Extreme-light laser is a universal source providing a vast range of high energy radiations and particles along with the highest field, highest pressure, temperature and acceleration. It offers the possibility to shed light on some of the remaining unanswered questions in fundamental physics like the genesis of cosmic rays with energies in excess of 1020 eV or the loss of information in...
Successful applications of laser-plasma accelerators require stable electron beams. The drive laser plays a crucial role in the generation of such beams: even slight variations in laser pulse quality on target deform the shape of the plasma wake and thereby the fields inside the plasma cavity with direct impact on the generated electron phase space. All efforts to improve the laser performance...
The Central Laser Facility at the STFC Rutherford Appleton Laboratory in the UK is now building a new laser application centre. This £81.2 M facility will use STFC’s patented diode-pumped laser technology (DiPOLE) to drive plasma accelerators, producing novel particle and x-ray beams for imaging critical industrial components and biomedical systems. This application centre will build a unique...
We will review our recent research activities on high-repetition rate laser-wakefield acceleration. In a recent series of experiments, we have used millijoule near-single-cycle laser pulses of 3.5 fs duration at kHz repetition rate to accelerate electrons to 5 MeV energies. The single-cycle laser pulses were able to excite nonlinear plasma wakefields and accelerate electrons to MeV energies in...
Laser-accelerated particles (protons and electrons alike) feature very short duration (often below 1 ps) and high peak current (~ kA). These characteristics makes them suitable for depositing dose in living tissues over a timescale at the heterogeneous chemistry level, at peak doserates exceeding several $10^9$ Gy/min. The effect of fractionated dose deposition and ultra-high dose rate has...
In order to perform strong field physics experiments such as particle acceleration, laboratory astrophysics, high energy density physics, high-energy ultra-short pulses (PW peak power) are strongly required.
The generation of such pulses can be performed through the Optical Parametric Chirped Pulse Amplification (OPCPA) technique. OPCPA main advantages, respect to the CPA, are the high...
Laser wakefield accelerators (LWFA) feature unique electron bunch characteristics, namely micrometer beam size with duration ranging from a few fs to tens of fs. Precise knowledge of the longitudinal profile of such ultra-short electron bunches is essential for the design of future table-top x-ray light-sources.
Spectral measurements of broadband transition radiation from LWFA electron bunches...
Exploring new regimes, optimizing experimental setups, or quantifying sensitivity of final beam parameters on experimental parameters, represent current challenges for simulations of laser plasma accelerators. Time-to-solution and scalability are key parameters for codes to minimize turnaround times in order to scan e.g. tens of parameters such as the laser leading edge, resolve solid density...
We report on the status of the next generation DLA experiments at the UCLA Pegasus laboratory. These experiments, carried out in the framework of the ACHIP collaboration will use a newly commissioned 40 mJ laser system and take full advantage of the capabilities to manipulate nearly arbitrarily the phase and amplitude of a laser wave with liquid crystal phase mask technology. We show how...
We have installed an interaction chamber in the electron beam line of SwissFEL. Electrons with a particle energy of 3 GeV are focused into the sample, which can be aligned to electron and laser beam with a hexapod. The goal of this installation is to demonstrate laser-driven acceleration inside dielectric structures. We present here the layout of this chamber, as well as first measurements of...
The LUX laser-plasma accelerator, built in close collaboration of the University of Hamburg and DESY, is designed to provide plasma electron beams with enhanced stability as a driver for future compact light sources. After significant in-house development of the driving 200 TW ANGUS laser system, the
laser has reached an operational stability, that enabled us to repeatedly demonstrate 24-hour...
Charged particle radiotherapy is nowadays used in an increasing number of centres worldwide.
In particular, carbon ions have shown many advantages for the treatment of radioresistant tumours, thanks to their higher Linear Energy Transfer (LET) and Relative Biological Effectiveness (RBE).
The complexity of the conventional carbon therapy facilities has stimulated the investigation of...
Low-emittance ultra-relativistic electron beams delivered for next gener- ation of plasma wakefield acceleration (PWFA) experiments are expected to produce very high wakefields over very large distances when going through a plasma. Assessing electron beam dynamics under such fields will be of key importance to achieve the next milestones of the PWFA concept. Here we report on the use of the...
The hybrid L|PWFA acceleration scheme combines laser- (LWFA) with plasma-wakefield acceleration (PWFA) to provide an ultra-compact, high-brightness electron source. Recently, the acceleration of a witness bunch using this hybrid scheme was demonstrated at HZDR. In this talk, we present recent start-to-end simulations, that accompanied the experimental campaign, and provided fundamental...
Modelling the complex dynamics in plasma accelerators requires computationally demanding Particle-In-Cell codes. These codes self-consistently solve the electromagnetic particle interaction inside the plasma. We present the latest features of FBPIC - a highly efficient, multi-GPU Particle-In-Cell code. It features a quasi-3D geometry that greatly reduces the computational costs, a spectral...
A crucial parameter for the demonstration of a laser-plasma driven free-electron laser is the electron beam emittance and its stability. Here, we show energy resolved emittance measurements of ionisation-injected plasma electron beams performed with both a conventional quadrupole scan and measured from single-shots. We show that the initial phase-space properties obtained from both methods...
Laser-plasma acceleration promises to be a powerful technology for driving future compact light sources. The LUX laser-plasma accelerator is driven by the 200 TW ANGUS Ti:Sapphire laser system which has been designed aiming for long-term stability, enabling stable operation over many hours. Demonstrating this during several 24-hour runs, enough data for reliable statistics could be taken....
The quest to realize a particle accelerator on a chip has led to the emergence of dielectric laser accelerators (DLAs). DLAs have the capability of sustaining accelerating gradient in ~ GV/m using the grating-shaped dielectric microstructures. The geometry of these microstructures is one of the decisive features to affect the acceleration gradient and energy gain. Here we present an...
Laser WakeField Acceleration allows electron bunches with energy in the range of several tens to hundreds of MeV to be delivered by compact, table-top devices, thus holding the promise for a possible widespread deployment of such machines into medium scale clinical environments. This has spurred the study of the properties of the so-called very high energy electrons (VHEE) which could be...
Utilizing photonic nanostructures and ultra-short laser pulses, dielectric laser acceleration (DLA) provides a scheme for high gradient particle accelerators. In the past, this concept was limited by insufficient beam transport through longer structures and the inability to stage multiple structures without particle loss. The concept of alternating phase focusing (APF) provides a way to...
High peak power lasers have been succesfully used to accelerate particles, for example producing a 8 GeV record for electron acceleration with a PetaWatt laser. However laser repetition rate is quite limited, to 1 Hz maximum and this prevents use of lasers in applications requiring significantly higher repetition rate. To be able to build the next generation of laser-based machines such as...
The low emittance of electron bunches from laser wakefield accelerators (LWFAs) makes them attractive for compact FELs and colliders. Single-shot, direct, non-intercepting diagnostics of this emittance outside the LWFA are, however, needed. Here we present single-shot coherent transition radiation (CTR) imaging and interferometry data from electron bunches ~2 mm after emerging from a 300 MeV...
Particle-in-Cell (PIC) codes have proven to be a vital tool for studying the physics of plasma based accelerators. However, the enormous cost of a single full 3D simulation limits their applicability for extensive stability or parameter studies. Further, numerical errors from commonly used finite difference solvers can cause unphysical results. The quasi-cylindrical, pseudo-spectral code FBPIC...
There is increasing demand for high average, high peak power laser systems to drive laser wakefield plasma accelerators (LWFAs) at > kHz repetition rates. One promising route to these systems is the coherent combination of lower power laser systems and much attention has focused on fibre lasers as suitable candidates, in both filled and tiled aperture configurations. However, previous work has...
