Charged-Particle Probing of X-Ray-Driven Inertial-Fusion Implosions

International audienc

The role of experimental science in ICF – Examples from X-ray diagnostics and targets

The USA Inertial Confinement Fusion (ICF) Program evolved from the Nuclear Test Program which had restricted shot opportunities for experimentalists to develop sophisticated experimental techniques. In contrast the ICF program in the U.S. was able to increase the shot availability on its large facilities, and develop sophisticated targets and diagnostics to measure and understand the properties of the high energy density plasmas (HEDP) formed. Illustrative aspects of this evolution at Lawrence Livermore National Laboratory (LLNL), with examples of the development of diagnostics and target fabrication are described

Hohlraum drive and implosion experiments on Nova. Revision 1

Experiments on Nova have demonstrated hohlraum radiation temperatures up to 300 eV and in lower temperature experiments reproducible time integrated symmetry to 1--2%. Detailed 2-D LASNEX simulations satisfactorily reproduce Nova`s drive and symmetry scaling data bases. Hohlraums has been used for implosion experiments achieving convergence ratios (initial capsule radius/final fuel radius) up to 24 with high density glass surrounding a hot gas fill

Studying electron distributions using the time-resolved free-bound spectra from coronal plasmas

Absorption of laser light in a plasma by inverse bremsstrahlung, I.B., can lead to a non-Maxwellian velocity distribution provided the electron-elecron collision frequency is too low to equilibrate the velocity distribution in the coronal plasma region of a laser heated aluminum disk by measuring the radiation recombination continuum. The experiments are performed using lambda/sub L/ = 0.532 ..mu..m laser light at intensities of approx. 10/sup 16/ W/cm/sup 2/. Such parameters are predicted to produce conditions suitable for a non-thermal electron distribution. The shape of the K-shell recombination radiation has been measured using a time-resolved x-ray spectrograph. The electron distribution can be determined from deconvolution of the recombination continuum shape