercial nuclear energy. Furthermore, comprehensive thermodynamic data on Rare Earth (RE) carbides, such as the Nd-C and Ce-C binary systems, remain limited. Presented in this study are the synthesis methods and characterizations of several Nd-C and Ce-C compositions. The findings from this research provide insights on the stability of RE-C binaries that form in irradiated nuclear fuels and address a critical knowledge gap in the current state of thermodynamics for two key RE-C systems.

Cavazos, Steven J. (ORCID:0009000130329363)↗
DOE OSTI2020

Materials Data on Ce(P3Ru)4 by Materials Project

CeRu4P12 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Ce3+ is bonded to twelve equivalent P1- atoms to form CeP12 cuboctahedra that share faces with eight equivalent RuP6 octahedra. All Ce–P bond lengths are 3.11 Å. Ru+2.25+ is bonded to six equivalent P1- atoms to form RuP6 octahedra that share corners with six equivalent RuP6 octahedra and faces with two equivalent CeP12 cuboctahedra. The corner-sharing octahedral tilt angles are 62°. All Ru–P bond lengths are 2.36 Å. P1- is bonded in a 5-coordinate geometry to one Ce3+, two equivalent Ru+2.25+, and two equivalent P1- atoms. There are one shorter (2.32 Å) and one longer (2.33 Å) P–P bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(FeP3)4 by Materials Project

CeFe4P12 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Ce3+ is bonded to twelve equivalent P1- atoms to form CeP12 cuboctahedra that share faces with eight equivalent FeP6 octahedra. All Ce–P bond lengths are 2.98 Å. Fe+2.25+ is bonded to six equivalent P1- atoms to form FeP6 octahedra that share corners with six equivalent FeP6 octahedra and faces with two equivalent CeP12 cuboctahedra. The corner-sharing octahedral tilt angles are 59°. All Fe–P bond lengths are 2.24 Å. P1- is bonded in a 2-coordinate geometry to one Ce3+, two equivalent Fe+2.25+, and two equivalent P1- atoms. There are one shorter (2.32 Å) and one longer (2.36 Å) P–P bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(MgSi)2 by Materials Project

CeMg2Si2 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Mg2+ is bonded in a square co-planar geometry to four equivalent Si4- atoms. All Mg–Si bond lengths are 2.75 Å. Ce4+ is bonded to eight equivalent Si4- atoms to form a mixture of edge and face-sharing CeSi8 hexagonal bipyramids. All Ce–Si bond lengths are 3.19 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Mg2+, four equivalent Ce4+, and one Si4- atom. The Si–Si bond length is 2.29 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(BO2)3 by Materials Project

CeB3O6 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ce3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ce–O bond distances ranging from 2.40–2.86 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.46 Å) and two longer (1.50 Å) B–O bond length. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.34–1.42 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ce3+ and two B3+ atoms. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ce3+ and one B3+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Ce3+ and two B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(NiAs)2 by Materials Project

CeNi2As2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce3+ is bonded in a distorted body-centered cubic geometry to eight equivalent As3- atoms. All Ce–As bond lengths are 3.19 Å. Ni+1.50+ is bonded to four equivalent As3- atoms to form a mixture of corner and edge-sharing NiAs4 tetrahedra. All Ni–As bond lengths are 2.37 Å. As3- is bonded in a 9-coordinate geometry to four equivalent Ce3+, four equivalent Ni+1.50+, and one As3- atom. The As–As bond length is 2.64 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SiPt)2 by Materials Project

CePt2Si2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce4+ is bonded in a 8-coordinate geometry to eight Pt2- atoms. There are four shorter (3.26 Å) and four longer (3.28 Å) Ce–Pt bond lengths. There are two inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in a 4-coordinate geometry to four equivalent Ce4+ and four equivalent Si atoms. All Pt–Si bond lengths are 2.50 Å. In the second Pt2- site, Pt2- is bonded in a 5-coordinate geometry to four equivalent Ce4+ and five Si atoms. There are one shorter (2.42 Å) and four longer (2.44 Å) Pt–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded to four equivalent Pt2- atoms to form a mixture of edge and corner-sharing SiPt4 tetrahedra. In the second Si site, Si is bonded in a 5-coordinate geometry to five Pt2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(MnSi)2 by Materials Project

