Radiographic image analysis of cylindrical implosion experiments (invited)

Abstract

Radiography is a heavily used tool for diagnosing laser-based hydrodynamic experiments. A successful experiment relies on the gathering of data over a time window where the relevant physics occurs and on an accurate analysis of those data. Comparison of this experimental data to theory is often best done by generating simulated images from hydrodynamic calculations, including all necessary and important experimental details. Care must be taken to treat both the experimental and theoretical images identically in the analysis. Frequently, image filtering and enhancement routines are used to obtain interface location and perturbation information from the radiographic image. Previous techniques were found to be too sensitive to global image details. New procedures have been developed which utilize local operators that provide better edge or interface identification without bias. These procedures are benchmarked and validated using static radiographic targets of known configuration that mock up experimental situations of interest. The experiment and the image analysis development are described, including discussion of key contributions to the uncertainty of the results.

Characterization of Surface Roughness and Initial Conditions for Cylindrical Hydrodynamic and Mix Experiments

“…An example of this type of metrology is the "static targets" used for radiographic image analysis. 7 Determination of initial amplitudes is important in comparing mode growth to hydro simulations. Figure 6 shows typical data for an m=10 machined perturbation with 1.5-µm amplitude used in Nova ablative Rayleigh-Taylor experiments 8 along with the step calibration data from 10-millionths of an inch (0.254 µm) step wedge.…”

Best Practice Procedures for Making Direct Drive Cylindrical Targets for Studies of Convergent Hydrodynamics

“…Also detailed work on the techniques of comparison of hydrodynamic simulations to experimental measurements has been done using static targets. 3 To achieve sufficient quality data for significant comparison to theoretical simulations, the target dimensions, densities, surfaces, and quality must be carefully controlled and measured. A previous description of the manufacture of cylinder targets for the indirect drive Nova experiments, concentrating on the machining of perturbations, has been published.…”