Collimated fast electron emission from long wires irradiated by intense femtosecond laser pulses.

We have experimentally demonstrated that fast electrons emitted from a metallic wire irradiated by a 5 × 10(18) W/cm(2) laser pulse can be collimated along the wire, and that their intensity is significantly enhanced in the axial direction of the wire. As the wire length is increased up to 30 mm from the laser focal spot, the angular divergence of the emitted electrons with energies of hundreds of keV decreases to 65 mrad. Numerical simulations reveal that the electrons are trapped by the transient electric field surrounding the wire and guided along the axial direction.