Fundamental Research on Lightning Triggering By Means of UV Lasers.

This study is carried out to examine the possibility of lightning control using a photoionized plasma produced by a UV laser without an optical air breakdown. As the fundamental experiment, the characteristics of a laser-triggered spark gap (LTSG) are examined, where a laser beam is not irradiated on the surface of the electrodes. In this experiment, the KrF excimer laser is very effective in increasing the plasma density ne and the reduction ratiop of 50 percent breakdown voltage against the self-breakdown voltage. The relation between ne and p is increased by generating a long and high-density plasma parallel to the discharge axis. On the other hand, the abnormal discharge process in triggered lightning using a rocket is examined, and it is indicated that the most important condition to trigger a lightning discharge is the production of a plasma channel of length 200 m and density about 1019 m-3. It is suggested that such a plasma channel could be produced by a KrF excimer laser with an energy of only about 3.67 J. [ABSTRACT FROM AUTHOR]