Recent progress in laser wakefield acceleration (LWFA) has demonstrated the generation of high peak current electron beams with improved shot to shot stability [1]. Using high-current electron beams from a LWFA as drivers of a beam-driven plasma wakefield accelerator (PWFA) has been proposed as a beam energy and brightness transformer [2], aiming to fulfill the demanding quality requirements...
Dielectric laser acceleration is a versatile scheme to accelerate and control electrons with femtosecond laser pulses in nanophotonic structures. We show recent results of the generation of a train of electron pulses with individual pulse durations as short as 270 +/- 80 attoseconds. We achieve these attosecond micro-bunch trains based on two subsequent dielectric laser interaction regions...
The ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) beamline has been recently installed at ELI-Beamlines in the Czech Republic. The main goal of ELIMAIA is to offer short ion bunches accelerated by lasers with high repetition rate to users from different fields (physics, biology, material science, medicine, chemistry, archaeology) and, at the same time, to demonstrate...
Smilei is an open-source particle-in-cell (PIC) simulation code. It is developed by a collaboration of scientific computing experts and plasma physicists for applications ranging from astrophysics to laser-plasma interactions. In order to address this large variety of scientific cases, Smilei gathers many different features in a single software suit and adopts flexible data structures and...
Novel optical, plasma based accelerators require high peak-power laser drivers at high repetition rate and kW-scale average power for their operation. Significant progress has been made in laser performance during the past decades, mainly concerning peak-power, now in the 10 PW range, well beyond what needed for driving laser-wakefied acceleration. Enhancement of other parameters, like...
The advent of ultra short high intensity lasers has paved the way to new and promising, yet challenging, areas of research in the laser-plasma interaction physics. The success of constructing petawatt femtosecond lasers, that helps designing future particle accelerators, intrinsically relies on the combination between experiments and massively parallel simulations. Hitherto, Particle-In-Cell...
The main direction proposed by the community in the field of laser-driven ion acceleration is to improve particle beam features in order to demonstrate reliable approaches to be used for multidisciplinary applications. The mission of the laser-driven ion target area at ELI-Beamlines (Extreme Light Infrastructure) in Czech Republic, called ELI-Multidisciplinary Applications of laser-Ion...
During laser solid interactions, the onset of Weibel instability can generate super strong magnetic field structures (up to several kT) at the surface and within the bulk of the solid targets. Weibel magnetic fields can be used to understand several physical events in astrophysics [1], laser driven inertial confinement fusion process [2] and gamma-ray generation [3].
Here we report on the...
DLA structures are five to six orders of magnitude smaller than conventional radio frequency accelerating structures. Precision of the microfabrication process will be crucial for the construction of a practical DLA device. In this study, finite-element method models are constructed for selected DLA structures to show what level of precision, in terms of a fraction of the driving wavelength,...
In order to validate the dielectric-based short-pulse wakefield Two Beam Accelerator concept on a relatively large scale without a significant budget increase, the High Energy Physics Division of Argonne National Laboratory plans to demonstrate a ~500-MeV module in the current Argonne Wakefield Accelerator facility within the next 5 years. A new high shunt impedance dielectric wakefield...
We performed experiments with the Petawatt beam of the Dresden laser acceleration source Draco to investigate the feasibility of controlled volumetric tumour irradiations with laser-accelerated protons. Therefore, a beamline of two pulsed solenoid magnets was implemented to efficiently capture and shape the beam, which was then analysed by a comprehensive suite of detectors (ionization...
Three dimensional Particle in Cell simulations of Laser Wakefield Acceleration require a considerable amount of resources but are necessary to have realistic predictions and to design future experiments. The planned experiments for the CILEX facility also include two stages of plasma acceleration, for a total plasma length of the order of centimiters. In this context, where traditional 3D...
Wakefield acceleration of electrons to energies in the GeV range has been performed with a multitude of methods e.g. laser driven, particle driven or by a combination of the two. The overall improvement of the stability in terms of energy, pointing and emittance marks the path from acceleration to an accelerator. The injection process hereby plays a central role.
Using few-cycle microscopy to...
Laser-plasma accelerators are promising candidates to drive a next generation of compact FELs. The LUX plasma accelerator, developed and operated in a collaboration of Hamburg University and DESY, recently demonstrated the generation of spontaneous undulator radiation from a laser-plasma electron beam. A future upgrade of the beamline, currently under commissioning, will include the cryogenic...
Here we report on beam quality optimization in a stable and robust nanocoulomb-class laser wakefield accelerator. The self-truncated ionization injection scheme enables precise control over the amount of injected charges up to 0.5 nC (FWHM) at a quasi-monoenergetic peak. Stable operation of the accelerator is achieved, enabling us to study key parameters in statistical data-sets. Employing the...
Proof-of-concept experiments in AWAKE Run 1 have demonstrated electron acceleration in a proton-driven wakefield$^1$. A high momentum proton beam can drive a wakefield over long distances and overcome some limitations of lepton-driven schemes, which are susceptible to energy depletion. AWAKE Run 2 aims to preserve the beam quality of an injected electron beam throughout acceleration, and...
In an initially uniform plasma, the lifetime of a weakly nonlinear plasma wave excited by a short driver is limited by the ion dynamics. The wakefield contains a slowly varying radial component, which results in a perturbation of the ion density profile and consequent destruction of the plasma wave. We suggest a novel method of quantitative characterization of the plasma wave lifetime in...
We propose a method to generate isolated relativistic terahertz (THz) pulses using a high-power laser irradiating a mirco-plasma-waveguide (MPW). When the laser pulse enters the MPW, high charge electron bunches are produced and accelerated to 100 MeV by the transverse magnetic modes. A substantial part of the electron energy is transferred to THz emission through coherent diffraction...
The interaction of both linearly and circularly polarized laser pulses with high-Z solid targets is investigated through PIC simulations, using the SMILEI particle-in-cell code that features a thoroughly benchmarked relativistic collisional module. Even though circular polarization (CP) mitigates collisionless hot-electron acceleration processes compared with linear polarization, inverse...
AWAKE (the Advanced WAKefield Experiment at CERN) aimed to demonstrate the first controllable self-modulation of a long ultrarelativistic proton beam in plasma and acceleration of electrons in the wakefield from the resulting train of microbunches. The experiment fully completed these tasks in 2017 and 2018. Three main diagnostics: OTR, CTR screens and imaging stations measured longitudinal...
Spontaneous undulator radiation emission, after the COXINEL line using a Laser Plasma acceleration (LPA) source, has been observed. The line enables to manipulate the electron beam phase space such as emittance, dispersion and energy spread along a 10 m long transport. The large divergence is handled at a very early stage to mitigate the chromatic emittance, using high gradient permanent...
The ARES (Accelerator Research experiment at SINBAD) Linac at SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility at DESY aims to produce high brightness ultrashort electron bunches (sub fs to few fs) at around 100 MeV, suitable for injection into novel accelerators e.g. dielectric Laser acceleration (DLA) and Laser Driven Wakefield acceleration (LWFA). The external...
The proton driven plasma wakefield acceleration experiment AWAKE at CERN demonstrated basic electron capturing and acceleration using a rather long electron bunch spreading out over several plasma wavelengths. For the second phase of the experiment, the aim is to inject a short electron bunch with appropriate emittance and charge to achieve full capture and emittance preservation of the...
We present the work on development of the millimeter wavelength accelerating structure. It consists of cylindrical cavities with the operating frequency of 96 GHz. The structure will be excited by the picosecond electron beam from the photocathode RF gun. In order to define exact both structure and exciting beam parameters, analytical estimations and simulations of the structure excitation...
We investigate possibilities that dielectric accelerator structures, excited by fs lasers, offer for X-ray free electron lasers. The present scheme uses a dielectric laser accelerator to modulate an electron beam to create a pulse train of short (100 as) X-ray pulses in the undulators of SwissFEL. The implementation of such a scheme would be enabled by using the experimental chamber installed...
