Analysis of energy exchanges during the interaction between pulsed lightning arcs and metallic plates

Lightning electrical arcs lead to high temperature and high pressure air plasmas where radiation is a dominant energy transfer mechanism. The aim of this work is to evaluate the energy exchanges during the arc–electrode interaction for metallic plates impacted by pulsed lightning arcs that can reach 100 kA, with a peak time of around 13 μs and a full width at half maximum of 40 μs. Rear surface temperatures are measured with an infrared camera, and an experimental parametric study on current amplitude, material, plate thickness, and arc polarity is performed, with a total of 18 studied configurations. An inverse method using the heat conduction equation and taking into account Joule heating is applied to estimate the incoming heat flux at the plate surface. To compare with experimental results and to analyze the contribution of radiative transfer, calculations of the incoming radiative flux from the arc column on the plate are performed. Experimental time- and space-resolved temperature and pressure distributions of the arc column are used for these computations, which are performed using a line-by-line calculation based on accurate plasma spectroscopic data, in association with a ray tracing method. An energy budget analysis is proposed, and the influence of the different mechanisms is discussed. A transferred energy higher than 300 J is observed for the 100 kA current waveform. The comparisons show that the radiative flux from the arc channel can play an important role in the energy balance at the plate surface.