Hard diamond-like layers produced during DIII-D tokamak operations

Денисов, В. Н.; Kuzik, L. A.; Lvova, N.A.; Opimach, I.V.; Popov, M.; West, W.P.

doi:10.1016/s0375-9601(98)00002-4

Cited by 6 publications

(5 citation statements)

References 9 publications

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“…The Raman spectrum of the released sample shows only two asymmetrical broad bands at 600–800 and 1100–1800 cm −1 (with the most intensive position at 1552 cm −1 ), assigned to vibrational modes of the CC/CC bonds in fullerenes or fullerene fragments, containing hexagonal and pentagonal carbon rings . A similar broad and asymmetric peak at 1552 cm −1 has also been observed in diamond‐like carbon film and in 3D C 60 polymers containing large amounts of sp 3 carbons . Such Raman bands are characteristic for mixed sp 2 and sp 3 bonded disordered carbon .…”

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confidence: 62%

New Ordered Structure of Amorphous Carbon Clusters Induced by Fullerene–Cubane Reactions

Yao

Dong

et al. 2018

Advanced Materials

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As a new category of solids, crystalline materials constructed with amorphous building blocks expand the structure categorization of solids, for which designing such new structures and understanding the corresponding formation mechanisms are fundamentally important. Unlike previous reports, new amorphous carbon clusters constructed ordered carbon phases are found here by compressing C H /C cocrystals, in which the highly energetic cubane (C H ) exhibits unusual roles as to the structure formation and transformations under pressure. The significant role of C H is to stabilize the boundary interactions of the highly compressed or collapsed C clusters which preserves their long-range ordered arrangement up to 45 GPa. With increasing time at high pressure, the gradual random bonding between C H and carbon clusters, due to "energy release" of highly compressed cubane, leads to the loss of the ability of C H to stabilize the carbon cluster arrangement. Thus a transition from short-range disorder to long-range disorder (amorphization) occurs in the formed material. The spontaneous bonding reconstruction most likely results in a 3D network in the material, which can create ring cracks on diamond anvils.

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confidence: 62%

New Ordered Structure of Amorphous Carbon Clusters Induced by Fullerene–Cubane Reactions

Yao

Dong

et al. 2018

Advanced Materials

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“…The interaction of hydrogen with carbon-based plasma-facing components (PFCs) leads to their erosion by both momentum transfer processes (physical sputtering) and chemical reactions [4]. The various eroded hydrocarbon (C x H y ) radicals get deposited in the form of a thin layer on the inner surface of fusion devices [5]- [9]. Future reactors will use tritium as fuel, and hence the tritium inventory build-up may lead to various safety issues limiting the operation as well as to economic constraints due to fuel retention.…”

Section: Introductionmentioning

confidence: 99%

Synergistic erosion process of hydrocarbon films: a molecular dynamics study

2008

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Abstract. Fundamental processes leading to the erosion of hydrocarbon films due to energetic argon ions and hydrogen atoms have been investigated using molecular dynamics simulations. A generic mechanism has been identified for carbon erosion due to energetic (150 eV) argon ions in the presence of sub-eV hydrogen atoms. This surface erosion process, which we call hydrogen enhanced physical sputtering (HEPS), is primarily a physical sputtering mechanism, enhanced due to the screening effect of hydrogen atoms. The energetic argon ions create open bonds within their penetration range. The hydrogen atoms passivate the open bonds created within the first few atomic layers. Subsequent ion bombardment causes the breaking of C-C bonds within and beyond the H penetration range. The steric effect of H atoms bound to the top layer of carbon atoms prevents the re-attachment of the broken bonds, and this leads to unsaturated molecule emission from the surface. The kinetic energy of the emitted molecules is above thermal energy and the emission takes place within 5 ps after the ion impact.

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“…Erosion of carbon [1][2][3][4] as hydrocarbons and its co-deposition form hydrocarbon films on the inner surface of these devices. The deposits are porous and can form both hard and soft films [5][6][7][8]. The hard films are found in regions of the fusion device where annealing of the deposits is possible due to energetic particle incidence.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Monte-Carlo modeling of hydrogen isotope diffusion in co-deposited layers

Rai

Maya

Schneider

et al. 2007

Journal of Nuclear Materials

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Reactive-diffusive transport of hydrogen in the porous, 3-dimensional structure of codeposited films is simulated using a kinetic Monte Carlo (KMC) method. The simulations are carried out on samples generated from the film growth Monte Carlo (FGMC) code which simulates the film-growth process in remote regions of fusion devices. It is seen that the steric repulsion between the incoming hydrocarbon and the surface atoms is an important parameter which affects the structure and trap concentrations of these soft films. Initial results indicate that diffusion of hydrogen through pores in the co-deposited films could be a major contributor to the high density of hydrogen in co-deposits seen at remote locations of fusion devices.

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Hard diamond-like layers produced during DIII-D tokamak operations

Cited by 6 publications

References 9 publications

New Ordered Structure of Amorphous Carbon Clusters Induced by Fullerene–Cubane Reactions

New Ordered Structure of Amorphous Carbon Clusters Induced by Fullerene–Cubane Reactions

Synergistic erosion process of hydrocarbon films: a molecular dynamics study

Dynamic Monte-Carlo modeling of hydrogen isotope diffusion in co-deposited layers

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