Abstract

With ultrashort pulse laser systems a strongly nonequilibrium plasma can be created by optical field ionization (OFI) of a gaseous medium in an intense laser field Investigations of OFI plasmas are important for soft x-ray laser applications. We present results of time-resolved studies of Helium and Oxygen plasmas produced by focusing of 150 fs Ti:sapphire laser pulses into He and O₂ gas jets. Linearly and circularly polarized laser pulses at 800 nm and at the second harmonic (400 nm) with energies of 100 mJ or 60 mJ are used.

© 1998 IEEE