Fast Protons Generated with Double-Layer Foil Targets

Using 1-ps pulses from an Nd:glass laser, researchers have shown that double-layer thin foils containing a high atomic number front layer and a low atomic number, hydrogen-rich back layer can generate fast protons with greater energies and current than is possible with conventional single-layer methods.

The results of the study by a team from the Institute of Plasma Physics and Laser Microfusion in Warsaw, Poland, and St. Petersburg State Technical University and the Research Institute for Laser Physics, both in St. Petersburg, Russia, were published in the Nov. 19 issue of Physical Review Letters. During the double-layer method, a laser pulse interacts with the front of the target, producing a short burst of hot electrons that ionize atoms on the back target. As a result, protons on the back surface are accelerated up to 100 keV and at a laser intensity of 10¹⁷ W/cm².

The researchers anticipate that the method, combined with spatial particle beam shaping, could lead to construction of efficient tabletop, laser-driven accelerators.