High-Efficiency 2 MeV Beam-Driven Accelerator

A novel beam-driven electron accelerator, which we name the Electron Voltage Transformer (EVT), falls into the broad class of two-beam accelerators, but differs significantly from other configurations in that the RF source and the accelerator are built into the same vacuum envelope. Multiple drive beamlets and the beam to be accelerated receive radiofrequency (RF) modulation in a set of RF buncher cavities, from which the beams pass into the accelerating structure. The latter structure comprises decoupled, inductively-tuned cavities, wherein energy is transferred from the drive beams to the accelerated beam. Correct phasing-to achieve initial RF bunching, followed by acceleration-is accomplished by appropriate spacing of the cavity gaps. Preliminary results of numerical simulations are presented for a prototype of EVT, operating at L-band, in which a 6 A 110 kV beam is accelerated to 2 MeV with an overall efficiency of 60%. This unusually-high efficiency, high average power electron beam source should be attractive for a range of industrial applications.