CeMn2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce4+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Ce–Si bond lengths are 3.06 Å. Mn2+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing MnSi4 tetrahedra. All Mn–Si bond lengths are 2.38 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ce4+, four equivalent Mn2+, and one Si4- atom. The Si–Si bond length is 2.53 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(FeSi)2 by Materials Project

CeFe2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Ce–Si bond lengths are 3.12 Å. Fe+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing FeSi4 tetrahedra. All Fe–Si bond lengths are 2.28 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ce3+, four equivalent Fe+2.50+, and one Si4- atom. The Si–Si bond length is 2.59 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(CoSi)2 by Materials Project

CeCo2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Ce–Si bond lengths are 3.06 Å. Co2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing CoSi4 tetrahedra. All Co–Si bond lengths are 2.29 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ce4+, four equivalent Co2+, and one Si4- atom. The Si–Si bond length is 2.56 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SiRu)2 by Materials Project

CeRu2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce3+ is bonded in a 8-coordinate geometry to eight equivalent Si4- atoms. All Ce–Si bond lengths are 3.24 Å. Ru+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing RuSi4 tetrahedra. All Ru–Si bond lengths are 2.39 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ce3+ and four equivalent Ru+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SiPd)2 by Materials Project

CePd2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce4+ is bonded to eight equivalent Si4- atoms to form CeSi8 hexagonal bipyramids that share corners with sixteen equivalent PdSi4 tetrahedra, edges with four equivalent CeSi8 hexagonal bipyramids, edges with eight equivalent PdSi4 tetrahedra, and faces with four equivalent CeSi8 hexagonal bipyramids. All Ce–Si bond lengths are 3.19 Å. Pd2+ is bonded to four equivalent Si4- atoms to form PdSi4 tetrahedra that share corners with eight equivalent CeSi8 hexagonal bipyramids, corners with four equivalent PdSi4 tetrahedra, edges with four equivalent CeSi8 hexagonal bipyramids, and edges with four equivalent PdSi4 tetrahedra. All Pd–Si bond lengths are 2.49 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ce4+, four equivalent Pd2+, and one Si4- atom. The Si–Si bond length is 2.35 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SiNi)2 by Materials Project

CeNi2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Ce–Si bond lengths are 3.10 Å. Ni2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.33 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ce4+, four equivalent Ni2+, and one Si4- atom. The Si–Si bond length is 2.43 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(TeO3)2 by Materials Project

CeTe2O6 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ce4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.23–2.68 Å. There are two inequivalent Te4+ sites. In the first Te4+ site, Te4+ is bonded in a 4-coordinate geometry to three O2- atoms. There are a spread of Te–O bond distances ranging from 1.90–1.93 Å. In the second Te4+ site, Te4+ is bonded in a 3-coordinate geometry to three O2- atoms. There is one shorter (1.91 Å) and two longer (1.92 Å) Te–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ce4+ and one Te4+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Ce4+ and one Te4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Ce4+ and one Te4+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ce4+ and one Te4+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to one Ce4+ and one Te4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ce4+ and one Te4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SiOs)2 by Materials Project

CeOs2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce3+ is bonded in a 8-coordinate geometry to eight equivalent Os+1.50- atoms. All Ce–Os bond lengths are 3.22 Å. Os+1.50- is bonded in a 4-coordinate geometry to four equivalent Ce3+ and four equivalent Si atoms. All Os–Si bond lengths are 2.41 Å. Si is bonded in a 5-coordinate geometry to four equivalent Os+1.50- and one Si atom. The Si–Si bond length is 2.52 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SiAu)2 by Materials Project

CeAu2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce3+ is bonded to eight equivalent Si4- atoms to form CeSi8 hexagonal bipyramids that share corners with sixteen equivalent AuSi4 tetrahedra, edges with four equivalent CeSi8 hexagonal bipyramids, edges with eight equivalent AuSi4 tetrahedra, and faces with four equivalent CeSi8 hexagonal bipyramids. All Ce–Si bond lengths are 3.28 Å. Au+2.50+ is bonded to four equivalent Si4- atoms to form AuSi4 tetrahedra that share corners with eight equivalent CeSi8 hexagonal bipyramids, corners with four equivalent AuSi4 tetrahedra, edges with four equivalent CeSi8 hexagonal bipyramids, and edges with four equivalent AuSi4 tetrahedra. All Au–Si bond lengths are 2.58 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Ce3+, four equivalent Au+2.50+, and one Si4- atom. The Si–Si bond length is 2.32 Å.

36 MATERIALS SCIENCE↗