Studies of High-Energy Photon Sources from a Laser Wakefield Accelerato

Since the demonstration of a chirped-pulse amplification laser was first made in 1985, the amount of research in laser driven particle accelerators (LPAs) has grown tremendously. Particularly in the past 15 years, there has been significant research into laser wakefield acceleration (LWFA) and its potential for high energy radiation production. While the tunability, stability, and consistency of these LPAs still lag behind traditional accelerators, recent work has demonstrated successful electron acceleration up to a few GeV and creative ways to generate MeV-level photons. With electron energies reaching the multi-GeV level and photon production ranging from a few keV to 10's of MeV, laser-plasma accelerators are capable of performing important research on a scale that is thousands of times smaller than traditional accelerator technology.;This thesis describes several experiments carried out on both the HERCULES laser at the Center for Ultrafast Optical Science at the University of Michigan and on the Astra-Gemini laser system at Rutherford Appleton Labs in the United Kingdom. The goal of this thesis is to present empirical evidence of laser wakefield accelerators as an all-in-one tool capable of rivaling the research carried out at linear accelerators, synchrotrons, and Compton gamma ray facilities.;Experiments presented here were carried out to both understand the laser wakefield accelerator as a high energy radiation source and to demonstrate its ability to perform cutting edge research. In the first experiment, measurements of trapped and un-trapped electrons are used to seek a better understanding of electron motion and trapping in the wakefield structure. Additionally, x-rays produced via betatron oscillations in the plasma bubble were studied under a variety of experimental conditions. The working gas was switched between helium and N2-doped helium showing that ionization injection (a trapping mechanism) on average, results in the production of lower energy photons. This experiment was performed to characterize the radiation produced through laser wakefield acceleration on HERCULES while developing x-ray detection diagnostics to be used on future work.;The next experiment utilized the x-ray detector developed earlier to measure a blue shift in the K-edge of heated aluminum using absorption spectroscopy. The experiment was carried out in a pump-probe setup with a split laser beam being used to heat an aluminum target with one arm and produce betatron x-rays through LWFA with the other arm. By varying the delay between the two beam lines, changes in the aluminum absorption K-edge were measured on the femtosecond timescale. This work demonstrates the benefits to performing pump-probe experiments using an all-optical source.;The final piece of work presented here is an inverse Compton scattering experiment that was performed on the Astra-Gemini laser. A LWFA electron beam was scattered from a counter-propagating laser pulse which resulted in a measured radiation reaction of the electrons along with the production of gamma rays in excess of 100 MeV. A gamma ray spectrometer consisting of an array of cesium-iodide scintillation crystals was developed to calculate the gamma ray spectrum and measure the effects of radiation reaction for the first time.