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Rosen, M. D.

Publications and source records attributed to Rosen, M. D..

4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Hohlraum Reheating from Burning NIF Implosions

As fusion experiments at the National Ignition Facility (NIF) approach and exceed breakeven, energy from the burning capsule is predicted to couple to the gold walls and reheat the hohlraum. For example, on December 5, 2022, experiment N221204 exceeded target breakeven, historically achieving 3.15 MJ of fusion energy from 2.05 MJ of laser drive; for the first time, energy from the igniting capsule reheated the hohlraum beyond the peak laser-driven radiation temperature of 313 eV to a peak of 350 eV, in less than half a nanosecond. This reheating effect has now been unambiguously observed by the two independent Dante calorimeter systems across multiple experiments, and is shown to result from reheating of the remnant tungsten-doped ablator by the exploding core, which is heated by alpha deposition.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Characterization of thermal transport and evolution of Au plasma in ICF experiments by Thomson scattering

Here, this paper demonstrates the capability of optical Thomson scattering (OTS) to measure thermal transport, and provides support to radiation hydrodynamic and kinetic simulations of electron thermal transport and plasma evolution. OTS theory and plasma simulations are applied to the interpretation of experimental measurements of laser-produced plasma from spherical gold targets on the OMEGA laser facility. The dynamical form factor, S($\vec{k}$, ω), of electron density fluctuations that is used in the fitting of Thomson scattering spectra includes ion–ion collisions and effects of non-Maxwellian distribution functions. OTS measurements and their interpretation are consistent with the nonlocal transport model in radiation hydrodynamic simulations as well as with kinetic simulations in the second half of the probe pulse duration. In particular, the reversal of heat transport during cooling is observed to be consistent with simulations, while some discrepancies are noted during the initial heating of the Au targets.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Density evolution after shock release from laser-driven polystyrene (CH) targets in inertial confinement fusion

The evolution of the plasma density in the rarefaction wave formed after a laser-driven shock is released from a CH foil was measured using optical interferometry. Here, it was found that the plasma density profile is very sensitive to the conditions at the back surface of the foil before the shock release. Dedicated experiments demonstrated that radiation preheat by coronal x-rays caused early expansion of the back surface and faster expansion of the rarefaction wave. Radiation-hydrodynamics simulations with accurate modeling of radiation preheat from the plasma corona are in good agreement with the experimental results. The early expansion of material interfaces due to coronal x-ray preheat must be evaluated in designing and interpreting laser-driven inertial confinement fusion experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