A matter of brightness: table-top X-ray generation inside waveguides and X-ray holography with single free-electron laser pulses

Abstract

Date of the oral examination: 26.03.2021 Contents 1 Introduction 2 Observation of electron-induced characteristic X-ray and bremsstrahlung radiation from a waveguide cavity 3 Pump-probe X-ray holographic imaging of laser-induced cavitation bubbles with femto-second FEL pulses 4 Structural dynamics of water after dielectric breakdown 5 Conclusion and outlook A Appendix Bibliography Author contributions List of publications Acknowledgements 1.1.1 Propagation-based phase contrast imaging Dennis Gabor's invention of holography [Gab48; GB49] is the basis for X-ray near-field holography or propagation-based phase contrast imaging. As a phase-sensitive imaging Requirements for propagation-based phase contrast imagingLet us consider a cone-beam setup with an incoherent source of finite source size σ s and let us assume a detector with finite resolution σ d . We will now estimate which structure sizes p are resolvable and exhibit phase contrast under experimental conditions of partial lateral coherence and limited detector resolution. While we aim at equipping the reader with an intuitive understanding of the key aspects, we refer to several studies [PGW97; WL04; WL07; HS18] treating the topic in detail. in the limit of thick anodes [GWA86]. A minimal source size using thick anodes is imposed by multiple scattering of electrons, however. Thin anodes as commonly used in transmission target X-ray tubes allow for smaller source spots, but only at the cost of further reducing the flux [Beh16]. In conclusion, all three options to increase the range for structure sizes p accessible with phase contrast decrease the photon flux.