Quantum materials exhibit complex interactions between electron, structural and spin degrees-of-freedom over a wide range of length scales, leading to exotic phenomenon that are challenging to study. Ultrafast excitation can disentangle these degrees-of-freedom, but resolving the different length scales remains challenging. Here I will present recent results using X-ray free electron lasers to...
Despite tremendous progress in X-ray free-electron laser (XFEL) science over the last decade, future applications still demand fully coherent, stable X-rays that have not been demonstrated in existing X-ray FEL facilities. In this talk, we review the progress toward an X-ray regenerative amplifier FEL (XRAFEL) to produce both high-peak and high-average power FEL pulses with full temporal...
SwissFEL at the Paul Scherrer Institute is a free-electron laser facility providing hard and soft X-rays, based on the SASE principle. In addition, the soft X-ray beamline Athos is currently extended for electron beam manipulation with external lasers, aiming to provide seeding capabilities based on the two-stage echo-enabled
harmonic generation (EEHG) scheme. Completion of the installation...
We present the design study of an innovative scheme to generate high repetition rate
(multi-MHz-class) THz and X synchronized radiation pulses
by using an Energy Recovered Super Conducting Linac operating in Continuous Wave
mode driving a Free-Electron Laser Oscillator.
The FEL and X rays performances are illustrated for one and two color operation.
Start-to-end simulations are...
High intensity, sub-femtosecond XFEL pulses are key to taking full advantage of nonlinear x-ray spectroscopies and advanced imaging methods. The X-ray Laser-Enhanced Attosecond Pulses (XLEAP) collaboration is an ongoing project for the development of attosecond x-ray modes at the Linac Coherent Light Source (LCLS). Here we report development of a high power attosecond mode via cascaded...
The ongoing Plasma-driven Attosecond X-ray source experiment (PAX) at FACET-II aims to produce coherent soft X-ray pulses of attosecond duration using a Plasma Wakefield Accelerator [1]. These kinds of X-ray pulses can be used to study chemical processes where attosecond-scale electron motion is important. For this first stage of the experiment, PAX plans to demonstrate that <100 nm bunch...
Compact sources offering high-brightness radiation in the extreme ultraviolet to X-ray regime are highly desired. Thomson scattering, in which an electron beam colliding with a laser pulse produces radiation, is a source of X-rays of increasing prevalence in modern labs, complementing large scale facilities like synchrotrons and X-ray free electron lasers. By imposing a density modulation on...
We report first observation of terahertz super radiant emission from the Israeli Free Electron Laser. This is first demonstration of a THz FEL source based on the scheme of coherent spontaneous superradiant (SR) emission by an ultra-short e-beam bunch. The first measured radiation signal corresponds to a 3.5THz beam output of 180 nanoJ.
The Israeli superradiant FEL operates in the FEL center...
The international collaboration towards a 5th-generation lightsource should adopt an open source platform to enable a) instantaneous collaboration between distributed design teams; b) code benchmarking, multiphysics and code chaining for end-to-end simulation; c) multi-level user support for all relevant codes, from GUI to supercomputer; d) applicability to all subsystems individually,...
S-band Standing-wave RF Photoguns represent the current state of the art for high brightness electron sources. These devices significantly contributed to the development of high brightness accelerators. However, the push for even brighter electron sources presents a significant technological challenge. Aiming to continue to push the boundaries of high brightness electron beams, a...
Strongly tapered free-electron lasers (FELs) offer a promising avenue towards achieving higher peak and average power radiation sources. Through the strong seeding of an input laser or microbunched electron beam, larger efficiencies can be achieved by adapting the undulator parameters to maintain resonance with the decelerated electrons. Additionally, the use of an oscillator cavity driven by...
This talk will report on the status Cathodes And Radio-frequency Interactions in Extremes (CARIE) high gradient C-band RF photoinjector project at Los Alamos. Modern applications such as X-ray sources require electron beams with ultra-low emittance and very high brightness that may be achieved by accelerating the electron beam produced in an RF photoinjector with electric field higher than 100...
