PLASMA CHANNELS IN AIR PRODUCED BY UV LASER BEAM: MECHANISMS OF PHOTOIONIZATION AND POSSIBLE APPLICATIONS

摘要

Plasma channels in atmospheric air can be produced by UV laser beam combined of high-intensity 100-fs pulses for an effective 3- or 4-photon ionization and 100-ns pulses for maintaining the electron density. Ti:Sapphire/KrF laser facility GARPUN-MTW is described to be able producing ～1.5/100-J energies in short / long pulses at λ=248 nm. It is a fine tool to create plasma channels for triggering a long-distance HV discharge (lightning) and for other applications. The pilot experiments were performed with both short and long UV pulses to demonstrate 1 -m long perfectly guided HV discharge and to study ionization mechanisms in different gases (atmospheric air, nitrogen, argon).