Experimental simulation of a double return‐stroke lightning flash by lasers

A lightning flash is composed of various energetic discharges called return‐strokes which are believed to be responsible for the natural formation NOX in the atmosphere. We report the first experimental attempt in the simulation of such a process. The temporal evolution of electric breakdown in air at atmospheric pressure of two synchronized Nd:YAG nanosecond laser pulses was studied to understand the physical behavior of a double return‐stroke lightning flash by shadowgraphy and interferometry techniques. The temperature of the second return‐stroke reaches about 20,000 K after 1 μs of laser ignition of the second pulse and cools off more rapidly than the first discharge. The cooling rate of the heated gas is about a factor of two faster for the second simulated return‐stroke. The estimated production of nitric oxide of two synchronized laser induced plasmas seems to be not substantially modified as compared with the sum of the isolated single pulses.