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Pirozhkov, A. S.; Choi, I. W.*; Sung, J. H.*; Lee, S. K.*; Yu, T. J.*; Jeong, T. M.*; Kim, I. J.*; Hafz, N.*; Kim, C. M.*; Pae, K. H.*; et al.
AIP Conference Proceedings 1153, p.7 - 15, 2009/07
High-power laser contrast is challenging to measure, especially in the real target irradiation conditions. We present a convenient and relatively simple contrast diagnostic technique based on the measurement of target specular reflectivity. The reflectivity remains high even at irradiances above 
W/cm
in the case of a high-contrast prepulse-free laser. On the contrary, the specular reflectivity drops at high irradiances in the case of an insufficient contrast, due to the beam break-up and increased absorption caused by the preformed plasma. The technique was demonstrated using three laser systems with different contrast conditions: Astra (CLF, RAL), TiS laser at APRI, GIST, and J-KAREN (APRC, JAEA).
Kar, S.*; Borghesi, M.*; Bulanov, S. V.; Key, M. H.*; Liseykina, T. V.*; Macchi, A.*; Mackinnon, A. J.*; Patel, P. K.*; Romagnani, L.*; Schiavi, A.*; et al.
Physical Review Letters, 100(22), p.225004_1 - 225004_4, 2008/06
被引用回数：79 パーセンタイル：90.15(Physics, Multidisciplinary)Experimental evidence of plasma jets ejected from the rear side of thin solid targets irradiated by ultra-intense (
10
W cm
) laser pulses is presented. The jets, detected by transverse inter-ferometric measurements with high spatial and temporal resolutions, show collimated expansion, lasting for several hundreds of picoseconds, and have substantially steep density gradients at their periphery. The predominant role played by radiation pressure of the laser in the jet formation process is highlighted analytically and by extensive two dimensional particle in cell simulations.
