Collective-field acceleration of high-energy ions

A collective-field accelerator has evolved from experimental and theoretical research at the Lawrence Livermore Laboratory that uses a high-vacuum diode with an adjustable graphite cathode as well, as an insulated anode, and that operates with a relativistic electron beam with ν/γ of ~1. Alternate gradient lenses are used to focus collectively accelerated particles. The gradients are produced by alternate dielectric and grounded lenses. The dielectric lenses are self charged by the electron beam creating a potential difference in reference to the grounded lenses. These lenses focus both electrons and ions by convective processes. Deuterons have been accelerated in pulses of ~1014 producing up to 1011 D-D neutrons per burst by impingement on suitable targets. Hydrogen, deuterium, carbon, fluorine and chlorine ions have been accelerated to produce both light-and heavy-ion reactions. Analysis of activation data shows that heavy ions with >6 MeV per nucleon and protons with ~15 MeV energy have been produced. Theoretical analysis indicates that the collective ion acceleration mechanisms arise from interactions with plasma-wave trains created by near-resonant, beam-cavity interactions and accelerated (in group velocity) through density and temperature gradients in the secondary plasma beyond the anode. (author)