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

Ultrafast electron microscopy using relativistic electron beams requires beams of exquisite quality for maximum contrast at submicron scales. 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 an electron beam of higher quality than available with radiofrequency photocathode technology. For Phase I of this project, we will concentrate on producing the 3D particle-in-cell simulations needed to show that the process would produce an electron beam of superlative quality. We will also plan for an experimental proof-of-principle to be carried out during Phase II. Finally, we will design and test a system for holding dielectric tubes in a way than can also deliver and handle the cathode gas. 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.