Electron accelerators driven by modulated intense relativistic electron beams

A new high-gradient electron accelerator powered by modulated intense relativistic electron beams (MIREBs) has been developed at the Naval Research Laboratory. This accelerator is a combination of the two-beam and wake-field acceleration concepts. It relies on the interaction of two electron beams via a passive structure. The primary, or the driver beam is a large diameter MIREB, which transfers its RF power to a disk-loaded accelerating structure. The electromagnetic wave induced in this structure converges radially generating an average electric field of the order of 100 MV/m on the axis. A secondary electron beam is injected on the axis and accelerated by this high-gradient field. In the experiment, a 0.2-cm-dia. secondary electron beam emerged from a 1-m long accelerating structure, with a peak kinetic energy of 60 MeV and peak current of 200 Amperes. Simple scaling laws suggest that similar accelerators with much higher average electric fields can be built