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Title: Update on Specifications for NIF Ignition Targets

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1184728
Report Number(s):
UCRL-JRNL-229485
DOE Contract Number:
DE-AC52-07NA27344
Resource Type:
Journal Article
Resource Relation:
Journal Name: Fusion Science and Technology, vol. 51, no. 4, May 1, 2007, pp. 509-513
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 70 PLASMA PHYSICS AND FUSION

Citation Formats

Haan, S W, Amendt, P A, Callahan, D A, Dittrich, T R, Edwards, M J, Hammel, B A, Ho, D D, Jones, O S, Lindl, J D, Marinak, M M, Munro, D H, Pollaine, S M, Salmonson, J D, Spears, B K, and Suter, L J. Update on Specifications for NIF Ignition Targets. United States: N. p., 2007. Web.
Haan, S W, Amendt, P A, Callahan, D A, Dittrich, T R, Edwards, M J, Hammel, B A, Ho, D D, Jones, O S, Lindl, J D, Marinak, M M, Munro, D H, Pollaine, S M, Salmonson, J D, Spears, B K, & Suter, L J. Update on Specifications for NIF Ignition Targets. United States.
Haan, S W, Amendt, P A, Callahan, D A, Dittrich, T R, Edwards, M J, Hammel, B A, Ho, D D, Jones, O S, Lindl, J D, Marinak, M M, Munro, D H, Pollaine, S M, Salmonson, J D, Spears, B K, and Suter, L J. Wed . "Update on Specifications for NIF Ignition Targets". United States. doi:. https://www.osti.gov/servlets/purl/1184728.
@article{osti_1184728,
title = {Update on Specifications for NIF Ignition Targets},
author = {Haan, S W and Amendt, P A and Callahan, D A and Dittrich, T R and Edwards, M J and Hammel, B A and Ho, D D and Jones, O S and Lindl, J D and Marinak, M M and Munro, D H and Pollaine, S M and Salmonson, J D and Spears, B K and Suter, L J},
abstractNote = {},
doi = {},
journal = {Fusion Science and Technology, vol. 51, no. 4, May 1, 2007, pp. 509-513},
number = ,
volume = ,
place = {United States},
year = {Wed Mar 21 00:00:00 EDT 2007},
month = {Wed Mar 21 00:00:00 EDT 2007}
}
  • Indirect drive ignition target simulations are described as they are used to determine target fabrication specifications. Simulations are being used to explore options for making the targets more robust, and to develop more detailed understanding of the performance of a few point designs. The current array of targets is described. A new target is described with radially dependent Cu dopant in Be. This target has significantly looser specifications for high-mode perturbations than previous targets. Current estimates of size limitations for fill tubes, holes, and isolated defect are discussed. Recent 3D simulations are described.
  • Targets intended to produce ignition on NIF are being simulated and the simulations are used to set specifications for target fabrication. Recent design work has focused on designs that assume only 1.0 MJ of laser energy instead of the previous 1.6 MJ. To perform with less laser energy, the hohlraum has been redesigned to be more efficient than previously, and the capsules are slightly smaller. The main-line hohlraum design now has a SiO2 foam fill, a wall of U-Dy-Au, and shields mounted between the capsule and the laser entrance holes. Two capsule designs are being considered. One has a gradedmore » doped Be(Cu) ablator, and the other graded doped CH(Ge). Both can perform acceptably with recently demonstrated ice layer quality, and with recently demonstrated outer surface roughness. Smoothness of the internal interfaces may be an issue for the Be(Cu) design, and it may be necessary either to polish partially coated shells or to improve process control so that the internal layers are smoother. Complete tables of specifications are being prepared for both targets, to be completed this fiscal year. All the specifications are being rolled together into an error budget indicating adequate margin for ignition with the new designs.« less
  • Point design targets have been specified for the initial ignition campaign on the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 443, 2841 (2004)]. The targets contain D-T fusion fuel in an ablator of either CH with Ge doping, or Be with Cu. These shells are imploded in a U or Au hohlraum with a peak radiation temperature set between 270 and 300 eV. Considerations determining the point design include laser-plasma interactions, hydrodynamic instabilities, laser operations, and target fabrication. Simulations were used to evaluate choices, and to define requirements and specifications. Simulation techniquesmore » and their experimental validation are summarized. Simulations were used to estimate the sensitivity of target performance to uncertainties and variations in experimental conditions. A formalism is described that evaluates margin for ignition, summarized in a parameter the Ignition Threshold Factor (ITF). Uncertainty and shot-to-shot variability in ITF are evaluated, and sensitivity of the margin to characteristics of the experiment. The formalism is used to estimate probability of ignition. The ignition experiment will be preceded with an experimental campaign that determines features of the design that cannot be defined with simulations alone. The requirements for this campaign are summarized. Requirements are summarized for the laser and target fabrication.« less