Theoretical and experimental investigations of the excitation of high-frequency oscillations in an ion collective accelerator model based on the Doppler effect

Results are presented from studies of a two-beam scheme of ion acceleration by a high-frequency field excited by an electron beam due to the instabili ties associated with anomalous and normal Doppler effects. The dynamics of the excitation of eigenmodes in a periodic slow wave structure (SWS) by a r elativistic electron beam via the anomalous Doppler effect is investigated theoretically. Mechanisms for the saturation of the instability are conside red, analytical expressions for the maximum field amplitude and the efficie ncy with which the energy of beam electrons is converted into the energy of the excited wave are derived, and the results of numerical simulations of such excitation are presented. An experimental stand designed to test the p rinciples and possibility of proton acceleration up to an energy of 8 MeV a t a current up to 3 A is described. A double resonance (associated with ano malous and normal Doppler effects) occurring in the interaction of an elect ron beam with a helical SWS is studied experimentally. In this case, an inc rease in the efficiency with which the accelerating high-frequency field is excited is observed. (C) 2000 MAIK "Nauka/Interperiodica".