Research on Field Experiments of Laser Triggered Lightning

Abstract

Study of laser triggered lightning has been conducted at field experiments. The experimental site was constructed at Mt. Dake close to the Japan sea shore in Fukui prefecture. An electron-beam sustained two-beam 1kJ CO₂ laser, 500 and 1000-mm diameter Cassegrain type focusing mirrors and a 50-m tall lightning tower were prepared. To produce a plasma channel for leader initiation, a plastic target was set at the top of the lightning tower and irradiated by the CO₂ laser. An aerosol plasma channel was also produced from the top of the plastic target. The laser plasma channel successfully triggered a lightning stroke. Rogowski coil current detectors monitored the current growing rapidly and UHF interferometer set on Goichi observation site was detected an UHF radiation from Mt. Dake as same timing as the laser irradiating. The UHF radiation was correlated to the leader initiation both in time and space. Hence, we confirmed the laser triggered lightning.