title: The effect of long timescale gas dynamics on femtosecond filamentation.
abstract: Femtosecond laser pulses filamenting in various gases are shown to generate long- lived quasi-stationary cylindrical depressions or 'holes' in the gas density. For our experimental conditions, these holes range up to several hundred microns in diameter with gas density depressions up to ~20%. The holes decay by thermal diffusion on millisecond timescales. We show that high repetition rate filamentation and supercontinuum generation can be strongly affected by these holes, which should also affect all other experiments employing intense high repetition rate laser pulses interacting with gases.
authors.affiliation: Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Y-H
authors.initials: YH
authors.lastname: Cheng
authors.forename: J K
authors.initials: JK
authors.lastname: Wahlstrand
authors.forename: N
authors.initials: N
authors.lastname: Jhajj
authors.forename: H M
authors.initials: HM
authors.lastname: Milchberg
mesh_terms: D005740:Gases / Q000737:chemistry*; D007834:Lasers; D008422:Materials Testing; D012542:Scattering, Radiation
chemical_list: D005740:Gases