Neutral Beam Generation by Laser Irradiation of Thin Foils

We irradiated thin (< 10 μm) plastic and metal foils by a 1 TW, 50 fs, T3 laser. The foil surface was located at π/4 to the laser injection. Particle beams were obtained at both sides of the foil with respect to the laser injection. The beam at the rear side, flowing to the direction perpendicular to the foil surface, was insensitive to the magnetic field. Measurements using the track detector CR39 tell that it has small divergence (∼ 200 mrad) and suggest that their particles could have high energies (up to 1 MeV). We therefore conclude that these particles make a neutral beam. To the contrary, ions were obtained at the same side of the foil with respect to the laser injection. They also have energies up to ∼ 1 MeV, but larger angler distribution.