Triggering of a laser-guided positive leader from a ground rod for the purpose of lightning control

Summary form only given. Ultrashort pulse lasers have emerged as serious candidates for the accomplishment of laser-triggered lightning. Thanks to their very high peak intensity, they can generate long continuous plasma channels with a modest amount of energy, via multiphoton ionization. Such channels could be used in the future, during thunderstorms, to trigger and guide an upward positive leader from a ground rod. This leader could then connect with a negative leader coming down from a cloud, therefore "catching" the lightning bolt during its formation. In this talk, we will first summarize the main conclusions from i) our observations of triggering and propagation properties of positive leaders guided by a plasma channel produced with a picosecond laser pulse (X=800 nm) in rod-plane gaps ranging from 3 to 7 meters, and ii) our adaptation of the ONERA-University of Padova model of positive leader propagation to the case of laser-guided discharges. Afterwards, we will focus on the results of a laboratory study of the inception of a laser-guided positive leader from a 2-meter rod, placed on the ground plane of a 7-meter plane-plane gap. The experiment was designed to reproduce the electrical conditions generated by the approach of a downward negative leader during a thunderstorm. In conclusion, we will discuss our expectations regarding the possible realization of laser-triggered lightning.