High-volume and -adiabat capsule (“HVAC”) ignition: Lowered fuel compression requirements using advanced Hohlraums
- 1 December 2020
- journal article
- research article
- Published by AIP Publishing in Physics of Plasmas
- Vol. 27 (12), 122708
- https://doi.org/10.1063/5.0032380
Abstract
Lower-than-expected deuterium–tritium fuel areal densities have been experimentally inferred across a variety of high-convergence, nominally low-adiabat implosion campaigns at the National Ignition Facility (NIF) using cylinder-shaped Hohlraums [Hurricane et al., Phys. Plasmas 26, 052704 (2019)]. A leading candidate explanation is the presence of atomic mix between the fuel and ablator from hydrodynamic instability growth [Clark et al., Phys. Plasmas 26, 050601 (2019)], leading to reduced fuel compressibility and an effectively higher (in-flight) fuel adiabat α. Tolerating a high-α implosion can be obtained with significantly higher capsule absorbed energy according to the one-dimensional (1-D) ignition-threshold-factor analytic scaling [S. Atzeni and J. Meyer-ter-Vehn, Nucl. Fusion 41, 465 (2001)], . Recent experiments with large Al shells in rugby-shaped Hohlraums have established high laser-capsule coupling efficiencies of 30% [Ping et al., Nat. Phys. 15, 138 (2019)], enabling a path to 0.5 MJ at the NIF and increased performance margin M ≡ ITF − 1. The ability to operate at high adiabat with large capsules using nonstandard Hohlraums leads to the predicted onset of a volume-ignition mode, defined as when both the entire fuel is the “hot spot” and inertial confinement is principally provided by the ablator compared with the compressed fuel. Such an ignition mode, normally reserved for high-Z targets, e.g., double shells [Amendt et al., Phys. Plasmas 14, 056312 (2007)], is predicted to lead to lower fuel convergence and less exposure to mix due to the intended high adiabat—but at the expense of ∼3–4 reduced (1-D) yield compared with conventional central hot-spot ignition designs.
Keywords
Funding Information
- U.S. Department of Energy (DE-AC52-07NA27344)
- Lawrence Livermore National Laboratory (LDRD-17-ERD-119)
This publication has 42 references indexed in Scilit:
- High-Gain Magnetized Inertial FusionPhysical Review Letters, 2012
- The role of a detailed configuration accounting (DCA) atomic physics package in explaining the energy balance in ignition-scale hohlraumsHigh Energy Density Physics, 2011
- Advances in NLTE modeling for integrated simulationsHigh Energy Density Physics, 2010
- Prolate-Spheroid (“Rugby-Shaped”) Hohlraum for Inertial Confinement FusionPhysical Review Letters, 2007
- Assessing the prospects for achieving double-shell ignition on the National Ignition Facility using vacuum hohlraumsPhysics of Plasmas, 2007
- Buoyancy-drag mix model obtained by multifluid interpenetration equationsPhysical Review E, 2005
- Hohlraum-Driven High-Convergence Implosion Experiments with Multiple Beam Cones on the Omega Laser FacilityPhysical Review Letters, 2002
- Hot-spot dynamics and deceleration-phase Rayleigh–Taylor instability of imploding inertial confinement fusion capsulesPhysics of Plasmas, 2001
- Comments on the article A generalized scaling law for the ignition energy of inertial confinement fusion capsulesNuclear Fusion, 2001
- Onset of nonlinear saturation for Rayleigh-Taylor growth in the presence of a full spectrum of modesPhysical Review A, 1989