Intense High-Contrast FemtosecondK-Shell X-Ray Source from Laser-Driven Ar Clusters

Abstract

Bright Ar quasimonochromatic $K$-shell x ray with very little background has been generated using an Ar clustering gas jet target irradiated with a 30 fs ultrahigh-contrast laser, with a measured flux of $2.2\times {10}^{11}\mathrm{\text{photons}}/\mathrm{J}$ into $4\pi$. This intense x-ray source critically depends on the laser contrast and intensity. The optimization of source output with interaction length is addressed. Simulations point to a nonlinear resonant mechanism of electron heating during the early stage of laser interaction, resulting in enhanced x-ray emission. The x-ray pulse duration is expected to be only 10 fs, opening the possibility for single-shot ultrafast keV x-ray imaging applications.