Since the early 1970s, scientists have considered the potential of lasers to manipulate the path of lightning bolts. Such a capability might enable public utilities, airports and other sensitive sites to save billions of dollars per year by avoiding disrupted services and eliminating damage associated with lightning strikes.Researchers associated with the joint French/German Teramobile (mobile terawatt) lidar project report in the Dec. 6 issue of Applied Physics Letters that their experiments with femtosecond pulses from a chirped pulse amplified Ti:sapphire laser suggest that such ultrashort lasers may be suitable for real-world lightning control.In the work, they monitored the probability of high-voltage free discharges over a 1.2-m gap through dry air and a simulated dense cloud under normal conditions and in the presence of self-guided filaments of ionized plasma generated by 170-fs pulses of 800-nm laser radiation with energies of up to 230 mJ. A Marx generator served as the source of high-voltage discharges. They found that the laser-induced filaments triggered and guided discharges even in the dense cloud, albeit with a probability of discharge that was 30 percent lower than they displayed in dry air.The researchers, from Université Claude Bernard Lyon 1 in Villeurbanne, France, Freie Universität Berlin, École Nationale Supérieure de Techniques Avancées in Palaiseau, France, and Technische Universität Berlin, note that laser-induced self-guided filaments can propagate several hundred meters through the atmosphere. Coupled with repetition rates that compensate for even low probabilities of discharge, they suggest, femtosecond lasers are promising candidates for lightning control systems.