Methods for realizing resonant cavities with high field gradients have been studied in the last years. Cavities are often made of copper, which however has too low work function (WF) (thus eventually leading to dark currents) and tends to produce uncontrolled discharges (breakdowns) which might damage the copper surface, finally degrading the cavity performance. For this reason, the idea of...
The Photo Injector Test facility at DESY in Zeuthen (PITZ) develops high brightness photocathode RF guns, advanced diagnostics and applications of the high brightness electron beams, which currently can be accelerated up to 22 MeV. In this talk, we will present the latest development at the L-band normal conducting photoinjector (e.g., new prototype RF gun Gun5.1, photocathode laser shaping...
The development of attosecond methods at free-electron lasers has led to new possibilities in the probing and control of electronic dynamics in molecules. Beyond simple observation of ultrafast processes, one of the longstanding goals of atomic and molecular physics is control of the electronic wavefunction on attosecond timescales. This implies a need to go beyond impulsive excitation with...
Characterizing the phase space distribution of particle beams is essential in the study of accelerator systems. As the accelerator community keeps pushing the brightness frontier, resolving fine details in the 6D beam phase space density has become important in the optimization and control of next-generation beamlines. However, conventional reconstruction-based techniques either use...
The ion channel laser (ICL) is an alternative to the free electron laser (FEL) that uses the electric fields in an ion channel rather than the magnetic fields in an undulator to transversely oscillate a relativistic electron beam and produce coherent radiation. The strong focusing force of the ion channel leads to a Pierce parameter more than an order of magnitude larger than the typical...
In this work we present the result of a Dielectric Wakefield Acceleration (DWA) design that uses a longitudinally varying alternating gradient configuration of a planar-symmetric DWA structure to exploit the inherent quadrupole-mode transverse wakes to achieve second-order stability. We have designed and fabricated a new apparatus for positioning the DWA components in our setup. This allows us...
Free electrons are central to such diverse applications as electron microscopes, accelerators, and photo-emission spectroscopy. However, space charge effects of many electrons are often problematic and, when confined to extremely small space-time dimensions, already two electrons can interact strongly. Here, we demonstrate that the resulting Coulomb repulsion can also be advantageous, as it...
The out-of-equilibrium dynamics of engineered nanoscale systems, such as moiré materials, is an important domain for ultrafast science. Ultrafast electron diffraction (with high-angular magnification) is especially suited to investigating spatially coherent normal modes of oscillation in these systems, collective motion that could hold the key to novel device functionality. Nanometer and...
The Ultra Cold Electron Source (UCES) being developed at Eindhoven University of Technology is based on near-threshold, femtosecond photoionization of a laser-cooled rubidium gas in a magneto-optical trap. The UCES accelerates bunches containing ~1000 electrons in a DC field up to energies of ~10 keV with a normalized emittance of ~1 nm·rad.
Recently, bunch lengths as short as 735±7 fs (rms)...
Ultrafast electron probing modalities offer unique experimental tools to access the structural dynamics of ultrafast photoinduced processes in materials and molecules, in liquid, gas, and condensed phase systems. Here we propose to capitalize on the exceptional and versatile electron beam parameters of the SEALAB Superconducting RF (SRF) photoinjector to develop a world-wide unique facility...
Imaging time-resolved molecular dynamics demands atto- to few-femtosecond temporal and picometer spatial resolution. Laser-induced electron diffraction (LIED) is a strong-field method based on coherent laser-driven scattering with one of the target's own electrons after photoionization. In this way, LIED differs from conventional ultrafast electron diffraction (UED) with external electron...
In this talk, I will discuss how the collective field of a relativistic electron beam can be used to instigate novel quantum dynamics and allow us to study ultrafast physics beyond typical laser-excited systems. At LCLS, the beam-supported fields can be shaped into strong (V/A), broadband (0-10 eV), and/or microbunched pulses that are intrinsically synchronized and mutually coherent with a...
