Tungsten doped diamond shells for record neutron yield inertial confinement fusion experiments at the National Ignition Facility

Abstract We report on fabrication and characterization of layered, tungsten doped, spherical about 2 mm diameter microcrystalline diamond ablator shells for inertial confinement fusion (ICF) experiments at the National Ignition Facility. As previously reported, diamond ICF ablator shells can be fabr...

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Bibliographic Details
Published in:	Nuclear fusion Vol. 63; no. 1; pp. 16022 - 16031
Main Authors:	Braun, T., Kucheyev, S.O., Shin, S.J., Wang, Y.M., Ye, J., Teslich Jr, N.E., Saw, C.K., Bober, D.B., Sedillo, E.M., Rice, N.G., Sequoia, K., Huang, H., Requieron, W., Nikroo, A., Ho, D.D., Haan, S.W., Hamza, A.V., Wild, C., Biener, J.
Format:	Journal Article
Language:	English
Published:	United States IOP Publishing 01-01-2023 IOP Science
Subjects:	70 PLASMA PHYSICS AND FUSION TECHNOLOGY ablator chemical vapor deposition diamond doping inertial confinement fusion
Online Access:	Get full text
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Summary:	Abstract We report on fabrication and characterization of layered, tungsten doped, spherical about 2 mm diameter microcrystalline diamond ablator shells for inertial confinement fusion (ICF) experiments at the National Ignition Facility. As previously reported, diamond ICF ablator shells can be fabricated by chemical vapor deposition (CVD) on solid spherical silicon mandrels using an ellipsoidal microwave plasma reactor. In the present work, we further developed these ablator shells by embedding a W -doped diamond layer sandwiched between two undoped diamond regions. W incorporation in diamond was achieved by adding tungsten hexacarbonyl to the CH 4 /H 2 CVD feed gas. We observe that the W doping concentration decreases with increasing deposition rate which, in turn, is controlled by adjusting the total gas pressure. Cross sectional microstructural analysis reveals sharp interfaces between doped and undoped regions of the diamond shell and uniform W distribution with concentrations up to about 0.3 at.%. At higher W concentrations (>0.3 at.%) formation of tungsten carbide precipitates is observed. Using a 3‐shock 1.6 MJ laser pulse, the targets described in this work produced the first laser driven implosion to break the 1 × 10 16 neutron yield barrier, followed by experiments (described in future publications) with similar targets and slightly more laser energy producing yields as high as 4 × 10 17 .
Bibliography:	NF-105498.R3 AC52-07NA27344 USDOE National Nuclear Security Administration (NNSA) LLNL-JRNL-834808
ISSN:	0029-5515 1741-4326
DOI:	10.1088/1741-4326/aca4e4