Dusty plasma dynamics in Ar/C₂H₂ RF discharges
Abstract
The coupled effects of plasma dynamics, chemical kinetics, and aerosol dynamics in capacitively coupled RF Ar/C₂H₂ discharges are investigated computationally using a dedicated 1D numerical model. The model combines a fluid description of the plasma with a reactive flow model for the neutral and charged species, and a bimodal particle size distribution model for aerosol dynamics. Simulations of the transient plasma evolution were performed for different C₂H₂ concentrations in the feed gas (10%, 25%, and 50%). The results demonstrate that dusty plasma effects in Ar/C₂H₂ discharges differ significantly from silane systems, with positive ion chemistry playing a crucial role in the nucleation kinetics. In particular, three dusty plasma regimes were identified. At low acetylene concentration (10% C₂H₂), the nucleation is limited, leading to a relatively low particle density (∼108 m−3) and a mean particle diameter of 15 nm after 5 s of discharge duration. In this case, the particle dynamics and the plasma dynamics are decoupled, as indicated by a (numerical) coupling parameter, Pc=zp.Npne, much smaller than unity (Pc ≪ 1). At moderate concentrations (25% C₂H₂), the particle density is significant (i.e., 1013 m−3), resulting in a local coupling effect (Pc > 1) that affects the space distributions of electron density and temperature in the plasma, the particle cloud being concentrated at the sheath edges. At high C₂H₂ concentration (50% C₂H₂), the nucleation rate becomes very high, producing particle densities exceeding 1015 m−3 and a very strong coupling effect, i.e., Pc ≈ 12. In this case, a self-sustained nucleation phenomenon emerges, where particle formation enhances ion density, which in turn promotes further nucleation. Particle growth is then limited, resulting in smaller particles (7 nm) confined in the discharge center and, surprisingly, with only minor effects on the electron density and temperature. This study provides new insights into the modeling of carbon-based dusty plasmas and their applications in nanoparticle synthesis.
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BibTeX
@article{tetard2026dusty,
title = {{Dusty plasma dynamics in Ar/C₂H₂ RF discharges}},
author = {G. Tetard and A. Michau and Swaminathan Prasanna and P. Brault and K. Hassouni},
journal = {Physics of Plasmas},
year = {2026},
month = sep,
doi = {10.1063/5.0314475},
url = {https://hal.science/hal-05768393v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Dusty plasma dynamics in Ar/C₂H₂ RF discharges
AU - G. Tetard
AU - A. Michau
AU - Swaminathan Prasanna
AU - P. Brault
AU - K. Hassouni
PY - 2026
DA - 2026/09/29
JO - Physics of Plasmas
DO - 10.1063/5.0314475
UR - https://hal.science/hal-05768393v1
AB - The coupled effects of plasma dynamics, chemical kinetics, and aerosol dynamics in capacitively coupled RF Ar/C₂H₂ discharges are investigated computationally using a dedicated 1D numerical model. The model combines a fluid description of the plasma with a reactive flow model for the neutral and charged species, and a bimodal particle size distribution model for aerosol dynamics. Simulations of the transient plasma evolution were performed for different C₂H₂ concentrations in the feed gas (10%, 25%, and 50%). The results demonstrate that dusty plasma effects in Ar/C₂H₂ discharges differ significantly from silane systems, with positive ion chemistry playing a crucial role in the nucleation kinetics. In particular, three dusty plasma regimes were identified. At low acetylene concentration (10% C₂H₂), the nucleation is limited, leading to a relatively low particle density (∼108 m−3) and a mean particle diameter of 15 nm after 5 s of discharge duration. In this case, the particle dynamics and the plasma dynamics are decoupled, as indicated by a (numerical) coupling parameter, Pc=zp.Npne, much smaller than unity (Pc ≪ 1). At moderate concentrations (25% C₂H₂), the particle density is significant (i.e., 1013 m−3), resulting in a local coupling effect (Pc > 1) that affects the space distributions of electron density and temperature in the plasma, the particle cloud being concentrated at the sheath edges. At high C₂H₂ concentration (50% C₂H₂), the nucleation rate becomes very high, producing particle densities exceeding 1015 m−3 and a very strong coupling effect, i.e., Pc ≈ 12. In this case, a self-sustained nucleation phenomenon emerges, where particle formation enhances ion density, which in turn promotes further nucleation. Particle growth is then limited, resulting in smaller particles (7 nm) confined in the discharge center and, surprisingly, with only minor effects on the electron density and temperature. This study provides new insights into the modeling of carbon-based dusty plasmas and their applications in nanoparticle synthesis.
SN - 1070-664X
SN - 1089-7674
ER -