Periodic Reporting for period 3 - LLR (Laser Lightning Rod)
Période du rapport: 2021-01-01 au 2021-12-31
The LLR laser system was finalized by the beginning of January 2020 at the labs of Trumpf Scientific Lasers. A compressed pulse energy of 720 mJ could be achieved at the repetition rate of 1 kHz, with a pulse duration of < 1 ps, leading to a peak power as high as 720 GW. An horizontal campaign to characterize the filament produced by the laser has been realized in Orsay in 2020 and early 2021. Studies of the laser beam propagation with a telescope have shown that it is possible to generate filaments starting at a distance exceeding 110 m, which corresponds to the height of the Saentis tower.
Finally, during the Summer of 2021, the developed high-power 720 mJ, 1 kHz laser was installed near the Säntis Tower at the top of the 2504-m tall Säntis mountain. During this campaign the influence of the laser and filament to trigger and guide lightning was analyzed.
The guiding of an upward negative lightning leader over a distance of 50 m was recorded by two separate high-speed cameras. The guiding of negative lightning leaders by laser filaments was corroborated in three other instances by VHF interferometric measurements, and the number of X-ray bursts detected during guided lightning events was significantly increased. While this research field has been very active for more than 20 years with many research groups around the world working to achieve this goal, this result demonstrates lightning guiding by lasers, which may lead to the development of a laser lightning rod.
More generally, the target is the protection of industrial sites, chemical and nuclear power plants. It will more specifically concern the Space Industry (protection of launch pad and launcher/satellite integration buildings), airport (protection of aircraft during the take-off, landing and taxiing phases, protection of radars), wind turbines (for French, German, Danish, British, and Dutch offshore windfarms).