THz radiation is the most important portion of the electromagnetic spectrum in terms of multi disciplinary use in basic science and technology. Beyond the numerous applications, a great interest is its potential for future, compact linear accelerators. Conventional high brightness radio-frequency accelerating structures operate with 30-50 MV/m gradients; terahertz-driven accelerating...
A central challenge for next generation accelerator facilities (Linear Colliders and FELs) is to operate at high wall plug efficiency. However, the fraction of energy that can be transfer from the accelerating fields to the charge particle bunch is limited by beam loading. This is true for advanced acceleration schemes, Structure Wakefield Acceleration (SWFA), Plasma Wakefield Acceleration...
Laser-plasma accelerators [1] may become a compact, affordable and powerful alternative for delivering relativistic electron beams of relevance for medical treatment and imaging [2] to fundamental researches related to high-energy physics [3]. However, a main obstacle for this approach to fulfill its promise, for some of the applications, is the beam quality with large divergence and emittance...
Plasma-wakefield acceleration is a promising technique for future accelerators in that it can deliver significantly higher (factor of ~100-1000) accelerating fields compared to conventional RF accelerators, and also be used to generate beams of ultralow (≲0.1 mm mrad) normalized emittance. However, many challenges remain to be overcome, one of which is the hose instability, where a witness...
High intensity ultra-short laser pulses interacting with thin solid targets are able to produce energetic proton and ion beams by means of extremely large accelerating fields. The process starts with the emission of fast electrons that, escaping the target, set an electrostatic potential, responsible for the subsequent acceleration of heavier particles. The characterization of such electrons...
The transverse gradient undulator (TGU) scheme is a viable option to compensate for the challenging properties of the LWFA electron beam, in terms of beam divergence and energy spread, to enable FELs amplification. At Karlsruhe Institute of Technology (KIT, Germany), a 40-period superconducting TGU has been designed and built. In this contribution, we report on the first test operation of...
Operation of modern particle accelerators require high brightness beam and sensitive diagnostic system in order to monitories and characterize the beam during the acceleration and transport.
A turn-key high level software has been designed to fully characterise the 6D beam phase space and the trajectory in order to help operator during commissioning with an easily scalable suite for any high...
Ultra high-gradient accelerating structures are needed for the next generation of compact light sources. In the framework of the Compact Light XLS project, we are studying a high harmonic traveling-wave accelerating structure operating at a frequency of 35.982 GHz, in order to linearize the longitudinal space phase. In this paper, we propose a new analytical approach for the estimation of the...
Recent high RF power experiments show that hard structures, fabricated without high-temperature processes, achieve a better high gradient performance in terms of accelerating gradients. Two three-cell standing-wave accelerating structures, designed to operate in the pi-mode at 11.424 GHz, have been successfully built and cold tested. In order to guarantee a vacuum envelope and mechanically...
The design, installation and operation of AWAKE (run1) infrastructure and equipment took place from 2013 until 2019. This was the first PWA facility of this large scale, which influences many choices regarding infrastructure and design. Lessons learnt from designing, installing and running the AWAKE facility's infrastructure are shown, and are extrapolated to show how they could be implemented...
The two-photon (linear) Breit-Wheeler mechanism is the simplest process through which light can be converted into matter. Despite its simplicity only the multi-photon (non-linear) process has yet been measured definitively. The linear process remains elusive as the production threshold of $2 m_e c^2 \approx 1\,\mathrm{MeV}$ is comparatively high for two photons and requires two bright sources...
The plasma source during AWAKE run 1 consists of a 10 meter long rubidium vapor source ionized by a laser pulse from a 4 TW titanium:sapphire system focused to a mm spot size. Because the plasma column geometry can have an effect on the formation of the proton driven plasma wakefields when the plasma skin depth approaches the size of the plasma column, the geometry needs to be understood. ...
The bandwidth of Thomson sources are determined, amongst others, by the bandwidth- and the length of the laser pulse and the energy spread of the electrons. Here we show that if the electron bunch's energy spread is correlated, that the emitted radiation's bandwidth can be decreased by chirping the laser pulse. The instantaneous laser frequency is given by
\begin{equation}
\frac{\partial...
Advanced accelerator concepts usually address linear acceleration schemes. Storage rings, however, are often superior to linear machines regarding repetition rate, stability and efficiency. The radiative energy loss per turn in an electron storage ring is compensated by radiofrequency resonators with a wavelength of the order of 1 meter, which corresponds to the spacing between consecutive...
Accelerators based on LWFA are of great interest for a new generation of compact machines. Choosing external injection of the probe beam in LWFA has the advantage that a well-controlled and fully characterized beam can be injected. The matching of electron bunches into an accelerating wakefield makes high demands on the electron beam quality. The electron beam size must be extremely small to...
With the help of 3D numerical simulations, we demonstrate the possibility to accelerate a high number of electrons (tens of nC) to tens or even hundreds of MeVs using relativistic laser pulses ($\sim 10^{22}$ W/cm${}^2$) grazingly incident on solid targets. It is shown that in this regime, the electrons are accelerated mostly efficiently at some distance from the target, and the key factor in...
Guiding high-intensity laser pulses over long distances through low density plasma ($\sim 1 \times 10^{17} \ \rm{cm^{-3}}$) is one of the key challenges to create laser plasma accelerators for high energy physics and industrial applications. We recently demonstrated that low density channels suitable for such guiding could be generated by the hydrodynamic expansion of optical-field-ionised...
Intensities of the Purcell-Smith radiation from DLA-compatible grating and pillar structures are calculated numerically using the finite-element method. Geometric parameters are scanned in search of resonant radiation enhancement [1].
[1] Yi Yang et al, Maximal spontaneous photon emission and energy loss from free electrons, Nature Physics 14, 894–899 (2018)
Resonant wakefield excitation in two-beam electron-positron collider by a long train of relativistic electron bunches is difficult because it is difficult to support homogeneous and stationary plasma in experiment. In [1-5] the mechanism has been found of resonant plasma wakefield excitation by a nonresonant train of short electron bunches. The frequency synchronization results by defocusing...
Dielectric laser driven particle acceleration (DLA) is one of the candidates for novel high-gradient technologies to reduce the footprint of large scale particle acceleration facilities. On the other hand these devices can be used to interact with the particle beams of state-of-the-art photon science machines, especially with FELs, to manipulate the longitudinal phase space in a compact and...
Charged particle acceleration using solid-state nanostructures is attracting new attention in recent years as a method of achieving ultra-high acceleration gradients, in principle of up to ~1 TV/m [1]. The use of carbon nanotubes (CNT) has the potential to enable limitations of using natural crystals, e.g. in channeling aperture and thermo-mechanical robustness, to be overcome. In this work,...
The AWAKE project aims to accelerate electrons through proton driven plasma wakefields. The transverse extend of the wakefields is given by the plasma density and is of the order of one millimeter. With external injection, the exact position of the electron bunch in the wakefields determines the acceleration energy and the captured charge. The pointing jitter of the electron beam is of the...
The Relativistic Electron Gun for Atomic Exploration (REGAE) is a small accelerator located at DESY in Hamburg. The machine was designed and built to provide ultra-short electron bunches on the order of 10 fs, used as probe pulses for time-resolved electron diffraction experiments. Recently, REGAE has been upgraded and connected to the ANGUS high-power laser system. With this new...
The AWAKE experiment at CERN [1] recently demonstrated the world's first acceleration of electrons in a proton-driven plasma wakefield accelerator [2]. Such accelerators show great promise for a new generation of linear e-p colliders using GV/m accelerating fields. Effectively driving a wakefield in AWAKE requires 100-fold self-modulation of the 12 cm Super Proton Synchrotron (SPS) proton beam...
