Evaulation of B{sub 4}C as an ablator material for NIF capsules. Revision 1

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Boron carbide (B{sub 4}C) is examined as a potential fuel container and ablator for implosion capsules on the National Ignition Facility (NIF). A capsule of pure B{sub 4}C encasing a layer of solid DT implodes stably and ignites with anticipated NIF x-ray drives, producing 18 MJ of energy. Thin films of B{sub 4}C were found to be resistant to oxidation and modestly transmitting in the infrared (IR), possibly enabling IR fuel characterization and enhancement for thin permeation barriers but not for full-thickness capsules. Polystyrene mandrels 0.5 mm in diameter were successfully coated with 0.15-2.0 micrometers of B{sub 4}C. Thickness estimated ... continued below

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10 p.

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Burnham, A.K.; Alford, C.S.; Makowiecki, D.M.; Dittrich, T.R.; Wallace, R.J.; Honea, E.C. et al. March 26, 1997.

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Description

Boron carbide (B{sub 4}C) is examined as a potential fuel container and ablator for implosion capsules on the National Ignition Facility (NIF). A capsule of pure B{sub 4}C encasing a layer of solid DT implodes stably and ignites with anticipated NIF x-ray drives, producing 18 MJ of energy. Thin films of B{sub 4}C were found to be resistant to oxidation and modestly transmitting in the infrared (IR), possibly enabling IR fuel characterization and enhancement for thin permeation barriers but not for full-thickness capsules. Polystyrene mandrels 0.5 mm in diameter were successfully coated with 0.15-2.0 micrometers of B{sub 4}C. Thickness estimated from optical density agreed well with those measured by scanning electron microscopy (SEM). The B{sub 4}C microstructure was columnar but finer than for Be made at the same conditions. B{sub 4}C is a very strong material, with a fiber tensile strength capable of holding NIF fill pressures at room temperature, but it is also very brittle, and microscopic flaws or grain structure may limit the noncryogenic fill pressure. Argon (Ar) permeation rates were measured for a few capsules that had been further coated with 5 micrometers of plasma polymer. The B{sub 4}C coatings tended to crack under tensile load. Some shells filled more slowly than they leaked, suggesting that the cracks open and close under opposite pressure loading. As observed earlier for Ti coatings, 0.15-micrometer layers of B{sub 4}C had better gas retention properties than 2-micrometer layers, possibly because of fewer cracks. Permeation and fill strength issues for capsules with a full ablator thickness of B{sub 4}C are unresolved. 21 refs., 6 figs.

Physical Description

10 p.

Notes

INIS; OSTI as DE97053407

Medium: P; Size: 10 p.

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  • 11. target fabrication specialist meeting, Orcas Island, WA (United States), 8-12 Sep 1996

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  • Other: DE97053407
  • Report No.: UCRL-JC--125144-Rev.1
  • Report No.: CONF-9609225--4
  • Grant Number: W-7405-ENG-48
  • DOI: 10.2172/562806 | External Link
  • Office of Scientific & Technical Information Report Number: 562806
  • Archival Resource Key: ark:/67531/metadc692562

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  • March 26, 1997

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  • Aug. 14, 2015, 8:43 a.m.

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  • April 6, 2017, 7:12 p.m.

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Burnham, A.K.; Alford, C.S.; Makowiecki, D.M.; Dittrich, T.R.; Wallace, R.J.; Honea, E.C. et al. Evaulation of B{sub 4}C as an ablator material for NIF capsules. Revision 1, report, March 26, 1997; California. (digital.library.unt.edu/ark:/67531/metadc692562/: accessed August 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.