Table-top kHz hard X-ray source with ultrashort pulse duration for time-resolved X-ray diffraction

The interaction of ultrashort laser pulses with solid state targets is studied concerning the production of short X-ray pulses with photon energies up to about 10 keV. The influence of various parameters such as pulse energy, repetition rate of the laser system, focusing conditions, the application of prepulses, and the chirp of the laser pulses on the efficiency of this highly nonlinear process is examined. In order to increase the X-ray flux, the laser pulse energy is increased by a 2nd multipass amplifier from 750 mu J to 5 mJ. By applying up to 4 mJ of the pulse energy a X-ray flux of 4x10(10) Fe K (alpha) photons/s or 2.75x10(10) Cu K (alpha) photons/s are generated. The energy conversion efficiency is therefore calculated to eta (Fe)a parts per thousand 1.4x10(-5) and eta (Cu)a parts per thousand 1.0x10(-5). The X-ray source size is determined to 15x25 mu m(2). By focusing the produced X-rays using a toroidally bent crystal a quasi-monochromatic X-ray point source with a diameter of 56 mu mx70 mu m is produced containing a parts per thousand 10(4) Fe K (alpha 1) photons/s which permits the investigation of lattice dynamics on a picosecond or even sub-picosecond time scale. The lattice movement of a GaAs(111) crystal is shown as a typical application.