In the AWAKE experiment, a train of micro-bunches resonantly drives high-gradient wakefields in which electrons have been accelerated up to 2 GeV. The micro-bunches result from the 400 GeV CERN SPS proton beam self-modulating in a pre-formed plasma through a self-modulation (SM) process. Initial transverse wakefields focus and defocus the bunch at the scale of the plasma wavelength. When not...
Precise control over the longitudinal phase space (LPS) of electron bunches in accelerators can be of interest for example for bunch-compression, where in the ideal case a completely linear LPS is needed to reach maximum compression. We present a compact and completely passive way to alter the LPS of a given electron bunch in a way that arbitrary, pre-defined shapes can be achieved. The...
In modern experiments on plasma wakefield acceleration, relativistic electron bunches (or laser pulses) excite plasma wakes with energy density comparable to the rest energy density of plasma electrons. Breaking of such wake in a radially bounded plasma is followed by its energy redistribution between hot electrons, electric fields and radial ion motion and leads to plasma column expansion via...
Controlling the injection and trapping of electrons into plasma wakefields is key to improving the beam quality and reproducibility of accelerated beams. Injecting electrons into a narrow $(σ_r ≪ λ_p)$ transverse region of the wakefield is fundamental to achieving low beam emittance. Brief $(T_{inj} ≪ L_{acc} / c)$ injection into a short $(σ_z ≪ λ_p)$ longitudinal region yields low energy...
The recent installation of a double plasma mirror in the experimental area of the Lund High-Power Laser facility now allows the study of laser-plasma interactions with stable, pre-pulse and pedestal-free laser pulses. Such a regime of high contrast (10e-8 at 1 ps before the pulse peak) ensures that targets with nm-scale thicknesses can be irradiated without forming a pre-plasma at their...
The Advanced Wakefield Experiment AWAKE develops the first plasma wakefield accelerator with a high-energy proton bunch as driver [1]. The 400 GeV bunch from CERN SPS propagates through a 10 m long rubidium plasma, ionized by a 4 TW laser pulse co-propagating with the proton bunch. The relativistic ionization front seeds a self-modulation process. The seeded self-modulation (SSM) transforms...
To overcome dephasing and pulse depletion while maintaining a high average accelerating gradient, staging multiple 10 GeV level Laser Wakefield Accelerators has been proposed. To minimise the total length of a staged accelerator laser beams must be introduced at an angle to the beamline. A convenient solution to reflect the intense laser pulse on to the beamline is to use a thin, moveable tape...
Laser wakefield accelerators are highly tuneable sources of radiation with a correspondingly varied number of potential applications, including ultrafast imaging, high energy physics and radiation therapy. The Scottish Centre for the Application of Plasma-based Accelerators (SCAPA) is a facility designed to allow proof of concept investigations towards the realisation of next generation laser...
Beam driven wakefield acceleration in plasmas is one of the most promising candidates for novel, compact accelerators. Several aspects of this acceleration scheme can be optimised by transverse and longitudinal shaping of the bunch that drives the wake and of the bunch that is accelerated in the wake. The ratio between acceleration of the witness and deceleration of the driver, the transformer...
In a variety of electron accelerator based light sources relativistic electron bunches propagate through an undulator and emit intense narrow band radiation. Here, we propose new types of short period undulators, which are based on the alternating electromagnetic field pattern of THz-driven surface plasmon polaritons in sub-wavelength structures. Analytic undulator models are derived and...
Additive manufacturing techniques such as stereolithography can simplify prototyping of novel accelerator components.
A precise knowledge of the permittivity of the material is essential to the design of dielectric accelerating structures.
We present here measurements of the permittivity of commercially available polymers, as well as tests for vacuum compatibility.
Dielectric laser acceleration (DLA) is one of the advanced concepts for more compact accelerators. DLA gratings have apertures within the range of optical wavelengths. Wakefields limit the beam intensities of relativistic electrons required for possible applications. Particle tracking is needed to study the intensity limitations due to nonlinear laser fields in combination with wakefields. For...
Using newly available compact laser technology [1] one can produce 100 PW-class laser pulses with a single-cycle duration on the femtosecond timescale. With a fs intense laser one can produce a coherent X-ray pulse that is also compressed, well into the hard X-ray regime. Prof. T.Tajima suggested [2, 3] utilizing these coherent X-rays to drive the acceleration of particles. Such X-rays are...
Plasma-based waveguides are currently employed for laser wakefield acceleration to extend the focal region
of laser beams. Indeed, a parabolic transverse plasma density profile can be formed in a dielectric capillary as a thermal consequence of a gas discharge.
In this work, we report on a new ray tracing model, based on the Zemax software, able to simulate
the envelope of ...
Performing high intensity laser-plasma interactions at high repetition rate (>1 Hz) allows for a fundamental change in the way these phenomena are explored. The large quantity of data collected allows for statistical modelling and fine scans of parameter space. In addition, multi-dimensional optimisation becomes possible, which is of great importance when individual parameters are coupled in a...
During the last years, Research and Development (R&D) of X-band technology for normal conducting particle accelerators has witnessed a tremendous growth. The driving force behind this has been the interest of the Scientific Community in the construction of a Multi-TeV Linear Collider at a reasonable size and costs. Accelerating gradients three to four times larger than those in operational...
The use of particle accelerators in radiotherapy has significantly changed therapeutic outcomes for many types of solid tumours. While protons are well known for sparing normal tissues surrounding the tumour and increasing the overall therapeutic index, carbon ions have been suggested to be particularly effective in the treatment of radioresistant hypoxic tumour due to the higher Relative...
Short wavelength acceleration techniques, e.g. in the THz range, promise high field gradients but suffer from severe phase slippage at non-relativistic particle energies due to the small normalized vector potential that can be realized with these techniques. By combining a compact, amplifier driven S-Band rf gun with an adiabatically tapered dielectric-lined waveguide THz accelerator...
Matched beam loading in laser wakefield acceleration (LWFA) flattens the accelerating electric field along the bunch and leads to the minimization of energy spread at high bunch charges. By using the self-truncated ionization injection scheme for controlling the injected charge, we demonstrate that minimal energy spread coincides with a reduction of the normalized beam divergence.
Betatron...
One of the most challenging application of plasma accelerators is the development of a plasma-based collider for high-energy physics studies. Fast and accurate simulation tools are essential to study the physics toward configurations that enable the production and acceleration of very small beams with low energy spread and emittance preservation over long distances, as required for a collider....
Vorpal was designed nearly 20 years ago, with its first applications roughly four years later, as a highly performant, flexible plasma simulation code. Using object oriented methods, Vorpal was designed to allow runtime selection from multiple field solvers, particle dynamics, and reactions. It has been successful in modeling for many areas of accelerator physics, including RF structures,...
High brightness electron beam is required by several applications in the accelerator physics field, e.g., Plasma Wake Field Acceleration (PWFA) experiments and Free electron Laser (FEL) radiation sources. In order to have a high brightness beam, that means a high current and a low emittance beam, it is important to study, among other things, the beam’s non uniformity due to the non perfect...
The plasma wakefield accelerator has demonstrated high-gradient, high-efficiency acceleration of an electron beam. Numerical simulation results backed by theory indicate that also emittance preservation at the level needed for a high luminosity collider may be achievable in the blow out regime. Electron linacs based on plasma wakefield acceleration is therefore a promising technology for a...
The extraction of a laser driven electron beam from the plasma accelerating structure plays an important role in determining the final beam quality. If properly matched, the extraction mechanism can mitigate beam degradation and minimize emittance growth. Controlling this process poses a challenge for multi-stage acceleration schemes aiming to generate TeV level beams for particle collider...
The Free Electron Laser (FEL) application of Laser plasma acceleration (LPA) requires the handling of energy spread and divergence. The COXINEL (ERC340015) manipulation line designed and built at SOLEIL [1, 2] consists of variable permanent magnet quadrupoles [3] for divergence mitigation and a decompression chicane for energy sorting, enabling FEL amplification. The COXINEL line, installed at...
