Publication Date

2026

Document Type

Dissertation/Thesis

First Advisor

Chubenko, Oksana

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Physics

Abstract

Bright electron beams generated via photoinjectors have enabled many recent developments in accelerator technology, including x-ray free electron lasers and ultrafast electron microscopy and diffraction systems. The conceptual design, scientific reach, and accessibility of these and next-generation accelerator applications can be significantly improved by increasing electron beam brightness. Therefore, the development of novel methods to further enhance beam brightness remains a critical priority in the field.

One of the primary factors limiting beam brightness is the mean transverse energy (MTE) of photoemitted electrons. The MTE is an intrinsic property of the photocathode and is proportional to the square of the beam emittance, one of the key parameters determining beam quality. One objective of this work is to explore the implementation of low-MTE photocathodes at the Argonne Wakefield Accelerator (AWA) facility, focusing on identifying optimal configurations of the upgraded drive-beam linac to generate a 100 pC beam with 100 nm transverse emittance.

Another objective is to implement and investigate the sacrificial charge technique, recently proposed as a method to exploit non-linear space charge effects to linearize a beam's core. In this approach, a highly non-linear halo focuses through the core, linearizes it, and then is removed by a collimating aperture. This technique has been implemented and studied at AWA's current drive-beam linac, which is uniquely suited for this purpose due to its wide range of operation (from 100 pC to 100 nC).

In a photoinjector, the beam brightness scales proportionally with the applied electric field gradient. AWA's X-band photoinjector is powered by two-beam acceleration to allow the generation of extremely high electric field gradients using short RF pulses. This work also discusses the addition of a booster linac to achieve beam energies up to 10 MeV, and demonstrates the ability of this integrated photoinjector to generate bright beams with possible applications as an x-ray source via inverse Compton scattering or as a gateway to an even higher energy (~100 MeV) photoinjector.

Extent

109 pages

Language

en

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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