X-ray spectra of fast ions generated from clusters by ultrashort laser pulses

The high precision X-ray spectroscopy studies of plasma created from the CO 2 clusters in gas jet targets by the ultrashort laser pulses (35 and 60 fs duration) were performed at the intensities I L ∼ 10 17 –10 18 W cm −2 . The spectral line shape of the H-like and He-like oxygen ions gains an asymmetry with increasing the laser pulse intensity. Theoretical modeling of the line shape shows that the asymmetry can be explained by absorption of the Doppler-shifted line radiation from the essential fraction of ions (over 10 −3 ) with energies above 1 MeV due to photoionization of inner shells of carbon ions. The results obtained demonstrate measurement capabilities of the X-ray spectral measurements of multicharged ions accelerated during the interaction with a laser radiation.