QuickPIC is a 3D parallel quasi-static PIC code for efficiently simulating the plasma based accelerator (PBA). It is developed based on the framework UPIC. QuickPIC has been widely used and played an important role in studying PBA problems. In 2017, we made QuickPIC an open source code on Github (https://github.com/UCLA-Plasma-Simulation-Group/QuickPIC-OpenSource). The open source QuickPIC was...
The Gamma Factory (GF) proposal is based on the use of partially stripped ion (PSI) beams as drivers of a novel high intensity and high energy (0.1-400 MeV) photon source. We describe the GF concept, the results of the initial beam tests carried out in 2017-2018 at the SPS and LHC with partially stripped xenon and lead beams and we discuss the preparation for proof-of-principle experiment at...
If a charged particle bunch propagates near a plasma-vacuum boundary, it experiences an additional force caused by the boundary. Taking account of this force may be important for witness injection into plasma wakefields or in case of beam and plasma misalignments. For the linearly responding plasma and short and narrow bunch, this force is calculated analytically and approximated by elementary...
Plasma wakefield accelerators (PWFAs) are routinely accelerating electron beams to multi-GeV energies in cm-scale acceleration distances. This emerging technology is a promising approach towards ultra-compact X-ray free-electron lasers (XFELs). However, producing high-quality electron beams in plasma-based accelerators is still a challenging task. The R&D efforts within the community now...
The Argonne Wakefield Accelerator (AWA) group develops the Structure Wakefield Acceleration (SWFA) concept for a future multi-TeV electron-positron linear collider. The main SWFA approach being considered at the AWA is short-pulse (~25 nsec) two-beam accelerator (TBA). An important milestone for this technology will be to demonstrate substantial energy gain using the TBA scheme. To this end,...
Merging laser beams can be used to replenish the driver in a seamless multistage laser-plasma accelerator, and can enhance the X-ray emission produced by betatron electron oscillations. We experimentally demonstrate merging of two laser wakefields in plasma. A 150 TW peak-power laser beam is split in two halves which are focused at a small angle in a gas. Each laser pulse drives a plasma...
Focusing of electron and positron beams in collider is important [1-7]. The focusing mechanism in the plasma, in which all electron bunches are focused identically, has been proposed [5-7]. This lens is researched by simulation by lcode [8] in this paper for short positron bunches. It is shown that there are two lenses. It is necessary that in one case the length of 1st bunch should be equal...
Next generation accelerators demand sophisticated beam sources to produce ultra-low emittances with large gradients. The subsequent beamline optics are equally critical to transporting these beams between accelerating stages or to interaction points. Capillary discharge plasmas may address each of these challenges. Capillaries have been demonstrated as sources capable of increasing the peak...
The Plasma Lens Experiment at CERN is an experiment in active plasma lensing. It consists of a gas-filled sapphire capillary connected to a set of compact Marx banks, which breaks down the gas and drives a large current pulse through it. This generates a magnetic field, which is probed using the CLEAR electron beam and measured using various screens and magnetic elements behind the lens. We...
The accelerator R&D facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments in the fields of production of ultrashort electron bunches and test of advanced high gradient acceleration concepts.
The SINBAD-ARES (Accelerator Research Experiment at SINBAD) linac has been designed to allow the production of high brightness ultrashort electron...
The ELI Attosecond Light Pulse Source (ELI-ALPS) facility is the Hungarian pillar of the Extreme Light Infrastructure (ELI) project aimed at high-repetition rate, ultrafast science driven by ultrashort few-cycle laser pulses. ELI-ALPS aims to provide ultrashort light pulses from the THz to the x-ray regime as well as high-energy particle sources, all at high repetition rates for developers and...
Being promising alternatives to conventional accelerators and for application to high-energy physics also linear colliders, it is crucial for plasma accelerators to accelerate positrons, which is much more challenging than electron acceleration that most current researches focus on.
Plasma electron motion is one main source of beam quality degradation for positron acceleration in...
Future beam-driven plasma wakefield accelerator (PWFA) experiments at the Facility for Advanced Accelerator Experimental Tests (FACET-II) will require several detectors monitoring a multitude of plasma and electron bunch parameters. We present simulations demonstrating the ability of an electro-optic sampling beam position monitor (EOS-BPM) to analyze the femtosecond electron bunches that will...
A simplified model describing the PWFA transverse instability in the form of a wake function parameterized only with an effective cavity aperture radius $a$ is benchmarked against QuickPIC simulations. This wake function implies a $1/a^4$ scaling of the transverse wakefields, which indicates transverse intra-beam wakefields typically several orders of magnitude higher than in conventional...
Laser-driven electrostatic shocks have shown the potential to accelerate ions to very high energy with low energy spread and divergence and thus, they constitute a very promising ion acceleration mechanism [1,2,3]. Leveraging multi-dimensional realistic particle-in-cell simulations, this work explores how intense shocks can be excited in near-critical and underdense plasma targets. The...
We provide an overview of three areas of our programme which seek to address the challenge of realizing controlled laser wakefield accelerators (LWFAs) operating at kilohertz repetition rates. Driving plasma accelerators with trains of laser pulses offers the potential to use laser systems capable of multi-kilohertz pulse repetition rate with high wall-plug efficiency. We describe a...
Plans for a laser-ionized, beam-driven plasma wakefield accelerator at SLAC’s FACET-II facility are presented. The plasma source is formed by laser ionization of a volume of uniform density gas, and the plasma density profile is therefore determined by the focal pattern of the laser. This offers the advantage of a tunable density profile that can accommodate entrance and exit ramps suitable...
The major challenges of compact proton sources driven by an ultrashort high-intensity laser are currently to establish precise control over proton beam parameters and shot-to-shot stability. Shooting ultrathin targets has shown to yield higher proton energies, which became recently accessible due to temporal laser pulse shape control using plasma-mirror techniques. We find that the intensity...
In recent studies on LWFA staging and external injection-acceleration in PWFA only a very small fraction (from below 0.1% to few percent) of the injected charge (the coupling efficiency) was accelerated. For future colliders where beam energy will need to be boosted using multiple stages, the coupling efficiency per stage must approach 100%. Here we report the first demonstration of external...
Dielectric laser acceleration has made tremendous progress. We will give an overview of recent results, most of them obtained in the Gordon and Betty Moore Foundation-funded Accelerator on a Chip International Program, ACHIP. Highlight results include: acceleration gradients of around 1 GeV/m; the generation of electron pulse trains with attosecond bunchlet duration via optical near field or...
For the past two decades, the interaction of ultra-intense lasers with over-critical plasma has been motivated by acceleration of proton/ions for radiobiological applications. Despite some progress, the realization of a stable high-charge narrow-energy-spread protons of hundreds MeV remains a challenge. One promising scheme is the “light sail” acceleration, where laser pressure directly pushes...
The range of potential applications of compact laser-plasma ion sources motivates the development of new acceleration schemes to increase achievable ion energies and conversion efficiencies. Whilst the evolving nature of laser-plasma interactions can limit the effectiveness of individual acceleration mechanisms, it can also enable the development of hybrid schemes, allowing additional degrees...
GeV ($\gamma_e$ > 2000) electron bunches from petawatt-laser-driven plasma accelerators can be converted to tunable, narrowband or to broadband continuum $\gamma$-ray ($h\nu$ > 10 MeV) pulses by Thomson backscattering (TBS) or bremsstrahlung, respectively. Inserting a plasma mirror (PM) near the accelerator exit converts electrons to $\gamma$-rays compactly and inexpensively [1], in a...
