Focal-Length Dependence of Air Breakdown by a 20-psec Laser Pulse: Theoretical Interpretation through the Effective-Photon Concept

Abstract

It is shown that the use of the concept of effective photons offers a simple explanation of some recent experimental results of air breakdown by a 20-psec laser pulse, in which a quadratic dependence of breakdown laser power on lens focal length has been found. It is also demonstrated that the use of the same concept yields a different focal-length dependence in the case of gas breakdown with rectangular and Gaussian spatial beam profiles.