Terahertz radiation source based on self-wake beam bunching

Abstract

Argonne National Laboratory, Argonne IL, 60439, USA Abstract. A table top device for producing high power T-ray beams is described. A rectangular electron beam that can be produced out of a photoinjector via stacking of the laser pulse, and running off-crest of the photoinjector rf is sent through a dielectric loaded waveguide. Due to the beam's self-wake its energy becomes modulated. In the chicane beamline following the dielectric energy-bunching section this energy modulation is converted to a density modulationa bunch train. The density modulated beam can be sent through a power extraction section, like a dielectric loaded accelerating structure, or simply can intercept a foil target, producing THz radiation of various bandwidths and power levels.

Experimental Demonstration of Energy-Chirp Compensation by a Tunable Dielectric-Based Structure

“…While propagating along a dielectric-lined tube the ultra-relativistic electron bunch excites a set of waveguide modes with a phase velocity equal to electron velocity (the speed of light in the ultra-relativistic case). Unlike wakefield acceleration [4] and THz radiation generation [5] which employ primarily long-range wakefield radiation (rf energy left behind in the structure), here we exclusively consider short-range wakefields: the fields experienced by the beam itself. These short-range wakefields cause the head of the short beam to decelerate the tail.…”

Ballistic bunching of photoinjected electron bunches with dielectric-lined waveguides

“…Most recently, a technique to produce train of microbunches based on a dielectric-lined waveguide (DLW) was realized in a ∼70 MeV accelerator [23][24][25]. In the latter experiment a density modulation was produced using a small chicane to provide the longitudinal dispersion necessary to convert the energy modulation imparted by the beam selfinteraction with its short-range wakefield in the DLW structure.…”