Numerical study of cold atmospheric pressure plasma chemistry mechanisms using the spherical charge model
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Date
2026-10-13
Authors
Τουτουτζής, Ευθύμιος
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Abstract
This work presents a computationally efficient numerical model for the simulation of atmospheric-pressure plasma jets. Atmospheric-pressure plasma jets are widely studied due to their ability to generate chemically active species at near-room temperature, making them suitable for applications in medicine, aerospace engineering and materials processing. However, detailed three-dimensional plasma simulations are often computationally demanding, especially when complex plasma chemistry and electric-field calculations are included. For this reason, the present work focuses on the development of a simplified but physically meaningful numerical model that can describe the main mechanisms of plasma jet propagation with reduced computational cost. The model is based on a one-dimensional drift-diffusion approximation, where the temporal behavior of charged and neutral species is described through conservation equations. A key feature of the model is the replacement of the conventional Poisson equation solution with a spherical-charge approximation for the electric field. In this approach, the net charge distribution along the jet axis is represented by a sequence of overlapping charged spheres. The induced electric field is then calculated as the superposition of the analytical electric fields produced by these spheres. This method allows the model to preserve the three-dimensional character of the electric field while maintaining a one-dimensional computational structure. The model includes an externally applied electric field, a helium-air mixture profile and detailed plasma chemistry mechanisms. Electron transport properties, mean electron energy, and reaction rate coefficients for electron-impact reactions are obtained from BOLSIG+ data as functions of the local electric field. The species conservation equations are solved using a Kurganov-Tadmor central scheme with fourth-order Runge-Kutta method, while the time step is controlled by a CFL stability condition based on the electron drift velocity. Simulations were performed using three different chemistry mechanisms in order to evaluate the sensitivity of the model to the selected reaction set. The results show the propagation of the plasma front through the evolution of the electric field, electron density, and propagation speed. These quantities present similar spatial and temporal behavior for the examined mechanisms, indicating that the model captures the dominant physical processes governing plasma jet propagation.
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Keywords
Plasma bullet, Kurganov-Tadmor central scheme, Runge-Kutta 4th order method, Townsend