Ultracold Electron Bunch Generation via Plasma Photocathode Emission and Acceleration in a Beam-Driven Dielectric Waveguide

Ultrafast electron microscopy using relativistic electron beams requires very short beams of exquisite quality for maximum contrast at submicron scales with fast time resolution. State-of the-art microscopy systems are based on radiofrequency photocathode technology where the accelerating gradient, and thus the beam quality, is limited by breakdown of the copper walls. RadiaBeam Technologies plans to use a dielectric loaded waveguide driven by a low energy electron beam to drive a strong wakefield. In the wakefield a diffuse gas will be ionized at the appropriate location to produce a very low emittance electron beam which will be accelerated to several MeV. This system functions as an electron beam quality transformer, producing a short electron beam of higher quality than available with radiofrequency photocathode technology. During Phase I, we advanced the theoretical and simulation models of the concept to the point where we could plan a proof-of-principle experiment. This work has shown the superlative quality of the electron beam from our system, especially the very short time duration. The Phase II project is to show that the acceleration principle that we have developed will work experimentally and can be adapted to a commercial system. In addition to the body of experimental work to be accomplished, we are also planning more simulations to further develop our infrastructure for modeling.Commercial Applications and Other Benefits The principal users of this technology are industrial and university-scale researchers in materials development and basic science. The tools developed to perform the proof-of-principle experiment will be of general interest to the accelerator physics community. In addition, this technology might find use in multi-user light sources or basic energy science colliders.