Thermal Plasmas and Non-Thermal Arcs

This paper presents a comparative study of three modelling approaches for investigating the ignition of high-current arc discharges on cold cathodes in atmospheric-pressure argon: the cathodic model, the two-temperature plasma (2T) model, and the local thermal equilibrium (LTE) model. Each model is implemented using two computational platforms: COMSOL Multiphysics and OpenFOAM, which rely on the finite element method (FEM) and the finite volume method (FVM), respectively. We systematically compare these models in terms of their ability to describe plasma behaviour and its interactions with the electrodes, highlighting the advantages and limitations of each approach. Additionally, we evaluate the performance and results of FEM and FVM implementations across both platforms. Simulation results cover quasi-stationary current increases from 1 mA to 200 A and reveal three distinct modes of current transfer: a glow-like discharge mode, a hot arc spot mode on the cathode surface, and a diffuse mode characterized by a uniformly heated cathode tip with temperatures around 3500 K. Moreover, the ignition of a 200 A arc on a cold cathode is simulated. Our findings provide new insights into the selection of appropriate modelling frameworks and numerical methods for accurately describing arc discharge phenomena in different settings.

Funding acknowledgement

The work was supported by FCT of Portugal under projects UIDB/50010/2020, UIDP/50010/2020, and LA/P/0061/2020