Generation of hard x-rays by a forsterite terawatt laser

摘要

A compact, tabletop terawatt forsterite laser (1.24 μm /100 mJ/ 80 fs) is used for generation of fast hard x-ray radiation from laser-produced plasmas. Plasmas are created on massive solid Fe and Cu targets. X-ray radiation is studied using a focusing crystal von Hamos spectrometer with a CCD linear array as x-ray detector. High efficiency of the spectrometer in a wide spectral range allows us to record x-ray spectra by one laser shot. Intense Kα radiation is studied with high spectral resolution (λ/δλ~1000) at various focusing conditions: main laser radiation and second harmonic radiation. With a copper target the Kα radiation yield was equal to 4×109 photon/pulse in 4π steradian, that corresponds to conversion efficiency of 0.02%. Processes responsible for ultrafast hard x-ray radiation are discussed.