Enhanced ionization of W ions at a plasma-vacuum boundary in femtosecond laser plasma at moderate intensities

摘要

Experimental and numerical investigations of femtosecond laser plasma at the cleaned surface of W target are carried out. The constructed picture of ionization, acceleration and recombination of ions in plasma well explains main features of atomic, charge and energy spectra of fast and slow ions. It was shown that experimentally measured maximum charge of W ions exceed charge predicted by impact ionization and can be reached due to ambipolar field ionization.