Asymmetrically driven implosions

Techniques to achieve uniform near-spherical symmetry of radiation drive on a capsule in a laser-heated hohlraum have received detailed attention in the context of inertial confinement fusion. However, much less attention has been paid to the understanding of the hohlraum physics in cases where the radiation drive departs significantly from spherical symmetry. A series of experiments has been carried out to study the implosion dynamics of a capsule irradiated by a deliberately asymmetric x-ray drive. The experimental data provide a sensitive test of radiation transport in hohlraums in which drive symmetry is modulated by asymmetric laser beam timing and the use of wall materials of different albedos. Data from foam ball and thin-shell capsule experiments are presented together with modeling using consecutively linked Lagrangian and Eulerian calculational schemes. The thin-shell capsules exhibit much stronger sensitivity to early-time asymmetry than do the foam balls, and this sensitivity results in the fo...

[1]  Peter A. Amendt,et al.  Indirect drive experiments utilizing multiple beam cones in cylindrical hohlraums on OMEGA , 1997 .

[2]  L. Suter,et al.  Drive characterization of indirect drive targets on the Nova laser (invited) , 1995 .

[3]  Robert L. Kauffman,et al.  Measurement of 0.1-3-keV x rays from laser plasmas , 1986 .

[4]  Peter A. Amendt,et al.  HOHLRAUM RADIATION DRIVE MEASUREMENTS ON THE OMEGA LASER , 1997 .

[5]  T. S. Perry,et al.  The flexible x‐ray imager , 1996 .

[6]  Stephen D. Jacobs,et al.  Direct‐drive laser‐fusion experiments with the OMEGA, 60‐beam, >40 kJ, ultraviolet laser system , 1996 .

[7]  Peter A. Amendt,et al.  Hohlraum symmetry measurements with surrogate solid targets (invited) , 1999 .

[8]  Delamater,et al.  Reemission technique for symmetry measurements in Hohlraum targets containing a centered high-Z ball. , 1996, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[9]  Steven J. Rose,et al.  The stability of multiple-shell ICF targets , 1980 .

[10]  D. Youngs,et al.  Numerical simulation of turbulent mixing by Rayleigh-Taylor instability , 1984 .

[11]  J. A. Fleck,et al.  An implicit Monte Carlo scheme for calculating time and frequency dependent nonlinear radiation transport , 1971 .

[12]  Hammel,et al.  Direct Measurement of X-Ray Drive from Surrogate Targets in Nova Hohlraums. , 1996, Physical review letters.

[13]  Daniel N. Baker,et al.  The role of symmetry in indirect‐drive laser fusion , 1995 .

[14]  O. Landen,et al.  Review of drive symmetry measurement and control experiments on the Nova laser system (invited) , 1995 .

[15]  M. Rosen,et al.  New methods for diagnosing and controlling hohlraum drive asymmetry on Nova , 1997 .

[16]  Peter A. Amendt,et al.  Hohlraum Symmetry Experiments with Multiple Beam Cones on the Omega Laser Facility , 1998 .

[17]  A. Hauer,et al.  Measurements of early time radiation asymmetry in vacuum and methane-filled Hohlraums with the reemission ball technique , 1998 .