Interaction of a long laser spark with an atmospheric electric field

This paper discusses the interaction of a long laser spark (LLS) as a single conductive object with a homogeneous electric field E<10 kV/cm. The LLS is represented as a set of point sources of photoionization. The charge kinetics in the photoionization air plasma that surrounds the ionization sources and the dynamics of the charge-separation processes at the ends of the LLS are theoretically calculated. It is shown that the characteristic polarization time of the LLS is determined by its length and effective conductivity. Different regimes can be implemented in the interaction process, depending on the ratio of the polarization time and the photoionization pulsewidth. An ionization wave is excited at the positive end of the LLS when two parameters of the LLS (the ratio of its length to its diameter and the effective conductivity) simultaneously exceed threshold values. (C) 1999 The Optical Society of America.