High Repetition Rate and Coherent Free-Electron Laser Oscillator in the Tender X-ray Range Tailored for Linear Spectroscopy

Michele Opromolla,Marcello Rossetti Conti,Luca Serafini,Alberto Tagliaferri,Andrea Renato Rossi,Alberto Bacci,Vittoria Petrillo,Giorgio Rossi

doi:10.3390/app11135892

Michele Opromolla, Marcello Rossetti Conti + Show 6 more

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https://doi.org/10.3390/app11135892

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Abstract

Fine time-resolved analysis of matter—that is, spectroscopy and photon scattering—in the linear response regime requires fs-scale pulsed, high repetition rate, fully coherent X-ray sources. A seeded Free-Electron Laser, driven by a linac based on Super Conducting cavities, generating 108–1010 coherent photons at 2–5 keV with 0.2–1 MHz of repetition rate, can address this need. The scheme proposed is a Free-Electron Laser Oscillator at 3 keV, working with a cavity based on X-ray mirrors. The whole chain of the X-ray generation is here described by means of start-to-end simulations.

Highlights

Synchrotron radiation (SR) sources based on low-emittance electron storage rings, as well as Free Electron Lasers (FELs) driven by linear electron accelerators (Linacs), allow the fine analysis of matter, with applications extending from life sciences to material physics
Most FELs worldwide operate in the Self-Amplified Spontaneous Emission (SASE) mode [1,2,3,4,5,6,7,8], providing extremely brilliant and short pulses with more than 1012 photons per pulse, and shot-to-shot time and intensity jitters determined by the intrinsic fluctuations of the emission process
The studied X-ray FEL Oscillator configuration based on diamond mirrors produces 107– 1010 coherent photons per shot at 3–3.5 keV at 1 MHz

Summary

Introduction

Synchrotron radiation (SR) sources based on low-emittance electron storage rings, as well as Free Electron Lasers (FELs) driven by linear electron accelerators (Linacs), allow the fine analysis of matter, with applications extending from life sciences to material physics. Most FELs worldwide operate in the Self-Amplified Spontaneous Emission (SASE) mode [1,2,3,4,5,6,7,8], providing extremely brilliant and short pulses with more than 1012 photons per pulse, and shot-to-shot time and intensity jitters determined by the intrinsic fluctuations of the emission process These Ultra-Violet (UV) or X-ray flashes are used to probe matter in highly excited states, to study nonlinear processes or to test before destroying individual objects such as macromolecules constituting proteins, replacing crystallography with single object imaging. Spectroscopic applications with X-ray FELs are severely limited by SASE fluctuations and full seeding, successfully conducted at FERMI (Free-Electron laser for Multidisciplinary Investigations) in the XUV-soft X-ray range [9], should ideally be extended to X-ray energies

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