RUEDI (Relativistic Ultrafast Electron Diffraction & Imaging) is a proposed UK national facility in the which will deliver single-shot, time-resolved, imaging with MeV electrons, and ultrafast electron diffraction down to 10 fs timescales. RUEDI is being designed to enable the following science themes: dynamics of chemical change; materials in ex-treme conditions; quantum materials; energy...
Mega-electronvolt ultrafast electron diffraction (MeV-UED) is a complementary tool to X-ray based instruments that has enabled ground-breaking studies in condensed matter physics and chemical science. A significant opportunity exists for MeV-UED beyond current instrument capabilities in quantum materials, microelectronics and photo-chemical research. Further improvement in MeV-UED transverse...
Generation of high-quality electron beams in plasma-based acceleration is a critical and active topic in the past decade. By conducting full-scale particle-in-cell simulations, we have shown that electron beams with ultra-high brightness (10^20 ~10^21 A/m^2/rad^2) and 0.1~1 MeV energy spread can be produced in density downramp injection in the three-dimensional blowout regime of plasma-based...
We present a blueprint for an ultra-compact X-ray free-electron laser (X-FEL) powered by plasma wakefield acceleration (PWFA). The study shows in a high-fidelity S2E simulation how to produce and preserve ultra-high 6D brightness electron beams in a plasma photocathode PWFA stage. Then, a post-plasma beam transport line captures, isolates and refocuses these electron beams into an undulator...
Recent advances with the Resonant Multi Pulse Ionization Injection scheme [1,2], which was already proven by simulations to be able to generate few femtosecond long 5GeV beams [3] with beam quality large enough to efficiently drive a FEL [4], move toward the generation of high-brigthness beams with duration of a few hudreds of attoseconds. At the same time, with the aid of an advanced model...
The Hundred Terawatt Undulator (HTU) beamline at the BELLA Center is being used as a test bed for the development of compact laser plasma accelerator (LPA)-driven light sources, with a particular focus on developing a reliable LPA-driven FEL. While LPA technology is well established, hurdles remain to make it usable for practical light source applications. Stability and reliability are primary...
The breakthrough provided by plasma-based accelerators enabled unprecedented accelerating fields by boosting electron beams to GeV energies within few cm.
This enables the realization of table-top accelerators able to drive a Free-Electron Laser (FEL), a formidable tool to investigate matter at sub-atomic level by generating X-UV coherent light pulses with fs and sub-fs durations.
So far,...
Laser wakefield accelerators (LWFA) have produced electron beams with up to ~10 GeV of energy in tens of centimeters. In addition to producing high accelerating gradients, theory predicts the existence of linear focusing forces when an LWFA is driven in the blowout regime, where all electrons behind the laser are expelled. Such linear fields are essential for maintaining an electron beam’s...
The energy spread is one of the properties that determine the brightness of electron beams and a fundamental parameter in X-ray free-electron lasers (FELs). In the last couple of years, measurements at different FEL injectors have shown energy spread values much larger than predicted by simulations. This talk will present high-resolution energy spread measurements at the SwissFEL injector as a...
Compensating the emittance growth due to linear and nonlinear space charge effects in photoinjectors is critical for high-brightness electron beam applications ranging from XFELs to various ultrafast electron probes. While linear emittance compensation is extremely robust, nonlinear emittance compensation depends on the detailed nature of the charge distribution, and in general, producing...
The Argonne Wakefield Accelerator (AWA) supports an extensive research portfolio along three themes: electron beam production, electron beam manipulation, and electron beam-driven wakefield acceleration. Current research activities focus on longitudinal distribution shaping and cross-plane manipulations for emittance redistribution between two and three degrees of freedom, such as...
The space charge emittance compensation in the C-band TopGun design has been demonstrated with 100 pC bunch charge. It has shown that a minimum emittance is limited by the intrinsic emittance at the cathode. Scaling this approach to higher bunch charges, however, requires a larger transverse size and a longer pulse duration. The rf emittance dilution due to the iris kick scales quadratically...
The transverse emittance of a charged particle beam is an important figure of merit for many accelerator applications. One of the easiest to implement methods to determine the transverse emittance is the phase advance scan method using a focusing element and a screen. This method has been shown to work well in the thermal regime. In the space charge dominated laminar flow regime, however, the...
