title: Observation of self-sustaining relativistic ionization wave launched by a sheath field.
abstract: We present experimental evidence supported by simulations of a relativistic ionization wave launched into a surrounding gas by the sheath field of a plasma filament with high energy electrons. Such a filament is created by irradiating a clustering gas jet with a short pulse laser (115  fs) at a peak intensity of 5×10(17)  W/cm2. We observe an ionization wave propagating radially through the gas for about 2 ps at 0.2-0.5 c after the laser has passed, doubling the initial radius of the filament. The gas is ionized by the sheath field, while the longevity of the wave is explained by a moving field structure that traps the high energy electrons near the boundary, maintaining a strong sheath field despite the significant expansion of the plasma.
authors.affiliation: Center for High Energy Density Science, The University of Texas, Austin, Texas 78712, USA.
authors.forename: M
authors.initials: M
authors.lastname: McCormick
authors.affiliation: Institute for Fusion Studies, The University of Texas, Austin, Texas 78712, USA.
authors.forename: A V
authors.initials: AV
authors.lastname: Arefiev
authors.affiliation: Center for High Energy Density Science, The University of Texas, Austin, Texas 78712, USA.
authors.forename: H J
authors.initials: HJ
authors.lastname: Quevedo
authors.affiliation: Center for High Energy Density Science, The University of Texas, Austin, Texas 78712, USA.
authors.forename: R D
authors.initials: RD
authors.lastname: Bengtson
authors.affiliation: Center for High Energy Density Science, The University of Texas, Austin, Texas 78712, USA.
authors.forename: T
authors.initials: T
authors.lastname: Ditmire