A5039369518- Particle Accelerators and Free-Electron Lasers
- Advanced X-ray Imaging Techniques
- Laser-Plasma Interactions and Diagnostics
- Advanced Electron Microscopy Techniques and Applications
- Particle accelerators and beam dynamics
- Gyrotron and Vacuum Electronics Research
- Force Microscopy Techniques and Applications
- Optical Coatings and Gratings
- Quantum and Classical Electrodynamics
- Electron and X-Ray Spectroscopy Techniques
- Photonic and Optical Devices
- Laser-Matter Interactions and Applications
- Mechanical and Optical Resonators
- Earthquake Detection and Analysis
- Photocathodes and Microchannel Plates
- Astrophysics and Cosmic Phenomena
- Geophysics and Sensor Technology
- Radioactive Decay and Measurement Techniques
- Particle Detector Development and Performance
- Laser Material Processing Techniques
- Scientific Measurement and Uncertainty Evaluation
- Crystallography and Radiation Phenomena
- Magnetic Field Sensors Techniques
- Advanced Surface Polishing Techniques
- Magnetic and Electromagnetic Effects
European X-Ray Free-Electron Laser
2025
Elettra-Sincrotrone Trieste S.C.p.A.
2020-2024
University of Trieste
2020-2024
Vitenparken
2024
Uppsala University
2023-2024
We demonstrate the generation of extreme-ultraviolet (XUV) free-electron laser (FEL) pulses with time-dependent polarization. To achieve polarization modulation on a femtosecond timescale, we combine two mutually delayed counterrotating circularly polarized subpulses from cross-polarized undulators. The profile is probed by angle-resolved photoemission and above-threshold ionization helium; results agree solutions Schrödinger equation. stability limit scheme mainly set electron-beam energy...
The systematic comparison of two semianalytical models microbunching instability affecting electron beams in single pass or recirculating linear accelerators is reported. comprehensive numerous features the instability, such as low and high gain contributions, either linearized at second order, coherent synchrotron edge radiation, Landau damping by transverse emittance laser heater, investigated for double magnetic bunch length compression. enriched three different expressions—one which...
When charged particles interact with laser fields, they are usually thought to be pushed out from the regions of higher intensity via mechanism known as ponderomotive force (PMF). In contrast existing theories, we show that there exist several regimes in which drawn into strongly focused fields. We derive a simple, covariant, and relativistically correct expression for holds arbitrary strength field focusing all particle velocities. predict three new, best our knowledge, physical effects:...
FERMI is a seeded free electron laser (FEL) based on the high gain harmonic generation (HGHG) scheme and has been generating intense fully coherent extreme ultra-violet soft x-ray pulses for several years. The high-degree performance of FEL leans brightness beam, with small transverse emittance ($\ensuremath{\sim}1\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$) peak current about 700-800 A. main constraint lasing at harmonics seed low time-slice energy spread. optimization photoinjector some...
Abstract The effect of multiple small-angle Coulomb scattering, or intrabeam scattering (IBS) is routinely observed in electron storage rings over the typical damping time scale milliseconds. So far, IBS has not been single pass accelerators because charge density orders magnitude higher than would be needed. We show that such now available at high brightness linacs for free-electron lasers (FELs). report measurements beam energy spread FERMI linac presence microbunching instability, which...
Initiating the amplification process in a short-wavelength free-electron laser (FEL) by external seed pulses results radiation with high degree of longitudinal and transverse coherence. The basic layout seeded harmonic generation involves periodic electron energy modulation laser-electron interaction short undulator (the “modulator”), which is converted into density dispersive section immediately followed long FEL “radiator”) tuned to wavelength. With advent more complex seeding schemes,...
The microbunching instability has been a long-standing issue for high-brightness free-electron lasers (FELs) and is significant showstopper to achieve full longitudinal coherence in the x-ray regime. This paper reports first experimental demonstration of mitigation through transverse Landau damping, based on linear optics control dispersive region. Analytical predictions content are supported by numerical calculations gain. effect confirmed characterization spectral brightness FERMI FEL...
The advent of free-electron lasers (FELs) in the soft- and hard-x-ray spectral regions has introduced possibility to probe electronic, magnetic, structural dynamics, both diluted condensed matter samples, with femtosecond time resolution. In particular, FELs have strongly enhanced capabilities several analytical techniques, which taken advantage high degree transverse coherence provided. Free-electron based on harmonic up-conversion an external coherent source (seed) are characterized also...
We present high-resolution measurements of the electron beam energy spread at SwissFEL injector as a function bunch charge, optics, and longitudinal dispersion lattice. The measured values are in general an order magnitude higher than what is predicted by standard simulation codes. dependences indicate that blowup caused primarily intrabeam scattering microbunching instabilities, effects not covered conventional modeling radio-frequency injectors. further numerical model qualitatively...
We have generated elliptically polarized femtosecond pulses from a seeded free-electron laser (FEL) in the spectral range 700–800 eV and conducted demonstrative experiments based on magnetic circular dichroism, at Fe L3 edge. This was achieved by making use of radiation produced third harmonic fundamental FEL wavelength λ. A planar radiator emits linearly harmonics along undulator axis, while helical produces off-axis with polarization. However, circularly light is characterized rather low...
