X-ray generation from dense electron shells irradiated by intense laser pulses

Kando, Masaki; Pirozhkov, A. S.; Nakamura, Tatsufumi; Esirkepov, T. Z.; Hayashi, Yukio; Pikuz, T.; Faenov, A.*; Kotaki, Hideyuki; Koga, J. K.; Bulanov, S. V.

Novel schemes for generating short-pulse, coherent XUV-X-ray photons are presented. They are the relativistic flying mirror and the high order harmonics generation at the relativistic intensities. In the flying mirror scheme, two laser pulses are employed; the driver pulse excites a nonlinear plasma wave, which eventually starts to break, and the source pulse is incident on the breaking wave. Recently, we have been seeking optimum conditions for flying mirrors to generate soft X-ray photons with currently-available lasers. We also present the results of high order harmonics generation, which can be explained with a novel mechanism.