Long laser spark for controlling the trajectory of an atmospheric electricdischarge

This paper discusses the conditions for the efficient use of a long laser s park in lightning-protection systems. It is shown that, when the spark is a bout 50 m long, it is possible to obtain reliable protection at the 0.999 l evel and above. The necessary conditions for achieving such reliability are high initial conductivity of the resulting plasma channel (about 0.01-0.1 S/cm) and space-time accuracy of its formation in the direction of the ligh tning. (C) 1999 The Optical Society of America.