Exploring the limits of the National Ignition Facility’s capsule coupling

The original ignition “point designs” (circa 1992) for the National Ignition Facility (NIF) [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technol. 26, 755 (1994)] were made energetically conservative to provide margin for uncertainties in laser absorption, x-ray conversion efficiency and hohlraum-capsule coupling. Since that time, extensive experiments on Nova [J. T. Hunt and D. R. Speck, Opt. Eng. 28, 461 (1989)] and Omega [J. M. Soures et al., Phys. Plasmas 3, 2108 (1996)] and their related analysis indicate that NIF coupling efficiency may be almost “as good as we could hope for.” Given close agreement between experiment and theory/modeling, one can credibly explore target enhancements which couple more of NIFs energy to an ignition capsule. These include using optimized mixtures of materials to reduce x-ray wall losses, slightly reduced laser entrance holes, and laser operation strategies which increase the amount of energy one can extract from NIF. It is found that 3–4× increases in absorbe...

[1]  Turner,et al.  Modeling and interpretation of Nova's symmetry scaling data base. , 1994, Physical review letters.

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

[3]  D. S. Bailey,et al.  High yield inertial confinement fusion target design for a z-pinch-driven hohlraum , 1999 .

[4]  Porter,et al.  The Rosseland Mean Opacity of a Mixture of Gold and Gadolinium at High Temperatures. , 1996, Physical review letters.

[5]  K. Shuler,et al.  Atomic theory of gas dynamics , 1965 .

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

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

[8]  Peter A. Amendt,et al.  Design and modeling of ignition targets for the National Ignition Facility , 1995 .

[9]  D. Kuizenga.  Generation of short pulses for laser fusion in an actively mode-locked Nd:YAG laser , 1977, IEEE Journal of Quantum Electronics.

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

[11]  Douglass E. Post,et al.  Steady-state radiative cooling rates for low-density, high-temperature plasmas , 1977 .

[12]  M. Rosen,et al.  Radiation drive in laser‐heated hohlraums , 1996 .

[13]  Steven W. Haan,et al.  NIF capsule design update , 1997 .

[14]  D. Harris,et al.  Ignition target design and robustness studies for the National Ignition Facility , 1996 .

[15]  John T. Hunt,et al.  Present And Future Performance Of The Nova Laser System , 1989 .

[16]  Rosen,et al.  High temperatures in inertial confinement fusion radiation cavities heated with 0.35 microm light. , 1994, Physical review letters.

[17]  D. Colombant,et al.  Increase in Rosseland mean opacity for inertial fusion hohlraum walls , 1998 .

[18]  J. Moody,et al.  Laser beam smoothing and backscatter saturation processes in plasmas relevant to National Ignition Facility hohlraums , 1998 .