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

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 Dc, defined as a distance between the ablation front and the laser deposition region. Modes with kDc>1 are stable and experience oscillatory behavior [V. N. Goncharov, Phys. Rev. Lett. 82, 2091 (1999)]. The model shows that the main stabiliz...

[1]  C. Capjack,et al.  Heat transport and electron distribution function in laser produced plasmas with hot spots , 2002 .

[2]  J. Virmont,et al.  Nonlocal heat transport due to steep temperature gradients , 1983 .

[3]  Rozmus,et al.  Nonlocal electron transport in a plasma. , 1995, Physical review letters.

[4]  V. Goncharov.  Theory of the Ablative Richtmyer-Meshkov Instability , 1999 .

[5]  Gary S. Fraley,et al.  Rayleigh–Taylor stability for a normal shock wave–density discontinuity interaction , 1986 .

[6]  Adam T. Drobot,et al.  Computer Applications in Plasma Science and Engineering , 2011, Springer New York.

[7]  R. Town,et al.  A model of laser imprinting , 1999 .

[8]  Robert L. McCrory,et al.  Indications of strongly flux-limited electron thermal conduction in laser- target experiments , 1975 .

[9]  Gregory A. Moses,et al.  Inertial confinement fusion , 1982 .

[10]  K. Nishihara,et al.  PROPAGATION OF A RIPPLED SHOCK WAVE DRIVEN BY NONUNIFORM LASER ABLATION , 1997 .

[11]  K. Mima,et al.  Kinetic effects of electron thermal conduction on implosion hydrodynamics , 1992 .

[12]  R. Short,et al.  A practical nonlocal model for electron heat transport in laser plasmas , 1991 .

[13]  Robert L. McCrory,et al.  Self-consistent reduction of the Spitzer-Härm electron thermal heat flux in steep temperature gradients in laser-produced plasmas , 1981 .

[14]  KB–PJX—A streaked imager based on a versatile x-ray microscope coupled to a high-current streak tube (invited) , 2004 .

[15]  M. Honda,et al.  Analysis of rippled shock-wave propagation and ablation-front stability by theory and hydrodynamic simulation , 1999 .

[16]  Robert L. McCrory,et al.  Growth rates of the ablative Rayleigh–Taylor instability in inertial confinement fusion , 1998 .

[17]  S. P. Gill,et al.  Physics of Shock Waves and High-Temperature Hydrodynamic Phenomena , 2002 .

[18]  R. D. Richtmyer.  Taylor instability in shock acceleration of compressible fluids , 1960 .

[19]  Mora,et al.  Magnetic field and nonlocal transport in laser-created plasmas. , 1985, Physical review letters.

[20]  Guy Schurtz,et al.  A nonlocal electron conduction model for multidimensional radiation hydrodynamics codes , 2000 .

[21]  R. Town,et al.  Analysis of a direct-drive ignition capsule designed for the National Ignition Facility , 2001 .

[22]  W. Manheimer,et al.  Beam deposition model for energetic electron transport in inertial fusion: Theory and initial results , 2004 .

[23]  J. Meyer-ter-Vehn,et al.  The physics of inertial fusion - Hydrodynamics, dense plasma physics, beam-plasma interaction , 2004 .

[24]  Bell,et al.  Two-dimensional nonlocal electron transport in laser-produced plasmas. , 1988, Physical review letters.

[25]  L. M. Barker,et al.  Laser interferometer for measuring high velocities of any reflecting surface , 1972 .

[26]  S. Anisimov,et al.  Ablative stabilization in the incompressible Rayleigh--Taylor instability , 1986 .

[27]  John H. Gardner,et al.  Richtmyer–Meshkov-like instabilities and early-time perturbation growth in laser targets and Z-pinch loads , 2000 .

[28]  R. Betti,et al.  Self‐consistent stability analysis of ablation fronts with large Froude numbers , 1996 .

[29]  Denis G. Colombant,et al.  Direct-drive laser fusion: status and prospects , 1998 .

[30]  Sanz.  Self-consistent analytical model of the Rayleigh-Taylor instability in inertial confinement fusion. , 1994, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[31]  A. Piriz,et al.  Landau–Darrieus instability in an ablation front , 2003 .

[32]  J. R. Albritton.  Laser absorption and heat transport by non-Maxwell-Boltzmann electron distributions , 1983 .

[33]  Samuel A. Letzring,et al.  Initial performance results of the OMEGA laser system , 1997 .

[34]  J. Virmont,et al.  Electron heat transport down steep temperature gradients , 1982 .

[35]  Stephen E. Bodner,et al.  Critical elements of high gain laser fusion , 1981 .

[36]  M. H. Key,et al.  The Physics of Laser Plasma Interactions , 1989 .

[37]  Gilbert W. Collins,et al.  Accurate measurement of laser-driven shock trajectories with velocity interferometry , 1998 .

[38]  S P Obenschain,et al.  Direct observation of mass oscillations due to ablative Richtmyer-Meshkov instability in plastic targets. , 2001, Physical review letters.

[39]  Y. Lin,et al.  Distributed phase plates for super-Gaussian focal-plane irradiance profiles. , 1995, Optics letters.

[40]  N. A. Krall,et al.  Principles of Plasma Physics , 1973 .

[41]  C Stoeckl,et al.  Time-dependent electron thermal flux inhibition in direct-drive laser implosions. , 2003, Physical review letters.

[42]  Iu.M. Nikolaev.  Solution for a plane shock wave moving through a lightly curved interface of two media , 1965 .

[43]  R. G. Evans,et al.  Electron energy transport in steep temperature gradients in laser-produced plasmas , 1981 .

[44]  Samuel A. Letzring,et al.  Improved laser‐beam uniformity using the angular dispersion of frequency‐modulated light , 1989 .

[45]  A. R. Piriz,et al.  Rayleigh-Taylor instability of steady ablation fronts: The discontinuity model revisited , 1997 .

[46]  A. Velikovich,et al.  Saturation of perturbation growth in ablatively driven planar laser targets , 1998 .

[47]  P. Clavin,et al.  Instabilities of ablation fronts in inertial confinement fusion: A comparison with flames , 2004 .

[48]  S. Skupsky,et al.  Improved performance of direct-drive inertial confinement fusion target designs with adiabat shaping using an intensity picket , 2003 .

[49]  J. Bates.  Initial-value-problem solution for isolated rippled shock fronts in arbitrary fluid media. , 2004, Physical review. E, Statistical, nonlinear, and soft matter physics.

[50]  L. Spitzer,et al.  TRANSPORT PHENOMENA IN A COMPLETELY IONIZED GAS , 1953 .

[51]  P. M. Zaidel.  Shock wave from a slightly curved piston , 1960 .