Numerical Investigation of Molten Pool Deformation in Copper Electrodes Under DC Arc Discharge With a Fully Coupled Model

Arc-induced electrode erosion severely limits the performance of DC switching devices and is difficult to characterize experimentally due to its highly transient nature. In this work, a fully coupled transient numerical model is developed to investigate copper electrode erosion under DC arc discharge. The model integrates arc magnetohydrodynamics (MHD) with molten pool dynamics using a level-set method, enabling two-way interaction between the arc plasma and the electrode surface while accounting for phase change, arc pressure, and vapor-induced recoil pressure. The results show that molten pool deformation is governed by a force-dominated mechanism rather than thermal loading alone. In the baseline case, molten pool evolution proceeds through molten pool convergence, jet spattering, and crater formation. When recoil pressure is neglected, molten pool deformation remains limited, and no jetting or crater formation occurs. A force comparison reveals that recoil pressure exhibits a sharp transient increase during intense metal evaporation, far exceeding arc pressure. In addition, simulations at different current levels indicate a transition from weak deformation at a low current to recoil-pressure-dominated erosion at higher current.