Experimental study on the influence of ion state of arc on ion enthalpy flux at the interface during a lightning return stroke

During natural lightning return strokes, ion enthalpy flux makes a nonnegligible contribution to lightning-induced damage. To improve its evaluation in damage models, this study experimentally investigates how the ionic state of lightning arcs influences interfacial ion energy transfer across different material thermal responses. Focusing on impulse currents, an experimental platform is constructed using a modified lightning impulse generator circuit. Time-resolved spectral images of lightning arcs are obtained with a high-speed spectroscopic observation system to characterize the ion state within the arc channel. An interfacial energy-transfer inversion model is then developed based on measured damage data to estimate interfacial ion energy under different experimental conditions. By integrating material thermophysical properties with partial correlation analysis and standardized regression equations, the influence mechanism of arc-channel ion parameters on ion enthalpy flux is identified. Results show that ion density has the strongest correlation with ion enthalpy flux (partial correlation coefficient r > 0.85) and dominates the interfacial damage process during the tail of the impulse current waveform. Ion enthalpy flux is also influenced by the comprehensive thermophysical properties of the material. As the material melting point decreases, the effect of ion density becomes more pronounced, leading to higher interfacial ion energy transfer and increased energy conversion efficiency. By revealing the critical role of plasma ionic states in material damage, these quantitative findings provide a further theoretical basis for improving conventional lightning thermal damage criteria.