International Journal of Physics | Vol. 8, No. 3, March 2017 | pp. 17–24
DOI: 10.46882/2017/IJP/000083
Research Article
Title: Kinetic Modelling of Electron Transport Parameters and Reaction Rates in Acetylene-Hydrogen Discharges
Names of Authors: D. L. Santos¹, S. H. Zhang²
Authors’ Affiliations: ¹Department of Physics, University of Coimbra, Coimbra, Portugal; ²Department of Physics, Tsinghua University, Beijing, China
Abstract: Acetylene-hydrogen (C2H2-H2) gas discharges are widely used in the material processing industries to deposit high-quality diamond-like carbon thin films and carbon nanotubes. This paper develops a self-consistent kinetic model to evaluate electron transport parameters and calculate ionization coefficients in low-pressure acetylene-hydrogen mixtures. We solved the electron Boltzmann equation using a multi-term spherical harmonic expansion framework across a wide reduced electric field range (E/N) from 5.0 Td to 600.0 Td. The cross-section dataset included elastic momentum transfer, rotational, vibrational excitation, dissociative attachment, and direct impact ionization processes. Our modeling results show that adding small fractions of acetylene (from 2.0% to 10.0% by volume) drastically distorts the electron energy distribution function. At E/N = 60.0 Td, the total dissociation rate coefficient increases by an order of magnitude due to the low threshold energy of acetylene vibrational modes. The calculated electron drift velocities and diffusion coefficients match independent swarm experimental measurements within a tight ±5.0% variance. These kinetic parameters provide essential input data for optimizing industrial chemical vapor deposition reactors.
Keywords: Acetylene plasmas; Boltzmann equation; electron transport; ionization coefficient; carbon deposition; cross-section
Manuscript Timeline: Received: December 14, 2016; Revised: January 20, 2017; Accepted: February 08, 2017; Published: March 15, 2017
Citation: Santos, D. L., & Zhang, S. H. (2017). Kinetic Modelling of Electron Transport Parameters and Reaction Rates in Acetylene-Hydrogen Discharges. International Journal of Physics, 8(3), 17–24.
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