The results of studies of fast-proton generation from foil targets irradiated by 1-ps laser pulse at ${10}^{17}\mathrm{W}/\mathrm{cm}{}^2$ are presented. It is shown that a considerable increase in proton energy and current is possible when a double-layer foil target containing a high- $Z$ layer and a low- $Z$ hydrogen-rich layer is used instead of a single-layer target. Proton energies and current increase with the $Z$ of the high- $Z$ layer and depend essentially on the target and the layer thicknesses. Above ${10}^9$ forward-emitted protons of energy $>100\mathrm{keV}$ have been recorded within a cone angle $<3\mathrm{}°$.

• Received 19 June 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.215001