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.