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Krstic PS, Dwivedi S, Ostrowski ET, Abe S, Maan A, van Duin ACT, Koel BE. Hydrogen irradiation-driven computational surface chemistry of lithium oxide and hydroxide. J Chem Phys 2023; 159:244703. [PMID: 38153149 DOI: 10.1063/5.0177460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 12/04/2023] [Indexed: 12/29/2023] Open
Abstract
We have investigated, using molecular dynamics, the surface chemistry of hydrogen incident on the amorphous and crystalline lithium oxide and lithium hydroxide surfaces upon being slowed down by a collision cascade and retained in the amorphous surface of either Li2O or LiOH. We looked for the bonding of H to the resident structures in the surface to understand a possible chain of chemical reactions that can lead to surface transformation upon H atom impact. Our findings, using Density-Functional Theory (DFT) trained ReaxFF force field/electronegativity equalization method potentials, stress the importance of inclusion of polarization in the dynamics of a Li-O-H system, which is also illustrated by DFT energy minimization and quantum-classical molecular dynamics using tight binding DFT. The resulting polar-covalent chemistry of the studied systems is complex and very sensitive to the instantaneous positions of all atoms as well as the ratio of concentrations of various resident atoms in the surface.
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Affiliation(s)
- P S Krstic
- TheoretiK, Port Jefferson Station, New York 11776, USA
- Stony Brook University, Stony Brook, New York 11749, USA
| | - S Dwivedi
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - E T Ostrowski
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - S Abe
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - A Maan
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - A C T van Duin
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - B E Koel
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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Beers CJ, Jaramillo C, Reid NC, Schamis H, Allain JP, Caughman JBO, Meitner SJ, Rapp J, Zinkle SJ. Development of the materials analysis and particle probe for Proto-MPEX. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:045108. [PMID: 34243379 DOI: 10.1063/5.0043111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/31/2021] [Indexed: 06/13/2023]
Abstract
The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) is a linear plasma device being used in plasma source research and development (R&D) for the proposed MPEX. Once the R&D is completed, this device can also be used to perform plasma-material interaction studies. To perform these studies, a new materials analysis and particle probe (MAPP) has been constructed. The MAPP's components are a sample holder and manipulator and a custom vacuum chamber with ports to facilitate surface chemistry diagnostics. The MAPP's overall design enables rapid sample turnaround and in vacuo surface characterization. The surface analysis vacuum chamber has ports for x-ray photoelectron spectroscopy, thermal desorption spectroscopy, back-scatter ion scattering spectroscopy, forward-scatter ion scattering spectroscopy, and direct recoil spectroscopy. The sample manipulator and holder is a Lesker/UHV Multi-Centre Analytical Stage, which is used to place the samples in the exposure region of the Proto-MPEX or the analysis position in the MAPP vacuum chamber. The sample holder has a heating capability of up to 1200 °C for heated exposure and for desorption studies. In this work, we present the MAPP's design and the first tungsten sample exposure with ex situ analysis that shows a surface deposition layer on the exposed target, highlighting the need for additional in situ measurements on the Proto-MPEX.
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Affiliation(s)
- C J Beers
- Department of Energy Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - C Jaramillo
- Ken and Mary Lindquist Department of Nuclear Engineering, Penn State University, State College, Pennsylvania 16801, USA
| | - N C Reid
- Department of Nuclear, Plasma and Radiological Engineering, University of Illinois, Urbana, Illinois 61801, USA
| | - H Schamis
- Ken and Mary Lindquist Department of Nuclear Engineering, Penn State University, State College, Pennsylvania 16801, USA
| | - J P Allain
- Ken and Mary Lindquist Department of Nuclear Engineering, Penn State University, State College, Pennsylvania 16801, USA
| | - J B O Caughman
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S J Meitner
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J Rapp
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S J Zinkle
- Department of Energy Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
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Bedoya F, Allain JP, Dominguez-Gutierrez FJ, Krstic PS. Effect of deuterium irradiation on graphite boronized in the NSTX-U tokamak. Sci Rep 2019; 9:2435. [PMID: 30792416 PMCID: PMC6385375 DOI: 10.1038/s41598-019-38941-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 01/15/2019] [Indexed: 11/09/2022] Open
Abstract
Boronization has been used in the National Spherical Torus-Upgrade (NSTX-U) as first wall conditioning technique. The technique decreased the oxygen impurities in the plasma and the O% on the Plasma Facing Components (PFC) as measured with an in-vacuo probe. Samples were extracted from tiles removed from the tokamak for post-mortem and controlled studies. Ex-vessel low energy and fluence D2+ and Ar+ irradiations were characterized in-situ to elucidate surface evolution of a cored graphite sample with an intrinsic concentration of boron from a tokamak environment. In addition, quadrupole mass spectrometer measurements of emitted D-containing species during irradiation, indicate potential retention of D by the boronized graphite interface and correlated back to the surface chemistry evolution. Classical Molecular Dynamics (CMD) simulations were used to investigate the chemistry of the B-C-O-D system. The results suggest that boron coatings retain oxygen by forming oxidized boron states in the presence of deuterium plasmas and corroborate empirical findings. A four times increase in the O% of the boron coatings was observed following in-situ deuterium exposures, in contrast with a reduction of equal magnitude observed after Ar irradiations. These results illustrate the complex chemistry driven by energetic ions at the edge of tokamaks plasmas on the PFCs.
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Affiliation(s)
- F Bedoya
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - J P Allain
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois, Urbana, IL, 61801, USA
| | | | - P S Krstic
- Institute for Advanced Computational Science, Stony Brook University, Stony Brook, NY, 11749, USA
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Effect of boronization on plasma-facing graphite surfaces and its correlation with the plasma behavior in NSTX-U. NUCLEAR MATERIALS AND ENERGY 2018. [DOI: 10.1016/j.nme.2018.10.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Initial studies of plasma facing component surface conditioning in the national spherical tokamak experiment upgrade with the materials analysis particle probe. NUCLEAR MATERIALS AND ENERGY 2017. [DOI: 10.1016/j.nme.2017.03.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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