Diagnostic methods that are enhanced with machine learning are improving the speed and detail with which beam behavior can be characterized on-the-fly in real accelerator systems. Detailed characterization can in turn improve both high-precision modeling of accelerator systems and high-precision optimization/control for high brightness beams. This talk will outline the state-of-the-art in...
Highly accurate simulation tools have become a staple in the design and operation of high-brightness particle accelerators. These tools are not without limitations, however. They are often computationally expensive. Many codes are incompatible with automatic differentiation (for machine learning). It can also be unclear how to include real-world measurements in a way that improves the model....
The EuPRAXIA Advanced Photon Sources (EuAPS) project, led by INFN in collaboration with the CNR and the University of Tor Vergata, involves the construction of a laser-driven “betatron” X-ray user facility at the SPARC_LAB laboratory of the LNF. EuAPS also includes the development of high power (up to 1 PW at LNS) and high repetition frequency (up to 100 Hz at CNR Pisa) laser drives for...
Plasma accelerators are emerging as formidable and innovative technology thanks to their compactness and reduced costs to drive of user facilities being able to sustain several GV/m accelerating gradients at normal conducting temperature.
The EuPRAXIA@SPARC_LAB collaboration is preparing a technical design report for a multi-GeV plasma-based accelerator with outstanding electron beam quality...
The Munich Compact Light Source (MuCLS) is a tuneable, brilliant and compact hard X-ray synchrotron source. Electrons are accelerated in a classical RF-accelerator and injected into a small storage ring (4.6 m circumference). X-rays are generated via a laser-undulator, realised as a short laser pulse circulating in an enhancement cavity. Thus, the MuCLS provides incoherently-produced brilliant...
The underdense passive plasma lens (UPPL) has several features that make it uniquely attractive for the focusing high-energy electron beams. Nominally formed via laser ionization of gas in the outflow of a supersonic jet, it is a simple, ultra-compact, and easily tunable device. Because it operates in the nonlinear blowout regime, the focusing strength scales with the plasma density and lens...
While XFEL electron bunches can be manipulated for tailored x-ray generation via laser-electron interactions in select locations along the accelerator, such as laser heaters, XFEL performance is dominantly impacted by the electron bunch parameters directly after generation in the photoinjector. Optimal performance of the photoinjector requires excitation laser pulses, typically in the...
Large-core anti-resonant fibers have recently found key applications in non-linear optics. Here we report on their applications to charged beams. We show that large energy modulations can be applied via a TM01-like mode, which can be further exploited to produce attosecond microbunches. We also report on the dipole HE11-like mode, to support high-power streaking resolutions for diagnostics...
The $\lambda^2$ scaling of the ponderomotive force underpinning laser-based particle accelerators encourages the use of long wavelengths in regimes such as laser wakefield acceleration of electrons at low plasma densities. High pressure $\mathrm{CO_2}$ amplifiers are the workhorse source of such lasers, able to achieve multi-TW peak powers and picosecond pulse lengths. We are developing...
Hybrid combinations of lasers and electron beams allow LWFA->PWFA and plasma photocathodes to be realized. This is a pathway to ultrabright electron and photon pulses. Experimental progress on hybrid LWFA->PWFA, and on plasma photocathodes driven by linac-PWFA, and now also by the hybrid LWFA->PWFA approach, will be presented. Intrinsically synchronized, ultrabright electron and photon pulses...
Flat or transversely asymmetric beams create transversely asymmetric wakefields. These wakefields are characterized by the creation of an elliptical cavity created by the evacuated plasma electrons and remnant ions. The potential inside these elliptical cavities is quadratic and yields transverse electric fields that are linear. Particle beams inside the blowout cavity can be matched to these...
RUEDI is a proposed Relativistic Ultrafast Electron Diffraction and Imaging facility for the UK. It will deliver single-shot time-resolved imaging with MeV electrons, as well as ultrafast electron diffraction at 10 fs timescales. The few-MeV-scale imaging and microscopy line aims to deliver high charge (up to 10^8 electrons), ultra-low emittance electron bunches to a 10µm sample with minimal...
