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Zou, J.

Publications and source records attributed to Zou, J..

14 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Talbot-Lau x-ray deflectometer: Refraction-based HEDP imaging diagnostic

Talbot-Lau x-ray interferometry has been implemented to map electron density gradients in High Energy Density Physics (HEDP) experiments. X-ray backlighter targets have been evaluated for Talbot-Lau X-ray Deflectometry (TXD). Cu foils, wires, and sphere targets have been irradiated by 10–150 J, 8–30 ps laser pulses, while two pulsed-power generators (∼350 kA, 350 ns and ∼200 kA, 150 ns) have driven Cu wire, hybrid, and laser-cut x-pinches. A plasma ablation front generated by the Omega EP laser was imaged for the first time through TXD for densities >1023 cm−3. Backlighter optimization in combination with x-ray CCD, image plates, and x-ray film has been assessed in terms of spatial resolution and interferometer contrast for accurate plasma characterization through TXD in pulsed-power and high-intensity laser environments. The results obtained thus far demonstrate the potential of TXD as a powerful diagnostic for HEDP.

Valdivia, M. P.↗
DOE OSTI2020

Optical characterization of the on-target OMEGA focal spot at high energy using the full-beam in-tank diagnostic

The full-beam in-tank (FBIT) diagnostic has been deployed to directly measure the target-plane beam fluence profile, when operated at high energy, of the OMEGA Laser System at the University of Rochester’s Laboratory for Laser Energetics. This article presents the results of early measurements taken with this diagnostic and discusses an improvement that has overcome performance limitations discovered during the initial testing. The diagnostic gives new insight into the ability of the OMEGA Laser System to provide uniform fluence profiles that are consistent across all 60 beams in the laser. Overall, the ultimate goal of the FBIT diagnostic is to allow accurate assessment of the fluence uniformity on a spherical target in 60-beam implosion experiments

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Implementation of a Talbot–Lau x-ray deflectometer diagnostic platform for the OMEGA EP laser

A Talbot–Lau X-ray Deflectometer (TXD) was implemented in the OMEGA EP laser facility to characterize the evolution of an irradiated foil ablation front by mapping electron densities >10 22 cm -3 by means of Moiré deflectometry. The experiment used a short-pulse laser (30–100 J, 10 ps) and a foil copper target as an x-ray backlighter source. In the first experimental tests performed to benchmark the diagnostic platform, grating survival was demonstrated and x-ray backlighter laser parameters that deliver Moiré images were described. Finally, the necessary modifications to accurately probe the ablation front through TXD using the EP-TXD diagnostic platform are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Clinical and CT Angiographic Follow-Up Outcome of Spontaneous Isolated Intramural Hematoma of the Superior Mesenteric Artery

Objectives: The aim of this study was to evaluate the clinical course and vascular remodeling of spontaneous isolated intramural hematoma of the superior mesenteric artery (SIHSMA) after treatment. Methods: In this retrospective study, 24 consecutive patients with SIHSMA admitted from January 2009 through December 2016 were included in this study. The clinical characteristics, type and location of the dissection, clinical outcome and vascular remodeling were analyzed retrospectively. Results: The subjects included 21 men and three women, with a mean age of 50.58 years. The chief complaint was abdominal pain in all patients. The mean follow-up was 10.08 months. Among the 24 patients examined, two patients (8.33%) showed no obvious changes in the CT. Twenty patients were treated by conservative strategy. One case underwent exploratory laparotomy along with embolectomy and arteriotomy. Another three cases received angioplasty and stent implanting. Complete and partial remodeling was observed in 15 (62.5%) and four patients (16.67%). Three (12.5%) of the lesions had dissection remodeling and aneurysm change. Conclusions: SIHSMA represented variable vascular remodeling, while most of the patient got a complete resolution during follow-up, and its clinical course was benign in this study. Vast majority of patients can be managed conservatively when there are no signs indicating organ ischemia.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Negative Electron Affinity Gallium Arsenide Photocathodes Based on Optically Resonant Nanostructure

We report the design and fabrication of a new type of negative electron affinity (NEA) gallium arsenide (GaAs)photocathode with optically resonant nanostructures. We observed a significant enhancement of the quantum efficiency(QE) from the GaAs photocathode with nanowire arrays (NWA) due to the Mie resonance effect within the intended wavelength range. Theoretical calculations of the expected reflectance behaviour together with experimental results of optical and photoemission characteristics are presented.

Zhang, Shukui↗
DOE OSTI2016

Nonlinear Cherenkov difference-frequency generation exploiting birefringence of KTP

In this letter, we demonstrate the realization of nonlinear Cherenkov difference-frequency generation (CDFG) exploiting the birefringence property of KTiOPO{sub 4} (KTP) crystal. The pump and signal waves were set to be along different polarizations, thus the phase-matching requirement of CDFG, which is, the refractive index of the pump wave should be smaller than that of the signal wave, was fulfilled. The radiation angles and the intensity dependence of the CDFG on the pump wave were measured, which agreed well with the theoretical ones.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1998

Stable and Metastable InGaAs/GaAs Island Shapes and Surfactant-like Suppression of the Wetting Transformation

Diverging behaviors are observed in the InGaAs/GaAs Stranski-Krastanow (S-K) island formation during vapor phase epitaxy: varying group V partial pressures gives different critical thicknesses for the onset of the S-K transformation, island surface coverages, ratios between coherent and incoherent islands, and dissimilar morphologies upon annealing.

InGaAs/GaAs wetting transformation Stranski-Krasta↗