Generation of ultrashort hard-x-ray pulses with tabletop laser systems at a 2-kHz repetition rate

Abstract

We describe the generation of ultrafast x-ray pulses at a 2-kHz repetition rate with a new tabletop laser and x-ray generation system. The range of the emitted x-radiation wavelength is approximately a single ångstrom, from 0.3 to 0.1 nm. Specific emphasis is placed on the generation of broad continuum radiation for x-ray absorption spectroscopy. High-contrast laser pulses are desirable for generation of ultrashort pulses, which we achieve by dividing the laser system into a section for generation of high-contrast microjoule pulses followed by pulse cleaning and a section for chirped pulse amplification and pulse compression. Using this system, we generated x radiation from solid-copper and liquid-mercury targets in a helium atmosphere. From copper targets an average x-ray flux of 1013 photons/(s 4π sr keV) at 3 keV and 109 photons/(s 4π sr) above 5 keV photon energy was produced. X radiation from the mercury target did not exhibit emission lines within the spectral range 3–13 keV.