Electric-discharge guiding by a continuous spark by focusing CO2-laser radiation with a conic mirror

The feasibility of producing continuous laser sparks (CLSs) with a resistance per unit length of 100 – 400 Ω cm^-1 by focusing radiation from CO₂ laser with a conic mirror is demonstrated. The laser energy input per unit length required for this is experimentally found to be equal to ~200 J m^-1. The possibility to efficiently control the trajectory of an electric discharge by means of a CLS is demonstrated. A CLS is found to be an analogue of a high-conductivity metal rod during the electric breakdown and electric potential transfer. The effect of polarity in the electric breakdown of air gaps between the CLS plasma channel and a metal rod is discovered and interpreted. The transverse structure of the CLS conductivity is investigated. Most likely the CLS conductivity at the initial stage is due to the photoionisation of air by the radiation of primary nuclei of the optical breakdown.