RUEDI is a proposed facility for ultrafast electron microscopy (UEM) and ultrafast electron diffraction (UED) which is currently being designed and would be built in the UK. It will have two beamlines, one for microscopy and one for diffraction, which share a common electron gun. The diffraction beamline will operate with a kinetic energy of 4 MeV meaning that both space charge and ballistic...
The EuPRAXIA@SPARC_LAB RF injector provides high brightness electron beams accelerated and longitudinally manipulated in the velocity bunching regime (VB). The RF injector consists of a SPARC_LAB like S-band RF Gun (2.856 GHz) followed by four S-band TW accelerating structures with an overall length of 12.3 m. The RF injector works with the so called comb configuration, foresees a 30pC witness...
Betatron radiation spectroscopy is a valuable diagnostic technique for studying the interaction between a beam and a plasma in plasma wakefield acceleration (PWFA) experiments. In this project, we investigate the effects of beam perturbations on the betatron radiation. We analyze how perturbations can result in hosing, a transverse instability that can degrade the quality of the beam. We also...
We present the first analytic theoretical model describing the chromatic transverse dynamics of an electron beam in a nonlinear plasma-based accelerator that can account for the evolution of the projected, longitudinal sliced, and energy sliced emittance. Beginning with a description of single particle motion, the evolution of the beam moments and centroid position for each slice is...
Ultra-short pulsed electron beam has a wide range of applications in accelerator-based X-ray sources, wakefield acceleration, ultrafast electron microscopy, etc. Using pump-probe technology, MeV ultrafast electron diffraction (MeV-UED) can reveal the ultrafast dynamic processes of matter changes at the atomic scale. Further improving its temporal resolution to few-fs or even sub-fs will open...
We present measurements of the slice energy spread of the electron beam using two methods. The first and more standard way consists in measuring the slice beam size of the electrons in a dispersive location. The second method is based on the optical klystron mechanism, where the radiation produced in undulator modules is enhanced with magnetic chicanes between the modules. In this approach,...
Measuring the fermion statistics of free electrons has been a considerable experimental challenge of fundamental interest for many years. The attempts up to now, such as by Tonomura, have remained inconclusive because of the limited temporal resolution of the available detectors. The fermion statistics experimentally show up as electron anti-bunching - i.e., as a changed coincidence rate on a...
Challenges for future accelerators include characterization of high current beams and the need for continual drift correction while delivering beams with non-trivial phase space correlations. Concomitantly, there is potential for Artificial Intelligence/Machine Learning to improve beam quality, increase delivery time to users and enable exotic beam configurations. Non-invasive diagnostics...
Particle driven plasma wakefield acceleration (PWFA) exploits the intense wakefields excited in a plasma by a high brightness driver beam in order to accelerate a trailing, properly delayed witness beam. Moreover, multi-pulse driver beams with suitable spacing resonantly excite the plasma which enhances the amplitude of the accelerating field. However, before the injection into the plasma...
Plasma photocathode injection in plasma wakefield acceleration (PWFA) has the potential to produce ultrahigh brightness beams with normalized emittance down to 10s of nm-rad and kA peak currents. Electron beams in PWFA may develop a large energy chirp due to the high accelerating gradient, which can be detrimental to beam quality preservation and prevent use in demanding applications such as...
The SEALab accelerator test facility is currently commissioning the superconducting radio-frequency photoelectron injector (SRF photoinjector), which has the potential to cover a wide range of beam parameters. With the ability to accelerate electron bunches from femtoseconds to picoseconds in length, with a charge range from femtocoulombs to nanocoulombs, the SRF photoinjector can produce beam...
We present simulation results of a scheme to generate high-power and short FEL pulses using an electron beam with irregularly spaced current peaks. Such an electron beam produces a train of short pulses with low power in the first undulator section. In the next sections, the electron beam is delayed in a way that only one of the short pulses is continuously amplified to a very high power. The...
