Intense accelerated metal ion beam utilizing laser blowoff

An intense pulsed beam of energetic metal ions has been produced by electrically accelerating ions extracted from a laser-produced plasma. A pulsed laser focused on a metal surface in a vacuum provides the expanding metal plasma. The plasma is intercepted by a pair of shaped grids located at a distance where the plasma cloud has become collisionless. An electric field between the grids accelerates and focuses the ions. Electrons from a heated filament are introduced into the ion stream in an effort to neutralize the space charge spreading of the ion beam (plasma). Ion beams were produced with energies from 1 to 10 keV. Ion fluences per pulse in the fast beam have reached 1013 cm−2, and 1012 ions per pulse have been injected through a cylindrical channel 0.8 cm diam×2.0 cm long. The beam pulse lengths were typically less than 20 μsec. Aluminum has been used principally but the method should be applicable to a wide range of materials.