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Title: Capsule Shimming Developments for National Ignition Facility (NIF) Hohlraum Asymmetry Experiments

Abstract

Capsule drive in National Ignition Facility (NIF) indirect drive implosions is generated by x-ray illumination from cylindrical hohlraums. The cylindrical hohlraum geometry is axially symmetric but not spherically symmetric causing capsule-fuel drive asymmetries. We hypothesize that fabricating capsules asymmetric in wall thickness (shimmed) may compensate for drive asymmetries and improve implosion symmetry. Simulations suggest that for high compression implosions Legendre mode P 4 hohlraum flux asymmetries are the most detrimental to implosion performance. General Atomics has developed a diamond turning method to form a GDP capsule outer surface to a Legendre mode P 4 profile. The P 4 shape requires full capsule surface coverage. Thus, in order to avoid tool-lathe interference flipping the capsule part way through the machining process is required. This flipping process risks misalignment of the capsule causing a vertical step feature on the capsule surface. Recent trials have proven this step feature height can be minimized to ~0.25 µm.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [2];  [2];  [2]
  1. General Atomics, San Diego, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1402460
Alternate Identifier(s):
OSTI ID: 1458701
Report Number(s):
LLNL-JRNL-736455
Journal ID: ISSN 1536-1055
Grant/Contract Number:  
NA0001808; AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Fusion Science and Technology
Additional Journal Information:
Journal Volume: 73; Journal Issue: 2; Journal ID: ISSN 1536-1055
Publisher:
American Nuclear Society
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Hohlraum; National Ignition Facility; capsule shimming

Citation Formats

Rice, Neal G., Vu, M., Kong, C., Mauldin, M., Tambazidis, A., Hoppe Jr, M., Fitzsimmons, P., Farrell, Michael, Clark, D., Dewald, E., and Smalyuk, V.. Capsule Shimming Developments for National Ignition Facility (NIF) Hohlraum Asymmetry Experiments. United States: N. p., 2017. Web. doi:10.1080/15361055.2017.1389603.
Rice, Neal G., Vu, M., Kong, C., Mauldin, M., Tambazidis, A., Hoppe Jr, M., Fitzsimmons, P., Farrell, Michael, Clark, D., Dewald, E., & Smalyuk, V.. Capsule Shimming Developments for National Ignition Facility (NIF) Hohlraum Asymmetry Experiments. United States. doi:10.1080/15361055.2017.1389603.
Rice, Neal G., Vu, M., Kong, C., Mauldin, M., Tambazidis, A., Hoppe Jr, M., Fitzsimmons, P., Farrell, Michael, Clark, D., Dewald, E., and Smalyuk, V.. Wed . "Capsule Shimming Developments for National Ignition Facility (NIF) Hohlraum Asymmetry Experiments". United States. doi:10.1080/15361055.2017.1389603.
@article{osti_1402460,
title = {Capsule Shimming Developments for National Ignition Facility (NIF) Hohlraum Asymmetry Experiments},
author = {Rice, Neal G. and Vu, M. and Kong, C. and Mauldin, M. and Tambazidis, A. and Hoppe Jr, M. and Fitzsimmons, P. and Farrell, Michael and Clark, D. and Dewald, E. and Smalyuk, V.},
abstractNote = {Capsule drive in National Ignition Facility (NIF) indirect drive implosions is generated by x-ray illumination from cylindrical hohlraums. The cylindrical hohlraum geometry is axially symmetric but not spherically symmetric causing capsule-fuel drive asymmetries. We hypothesize that fabricating capsules asymmetric in wall thickness (shimmed) may compensate for drive asymmetries and improve implosion symmetry. Simulations suggest that for high compression implosions Legendre mode P4 hohlraum flux asymmetries are the most detrimental to implosion performance. General Atomics has developed a diamond turning method to form a GDP capsule outer surface to a Legendre mode P4 profile. The P4 shape requires full capsule surface coverage. Thus, in order to avoid tool-lathe interference flipping the capsule part way through the machining process is required. This flipping process risks misalignment of the capsule causing a vertical step feature on the capsule surface. Recent trials have proven this step feature height can be minimized to ~0.25 µm.},
doi = {10.1080/15361055.2017.1389603},
journal = {Fusion Science and Technology},
number = 2,
volume = 73,
place = {United States},
year = {Wed Dec 20 00:00:00 EST 2017},
month = {Wed Dec 20 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on December 20, 2018
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Cited by: 1 work
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