Molecular dynamics calculation of carbon/hydrocarbon reflection coefficients on a hydrogenated graphite surface

D. A. Alman, D. N. Ruzic

Research output: Contribution to journalConference article

Abstract

Reflection coefficients for carbon atoms and hydrocarbon molecules on a carbon surface are critically needed for plasma-surface interaction analysis of carbon surfaces. These coefficients have been calculated with a molecular dynamics code using the Brenner hydrocarbon potential. The surface was prepared by bombarding a pure graphite lattice with energetic hydrogen, until a saturation was reached at ~0.42 H:C. Carbon atoms and several hydrocarbons (CH, CH2, CH3, and CH4) were incident on this surface at different energies and angles. Typical results for carbon incident at 45° show reflection coefficients of 0.64±0.01 at thermal energy, decreasing to 0.19±0.01 at 10 eV. Hydrocarbons show more complicated behavior, tending to reflect as molecules at thermal energies and break up at higher energies, producing a spectrum of different reflected species. The total reflection of carbon via these fragments tends to decrease with incident energy, and increase with hydrogen content in the original molecule. The reflection coefficients, together with the energy and angular distribution of reflected particles, can be incorporated in erosion/redeposition codes to allow improved modeling of chemically eroded carbon transport in fusion devices.

Original languageEnglish (US)
Pages (from-to)182-186
Number of pages5
JournalJournal of Nuclear Materials
Volume313-316
Issue numberSUPPL.
DOIs
StatePublished - Mar 1 2003
EventPlasma - Surface Interactions in Controlled Fusion Devices - Gifu, Japan
Duration: May 26 2002May 31 2002

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Graphite
Hydrocarbons
Molecular dynamics
Carbon
graphite
hydrocarbons
molecular dynamics
reflectance
carbon
Thermal energy
thermal energy
Molecules
Hydrogen
molecules
Atoms
Angular distribution
Beam plasma interactions
hydrogen
surface reactions
erosion

Keywords

  • Carbon
  • Erosion/redeposition
  • Hydrocarbon
  • Molecular dynamics
  • Plasma facing components
  • Reflection

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

Cite this

Molecular dynamics calculation of carbon/hydrocarbon reflection coefficients on a hydrogenated graphite surface. / Alman, D. A.; Ruzic, D. N.

In: Journal of Nuclear Materials, Vol. 313-316, No. SUPPL., 01.03.2003, p. 182-186.

Research output: Contribution to journalConference article

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N2 - Reflection coefficients for carbon atoms and hydrocarbon molecules on a carbon surface are critically needed for plasma-surface interaction analysis of carbon surfaces. These coefficients have been calculated with a molecular dynamics code using the Brenner hydrocarbon potential. The surface was prepared by bombarding a pure graphite lattice with energetic hydrogen, until a saturation was reached at ~0.42 H:C. Carbon atoms and several hydrocarbons (CH, CH2, CH3, and CH4) were incident on this surface at different energies and angles. Typical results for carbon incident at 45° show reflection coefficients of 0.64±0.01 at thermal energy, decreasing to 0.19±0.01 at 10 eV. Hydrocarbons show more complicated behavior, tending to reflect as molecules at thermal energies and break up at higher energies, producing a spectrum of different reflected species. The total reflection of carbon via these fragments tends to decrease with incident energy, and increase with hydrogen content in the original molecule. The reflection coefficients, together with the energy and angular distribution of reflected particles, can be incorporated in erosion/redeposition codes to allow improved modeling of chemically eroded carbon transport in fusion devices.

AB - Reflection coefficients for carbon atoms and hydrocarbon molecules on a carbon surface are critically needed for plasma-surface interaction analysis of carbon surfaces. These coefficients have been calculated with a molecular dynamics code using the Brenner hydrocarbon potential. The surface was prepared by bombarding a pure graphite lattice with energetic hydrogen, until a saturation was reached at ~0.42 H:C. Carbon atoms and several hydrocarbons (CH, CH2, CH3, and CH4) were incident on this surface at different energies and angles. Typical results for carbon incident at 45° show reflection coefficients of 0.64±0.01 at thermal energy, decreasing to 0.19±0.01 at 10 eV. Hydrocarbons show more complicated behavior, tending to reflect as molecules at thermal energies and break up at higher energies, producing a spectrum of different reflected species. The total reflection of carbon via these fragments tends to decrease with incident energy, and increase with hydrogen content in the original molecule. The reflection coefficients, together with the energy and angular distribution of reflected particles, can be incorporated in erosion/redeposition codes to allow improved modeling of chemically eroded carbon transport in fusion devices.

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