Measurements of Shock Release Dynamics in Polystyrene Foils*

Understanding shock release—the rarefaction wave launched at shock breakout of the shell inner surface—is crucial to determine the degree of compression in inertial confinement fusion implosions. A higher-than-predicted release mass causes a premature increase in hot-spot pressure at the beginning of the deceleration phase and lower final convergence at stagnation. A new experimental platform was developed to study the release dynamics via VISAR measurements of the shock velocity driven by the collision of release material with a quartz witness foil. The release dynamics were probed over a range of different release mass amounts and velocities of the released material by measuring the time evolution of the release-induced shock velocity in the witness foil.