title: Intense high-contrast femtosecond K-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 2.2×10(11)   photons/J into 4π. 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.
authors.affiliation: Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080, China. lmchen@aphy.iphy.ac.cn
authors.forename: L M
authors.initials: LM
authors.lastname: Chen
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authors.lastname: Zhang
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authors.lastname: Wei
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authors.lastname: Zhang