Development of ultrafast laser-plasma X-ray sources for time-resolved absorption studies in the 4-5 keV energy range

Summary form only given. We present the progress in the optimization of laser produced plasma sources, specifically aimed the 4-5 keV X-ray energy range, using Ti and Ta wire and plane targets. Two table-top Chirped Pulse Amplification (CPA) laser systems were used: the INRS CPA laser (Nd:glass second harmonic @532 nm, 400 fs, 400 mJ, high pulse/pedestal contrast ratio, low repetition rate), and the UCSD CPA laser (Ti:sapphire @800 nm, 30 fs, 100 mJ 20 Hz repetition rate). The spectra of the emitted radiation were analyzed by the combination of a curved Si crystal spectrometer and an X-ray CCD camera arrangement. The PX-1 X-ray streak camera of INRS has also been used to follow the time history of multi-keV X-ray emission with subpicosecond temporal resolution. Comparison of the data collected with the two systems (INRS vs. UCSD) suggests the important role of the pre-pulse in achieving the maximum yield in a particular emission wavelength range. The pulse duration of the excitation pulses also has a strong effect in controlling the hot electron production processes in the rapidly expanding solid density plasma. Preliminary experiments on static absorption spectra of iodine at the L-III edge gave important data (photon statistics, signal-to-noise ratio) for designing future time-resolved EXAFS experiments based on laser produced X-ray sources.