Study Plasma Stagnation in Laser-Driven Hohlraums

Understanding plasma stagnation in laser-driven hohlraums is important for inertial confinement fusion. It has been realized that the use of conventional single-species-averaged hydrodynamic codes for modelling stagnation is largely responsible for some disagreements between the experimental results and numerical simulations. A number of mechanisms which play important roles in this process have been missed in hydrodynamic simulations, including ion interpenetration and diffusion. Self-generated fields and plasma instabilities observed in connection with plasma blow-off seen at hohlraum laser entrance holes provides additional compelling experimental evidence of non-hydrodynamic processes. To explore such phenomena, a series of experiments was performed at the Omega laser facility. Data obtained from several diagnostics, including monoenergetic-proton radiography and x-ray imaging, are compared with modified three-dimensional hydrodynamic simulations, providing new insight into hohlraum stagnation and a more complete physical picture of hohlraum dynamics. This work was supported in part by US DOE, LLNL and LLE.