Early stage of implosion in inertial confinement fusion: Shock timing and perturbation evolution

Journal Article · Sun Jan 15 00:00:00 EST 2006 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2162803· OSTI ID:20782458

Goncharov, V N; Gotchev, O V; Vianello, E; Boehly, T R; Knauer, J P; McKenty, P W; Radha, P B; Regan, S P; Sangster, T C; Skupsky, S; Smalyuk, V A; Betti, R; McCrory, R L; Meyerhofer, D D; Cherfils-Clerouin, C ^[1]

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1. Laboratory for Laser Energetics, Department of Mechanical Engineering, University of Rochester, Rochester, New York 14623 (United States)

Excessive increase in the shell entropy and degradation from spherical symmetry in inertial confinement fusion implosions limit shell compression and could impede ignition. The entropy is controlled by accurately timing shock waves launched into the shell at an early stage of an implosion. The seeding of the Rayleigh-Taylor instability, the main source of the asymmetry growth, is also set at early times during the shock transit across the shell. In this paper we model the shock timing and early perturbation growth of directly driven targets measured on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. By analyzing the distortion evolution, it is shown that one of the main parameters characterizing the growth is the size of the conduction zone D{sub c}, defined as a distance between the ablation front and the laser deposition region. Modes with kD{sub c}>1 are stable and experience oscillatory behavior [V. N. Goncharov, Phys. Rev. Lett. 82, 2091 (1999)]. The model shows that the main stabilizing mechanism is the dynamic overpressure due to modulations in the blow-off velocity inside the conduction zone. The long wavelengths with kD{sub c}<1 experience growth because of coupled Richtmyer-Meshkov-like and Landau-Darrieus instabilities [L. D. Landau and E. M. Lifshitz, Fluid Mechanics (Pergamon, New York, 1982)]. To match the simulation results with both the shock timing and perturbation growth measurements a new nonlocal thermal transport model is developed and used in hydrocodes.

• OSTI ID: 20782458
• Journal Information: Physics of Plasmas, Vol. 13, Issue 1; Other Information: DOI: 10.1063/1.2162803; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ASYMMETRY
CHARGED-PARTICLE TRANSPORT
DISTURBANCES
ENTROPY
FLUID MECHANICS
INERTIAL CONFINEMENT
LASER IMPLOSIONS
LASERS
MODULATION
OMEGA FACILITY
PLASMA
PLASMA SIMULATION
PLASMA WAVES
RAYLEIGH-TAYLOR INSTABILITY
SHOCK WAVES
SYMMETRY
THERMODYNAMICS
THERMONUCLEAR IGNITION
TRANSPORT THEORY