Multi-frame, ultrafast, x-ray microscope for imaging shockwave dynamics
Daniel Hodge, Andrew F. T. Leong, Silvia Pandolfi, Kelin Kurzer-Ogul, D. S. Montgomery, Hussein Aluie, C. A. Bolme, Thomas E. Carver, Eric Cunningham, C. B. Curry, Matthew S. Dayton, Franz-Joseph Decker, Eric Galtier, Philip Hart, Dimitri Khaghani, Hae Ja Lee, Kenan Li, Yanwei Liu, Kyle Ramos, Jessica K. Shang, Sharon Vetter, Bob Nagler, Richard L. Sandberg, A. E. Gleason
Abstract
Inertial confinement fusion (ICF) holds increasing promise as a potential source of abundant, clean energy, but has been impeded by defects such as micro-voids in the ablator layer of the fuel capsules. It is critical to understand how these micro-voids interact with the laser-driven shock waves that compress the fuel pellet. At the Matter in Extreme Conditions (MEC) instrument at the Linac Coherent Light Source (LCLS), we utilized an x-ray pulse train with ns separation, an x-ray microscope, and an ultrafast x-ray imaging (UXI) detector to image shock wave interactions with micro-voids. To minimize the high- and low-frequency variations of the captured images, we incorporated principal component analysis (PCA) and image alignment for flat-field correction. After applying these techniques we generated phase and attenuation maps from a 2D hydrodynamic radiation code (xRAGE), which were used to simulate XPCI images that we qualitatively compare with experimental images, providing a one-to-one comparison for benchmarking material performance. Moreover, we implement a transport-of-intensity (TIE) based method to obtain the average projected mass density (areal density) of our experimental images, yielding insight into how defect-bearing ablator materials alter microstructural feature evolution, material compression, and shock wave propagation on ICF-relevant time scales.