Temporal and spectral dependence of samarium X-ray emission in subpicosecond and nanosecond laser-produced plasmas

Ultra-short X-ray sources are generated by focusing sub-picosecond lasers on massive targets. The emission duration of a samarium X-ray source produced with a 100 TW sub-picosecond laser was measured using an ultra-fast X-ray streak camera. The spectral range was limited around 7.5-8.5 Å, the range in which samarium can be used as a backlighter for Kα aluminum absorption experiments. The spectral time-evolution and the duration of samarium emission were measured. Preliminary calculations performed with non-local-thermodynamic equilibrium atomic physics show the plasma cooling which occurs with a characteristic time longer than predicted by radiative hydrocode simulaitons.