Studying plasma inter-diffusion in a high-energy-density plasma transitioning from a kinetic to hydrodynamic-like regime in shock-driven implosions at OMEGA
ORAL · Invited
Abstract
Obtaining a fundamental understanding of particle and energy transport
near an interface is essential for advancing high-energy-density-plasma
science and for accurately modeling Inertial Confinement Fusion (ICF)
implosions. Hot-spot ignition designs require a cold-dense shell to
compress a hot-diffuse core, and inter-diffusion across this boundary
plays a significant role in the transport of particles and energy.
Previous work studied the mix between the shell and hot spot, specifically
examining the yield degradation. Radiation-hydrodynamic simulations, which
used empirically-tuned ion-kinetic models were able to explain the data
set by varying the amount of inter-diffusion in an ad-hoc fashion. This
work advances previous studies by constraining an ion-kinetic modeling of
plasma inter-diffusion using a suite of data from new x-ray and nuclear
diagnostics. A set of D3He gas-filled, thin-glass, low-convergence
implosions were conducted at OMEGA with initial gas-fill densities ranging
from 0.4 to 2.9 mg/cc, which changed the inter-diffusion coefficient at
the glass-D3He-gas interface. The observed x-ray yield was tripled by
transitioning from hydrodynamic-like to kinetic regime. The x-ray emission
transitioned from a shell-like to center-like emission source as the
initial gas-fill pressure decreased and the plasma transitioned into a
kinetic regime, predominantly caused by a 2× increase if hot-spot mass due
to enhanced inter-diffusion. While a binary diffusion model underestimated
the level of mixing and enhancement due to kinetic effects, ion
Fokker-Planck simulations were able to capture the resulting data. The
nuclear-yield degradation was also captured by the kinetic simulations as
the inter-diffusion increased, which indicates that kinetic effects must
be considered in the mixing process in addition to the hydrodynamic
picture of collisional inter-diffusion.
near an interface is essential for advancing high-energy-density-plasma
science and for accurately modeling Inertial Confinement Fusion (ICF)
implosions. Hot-spot ignition designs require a cold-dense shell to
compress a hot-diffuse core, and inter-diffusion across this boundary
plays a significant role in the transport of particles and energy.
Previous work studied the mix between the shell and hot spot, specifically
examining the yield degradation. Radiation-hydrodynamic simulations, which
used empirically-tuned ion-kinetic models were able to explain the data
set by varying the amount of inter-diffusion in an ad-hoc fashion. This
work advances previous studies by constraining an ion-kinetic modeling of
plasma inter-diffusion using a suite of data from new x-ray and nuclear
diagnostics. A set of D3He gas-filled, thin-glass, low-convergence
implosions were conducted at OMEGA with initial gas-fill densities ranging
from 0.4 to 2.9 mg/cc, which changed the inter-diffusion coefficient at
the glass-D3He-gas interface. The observed x-ray yield was tripled by
transitioning from hydrodynamic-like to kinetic regime. The x-ray emission
transitioned from a shell-like to center-like emission source as the
initial gas-fill pressure decreased and the plasma transitioned into a
kinetic regime, predominantly caused by a 2× increase if hot-spot mass due
to enhanced inter-diffusion. While a binary diffusion model underestimated
the level of mixing and enhancement due to kinetic effects, ion
Fokker-Planck simulations were able to capture the resulting data. The
nuclear-yield degradation was also captured by the kinetic simulations as
the inter-diffusion increased, which indicates that kinetic effects must
be considered in the mixing process in addition to the hydrodynamic
picture of collisional inter-diffusion.
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Presenters
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Patrick J Adrian
Massachusetts Institute of Technology (MIT)
Authors
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Patrick J Adrian
Massachusetts Institute of Technology (MIT)