High contrast fs laser driven intense Ar K-shell X-ray source and its imaging application

Chen, L. M.

We present the result of hard X-ray spectroscopy from an Ar gas target irradiated by a femtosecond (fs) laser pulse. The spectrum shows a high contrast characteristic K-shell emission, a compressed continuum and the elimination of the energetic X-ray tail typically observed with solid and cluster targets. This Ar K-shell X-ray with very little continuum background possesses the measured flux of 1.210 photons/mrad/pulse. This compact quasi-monochromatic X-ray source, with a source size of only 12 um, has been applied to X-ray radiographic imaging of a biological specimen, resulting in high-resolution, high-quality phase-contrast images. Correlation between this intense K-shell emission with the laser channeling in the Ar gas is addressed.