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

Nuclear Fushion

article

T. Braun¹  S.O. Kucheyev¹  S.J. Shin¹  Y.M. Wang²  J. Ye¹  N.E. Teslich Jr¹  C.K. Saw¹  D.B. Bober¹  E.M. Sedillo¹  N.G. Rice³  K. Sequoia³  H. Huang³  W. Requieron³  A. Nikroo¹  D.D. Ho¹  S.W. Haan¹  A.V. Hamza¹  C. Wild⁴  J. Biener¹ 

[1]Lawrence Livermore National Laboratory

[2]Department of Materials Science and Engineering, University of California

[3]General Atomics

[4]Diamond Materials GmbH

关键词: diamond;    chemical vapor deposition;    doping;    ablator;    inertial confinement fusion;   

DOI  :  10.1088/1741-4326/aca4e4

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

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 aW -doped diamond layer sandwiched between two undoped diamond regions.Wincorporation in diamond was achieved by adding tungsten hexacarbonyl to the CH₄/H₂ CVD feed gas. We observe that theWdoping 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 uniformWdistribution with concentrations up to about 0.3 at.%. At higherWconcentrations (>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 1×10¹⁶ neutron yield barrier, followed by experiments (described in future publications) with similar targets and slightly more laser energy producing yields as high as 4×10¹⁷.

【 授权许可】

Unknown