title: Evolution of elastic x-ray scattering in laser-shocked warm dense lithium.
abstract: We have studied the dynamics of warm dense Li with near-elastic x-ray scattering. Li foils were heated and compressed using shock waves driven by 4-ns-long laser pulses. Separate 1-ns-long laser pulses were used to generate a bright source of 2.96 keV Cl Ly- alpha photons for x-ray scattering, and the spectrum of scattered photons was recorded at a scattering angle of 120 degrees using a highly oriented pyrolytic graphite crystal operated in the von Hamos geometry. A variable delay between the heater and backlighter laser beams measured the scattering time evolution. Comparison with radiation-hydrodynamics simulations shows that the plasma is highly coupled during the first several nanoseconds, then relaxes to a moderate coupling state at later times. Near-elastic scattering amplitudes have been successfully simulated using the screened one-component plasma model. Our main finding is that the near-elastic scattering amplitudes are quite sensitive to the mean ionization state Z[over ] and by extension to the choice of ionization model in the radiation-hydrodynamics simulations used to predict plasma properties within the shocked Li.
authors.affiliation: Physics Department, University of California-Los Angeles, Los Angeles, California 90095, USA.
authors.forename: N L
authors.initials: NL
authors.lastname: Kugland
authors.forename: G
authors.initials: G
authors.lastname: Gregori
authors.forename: S
authors.initials: S
authors.lastname: Bandyopadhyay
authors.forename: C M
authors.initials: CM
authors.lastname: Brenner
authors.forename: C R D
authors.initials: CR
authors.lastname: Brown
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authors.initials: C
authors.lastname: Constantin
authors.forename: S H
authors.initials: SH
authors.lastname: Glenzer
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authors.initials: FY
authors.lastname: Khattak
authors.forename: A L
authors.initials: AL
authors.lastname: Kritcher
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authors.lastname: Niemann
authors.forename: A
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authors.lastname: Otten
authors.forename: J
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authors.lastname: Pasley
authors.forename: A
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authors.lastname: Pelka
authors.forename: M
authors.initials: M
authors.lastname: Roth
authors.forename: C
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authors.lastname: Spindloe
authors.forename: D
authors.initials: D
authors.lastname: Riley