Electron beam driven wakefield acceleration has been the main focus of research at AWA for many years, using high charge electron bunches (1 to 100 nC) for both Structure Wakefield Acceleration (SWFA) and Plasma Wakefield Acceleration (PWFA). We will present recent experimental results obtained with several types of X-band structures: metallic, dielectric loaded, photonic band gap (PBG), and...
Pre-plasma dynamics on the front side of a target foil in a laser-ion-acceleration process like Target-Normal-Sheath-Acceleration (TNSA) substantially influences the dynamics of the actual Debye-sheath formation and therefore eventually ion yield or ion energies. Acceleration dynamics on sub-picosecond timescales in the laser field are extremely challenging to probe experimentally. Therefore,...
First dielectric wakefield acceleration (DWA) experiments have been conducted on CLARA/VELA test facility at Daresbury Laboratory, UK. The DWA structure was of planar geometry with variable gap and dielectric thicknesses ranging from 0.025 to 0.2mm. The facility, in its current state, provided electron bunches with up to 100pC bunch charge, variable 0.2-2.0ps bunch lengths at the beam energy...
The AWAKE Experiment at CERN relies on the Seeded Self-Modulation (SSM) process, which transversely modulates the charge density of the SPS proton bunch and turns it into a train of micro-bunches. While the SSM process is axi-symmetric, the hosing instability (HI) is non-axi-symmetric and can grow from bunch or plasma axial asymmetries. As the growth rates of the Self-Modulation Instability...
High-intensity short-pulse lasers in the Petawatt regime offer the possibility to study new compact accelerator schemes by utilizing high-density targets for the generation of energetic ion beams. The optimization of the acceleration process demands comprehensive exploration of the plasma dynamics involved, for example via optical probing. In particular, experiments using low density cryogenic...
X-Ray fluorescence imaging (XFI) is a promising, new imaging method for in vivo localisation of low amounts of functionalised gold- nanoparticles (GNPs), enabling early cancer diagnostics and pharma- cokinetic tracking studies. At the moment, XFI is not applicable for human-scales, since the modality suffers from an intrinsic background, mainly caused by multiple Compton scattering processes....
Inverse Compton Scattering is one of the best ways to generate mono-energetic gamma rays. After Tsinghu Thomson Scattering X-ray source – TTX has been developed and used as an experiment tool for advanced x-ray imaging and other applications, XGLS with the gamma ray energy of 3MeV is now under commissioning. In this paper, we will mainly descript the very compact gamma ray source with photon...
A continuously tunable THz source driven by wakefields in a dielectric lined waveguide (DLW) has been experimentally demonstrated at the CLARA/VELA test facility at Daresbury Laboratory, UK. The source was tuned across the range 0.55 – 0.95 THz with a bandwidth of <50 GHz. The DLW was a planar structure with 25 um quartz dielectric layers and an aperture variable from 0.15 mm to 1.1 mm....
We report on the first experimental demonstration of radially symmetric focusing of laser-accelerated proton beams with an active plasma lens which provides tunable field gradients of the order of kT/m. MeV level proton beams generated from micrometer solid density targets interacting with a relativistically intense laser were used to examine the focusability and robustness of this new...
The attainable transformer ratio in plasma accelerators is limited by instabilities. Using three-dimensional particle-in-cell simulations, we demonstrate that these can be controlled using a hollow plasma channel with a coaxial plasma filament. The driver scatters electrons from the filament, and the slow pinch of the ions leads to a strong chirp of the effective betatron frequency, preventing...
Fundamental improvements of the quality, and stability of the electron output of plasma wakefield accelerators are required to realize key applications such as hard X-ray FELs and lepton colliders [1]. Here we report on the first realization of a plasma photocathode [2], in which a spatiotemporally synchronized laser beam is used to release tunnel-ionized electrons inside an electron beam...
The results of theoretical, numerical and experimental studies of THz laminated structures for particle acceleration are presented. The two-layer metallic and metal-dielectric structures are considered. The analytical presentations for longitudinal impedance and wake potential are given. The resonant properties of the synchronous TM01 fundamental mode are discussed and the conditions for the...
The transport and acceleration of positron beams is a crucial challenge on the path towards plasma-based particle colliders. We propose a scheme that allows for the simultaneous acceleration and transport of positron beams in plasma wakefield accelerators. A finite-radius plasma column is employed, leading to a reduction of the restoring force acting upon the plasma electrons forming the...
The interaction of ultra-intense high power lasers with solid state targets have been largely studying for twenty years as future compact proton and ion source. Indeed, the huge potential established on the target surface by the escaping electrons provides accelerating gradients of ~TV/m. This process, called TNSA, involves a large number of phenomena and is very difficult to study because of...
LWFA electron beams have evolved from their rather random performance of the early days to a well-controlled, tunable electron source able to serve real-world applications. The key ingredient for this evolution was the realization of various controlled injection schemes. Here we show that by combination of shock-front and colliding pulse injection it is possible to generate two independently...
The generation of polarized particle beams still relies on conventional particle accelerators, which are typically very large in scale and budget. Concepts based on laser-driven wake-field acceleration have strongly been promoted during the last decades. Despite many advances in the understanding of fundamental physical phenomena, one largely unexplored issue is how the particle spins are...
The Horizon2020-funded project EuPRAXIA is a conceptual design study aiming to develop a multi-GeV electron accelerator test facility based on plasma acceleration. With particular emphasis on compactness and cost-effectiveness, the project focuses on achieving high beam quality, stability and robustness, unprecedented for plasma accelerators and essential for their development towards user...
Hollow plasma channels are promising candidates for the acceleration of electron and positron beams as the transverse forces are nearly vanishing inside the hollow channel. The acceleration is effective as long as the accelerated bunches are perfectly cylindrically symmetric and injected on the axis of the hollow channel structure. Furthermore, the accelerating fields can also be nearly...
Recently, we proposed to use building blocks of THz metamaterials for streaking of ultrashort electron bunches. Such building blocks allow for a precise control of the electric and magnetic near-field distribution in a volume that is defined by the geometry of the structure. THz radiation with wavelengths on the order of a hundred micron is well matched to the transverse and longitudinal size...
Here we present the first demonstration of THz-driven acceleration of a fully relativistic electron beams. The experiments were carried out with the 35MeV bunches of the CLARA research facility at Daresbury Laboratory. The electrons were injected into a dielectric-lined waveguide simultaneously with a quasi-monochromatic laser-generated THz pulse with a longitudinal electric field containing...
EuPRAXIA is the first European project that develops a dedicated accelerator research infrastructure based on novel plasma concepts and laser technology. The aim is to construct electron accelerators with beam energy of 1 to 5 GeV, a significantly improved beam quality and demonstrated benefit in size and cost when compared to RF technology. EuPRAXIA accelerators will enable versatile...
Full 3D modeling of plasma-based accelerators using particle-in-cell (PIC) simulations is very computationally demanding. The use of a reduced model such as the ponderomotive guiding center algorithm (PGC) [1] allows us to bridge the large-scale disparity between the shortest (laser) wavelengths, which is in µm range, and the acceleration distance, which can exceed the meter range. Here, we...
The demonstration of a free-electron laser presents one of today’s main challenges in the field of plasma acceleration. Driving the FEL process with laser-plasma accelerated electron beams requires low transverse emittances and high spectral charge densities. Here we present our recent progress on the generation of high-quality electron beams at the LUX beamline. Few-percent relative energy...
This presentation will review the status of ion acceleration at the BELLA petawatt (PW) facility with a large laser spot (f\65) and give an outlook on science enabled by a short-focal length (f\2.5) laser beamline, currently under construction.
Proton beams from the long-focal length beam line exhibit a strongly reduced divergence and increased ion numbers and are hence, ideally suited for...
A hybrid concept for an Inverse Compton Scattering (ICS) based compact ultrafast X-ray pulse source, relying on the combination of a conventional S-band electron gun with a dielectric-loaded waveguide driven by a multicycle THz pulse (THz linac), is under investigation by the authors. The target of this hybrid concept is to generate pC-class ultrashort electron bunches (≤ 1 fs rms), at...
