Fundamental Studies of Thomson Scattering

Abstract

Thomson scattering is the name given to the scattering of light by electrons. This interaction is ubiquitous in daily life and responsible for a wealth interesting phenomenon. Additionally, the interaction can become nonlinear via relativistic effects further expanding its phenomenological reach. This work is dedicated to the study of these fundamental nonlinear interactions. The first chapter reviews theory for the relativistic nonlinearity induced by high intensity light fields interacting with electrons. A comprehensive theory is described with key insights into the origin of harmonics and understanding of nonlinearities. Then we experimentally demonstrate previously untested aspects of nonlinear Thomson scattering (NTS). First, we the study NTS in the mildly nonlinear regime with an elliptically driven laser pulse. This research bridges the experimental gap between NTS driven with linearly polarized laser fields and NTS driven with circularly polarized laser fields. It also reveals the complex polarization states of emitted radiation with applications in x-ray sources and cosmology. Next, we experimentally study the extremely nonlinear regime where the electron motion produces such high number of harmonics that they merge to a continuous broadband synchrotron spectrum. In this work, we study the spatial and spectral repercussions from the nonlinear motion of the electron. Thus, experimentally verifying untested theoretical work proposed over a century ago. Finally, we look toward future applications of highly NTS and propose a method to measure attosecond and sub-attosecond electron pulses. Such electron pulses have been proposed to study ultrafast atomic phenomenon, however, the ability to characterize the pulses is crucial. Our method is particularly valuable because it does not rely on a separate attosecond system as a clock for timing the electrons, of which there very few.

Link: https://digitalcommons.unl.edu/dissertations/AAI28489829