抄録
Laser induced spark discharge in atmospheric pressure of the familiar gases (N2, O2, Air) was studied by using several kind of lasers such as a N2-laser, a Ruby-laser, a Nd: glass-laser and two Dye-lasers as a basic research for a new technique of laser triggered lightning. The output level of each laser is lower than the threshold value above which gas breakdown takes place. The laser beam is introduced through a focus lens into a gas vessel in which spherical electrodes of 40 mm in diameter are settled with spacing of 10 mm. No effect of lasers on reduction of breakdown voltage in N2 gas and remarkable reduction in O2 gas and air with the laser wave lenghth shorter than 730 nm were observed. These results lead to conclude that the breakdown is promoted by electron production by photodetachment of O- ions produced in the space between electrodes to which DC voltage less than breakdown voltage is applied. Position control of breakdown path by the laser is also demonstrated.