We present the conceptual design of a new, advanced radiation source facility called MariX (Multi-disciplinary Advanced Research Infrastructure for the generation and application of X-rays). The facility has been conceived, following a scientific case delineated by users of FELs and Light Sources, for delivering fs-scale, high repetition rate, X-ray pulses for time-resolved fine analysis of...
Laser wakefield accelerators (LWFAs) using self- or ionisation-injection techniques have been demonstrated to produce GeV electron beams, but typically suffer from large energy spreads when operating in this regime. One promising alternative scheme is shock injection, where abrupt changes in the local density of a LWFA gas target can induce the injection of electrons into the wakefield. This...
In Laser WakeField Acceleration, when relevant scale lengths of the laser envelope and of the plasma waves are well separated from the wavelength of the laser fast oscillating component, the time-averaged particles trajectories can be computed by means of a set of more efficient, properly modified equations of motion [1,2]. Besides, in regimes well described by the Lorentz-Maxwell fluid...
High voltage sources are used in a variety of applications including X-ray tubes, electron microscopes and particle accelerators. One of the most common methods of high voltage generation is the Full-Wave Cockcroft-Walton voltage multiplier (FWCW), where each stage consists of three capacitors and four diodes. The aim of this work is to introduce a circuit design that provides a high voltage...
Relativistic, high intensity and small emittance electron bunches are the basis of linear collider and FEL projects. With this talk, our interest focused on wakefields generated by using dielectric based structures. We consider Dielectric Disk Accelerating (DDA) and other dielectric structure designs. The electrical properties of low loss ceramic, fused silica and diamond like materials will...
Plasma beam dumps use the large decelerating wakefields sustained by plasmas to achieve compact deceleration of spent beams. Besides the higher efficacy to absorb beam energy, plasma beam dumps are also safer if compared to conventional beam dumps. This is due to the lower production of radioactivation hazards in the low-density plasma medium. In this work, existing analytical models to...
Utilizing photonic nanostructures and ultra-short laser pulses, dielectric laser acceleration (DLA) provides a scheme for high gradient particle accelerators. In the past, this concept was limited by insufficient beam transport through longer structures and the inability to stage multiple structures without particle loss. The concept of alternating phase focusing (APF) provides a way to...
A goal of ESCULAP [1,2] experiment is the external injection of photo-injector electrons bunch with consequent LWFA acceleration in the moderate density plasma cell.
In our configuration small fraction of LASERIX laser is send to the photocathode, and the rest is delivered to the plasma cell for the wake excitation.
Stability of the laser beam, its shape, “flatness”, duration, intensity...
Laser Plasma Accelerators (LWFAs) operating in the linear and quasi-linear regime require the driving laser pulse to be guided over the length of the accelerator stage. Multi-GeV plasma stages, for example, require the driving pulse to be guided over 100s of millimetres of plasma of density $n_\mathrm{e}(0) \approx 10^{17}~\mathrm{cm}^{−3}$. These challenging parameters can be met by...
It is shown that external magnetic fields at tens of tesla can provide additional control of electron injection in laser wakefield acceleration (LWFA). In the first case, we consider ionization injection assisted by a transverse magnetic field. Both the electron trapping condition and the wakefield structure are changed significantly by the magnetic field such that injection occurs over a...
A highly efficient compact wakefield accelerator is being developed at Argonne National Laboratory for a future multiuser x-ray free electron laser facility [1]. A cylindrical metallic structure with a 2 mm internal diameter and fine corrugations on the wall is used to cause a Čerenkov radiation by a “drive” bunch at ~ 180 GHz in the fundamental mode and to obtain accelerating gradients on the...
Multi-pulse laser wakefield acceleration (MP-LWFA) is a promising scheme for increasing the repetition rate of LWFAs to to the kHz range [1-2] In this approach the laser wakefield is driven by a train of laser pulses spaced by the plasma wavelength such that the wakefields driven by each pulse interfere coherently.
A major consideration for MP-LWFA and related schemes is the decay time of...
Laser-driven plasma wakefield acceleration (LWFA) provides an innovative and compact alternative to conventional RF accelerators. The electron beam can be injected to a plasma accelerator using different techniques. The advantage of external injection from an RF accelerator is given by the possibility to inject fully characterized bunches with a well-controlled beam quality. In addition, the...
The prime challenge of laser-plasma based accelerators at the moment is to optimise the particle beams to obtain a steady mono-energetic and collimated bunch of energetic particles with the maximum possible efficiency. The present work is dedicated to optimising the laser and plasma parameters, and examining the ion acceleration processes that are present due to the laser plasma interactions....
The interaction of high-power, high-contrast laser pulses with nanostructured targets has largely been explored as a possible way to increase energy absorption and aim to more efficient proton acceleration. In these studies, the costs of target manufacturing and handling are a key factor to establish the soundness of each approach, and while advance of laser technologies now allow preserving...
Laser-driven ion acceleration is an attractive way to realize compact and affordable ion sources for many exciting applications including cancer therapy. Many of these applications require high energy ion beams with narrow
energy spread as well as high flux. When a near critical (or rather overdense) target is irradiated by a laser pulse, ions are compressed to form a density spike, which in...
Beam-driven plasma wakefield accelerators (PWFAs) allow for high gradient acceleration of electron beams and hence are promising candidates for compact and cost-efficient drivers of applications demanding high brightness beams. One of the main challenges in these accelerators is to control beam-plasma instabilities with rapid growth rates which are induced by the strong transverse components...
The report is devoted to the latest experimental results on the laser-driven acceleration of electrons obtained at the laser-plasma setup PEARL (IAP RAS, Russia). The main goal of the experimental campaign was to demonstrate in the laboratory an unmatched LPA regime, leading to higher acceleration gradients. Electrons with energies exceeding GeV were demonstrated for ~ 10 J, 50 fs laser pulses...
Particle acceleration beyond the few-MeV level currently requires large infrastructures, due to the low frequencies (a few GHz) and relatively low field amplitudes (a few tens of MV/m in the meter-long structures) used in conventional accelerating structures. One of the scheme currently investigated to reduce the footprint of particle accelerators by several orders of magnitude is to use...
Dielectric laser acceleration is a versatile scheme to accelerate and control electrons with femtosecond laser pulses in nanophotonic structures. We show recent results of the generation of a train of electron pulses with individual pulse durations as short as 270 +/- 80 attoseconds. We achieve these attosecond micro-bunch trains based on two subsequent dielectric laser interaction regions...
To realise a 10 GeV laser plasma accelerator stage, high-intensity pulses must be guided through low-density ($\sim 1 \times 10^{17} \rm{cm^{-3}}$) plasma over distances of order 100s of millimeters.
We recently presented simulations which showed that plasma channels with these parameters could be generated by the hydrodynamic expansion of optical-field-ionised plasma columns formed with an...
Fine time-resolved analysis of matter - i.e. spectroscopy and photon scattering - in the linear response regime requires fs-scale pulsed, high repetition rate, fully coherent X-ray sources. A seeded FEL driven by a Linac based on Super Conducting cavities, generating $10^{8}$-$10^{10}$ coherent photons at 2-5 keV with 0.2-1 MHz of repetition rate, can address this need. Three different seeding...
Plasma wakefield accelerators can provide gigavolt-per-centimetre energy gain, offering a promising path towards compact electron sources. They rely on the generation of plasma waves driven by either a high-current charged particle beam (PWFA) or an intense laser pulse (LWFA).
PWFAs offer particularly attractive regimes of injecting and accelerating a new high-quality electron beam, but...
