title: Resolving hot spot microstructure using x-ray penumbral imaging (invited).
abstract: We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: B
authors.initials: B
authors.lastname: Bachmann
authors.affiliation: General Atomics, San Diego, California 92186, USA.
authors.forename: T
authors.initials: T
authors.lastname: Hilsabeck
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: J
authors.initials: J
authors.lastname: Field
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: N
authors.initials: N
authors.lastname: Masters
authors.affiliation: General Atomics, San Diego, California 92186, USA.
authors.forename: C
authors.initials: C
authors.lastname: Reed
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: T
authors.initials: T
authors.lastname: Pardini
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Rygg
authors.affiliation: General Atomics, San Diego, California 92186, USA.
authors.forename: N
authors.initials: N
authors.lastname: Alexander
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Benedetti
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: T
authors.initials: T
authors.lastname: Döppner
authors.affiliation: General Atomics, San Diego, California 92186, USA.
authors.forename: A
authors.initials: A
authors.lastname: Forsman
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: N
authors.initials: N
authors.lastname: Izumi
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: S
authors.initials: S
authors.lastname: LePape
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: T
authors.initials: T
authors.lastname: Ma
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: A G
authors.initials: AG
authors.lastname: MacPhee
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: S
authors.initials: S
authors.lastname: Nagel
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: P
authors.initials: P
authors.lastname: Patel
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: B
authors.initials: B
authors.lastname: Spears
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: O L
authors.initials: OL
authors.lastname: Landen