Numerical simulation for the characterization of operating conditions of RF–RF hybrid plasma torches

A two-dimensional (r, z) numerical code has been developed to investigate the prominent features of RF–RF hybrid plasma torches with two stages of different diameter. Flow and temperature fields have been calculated within the assumptions of laminar flow and local thermodynamic equilibrium for the optically thin argon plasma operated at atmospheric pressure, taking into full account the electromagnetic interaction between the primary and the secondary stage of the hybrid device. Results from a detailed parametric study for various geometric, gas flow and electric configurations aim at putting into evidence the wide range of operating conditions that can characterize the use of RF–RF hybrid plasma torches for industrial applications, showing also their possibility to give high enthalpy plasma jets with high torch efficiencies. The magnetofluidynamic modelling described in this work can be an effective tool for providing the theoretical framework for a deep understanding of RF–RF hybrid plasma torches and for designing them as suitable sources for chemical processing of materials, when utilized within an integrated approach that would match the induction plasma torch simulation with the RF generator operating conditions to evaluate the total source efficiency for each particular hybrid configuration.