First graded metal pushered single shell capsule implosions on the National Ignition Facility

Journal Article · Wed May 04 00:00:00 EDT 2022 · Physics of Plasmas

DOI:https://doi.org/10.1063/5.0083089· OSTI ID:1984192

Dewald, E. L. ^[1]; MacLaren, S. A. ^[1]; Martinez, D. A. ^[1]; Pino, J. E. ^[1]; Tipton, R. E. ^[1]; Ho, D. D.-M. ^[1]; Young, C. V. ^[1]; Horwood, C. ^[1]; Khan, S. F. ^[1]; Hartouni, E. P. ^[1]; Rubery, M. S. ^[1]; Millot, M. ^[1]; Vazsonyi, A. R. ^[1]; Vonhof, S. ^[1]; Mellos, G. ^[1]; Johnson, S. ^[1]; Smalyuk, V. A. ^[1]; Graziani, F. ^[1]; Monzon, E. R. ^[1]; Tommasini, R. ^[1] ; Alessi, D. ^[1]; Ayers, S. ^[1]; Hall, G. N. ^[1]; Holder, J. ^[1]; Kalantar, D. ^[1]; MacKinnon, A. J. ^[1]; Okui, J. ^[1]; Prantil, M. ^[1]; Di Nicola, J. -M. ^[1]; Lanier, T. ^[1]; Thomas, A. ^[1]; Yang, S. ^[1]; Xu, H. W. ^[2]; Huang, H. ^[2]; Bae, J. ^[2]; Kong, C. W. ^[2]; Rice, N. ^[2]; Wang, Y. M. ^[3]; Volegov, P. ^[4]; Freeman, M. S. ^[4]; Wilde, C. ^[4]

---

1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
2. General Atomics, San Diego, CA (United States)
3. Univ. of California, Los Angeles, CA (United States)
4. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Graded metal pushered single shell (PSS) capsules are predicted to be a viable alternative to low-Z capsule indirect drive inertial confinement fusion (ICF) implosions for achieving high fusion yields [MacLaren et al., Phys. Plasmas 28, 122710 (2021)]. The first experiments with Be/Cr-graded metal PSS capsules indicate that the implementation of the principle design feature, the graded density inner metal layer, has succeeded in producing a stable implosion with performance in agreement with predictions. With 50% Cr concentration in the pusher, PSS capsules have greater than ~2× higher shell densities during stagnation for enhanced core confinement and radiation trapping at ~35% lower shell implosion velocities than low-Z capsules. High-energy >30 keV inflight shell radiography recorded 215 km/s implosion velocities and show that implosion Legendre mode P₂ asymmetry can be tuned via inner-to-outer beam wavelength separation, similar to other implosions. Shell radiographs and neutron core images show similar P₂ asymmetry, suggesting no symmetry swings between peak implosion velocity and stagnation times. Despite the modest implosion velocities, gas-filled deuterium–tritium capsule implosions generate 10¹⁵ neutron yields at relatively modest core ion temperatures of 2.75 keV, indicating that in spite of the high-density inner layer, the implosions have been stabilized by the design density gradient. When compared with hydrodynamic simulations, the measured yield-over-simulated is 35% due to fuel–pusher mix and other perturbations such as the capsule fill tube. Finally, simple analytical scalings of hot spot pressure and neutron yield show that PSS implosions reach similar performance at lower implosion velocities and higher shell densities to low-Z ICF capsules.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1984192
• Report Number(s): LLNL-JRNL-829438; 1045046
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 29; ISSN 1070-664X
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
hydrodynamics simulations
plasma confinement
plasma physics
radiation losses
radiation trapping
radiography