title: X-ray self-emission imaging used to diagnose 3-D nonuniformities in direct-drive ICF implosions.
abstract: As hydrodynamics codes develop to increase understanding of three-dimensional (3-D) effects in inertial confinement fusion implosions, diagnostics must adapt to evaluate their predictive accuracy. A 3-D radiation postprocessor was developed to investigate the use of soft x-ray self-emission images of an imploding target to measure the size of nonuniformities on the target surface. Synthetic self-emission images calculated from 3-D simulations showed a narrow ring of emission outside the ablation surface of the target. Nonuniformities growing in directions perpendicular to the diagnostic axis were measured through angular variations in the radius of the steepest intensity gradient on the inside of the ring and through changes in the peak x-ray intensity in the ring as a function of angle. The technique was applied to an implosion to measure large 3-D nonuniformities resulting from two dropped laser beam quads at the National Ignition Facility.
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Davis
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.
authors.forename: D T
authors.initials: DT
authors.lastname: Michel
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Craxton
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.
authors.forename: R
authors.initials: R
authors.lastname: Epstein
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hohenberger
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.
authors.forename: T
authors.initials: T
authors.lastname: Mo
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Froula