Biomedical subjects

J Delettrez

Publications and source records attributed to J Delettrez.

11 recordsLinked to original sources

PubMed2003

Measuring implosion dynamics through rhoR evolution in inertial-confinement fusion experiments.

The areal density (rhoR) of D3He filled plastic capsules imploded at OMEGA has been measured at shock coalescence (1.7 ns) and, 400 ps later, during compressive burn, through the energy downshift of 14.7-MeV D3He protons. In this time interval, the azimuthally averaged rhoR changes from 13+/-2.5 to 70+/-8 mg/cm(2). The experiments demonstrate that fuel-shell mix is absent in the central regions at shock coalescence, and that the shell has no holes during compressive burn. We conjecture that rhoR asymmetries measured during compressive burn may be seeded by the time of shock coalescence.

Journal Article↗

PubMed2002

Spectroscopic determination of dynamic plasma gradients in implosion cores.

The time-dependent gradient structure of a laser-compressed, high-energy-density plasma has been determined using a method based on the simultaneous analysis of time-resolved x-ray monochromatic images and x-ray line spectra from Ar-doped D2 implosion cores. The analysis self-consistently determines the temperature and density gradients that yield the best fits to the spatial-emissivity profiles and spectral line shapes. This measurement is important for understanding the spectra formation and plasma dynamics associated with the implosion process. In addition, since the results are independent of hydrodynamic simulations, they are also important for comparison with fluid-dynamic models.

Journal Article↗

PubMed1999

Comparison of measured and calculated X-ray and hot-electron production in short-pulse laser-solid interactions at moderate intensities.

Ultrashort pulse laser-solid interaction experiments with 4x10(16) W/cm(2),120 fs, 45 degrees incidence angle, p-polarized pulses are theoretically analyzed with the help of 1(1/2)-dimensional (1(1/2) D) particle-in-cell (PIC) simulations. The laser impinges upon preformed plasmas with a precisely controlled density-gradient scale-length. PIC electron distribution functions are used as an input to 3D Monte Carlo simulations to interpret measured electron distributions and Kalpha radiation emission. Satisfactory agreement between the experimental and simulation results is obtained for the measured absorption coefficient, the energy distribution of the back-scattered hot electrons, the hot-electron temperature in the bulk of the target, and the Kalpha yield, when the preplasma scale-length is varied.

Journal Article↗

PubMed1996