Computational Modeling of a Plasma Torch Using a Two-Fluid Modeling Approach

Plasma is a combination of different particles: electrons, ions, and neutrals. The movement and interaction between different particles are nonlinear, resulting in difficulties when modeling the plasma dynamics. Single-fluid modeling is an approach that combines separate equations of the particles into a single equation. This approach is widely used and straightforward, but with the disadvantage of not being able to capture the particle motion and the physics in the plasma sheath region. The two-fluid plasma model, on the other hand, separates the fluid equations solved for electrons and ions. The model hence captures the interaction between different plasma particles. In this study, the modeling of a plasma torch using a two-fluid modeling approach is presented. The model is developed by deriving the fluid equations using kinetic theory for neutrals, ions, and electrons. Further, the equations are adapted in Comsol Multiphysics using the transport of diluted species, laminar flow, heat transfer in solids and fluids, electric fields, and magnetic fields models respectively. Properties such as particle concentration, temperature, and velocity of the plasma jet are analyzed. Further, the obtained results are compared with the results obtained by the single-fluid approach. The work concludes by stating the advantage of the two-fluid modeling and the accuracy of the results obtained.