title: Exploration of the transition from the hydrodynamiclike to the strongly kinetic regime in shock-driven implosions.
abstract: Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D3He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly overpredict the observed nuclear yields, from a factor of ∼2 at 3.1  mg/cm3 to a factor of 100 at 0.14  mg/cm3. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Rosenberg
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: H G
authors.initials: HG
authors.lastname: Rinderknecht
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: N M
authors.initials: NM
authors.lastname: Hoffman
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Amendt
authors.affiliation: Dipartimento SBAI, Università di Roma "La Sapienza", Via A Scarpa, 14-16, I-00161 Roma, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Atzeni
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: Zylstra
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: C K
authors.initials: CK
authors.lastname: Li
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: F H
authors.initials: FH
authors.lastname: Séguin
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: H
authors.initials: H
authors.lastname: Sio
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: M Gatu
authors.initials: MG
authors.lastname: Johnson
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Frenje
authors.affiliation: Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: R D
authors.initials: RD
authors.lastname: Petrasso
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: V Yu
authors.initials: VY
authors.lastname: Glebov
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: C
authors.initials: C
authors.lastname: Stoeckl
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: W
authors.initials: W
authors.lastname: Seka
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: F J
authors.initials: FJ
authors.lastname: Marshall
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Delettrez
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: T C
authors.initials: TC
authors.lastname: Sangster
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: R
authors.initials: R
authors.lastname: Betti
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: V N
authors.initials: VN
authors.lastname: Goncharov
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: D D
authors.initials: DD
authors.lastname: Meyerhofer
authors.affiliation: Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA.
authors.forename: S
authors.initials: S
authors.lastname: Skupsky
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: C
authors.initials: C
authors.lastname: Bellei
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: J
authors.initials: J
authors.lastname: Pino
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Wilks
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: G
authors.initials: G
authors.lastname: Kagan
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: K
authors.initials: K
authors.lastname: Molvig
authors.affiliation: General Atomics, San Diego, California 92186, USA.
authors.forename: A
authors.initials: A
authors.lastname: Nikroo