Visualization of lightning impulse current discharge on CFRP laminate

In this study, we performed optical visualization experiments on lightning impulse current discharge phenomena on carbon-fiber-reinforced plastic (CFRP) laminates. Lightning discharge is a phenomenon in which an extremely intense flash of light and heat is caused by a large electric current flow over a very short period of time; therefore, it is extremely difficult to observe. For this reason, we used a high-speed video camera to visualize the phenomenon at a frame rate of 1 Mfps. In addition, we used Schlieren photography to visualize shock waves propagating from the discharging electrodes. A lightning impulse current generator was used to replicate natural lightning strikes. We used two types of discharging electrodes: a conical electrode and a jet diverting electrode with an insulating sphere. The waveform of the applied lightning impulse current was T1/T2 = 18/55 [µs], and the maximum current was 40 kA.