title: Propagation of a laser-driven relativistic electron beam inside a solid dielectric.
abstract: Laser probe diagnostics: shadowgraphy, interferometry, and polarimetry were used for a comprehensive characterization of ionization wave dynamics inside a glass target induced by a laser-driven, relativistic electron beam. Experiments were done using the 50-TW Leopard laser at the University of Nevada, Reno. We show that for a laser flux of ∼2 × 10(18) W/cm2 a hemispherical ionization wave propagates at c/3 for 10 ps and has a smooth electron-density distribution. The maximum free-electron density inside the glass target is ∼2 × 10(19) cm-3, which corresponds to an ionization level of ∼0.1%. Magnetic fields and electric fields do not exceed ∼15 kG and ∼1 MV/cm, respectively. The electron temperature has a hot, ringlike structure with a maximum of ∼0.7 eV. The topology of the interference phase shift shows the signature of the "fountain effect", a narrow electron beam that fans out from the propagation axis and heads back to the target surface. Two-dimensional particle-in-cell (PIC) computer simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields driven by laser. The very low ionization observed after the laser heating pulse suggests a fast recombination on the sub-ps time scale.
authors.affiliation: Raytheon Ktech, 1300 Eubank Blvd, Albuquerque, New Mexico 87123, USA.
authors.forename: G S
authors.initials: GS
authors.lastname: Sarkisov
authors.forename: V V
authors.initials: VV
authors.lastname: Ivanov
authors.forename: P
authors.initials: P
authors.lastname: Leblanc
authors.forename: Y
authors.initials: Y
authors.lastname: Sentoku
authors.forename: K
authors.initials: K
authors.lastname: Yates
authors.forename: P
authors.initials: P
authors.lastname: Wiewior
authors.forename: O
authors.initials: O
authors.lastname: Chalyy
authors.forename: A
authors.initials: A
authors.lastname: Astanovitskiy
authors.forename: V Yu
authors.initials: VY
authors.lastname: Bychenkov
authors.forename: D
authors.initials: D
authors.lastname: Jobe
authors.forename: R B
authors.initials: RB
authors.lastname: Spielman
mesh_terms: D003198:Computer Simulation; D004553:Electric Conductivity; D004583:Electrons; D005898:Glass / Q000737:chemistry* / Q000528:radiation effects*; D007834:Lasers; D008027:Light; D008962:Models, Theoretical; D012542:Scattering, Radiation