The flexible x-ray imager

Budil, K. S.; Perry, T. S.; Bell, P. M.; Hares, J. D.; Miller, Paul L.; Peyser, T. A.; Wallace, R. J.; Louis, H.; Smith, Donald E.

doi:10.1063/1.1146616

Cited by 77 publications

(29 citation statements)

References 8 publications

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“…The x-ray radiation at several keV, which is dominated by the K α radiation (at 4.3 keV for Sc), passes through the target, is imaged by an array of 16 pinholes, and is detected by a gated detector. 29 The 16 images are offset slightly in time, being distributed within the 1 ns backlighter pulse, but the evolution is gradual enough that they are effectively simultaneous. A gold grid, mounted to the target, provides a calibration of both location and magnification.…”

Section: B Laser Irradiation and Target Diagnosticsmentioning

confidence: 99%

Nonlinear mixing behavior of the three-dimensional Rayleigh–Taylor instability at a decelerating interface

et al. 2004

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We report results from the first experiments to explore the evolution of the RayleighTaylor (RT) instability from intentionally three-dimensional (3D) initial conditions at an embedded, decelerating interface in a high-Reynolds-number flow. The experiments used 5 kJ of laser energy to produce a blast wave in polyimide and/or brominated plastic having an initial pressure of ~ 50 Mbars. This blast wave shocked and then decelerated the perturbed interface between first material and a lower-density, C foam. This caused the formation of a decelerating interface with an Atwood number ~2/3, producing a longterm positive growth rate for the RT instability. The initial perturbations were a 3D perturbation in an "egg-crate" pattern with feature spacings of 71 µm in two orthogonal directions and peak-to-valley amplitudes of 5 µm. The resulting RT spikes were observed to overtake the shock waves at the undisturbed, "free-fall" rate, and to subsequently deliver material from behind the interface to the forward shock. This result is unanticipated by prior simulations and models.

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Section: B Laser Irradiation and Target Diagnosticsmentioning

confidence: 99%

Nonlinear mixing behavior of the three-dimensional Rayleigh–Taylor instability at a decelerating interface

et al. 2004

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“…The data presented in this paper were collected from two diagnostics during this NIF early light (NEL) experimental campaign namely; a gated flexible x-ray imager (FXI) [4] configured as a Hard X-ray Imager (HXRI) and a Filter Fluorescer Experiment (FFLEX) diagnostic [5]. The HXRI recorded time resolved hohlraum emission for > 9 keV photons through the thin walls of the hohlraums as well as the emission of > 6 keV photons from outside the hohlraums that passed through the Al filter.…”

Section: Methodsmentioning

confidence: 99%

Hard X-ray and hot electron environment in vacuum hohlraums at NIF

et al. 2006

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Abstract. Time resolved hard x-ray images (hv > 9 keV) and time integrated hard x-ray spectra (hv = 18-150 keV) from vacuum hohlraums irradiated with four 351 nm wavelength NIF laser beams are presented as a function of hohlraum size and laser power and duration. The hard x-ray images and spectra provide insight into the time evolution of the hohlraum plasma filling and the production of hot electrons. The fraction of laser energy detected as hot electrons (f hot ) and a comparison to a filling model are presented.

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“…The cloud is imaged using a gated x-ray framing camera [8]. X rays for the image are generated by a second set of time-delayed laser beams (backlighter beams) pointed at a metal foil, typically Ti, located on the opposite side of the shock tube from the camera.…”

Section: Experimental Setup and Diagnosticsmentioning

confidence: 99%

Mass-Stripping Analysis of an Interstellar Cloud by a Supernova Shock

Hansen

Robey

Miles

et al. 2006

Astrophys Space Sci

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The interaction of supernova shocks and interstellar clouds is an important astrophysical phenomenon since it can result in stellar and planetary formation. Our experiments attempt to simulate this mass-loading as it occurs when a shock passes through interstellar clouds. We drive a strong shock using the Omega laser ( 5 kJ) into a foam-…lled cylinder with an embedded Al sphere (diameter D = 120 m) simulating an interstellar cloud. The density ratio between Al and foam is 9. We have previously reported on the interaction between shock and cloud, the ensuing Kelvin-Helmholtz and Widnall instabilities, and the rapid stripping of all mass from the cloud.We now present a theory that explains the rapid mass-stripping. The theory combines (1) the integral momentum equations for a viscous boundary layer, (2) the equations for a potential ‡ow past a sphere, (3) Spalding's law of the wall for turbulent boundary layers, and (4) the skin friction coe¢ cient for a turbulent boundary layer on a ‡at plate. The theory gives as its …nal result the mass stripped from a sphere in a turbulent high Reynolds number ‡ow, and it agrees very well with our experimental observations.

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The flexible x-ray imager

Cited by 77 publications

References 8 publications

Nonlinear mixing behavior of the three-dimensional Rayleigh–Taylor instability at a decelerating interface

Nonlinear mixing behavior of the three-dimensional Rayleigh–Taylor instability at a decelerating interface

Hard X-ray and hot electron environment in vacuum hohlraums at NIF

Mass-Stripping Analysis of an Interstellar Cloud by a Supernova Shock

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