Effective temperature and the directional motion of fast ions in a picosecond laser plasma

Experimental data are reported on the generation of fast ions in a picosecond laser plasma at a laser-radiation intensity of 2 × 10¹⁸ W/cm². The results are obtained by measuring the Doppler spectra of hydrogen-like fluorine ions. An important feature of the energy distribution of fast ions is a slow decrease up to an energy of 1.4 MeV. In addition, the directional motion of fast ions deep into a target is found due to the redshift of the Doppler profile of the Ly _α line. The parameters of the energy distribution of the ions are theoretically estimated.