The Generation of Ultra-Low Emittance Beams by Downramp Injection in a Plasma Wakefield Accelerator

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The goal of this project is to explore a new method for generating high quality electron beams. High quality electron beams are needed for many applications such as electron microscopy, free electron lasers and high-energy colliders. One measure of quality of an electron beam is its emittance. This is because a small emittance beam can be focused to a very small spot size, desirable in these applications. This project will explore generation of extremely low emittance electron beams using three-dimensional simulations of a new electron acceleration scheme that takes advantage of the ability to control particle density in a Plasma-Based Accelerator.It is now well established that Plasma-Based Accelerators (PBAs) are capable of self-generating ultra-relativistic electron bunches that contain a significant amount of charge, have a short duration, and a low normalized emittance. These beam quantities are often combined into a single figure of merit called the normalized beam brightness. Ultra-high brightness beams are needed in accelerator-based X-ray light sources. While PBA experiments have produced useful beams, they have not yet produced beams with the necessary brightness and energy spread needed to drive an X-ray free-electron-laser, nor the charge and emittance needed as an injector for a future linear collider. This project will explore the acceleration of electrons across a sharp density downramp in a plasma through theory and computer simulations, and through an experiment that will be carried out at the FACET II facility at SLAC.