Measurement of Time-Dependent Drive Flux on the Capsule for Indirectly Driven Inertial Confinement Fusion Experiments

A new method for measuring the time-dependent drive flux at the hohlraum center is proposed as a better alternative to conventional wall-based techniques. The drive flux here is obtained by simultaneous measurement of the reemitted flux and shock velocity from a three-layered "cakelike" sample. With these two independent observables, the influence induced by the uncertainty of the material parameters of the sample can be effectively decreased. The influence from the closure of the laser entrance hole, which was the main challenge in conventional wall-based techniques, was avoided through localized reemitted flux measurement, facilitating drive flux measurement throughout the entire time history. These studies pave a new way for probing the time-dependent drive flux, for both cylindrical hohlraums and novel hohlraums with six laser entrance holes.