title: Kinetic effects and nonlinear heating in intense x-ray-laser-produced carbon plasmas.
abstract: The x-ray laser-matter interaction for a low-Z material, carbon, is studied with a particle-in-cell code that solves the photoionization and x-ray transport self-consistently. Photoionization is the dominant absorption mechanism and nonthermal photoelectrons are produced with energy near the x-ray photon energy. The photoelectrons ionize the target rapidly via collisional impact ionization and field ionization, producing a hot plasma column behind the laser pulse. The radial size of the heated region becomes larger than the laser spot size due to the kinetic nature of the photoelectrons. The plasma can have a temperature of more than 10 000 K (>1eV), an energy density greater than 10^{4} J/cm^{3}, an ion-ion Coulomb coupling parameter Γ≥1, and electron degeneracy Θ≥1, i.e., strongly coupled warm dense matter. By increasing the laser intensity, the plasma temperature rises nonlinearly from tens of eV to hundreds of eV, bringing it into the high energy density matter regime. The heating depth and temperature are also controllable by changing the photon energy of the incident laser light.
authors.affiliation: Department of Physics, University of Nevada, Reno, Nevada 89557, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Sentoku
authors.affiliation: Department of Physics, University of Nevada, Reno, Nevada 89557, USA.
authors.forename: I
authors.initials: I
authors.lastname: Paraschiv
authors.affiliation: Department of Physics, University of Nevada, Reno, Nevada 89557, USA.
authors.forename: R
authors.initials: R
authors.lastname: Royle
authors.affiliation: Department of Physics, University of Nevada, Reno, Nevada 89557, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Mancini
authors.affiliation: Graduate School of Engineering, Hiroshima University, Hiroshima Prefecture 739-8527, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Johzaki