Polarization Characteristics And CT Imaging Applications Of All-optical Inverse Compton Scattering Source

In recent years,all-optical inverse Compton scattering X-ray source(AOCS)based on laser wakefield accelerator(LWFA)has made impressive progress.Generated by colliding energetic LWFA electron beams with intense laser pulses,AOCS can produce high-flux polarized quasi-monoenergetic X-rays with tunable photon energy,micron-level source size and compact system scale,showing great potential in wide applications such as medical imaging,industrial nondestructive testing and nuclear physics research.However,current researches based on AOCS mainly focus on the optimization of basic source parameters and the preliminary absorption imaging,while little attention has been paid to its applications in high-resolution CT imaging.Therefore,it is necessary and urgent to carry out systematic studies on the CT imaging based on AOCS.Besides,studies on the polarization of AOCS are still quite deficient,which greatly limits the further application based on this characteristic,thus great efforts are needed in the studies on the generation and diagnosis of polarized AOCS.In-depth studies of the above two key issues are carried out through theoretical analyses,numerical simulations and experiments in this thesis.In Chapter 2,the physical properties of the inverse Compton scattering source,such as the spectrum,the polarization characteristics and the photon spatial distribution,are analyzed theoretically and demonstrated by Monte Carlo simulation,laying a solid theoretical foundation for the following researches on AOCS.High-flux stable AOCS is an important prerequisite for the study of its physical properties and applications.In Chapter 3,multi-shots stable AOCS with single-shot photon yield of～3×107,average photon energy of～71 kev and effective focus of～14μm are experimentally generated through single-laser AOCS scheme by optimizing the electron charge and plasma mirror system,and its spatial resolution is verified by absorption imaging.This high-quality AOCS creates conditions for further experimental study.The polarization characteristics of AOCS are experimentally studied in Chapter 4.Polarized AOCS are firstly obtained in the experiment by adjusting the polarization state of the laser pulses.A Compton scattering polarimeter is then used to diagnose the linearly and circularly polarized AOCS,verifying their polarization states,and showing that the polarization degree of the linearly polarized AOCS is～75%.The research in this chapter will significantly progress the applications based on AOCS’s polarization characteristics.CT imaging based on AOCS is systematically studied at last.In Chapter 5,the potential of AOCS in different CT imaging schemes are firstly analyzed,and an AOCS-based region-of-interest microfocus CT is then proposed and experimentally demonstrated,providing high-fidelity three-dimensional reconstruction of a real sample with～16μm spatial resolution.This experiment is also the first AOCS-based CT imaging result in the world.In Chapter 6,a novel dual-energy micro-focus CT scheme based on the angularly-chirped spectrum of AOCS is proposed and then demonstrated by a numerical simulation,providing high-resolution material-differentiated reconstructions of a test object.The above researches on AOCS-based CT imaging are key steps for its applications in medical imaging and industrial nondestructive testing.