XLO-II, a high-repetition rate X-ray laser oscillator

Recently we proposed to build an X-ray laser oscillator (XLO) in the 6-10 keV range providing intense, stable, transform-limited x-ray pulses in the 6-10 keV range, based on an x-ray pulse train operated at 100 Hz repetition rate. Here, we provide an analysis of recent experimental results and theoretical/numerical simulations showing that it is possible to build and operate a second generation x-ray laser oscillator, XLO-II, operating at up to 125 kHz and pumped by 6-10 keV x-ray SASE pulses generated by the new LCLS-II-HE x-ray free-electron laser (XFEL) now under construction at SLAC National Accelerator Laboratory. XLO-II will generate transform limited, coherent x-ray pulses, with an average power in the tens of mW range. It will open new experimental capabilities, for instance in fields like imaging, interferometry and quantum x-ray optics. We discuss the recent results leading to this conclusion and present the main characteristics of XLO-II and of its main components, like the optical cavity

Fast modeling of regenerative amplifier free-electron lasers

High-gain free-electron lasers (FELs) are becoming important light sources at short wavelengths such as the EUV and X-ray regimes. A particularly promising concept is the regenerative amplifier FEL (RAFEL), which can greatly increase the brightness and stability of a single pass device. One of the critical challenges of the x-ray RAFEL is maintaining electron-optical overlap over the relatively large (hundreds of meters) footprint of the system. Numerical modeling of x-ray RAFELs with angular and positional errors is critical for designing stable cavities, as well as to predict signatures of specific misalignment effects. Full-scale simulations of x-ray FELs are incredibly time-consuming, making large-scale parameter searches intractable on reasonable timescales. In this paper, we present a semi-analytical model that allows to investigate realistic scenarios - x-ray cavity without gain ("cold cavity" or x-ray FEL oscillator) and x-ray RAFEL - in the presence of angular/positional errors and electron trajectory oscillation. We especially focus on fast modeling of the FEL process and x-ray optics, while capturing effects pertaining to actual experimental setups at the Linac Coherent Light Source (LCLS) at SLAC. Such a method can be used to explore RAFEL at other wavelengths by suitable replacement of the optics modeling

Generation of Intense Phase-Stable Femtosecond Hard X-ray Pulse Pairs

Coherent nonlinear spectroscopies and imaging in the X-ray domain provide direct insight into the coupled motions of electrons and nuclei with resolution on the electronic length and time scale. The experimental realization of such techniques will strongly benefit from access to intense, coherent pairs of femtosecond X-ray pulses. We have observed phase-stable X-ray pulse pairs containing more thank 3 x 10e7 photons at 5.9 keV (2.1 Angstrom) with about 1 fs duration and 2-5 fs separation. The highly directional pulse pairs are manifested by interference fringes in the superfluorescent and seeded stimulated manganese K-alpha emission induced by an X-ray free-electron laser. The fringes constitute the time-frequency X-ray analogue of the Young double-slit interference allowing for frequency-domain X-ray measurements with attosecond time resolution.Comment: 39 pages, 13 figures, to be publishe

Electron beam shaping and its applications

Advisors: Philippe Piot.Committee members: Stephen Martin; Michael J. Syphers.Includes illustrations.Includes bibliographical references.Transverse and longitudinal electron beam shaping is a crucial part of high-brightness electron accelerator operations. In this dissertation, we report on the corresponding beam dy- namics research conducted at Fermilab Accelerator Science and Technology facility (FAST) and Argonne Wakefield Accelerator (AWA). We demonstrate an experimental method for spatial laser and electron beam shaping using microlens arrays (MLAs) at a photoinjector facility. Such a setup was built at AWA and resulted in transverse emittance reduction by a factor of 2. We present transverse emittance partitioning methods that were recently employed at FAST facility. A strongly coupled electron beam was generated in an axial magnetic field and accelerated in 1.3 GHz SRF cavities to 34 MeV. It was then decoupled in Round-To-Flat beam transformer and beams with emittance asymmetry ratio of 100 were generated. We introduce the new methods of measuring electron beam canonical angular momentum, beam transformer optimization and beam image analysis. We also describe a potential longitudinal space-charge amplifier setup for FAST high-energy beamline. As an outcome, a broadband partially coherent radiation in the UV range could be generated.Ph.D. (Doctor of Philosophy

Time-dependent dynamical Bragg diffraction in crystals by beam propagation method (BPM)

In this paper we describe how to solve time dependent x-ray dynamic diffraction problems in distorted crystal using a beam propagation method (BPM). We will show examples of using the BPM method to simulate propagation of x-ray beams in deformed crystals in space an time domain which are relevant to performance of x-ray optics at x-ray Free Electron Laser

XLO-II, a high-repetition rate X-ray laser oscillator

Recently we proposed to build an X-ray laser oscillator (XLO) in the 6-10 keV range providing intense, stable, transform-limited x-ray pulses in the 6-10 keV range, based on an x-ray pulse train operated at 100 Hz repetition rate. Here, we provide an analysis of recent experimental results and theoretical/numerical simulations showing that it is possible to build and operate a second generation x-ray laser oscillator, XLO-II, operating at up to 125 kHz and pumped by 6-10 keV x-ray SASE pulses generated by the new LCLS-II-HE x-ray free-electron laser (XFEL) now under construction at SLAC National Accelerator Laboratory. XLO-II will generate transform limited, coherent x-ray pulses, with an average power in the tens of mW range. It will open new experimental capabilities, for instance in fields like imaging, interferometry and quantum x-ray optics. We discuss the recent results leading to this conclusion and present the main characteristics of XLO-II and of its main components, like the optical cavity