NASA Scientific and Technical Aerospace Reports

20040070994 Lawrence Livermore National Lab., Livermore, CA
X-Ray Dose and Spot Size Calculations for the DARHT-II Distributed Target
McCarrick, J.; Apr. 05, 2001; In English
Report No.(s): DE2003-15005549; UCRL-ID-145186; No Copyright; Avail: National Technical Information Service (NTIS)
The baseline DARHT-II converter target consists of foamed tantalum within a solid-density cylindrical tamper. The
baseline design has been modified by D. Ho to further optimize the integrated line density of material in the course of multiple
beam pulses. LASNEX simulations of the hydrodynamic expansion of the target have been performed by D. Ho (documented
elsewhere). The resulting density profiles have been used as inputs in the MCNP radiation transport code to calculate the X-ray
dose and spot size assuming a incoming Gaussian electron beam with (sigma)= 0.65mm, and a PIC-generated beam taking
into account the ‘swept’ spot emerging from the DARHT-II kicker system.
NTIS
X Rays; Dosage; Computation; Electron Beams
20040070997 Lawrence Livermore National Lab., Livermore, CA
Predicting the Equilibrium Deuterium-Tritium Fuel Layer Thickness Profile in an Indirect-Drive Hohlraum Capsule
Sanchez, J. J.; Giedt, W. H.; Oct. 27, 2003; In English
Report No.(s): DE2003-15005466; UCRL-CONF-154933; No Copyright; Avail: National Technical Information Service
(NTIS)
A numerical procedure for calculating the equilibrium thickness distribution of a thin layer of deuterium and tritium on
the inner surface of an indirect drive target sphere ((approx) 2.0 mm in diameter) is described. Starting with an assumed
uniform thickness layer and with specified thermal boundary conditions, the temperature distribution throughout the capsule
and hohlraum (including natural convection in the hohlraum gas) is calculated. Results are used to make a first estimate of
the final non-uniform thickness distribution of the layer. This thickness distribution is then used to make a second calculation
of the temperature distribution with the same boundary conditions. Legendre polynomial coefficients are evaluated for the two
temperature distributions and the two thickness profiles. Final equilibrium Legendre coefficients are determined by linear
extrapolation. From these coefficients, the equilibrium layer thickness can be computed.
NTIS
Numerical Analysis; Equilibrium; Deuterium; Tritium; Boundary Layers; Thickness; Hohlraums
20040071021 Lawrence Livermore National Lab., Livermore, CA
Radiative Power Loss Calculations for Krypton and Argon in Intermediate-to-High Density Plasmas
Fournier, K. B.; Chung, H.; Lee, R. W.; Dec. 01, 2001; In English
Report No.(s): DE2003-15005445; UCRL-ID-14681; No Copyright; Avail: National Technical Information Service (NTIS)
The scope of work for this subcontract requires that state-of-the-art, detailed atomic kinetics calculations be applied to
compute the total radiative cooling rates for Ar and Kr in high density plasmas. This is in support of the Defense Threat
Reduction Agency’s program of development of simulators with high-fluence radiation and spectral fidelity. Using
collisional-radiative modeling codes and unique expertise at Lawrence Livermore National Laboratory (LLNL), the total
radiative yields from Ar and Kr, integrated over all photon energies, have been computed. Spectrally resolved yields from
K-shell Ar and K- and L-shell Kr have also been tabulated. The present calculations show that high electron density in the
plasma sources is essential to maximize the fraction of power output in various x-ray bands.
NTIS
Computation; Power Loss; Krypton; Argon; Plasmas (Physics); Electron Density (Concentration)
20040071026 Lawrence Livermore National Lab., Livermore, CA
Parallel Algorithm for Contact in a Finite Element Hydrocode
Pierce, T. G.; Jun. 2003; In English
Report No.(s): DE2003-15005375; UCRL-LR-154063; No Copyright; Avail: National Technical Information Service (NTIS)
A parallel algorithm is developed for contact/impact of multiple three dimensional bodies undergoing large deformation.
As time progresses the relative positions of contact between the multiple bodies changes as collision and sliding occurs. The
parallel algorithm is capable of tracking these changes and enforcing an impenetrability constraint and momentum transfer
across the surfaces in contact. Portions of the various surfaces of the bodies are assigned to the processors of a distributedmemory
parallel machine in an arbitrary fashion, known as the primary decomposition. A secondary, dynamic decomposition
is utilized to bring opposing sections of the contacting surfaces together on the same processors, so that opposing forces may
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