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We report K α x-ray production with a high energy (110 mJ per pulse at 800 nm before compression/15 mJ at 400 nm after compression), high repetition rate (100 Hz), and high pulse contrast (better than 10−9 at 400 nm) laser system. To develop laser-based x-ray sources for biomedical imaging requires to use high-energy and high-power ultrafast laser system where compression is achieved under vacuum. Using this type of laser system, we demonstrate long-term stability of the x-ray yield, conversion efficiency higher than 1.5×10−5 with a Mo target, and the x-ray spot size close to the optical focal spot. This high-repetition K α x-ray source can be very useful for x-ray phase-contrast imaging. [ABSTRACT FROM AUTHOR]

X-ray computed tomography of plants requires a high number of X-ray photons, good source stability, and a large field of view. We show that we can optimize a laser-based synchrotron X-ray source for this application. The X-ray beam is produced during electron acceleration by laser wakefield. These results were obtained using 160 TW on-target laser peak power, 4.6×1019Wcm-2 laser pulse intensity, and nitrogen gas target. We measured a critical energy ∼ 15 keV, enough X-ray photons to realize an image with one single laser shot, more than 50 mrad divergence, a good shot to shot stability and spatial distribution homogeneity required for tomography imaging. The gas jet target pressure is low enough to use the laser system at the laser nominal repetition rate (2.5 Hz). We produced a micrometer X-ray source size that allows high resolution (< 20 μm) and phase contrast imaging. [ABSTRACT FROM AUTHOR]

Presents measurements of the characteristic melting time of InSb with a technique of ultrafast time-resolved X-ray diffraction that provides a direct probe of the changing atomic structure. How the electronic energy is converted into thermal motions; Application for this ability to obtain the quantitative structural characterization of non-thermal processes in semiconductors.