title: Hot electron temperature and coupling efficiency scaling with prepulse for cone-guided fast ignition.
abstract: The effect of increasing prepulse energy levels on the energy spectrum and coupling into forward-going electrons is evaluated in a cone-guided fast-ignition relevant geometry using cone-wire targets irradiated with a high intensity (10(20) W/cm(2)) laser pulse. Hot electron temperature and flux are inferred from Kα images and yields using hybrid particle-in-cell simulations. A two-temperature distribution of hot electrons was required to fit the full profile, with the ratio of energy in a higher energy (MeV) component increasing with a larger prepulse. As prepulse energies were increased from 8 mJ to 1 J, overall coupling from laser to all hot electrons entering the wire was found to fall from 8.4% to 2.5% while coupling into only the 1-3 MeV electrons dropped from 0.57% to 0.03%.
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: T
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authors.lastname: Ma
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authors.lastname: Sawada
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authors.lastname: Patel
authors.forename: C D
authors.initials: CD
authors.lastname: Chen
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authors.lastname: Divol
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authors.lastname: Higginson
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authors.lastname: Kemp
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authors.lastname: Key
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authors.initials: DJ
authors.lastname: Larson
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authors.lastname: Le Pape
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authors.lastname: Link
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authors.lastname: MacPhee
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authors.lastname: McLean
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authors.lastname: Ping
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authors.lastname: Stephens
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authors.lastname: Wilks
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authors.lastname: Beg