Multimode hydrodynamic stability calculations for National Ignition Facility capsules

PDF Version Also Available for Download.

Description

The authors examine the hydrodynamic stability of imploding ICF capsules by explicitly calculating, the evolution of a realistic surface perturbation far into its nonlinear regime, using, a 2D Lagrangian radiation-hydrodynamics code. The perturbation, which consists initially of mesh displacements in the capsule, is represented by the sum of many spherical harmonic modes, having finite amplitudes and realistic spectrum. A 90-degree sector of the capsule is modeled, allowing proper boundary conditions for all modes simultaneously. Because of the large distortion of the mesh that occurs during the calculations, it is necessary to rezone the mesh frequently, by mapping physical variables to ... continued below

Physical Description

7 p.

Creation Information

Hoffman, N.M.; Wilson, D.C.; Varnum, W.S.; Krauser, W.J. & Wilde, B.H. May 1, 1995.

Context

This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this report can be viewed below.

Who

People and organizations associated with either the creation of this report or its content.

Sponsor

Publisher

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this report. Follow the links below to find similar items on the Digital Library.

Description

The authors examine the hydrodynamic stability of imploding ICF capsules by explicitly calculating, the evolution of a realistic surface perturbation far into its nonlinear regime, using, a 2D Lagrangian radiation-hydrodynamics code. The perturbation, which consists initially of mesh displacements in the capsule, is represented by the sum of many spherical harmonic modes, having finite amplitudes and realistic spectrum. A 90-degree sector of the capsule is modeled, allowing proper boundary conditions for all modes simultaneously. Because of the large distortion of the mesh that occurs during the calculations, it is necessary to rezone the mesh frequently, by mapping physical variables to a new undistorted mesh. No model-specific parameters are required in this technique. The authors have used the technique to calculate the yield of several designs for a National Ignition Facility capsule as a function of initial root-mean-square surface roughness {sigma} of the outer ablator surface or the inner cryogenic DT surface. Typically for a capsule they find a ``cliff`` at a critical value of {sigma} = {sigma}{sub crit} such that the yield of the capsule decreases abruptly for {sigma} > {sigma}{sub crit}, indicating a failure to ignite. The values of {sigma}{sub crit} they compute are probably upper limits because of the lack of 3D effects, and inaccuracies in Lagrangian modeling of such unstable flows. It is expected that more accurate modeling, perhaps with 3D Eulerian codes, will lead to smaller values for {sigma}{sub crit}. They are beginning to carry out studies of the coupling of low-mode radiation flux asymmetries to higher-mode surface perturbations. They report also on sensitivity studies that examine the response of a capsule to small variations in the driving laser`s power history. They find that realistic surfaces decrease a capsule`s ability to tolerate drive variations.

Physical Description

7 p.

Notes

INIS; OSTI as DE95012073

Source

  • 12. international conference on laser interaction and related plasma phenomena, Osaka (Japan), 24-28 Apr 1995

Language

Item Type

Identifier

Unique identifying numbers for this report in the Digital Library or other systems.

  • Other: DE95012073
  • Report No.: LA-UR--95-1306
  • Report No.: CONF-950476--3
  • Grant Number: W-7405-ENG-36
  • DOI: 10.2172/72980 | External Link
  • Office of Scientific & Technical Information Report Number: 72980
  • Archival Resource Key: ark:/67531/metadc712452

Collections

This report is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this report?

When

Dates and time periods associated with this report.

Creation Date

  • May 1, 1995

Added to The UNT Digital Library

  • Sept. 12, 2015, 6:31 a.m.

Description Last Updated

  • Feb. 25, 2016, 9:27 p.m.

Usage Statistics

When was this report last used?

Yesterday: 0
Past 30 days: 1
Total Uses: 3

Interact With This Report

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

International Image Interoperability Framework

IIF Logo

We support the IIIF Presentation API

Hoffman, N.M.; Wilson, D.C.; Varnum, W.S.; Krauser, W.J. & Wilde, B.H. Multimode hydrodynamic stability calculations for National Ignition Facility capsules, report, May 1, 1995; New Mexico. (digital.library.unt.edu/ark:/67531/metadc712452/: accessed October 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.