International Journal of Physics

International Journal of Physics | Vol. 10, No. 2, February 2019 | pp. 9–16

DOI: 10.46882/2019/IJP/000106

Research Article

Title: Kinetic Modelling of Electron Swarm Parameters and Fragmentation Pathways in Methane-Oxygen Discharges

Names of Authors: D. L. Santos¹, T. H. Nguyen²

Authors’ Affiliations: ¹Department of Physics, University of Coimbra, Coimbra, Portugal; ²Department of Physics, Vietnam National University, Hanoi, Vietnam

Abstract: Methane-oxygen (CH4-O2) gas discharges are widely deployed in material processing and chemical engineering sectors for diamond thin-film synthesis, surface activation, and greenhouse gas conversion. This paper develops a self-consistent kinetic model to evaluate electron swarm parameters and calculate molecular fragmentation pathways in low-pressure methane-oxygen 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 10.0 Td to 500.0 Td. The cross-section dataset accounted for elastic momentum transfer, rotational transitions, vibrational excitation states, dissociative attachment, and direct impact ionization processes. Our modeling results show that adding small fractions of oxygen (from 5.0% to 20.0% by volume) significantly distorts the high-energy tail of the electron distribution function. At E/N = 80.0 Td, the total methyl radical (CH3) production rate coefficient increases by over an order of magnitude due to efficient energy channeling into the primary vibrational thresholds of methane. The calculated electron drift velocities match independent swarm experimental measurements within a ±5.0% variance index. These kinetic parameters provide critical baseline inputs for optimizing commercial chemical vapor deposition reactors.

Keywords: Methane plasmas; Boltzmann equation; electron transport; fragmentation pathways; chemical vapor deposition; cross-section

Manuscript Timeline: Received: November 05, 2018; Revised: December 18, 2018; Accepted: January 11, 2019; Published: February 12, 2019

Citation: Santos, D. L., & Nguyen, T. H. (2019). Kinetic Modelling of Electron Swarm Parameters and Fragmentation Pathways in Methane-Oxygen Discharges. International Journal of Physics, 10(2), 9–16.

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