Abstract The optimal performance of high-brightness free-electron lasers (FELs) is limited by the microbunching instability, which can cause variations in both slice energy spread and longitudinal profile electron beams. In this paper, we perform 2D Fourier analysis full bunch phase space, such that modulations planes be studied simultaneously. Unlike standard 1D analysis, method able to reveal a folded would otherwise remain uncovered. Additionally, plasma oscillation between density also...
Extension of stable longitudinal coherence from vacuum ultraviolet to x rays is highly sought after in the free-electron laser (FEL) community, but it often prevented by bandwidth broadening originated electron beam microbunching instability. We demonstrate that a proper tuning linear optics before enters undulator mitigates microbunching-induced sideband The experiment was conducted at Fermi FEL operated echo-enabled harmonic generation mode, where spectral brightness 7 nm wavelength...
Abstract The possibility to predict, characterize and minimize the presence of spurious harmonic content in longitudinal profile high brightness electron beams, namely microbunching instability, has become vital ensure accurate modeling reliable operation radiofrequency plasma-based linear accelerators such as those driving free-electron lasers. Recently, impact intrabeam scattering (IBS) on instability been experimentally demonstrated by authors. This work complements that experimental...
Time-resolved X-ray Emission/Absorption Spectroscopy (Tr-XES/XAS) is an informative experimental tool sensitive to electronic dynamics in materials, widely exploited diverse research fields. Typically, Tr-XES/XAS requires pulses with both a narrow bandwidth and sub-picosecond pulse duration, combination that principle finds its optimum Fourier transform-limited pulses. In this work, we explore alternative xperimental approach, capable of simultaneously retrieving information about unoccupied...
The basic theory of free-electron lasers (FELs) indicates that the output wavelength a seeded FEL operated in high-gain harmonic generation (HGHG) configuration is determined by seed laser and light emitted when undulators are tuned to an exact harmonics laser. In realistic case, taking into account electron beam imperfections finite bandwidths amplification process, influenced these factors can deviate from resonance. These effects responsible for small fluctuations pulses but also be...
High-brightness electron bunches, such as those generated and accelerated in free-electron lasers (FELs), can develop small-scale structure the longitudinal phase space. This causes variations slice energy spread current profile of bunch which then undergo amplification, an effect known microbunching instability. By imposing modulations on low-energy section accelerator, using undulator a modulated laser pulse center dispersive chicane, it is possible to manipulate allows for control study...
Echo-enabled harmonic generation free-electron lasers (EEHG FELs) are promising candidates to produce fully coherent soft x-ray pulses by virtue of efficient high-harmonic frequency up-conversion from ultraviolet lasers. The ultimate spectral limit EEHG, however, remains unclear, because the broadening and distortions induced in output spectrum residual broadband energy modulations electron beam. We present a mathematical description impact incoherent (broadband) on bunching produced...
High-gain free-electron lasers (FELs) are driven by short, high-charge density electron beams as only produced at dedicated single pass or recirculating linear accelerators. We describe new conceptual, technical, and modeling solutions to produce subpicosecond, up $\ensuremath{\sim}100\text{ }\text{ }\ensuremath{\mu}\mathrm{J}$-energy extreme ultra-violet soft x-ray FEL pulses high- tunable repetition rates, from diffraction-limited storage ring light source. In contrast previously proposed...
The microbunching instability has been a long-standing issue for high-brightness free-electron lasers (FELs), and is significant show-stopper to achieving full longitudinal coherence in the x-ray regime. This paper reports first experimental demonstration of mitigation through transverse Landau damping, based on linear optics control dispersive region. Analytical predictions content are supported by numerical calculations gain confirmed characterization spectral brightness FERMI FEL under...
Light manipulation at the nanoscale is essential both for fundamental science and modern technology. The quest to shorter lengthscales, however, requires use of light wavelengths beyond visible. In particular, in extreme ultraviolet regime these capabilities are hampered by lack efficient optics, especially polarization control. Here, we present a method create periodic, modulations using tailored configuration FERMI free electron laser demonstrate its comparing dynamics induced this...
We present the generation of transient polarization gratings at nanoscale, achieved using a tailored accelerator configuration FERMI free electron laser. demonstrate capabilities such grating by comparing its induced dynamics with ones triggered more conventional intensity on thin film ferrimagnetic alloy. While signal is dominated thermoelastic response system, contribution suppressed in case grating. This exposes helicity-dependent magnetization that have so-far remained hidden under large...
Abstract X-ray free-electron lasers (XFELs) and megaelectronvolt ultrafast electron diffractometers (MeV UEDs) are revolutionary scientific instruments that allow visualizing the dynamics of elementary excitations in a wide range systems from atoms molecules to phonons, magnons plasmons. Femtosecond (fs) beams at heart XFELs MeV UEDs, formation fs with ultrahigh brightness is subject active research. We report an interesting regime non-adiabatic temporal compression by two orders magnitude....
The advent of x-ray free-electron lasers (FELs) drastically enhanced the capabilities several analytical techniques, for which degree transverse (spatial) coherence source is essential. FELs can be operated in self-amplified spontaneous emission (SASE) or seeded configurations, rely on a qualitatively different initialization amplification process leading to light emission. SASE and has been characterized past, both experimentally theoretically. However, direct experimental comparison...