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Title: Comparison of the Three NIF Ablators

Abstract

Indirect drive implosion experiments on NIF have now been performed using three different ablator materials: glow discharge polymer (GDP) or CH, high density carbon (HDC, which we also refer to as diamond), and sputtered beryllium (Be). It has been appreciated for some time that each of these materials has specific advantages and disadvantages as an ICF ablator.[1-4] In light of experiments conducted on NIF in the last few years, how do these ablators compare? Given current understanding, is any ablator more or less likely to reach ignition on NIF? Has the understanding of their respective strengths and weaknesses changed since NIF experiments began? How are those strengths and weaknesses highlighted by implosion designs currently being tested or planned for testing soon? This document aims to address these questions by combining modern simulation results with a survey of the current experimental data base. More particularly, this document is meant to fulfill an L2 Milestone for FY17 to “Document our understanding of the relative advantages and disadvantages of CH, HDC, and Be designs.” Note that this document does not aim to recommend a down-selection of the current three ablator choices. It is intended only to gather and document the current understanding ofmore » the differences between these ablators and thereby inform the choices made in planning future implosion experiments. This document has two themes: (i) We report on a reanalysis project in which post-shot simulations were done on a common basis for layered shots using each ablator. This included data from keyholes, 2D ConA, and so forth, from each campaign, leading up to the layered shots. (“Keyholes” are shots dedicated to measuring the shock timing in a NIF target, as described in Ref. 5. “2DConAs” are backlit implosions in which the symmetry of the implosion is measured between about half and full convergence, as described in Ref. 6.) This set of common-basis postshot simulations is compared to the respective shots. Each was then scaled to a “full NIF” experiment that could be done using the respective ablators at full NIF power and/or energy, and these scaled-up designs were simulated in detail. (ii) The report also contains a general survey of experimental and simulated results as pertinent to comparing and evaluating the three ablators.« less

Authors:
 [1];  [1];  [1];  [2];  [2];  [1];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1410040
Report Number(s):
LLNL-TR-741418
DOE Contract Number:
AC52-07NA27344
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Kritcher, A. L., Clark, D. S., Haan, S. W., Yi, S. A., Zylstra, A. B., Ralph, J. E., and Weber, C. R. Comparison of the Three NIF Ablators. United States: N. p., 2017. Web. doi:10.2172/1410040.
Kritcher, A. L., Clark, D. S., Haan, S. W., Yi, S. A., Zylstra, A. B., Ralph, J. E., & Weber, C. R. Comparison of the Three NIF Ablators. United States. doi:10.2172/1410040.
Kritcher, A. L., Clark, D. S., Haan, S. W., Yi, S. A., Zylstra, A. B., Ralph, J. E., and Weber, C. R. Wed . "Comparison of the Three NIF Ablators". United States. doi:10.2172/1410040. https://www.osti.gov/servlets/purl/1410040.
@article{osti_1410040,
title = {Comparison of the Three NIF Ablators},
author = {Kritcher, A. L. and Clark, D. S. and Haan, S. W. and Yi, S. A. and Zylstra, A. B. and Ralph, J. E. and Weber, C. R.},
abstractNote = {Indirect drive implosion experiments on NIF have now been performed using three different ablator materials: glow discharge polymer (GDP) or CH, high density carbon (HDC, which we also refer to as diamond), and sputtered beryllium (Be). It has been appreciated for some time that each of these materials has specific advantages and disadvantages as an ICF ablator.[1-4] In light of experiments conducted on NIF in the last few years, how do these ablators compare? Given current understanding, is any ablator more or less likely to reach ignition on NIF? Has the understanding of their respective strengths and weaknesses changed since NIF experiments began? How are those strengths and weaknesses highlighted by implosion designs currently being tested or planned for testing soon? This document aims to address these questions by combining modern simulation results with a survey of the current experimental data base. More particularly, this document is meant to fulfill an L2 Milestone for FY17 to “Document our understanding of the relative advantages and disadvantages of CH, HDC, and Be designs.” Note that this document does not aim to recommend a down-selection of the current three ablator choices. It is intended only to gather and document the current understanding of the differences between these ablators and thereby inform the choices made in planning future implosion experiments. This document has two themes: (i) We report on a reanalysis project in which post-shot simulations were done on a common basis for layered shots using each ablator. This included data from keyholes, 2D ConA, and so forth, from each campaign, leading up to the layered shots. (“Keyholes” are shots dedicated to measuring the shock timing in a NIF target, as described in Ref. 5. “2DConAs” are backlit implosions in which the symmetry of the implosion is measured between about half and full convergence, as described in Ref. 6.) This set of common-basis postshot simulations is compared to the respective shots. Each was then scaled to a “full NIF” experiment that could be done using the respective ablators at full NIF power and/or energy, and these scaled-up designs were simulated in detail. (ii) The report also contains a general survey of experimental and simulated results as pertinent to comparing and evaluating the three ablators.},
doi = {10.2172/1410040},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Nov 01 00:00:00 EDT 2017},
month = {Wed Nov 01 00:00:00 EDT 2017}
}

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