title: Optical-field-ionization effects on the propagation of an ultraintense laser pulse in high- Z gas jets.
abstract: Interaction of an ultraintense, a(0) >>1, laser pulse with an underdense Ar plasma is analyzed via a two-dimensional particle-in-cell simulation which self-consistently includes optical-field ionization. In spite of rapid growth of ion charge Z and, hence, electron density at the laser front, relativistic self-focusing is shown to persist owing to a reduction of the expected plasma defocusing resulting from the weak radial dependence of the ion charge on laser intensity (even for Z/gamma>1 where gamma is the electron relativistic factor).
authors.affiliation: Nuclear Engineering Research Laboratory, Graduate School of Engineering, The University of Tokyo, 22-2 Shirane-shirakata, Tokai, Naka, Ibaraki 319-1188, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Zhidkov
authors.forename: J
authors.initials: J
authors.lastname: Koga
authors.forename: T
authors.initials: T
authors.lastname: Esirkepov
authors.forename: T
authors.initials: T
authors.lastname: Hosokai
authors.forename: M
authors.initials: M
authors.lastname: Uesaka
authors.forename: T
authors.initials: T
authors.lastname: Tajima