Electrical Breakdown of Heterogeneous Rock Under High‐Voltage Electric Pulse: Multiphysics Modeling Framework and Plasma Channel Development Characteristics

ABSTRACT

This study investigates plasma channel formation in heterogeneous rocks. An image‐based heterogeneous parameterization method was employed to construct the rock‐property field. Based on the current continuity equation, heat conduction equation, breakdown criterion, and probability theory, an electro‐thermal coupled model for plasma channel development was established. A nonlinear conductivity evolution equation was incorporated into a time‐domain iterative framework, and an electric‐field‐dependent damage variable was introduced to quantify rock damage. The model enables dynamic two‐way coupling between the breakdown plasma and electric field. It was used to analyze the effects of rock heterogeneity and electrical parameters, clarify plasma channel development characteristics, and validate model accuracy through comparison with experimental results. The results show that rock heterogeneity induces localized electric field concentration, causing the plasma channel to develop preferentially along minerals with higher electrical conductivity; this guiding effect weakens as the applied voltage increases. At discharge voltages of 50, 70, and 90 kV, the damaged areas in heterogeneous rocks increase by 113.8%, 52.5%, and 28.7%, compared with those in the homogeneous control group. After plasma channel formation, the temperature difference between the channel interior and the surrounding region can reach 10 ⁴  K. Fine‐grained granite is the most susceptible to breakdown, followed by porphyritic granite, whereas rhyolitic granite is the most resistant to breakdown. Optimizing voltage and electrode spacing can reconstruct the electric‐field distribution and plasma channel development path, thereby mitigating the adverse effects of rock texture.