3D HYDRA simulations of NIF targets (open access)

3D HYDRA simulations of NIF targets

The performance of NIF target designs is simulated in three dimensions using the HYDRA multiphysics radiation hydrodynamics code. In simulations of a cylindrical NIF hohlraum that include an imploding capsule, all relevant hohlraum features and the detailed laser illumination pattern, the motion of the wall material inside the hohlraum shows a high degree of axisymmetry. Laser light is able to propagate through the entrance hole for the required duration of the pulse. Gross hohlraum energetics mirror the results from an axisymmetric simulation. A NIF capsule simulation resolved the full spectrum of the most dangerous modes that grow from surface roughness. Hydrodynamic instabilities evolve into the weakly nonlinear regime. There is no evidence of anomalous low mode growth driven by nonlinear mode coupling.
Date: October 30, 2000
Creator: Marinak, M. M.; Kerbel, G. D.; Gentile, N. A.; Jones, O.; Munro, D.; Pollaine, S. et al.
System: The UNT Digital Library
Comparing interval estimates for small sample ordinal CFA models (open access)

Comparing interval estimates for small sample ordinal CFA models

This article compares Bayesian, Robust maximum likelihood, and asymptotically generalized least squares interval estimates of factor correlations in ordinal confirmatory factor analysis models for small sample data.
Date: October 30, 2015
Creator: Natesan, Prathiba
System: The UNT Digital Library
Resolving the Formation of Protogalaxies. III.Feedback from the First Stars (open access)

Resolving the Formation of Protogalaxies. III.Feedback from the First Stars

The first stars form in dark matter halos of masses {approx}10{sup 6}M{sub {circle_dot}} as suggested by an increasing number of numerical simulations. Radiation feedback from these stars expels most of the gas from their shallow potential well of their surrounding dark matter halos. We use cosmological adaptive mesh refinement simulations that include self-consistent Population III star formation and feedback to examine the properties of assembling early dwarf galaxies. Accurate radiative transport is modeled with adaptive ray tracing. We include supernova explosions and follow the metal enrichment of the intergalactic medium. The calculations focus on the formation of several dwarf galaxies and their progenitors. In these halos, baryon fractions in 10{sup 8} M{sub {circle_dot}} halos decrease by a factor of 2 with stellar feedback and by a factor of 3 with supernova explosions. We find that radiation feedback and supernova explosions increase gaseous spin parameters up to a factor of 4 and vary with time. Stellar feedback, supernova explosions, and H{sub 2} cooling create a complex, multi-phase interstellar medium whose densities and temperatures can span up to 6 orders of magnitude at a given radius. The pair-instability supernovae of Population III stars alone enrich the halos with virial temperatures of 10{sup …
Date: October 30, 2007
Creator: Wise, John H.; Abel, Tom & /KIPAC, Menlo Park
System: The UNT Digital Library