Impact of high contrast ratio on 17.4 keV laser-based K α source for intensities 10 16 –10 19 W/cm 2 : A foot print of interaction mechanisms

Laser-driven ultrafast hard x-ray sources based on K α emission from solid targets are nowadays a powerful tool to monitor ultrafast lattice dynamics in condensed matter [1]. Such point-like sources are of great interest in biomedical imaging where spatial resolution and image quality can be highly improved [2]. Therefore, the development of high-flux K a sources with a small size remains important for the ultrafast x-ray community. Especially, with the routinally obtained now femtosecond laser performances (intensities I > 10 18 W/cm 2 with high contrast pulses >10 8 ), it is possible to explore interaction regimes where K α emission can be strongly enhanced.