Two- and three-dimensional simulation analysis of microwave excited plasma for deposition applications: operation with argon at atmospheric pressure

Abstract

The present work is concerned with the simulation analysis of a microwave plasma torch suitable for deposition applications prior to the admixture of any precursor. The self-consistent numerical model describes the electromagnetic field of the microwaves entering an R26 waveguide, the plasma generation, the gas flow through a tube crossing the waveguide, and the heat transfer in the gas. The plasma description avoids the assumption of quasi-neutrality and provides, therefore, a solution including the near-wall regions.The multiphysics model is applied to the source operated in argon at atmospheric pressure. Quasi-stationary solutions are obtained in a 2D Cartesian geometry and in a 3D geometry employing increasing degrees of complexity with respect to the physics, the reaction kinetics and the boundary conditions. The distribution of the electromagnetic field and the plasma parameters resulting from 2D fully coupled one-and two-ion models is analyzed for an incoming microwave power of 1 kW and a gas flow rate of 18 slm. The 2D model is capable of predicting the plasma parameters at a reasonable computational cost. The application of a 3D plasma-microwave model shows that the spatial distribution of the electromagnetic field and the plasma parameters is not, in general, axially symmetric. In the plane corresponding to the 2D work plane, the results of 3D one-ion plasma model show agreement with the 2D results, however, at significant computational costs. The 2D simulation analysis carried out allows us to draw up a decision-making with regard to the setup performance.

Resolving discharge parameters from atomic oxygen emission

“…In fact, the simulations in Ridenti et al (2018) have shown that T e in Thomson scattering measurements, such as those in van Gessel et al (2012), Carbone et al (2012), has a convex radial profile due to the Maxwellian assumption of this diagnostic, while T e obtained from the calculated EEDF (2/3 of mean electron energy) actually has a concave radial profile, as does E/n g . Conversely, the T e and E/n g radial profiles obtained in the 1D and 2D simulations in Martinez et al (2004), Jimenez-Diaz et al (2012), Georgieva et al (2017), Baeva et al (2018) have been reported as approximately radially homogeneous. We can conclude that the relationships between the spatial profiles of different discharge parameters so far are not completely understood and cannot be generalised.…”

Plasma‐based VAD process for multiply doped glass powders and high‐performance fiber preforms with outstanding homogeneity

“…To validate and refine the plasma model as derived in Baeva et al, [ 30 ] and for fundamental understanding of excitation and fragmentation processes occurring in the plasma, online OES measurements during deposition were carried out. The acquired OES spectra from pure oxygen plasma mixed with argon from the two‐component jet allow retrieving optimum working distance by extraction of decomposition length across the active plasma zone as a function of plasma parameters.…”

On the Interaction of a Microwave Excited Oxygen Plasma with a Jet of Precursor Material for Deposition Applications

“…The model avoided the assumption of quasi-neutrality and solved the Poisson equation to obtain the electrostatic potential. The results obtained in argon as a working gas [2] showed that for temperatures over ∼1350 K in the plasma, the atomic ion was dominant. The molecular ion played a role in the cold region near the tube wall.…”

“…A self-consistent model was developed to describe the MW plasma source employing the plasma, electromagnetic and hydrodynamic equations [2]. It was realized on the computational platform COMSOL Multiphysics in two-and three-dimensional geometry [3].…”