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The inner-shell photo-ionization (ISPI) scheme requires photon energies at least high enough to photo-ionize the K-shell, ∼286 eV, in the case of carbon. As a consequence of the higher cross-section, the inner-shell are "selectively" knocked out, leaving a hole state 1s2s[SUP2]2p[SUP2] in the singly charged carbon ion. This generates a population inversion to the radiatively connected state 1s[SUP2]2s[SUP2]2p in C+, leading to gain on the 1s-2p transition at 45 Å. The resonant character of the lasing transition in the single ionization state intrinsically allows much higher quantum efficiency compared to other schemes. Competing processes that deplete the population inversion include auto-ionization, Auger decay, and in particular collisional ionization of the outer-shell electrons by electrons generated during photo-ionization. These competing processes rapidly quench the gain. Consequently, the pump method must be capable of populating the inversion at a rate faster than the competing processes. This can be achieved by an ultra-fast, high intensity laser that is able to generate an ultra-fast, bright x-ray source. With current advances in the development of high-power, ultra-short pulse lasers it is possible to realize fast x-ray sources based that can deliver powerful pulses of light in the multiple hundred terawatt regime and beyond. We will discuss in greater detail concept, target design and a series of x-ray spectroscopy investigations we have conducted in order to optimize the absorber/x-ray converter - filter package. [ABSTRACT FROM AUTHOR]

Laser-driven Hugoniot experiments on precompressed samples access thermodynamic conditions unreachable by either static or single-shock compression techniques alone. Recent experiments using Rutherford Appleton Laboratory's Vulcan Laser achieved final pressures up to ∼200 GPa and temperatures up to 10,000 K in water samples precompressed to ∼1 GPa, thereby validating this new technique. Diamond anvils, used for sample precompression, must be thin in order to avoid rarefaction catch up; but thin diamonds fail under pressure. Anvils no more than 200 µm thick were encased in diamond cells modified to accommodate the laser-beam geometry. [ABSTRACT FROM AUTHOR]

We report preliminary results using the Lawrence Livermore National Laboratory (LLNL) Janus laser facility to generate high pressure laser-driven shocks in the 1 - 10 Mbar regime. These experiments address various issues, including shock steadiness, planarity, uniformity and low target preheat, important for making precision EOS measurements on a small (E < 250 J) laser facility. A brief description of the experimental techniques, target design and measurements will be given. [ABSTRACT FROM AUTHOR]