High-gradient high-frequency accelerating structures are in strong demand for the next generation of compact light sources. Accelerating structures operating in Ka-Band are foreseen to achieve gradients around 150 MV/m. Among possible applications of a Ka-Band accelerating structure we refer to the beam phase-space manipulation for the Compact Light XLS project as well and medical and...
The MariX project (Multi-disciplinary Advanced Infra-structure for Research with X-rays) is a free electron laser (FEL) light source proposed by the INFN-Milan. It will produce highly coherent X-rays, in the range 0.2-8 keV, with ultra-short pulses (10-50 fs) and a repetition rate up to 1MHz. At the same time, MariX will host a compact monochromatic X-ray source, called BriXS, by using an...
The FEL beam conditioning has been proposed 30 years ago as a method to mitigate an excessive electron beam emittance, which at that time was considered the principal limiting factors for the SASE FEL development at short wavelengths. In essence, the beam conditioning implies artificially inducing at the undulator entrance a correlation in the electrons’ energies and intra-undulator betatron...
Applications such as colliders and plasma wake field acceleration require high gradient quadrupoles, in the range of 400-500 T/m and with a bore of few millimeters in diameter.
The design of a tunable high gradient permanent magnet quadrupole, based on the QUAPEVA design developed for the SOLEIL synchrotron, is presented. The quadrupole has a fixed part made of a Halbach quadrupole surrounded...
The advent of laser wakefield acceleration of electrons to GeV energies and charges up to nanocoulombs offer a unique tool to generate high intensity bremsstrahlung with characteristics similar to conventional accelerators, but in a more compact setup. Future facilities like the ELI pillars will use laser-generated bremsstrahlung at high repetition rates to study nuclear physics phenomena....
The MariX FEL is a compact GeV-class X-ray source exploiting a two-pass 2-way acceleration in a Super-Conducting linac operated in continuous wave mode. A key component of this peculiar machine layout is the Arc Compressor (AC), a 300 m long beamline consisting of 14 "Double Bend Achromat" cells and a bidirectional quadrupole focusing channel, which allows the beam to be u-turned while it is...
Beam-driven plasma wakefield accelerators allow for the generation and subsequent acceleration of electron beams inside the plasma
with substantially lower emittance than the driving electron beam, eventually providing technology for final-focus brightness converters for versatile applications. Among a variety of internal injection techniques, density downramp injection has the potential to...
The field of plasma acceleration has undergone rapid advancement in recent years, with significant progress being made towards the production of stable high quality electron beams. With this progression comes new avenues of research into potential applications, facilitating the need for precise understanding and control of the femtosecond-micrometer scale interaction process. Experimental...
The acceleration of electrons with ultra-short, high-intensity laser pulses has a successful method. Although, the maximum accelerated electron energy is limited mostly due to de-phasing of the electrons with the driving laser pulse and the depletion of the laser pulse. Staging two laser wakefield accelerators with two laser beams can overcome these limitations. Using the first plasma cell for...
In the poster we will describe the most recent experimental results obtained at the Laser Light Ion beam-Line using both flat and nanostructured thin foil targets, where accelerated ions were characterized using a wide range of detection techniques, optimized for the severe conditions typical of a laser-plasma acceleration environment.
Advanced targets are also being explored to enhance...
Terahertz-driven electron beam manipulation promises femtosecond control of bunches with femtosecond timing jitter. A compact, terahertz-driven velocity bunched electron beam demonstration is under development at the Cockcroft Institute. A lithium niobate terahertz radiation source using the tilted pulse front scheme has been established experimentally and its interaction with a 100 keV...
Few-cycle shadowgraphy is a common tool to qualitatively investigate the longitudinal and transverse structure of laser generated wakefields. However the measured intensity distribution provides hardly any information about the wake amplitude since the wakefield itself is a pure phase object and the measured intensity distribution is a function of the imaging plane. Commonly this plane is not...
The recent activities of the SPARC_LAB test-facility (LNF-INFN) are focused on the study of the interaction of high-brightness electron beams with plasmas and on tests on new advanced diagnostics. Here we report the latest results, showing the progress toward plasma acceleration and demonstrating the use of plasmas to shape the beam longitudinal and transverse profiles.
We theorerically demonstrate a possibility to resonantly accelerate electrons by a moderately relativistic laser pulse (from $\sim 10^{19}-10^{20}$ W/cm${}^2$) interacting with the surface of a microstructured target with periodic grooves. If the structure period is equal to the laser wavelength, a resonant acceleration may occur and electron bunches can be accelerated up to high energies by...
Seeding of the drive bunch self-modulation (SM) process is essential when using a long particle bunch (σz>>λpe) to drive wakefields in plasma. Seeding in principle leads to a SM phase reproducible from event-to-event, allowing for deterministic injection of an electron witness bunch to be accelerated.
Since external injection requires generation of an electron bunch in an RF-gun or LWFA, we...
Plasma based technology will allow an unprecedented reduction of the size of accelerating machine. Both fundamental research and applied science and technology will take profit of this feature.
The same compactness is required downstream the accelerator module, where the plasma-accelerated beams usually experience a large angular divergences growth after the acceleration. Here compact, strong...
X-ray absorption spectroscopy can provide a wealth of information about a sample, including a simultaneous measurement of the temperature and structure of both the electrons and ions, via techniques such as XANES (X-ray Absorption Near Edge Structure). If these measurements can be made using a single ultrashort probe pulse at multi-keV energies, they provide a powerful tool for investigating...
The plasma photocathode particle-driven Wakefield accelerator (TH-PWFA) is a promising path towards ultrahigh 5D-brightness and multi-GeV electron beams for application such as X-Ray free-electron laser (XFEL), inverse Compton scattering (ICS) and High Energy Physics (HEP). Recent experimental breakthroughs within the "E210: Trojan Horse PWFA" collaboration obtained at Stanford Linear...
In order to measure emittance in single shot, it is necessary to obtain information about beam spot, angular divergence and correlation term. The former and the second terms can be provided by a simultaneous measurement of beam size and Optical Transition Radiation (OTR) angular distribution. The latter is acquired by means of a microlens array, producing several contiguous replicas of OTR...
We report on the status of the dielectric laser acceleration (DLA) experiments at the SINBAD/ARES linac at DESY, Hamburg. The experiments are performed in the context of the Accelerator on a CHip International Program (ACHIP). At SINBAD, the main goal is to show net energy gain of externally injected relativistic electron bunches in the high-gradient fields of a laser-illuminated dielectric...
The nascent technology of terahertz (THz)-based electron acceleration holds great promise for development of compact relativistic electron sources with femtosecond bunch durations suitable for applications from ultrafast electron diffraction to injectors for THz-based accelerators and light sources. These so-called “THz guns” present unique capabilities, but also unique challenges associated...
When long particle beams (compared to the plasma skin depth) propagate in plasma, they can be subject to two competing transverse instabilities: beam hosing and self-modulation. Hosing disrupts the beam and is considered a detrimental effect. Conversely, the self-modulation process can be seeded and exploited in plasma wakefield acceleration experiments to excite high-amplitude wakefields,...
We discuss the use of high power laser-generated THz waves for acceleration and electron beam phase space manipulation. These find application both as a compact alternative for radiofrequency-based accelerators as well for high frequency manipulation of electron beam longitudinal phase spaces and beam compression. We’ll present our different approaches to reach next goal in THz acceleration...
Full characterisation of ultra-intense laser pulses not only requires their separate characterisation in space and time, but also measurement of the entire spatio-temporal field distribution $E(x,y,t)$. While a variety of techniques has been developed for this purpose (e.g. STARFISH, TERMITES or INSIGHT), most of them rely on spatial or temporal scanning and thus require some thousand shots...
The efficiency of electron bunch acceleration by wakefield, excited in two-beam electron-positron dielectric resonator collider by train of electron bunches is determined by transformer ratio [1-14]. Two trains are considered. First is train of homogeneous bunches, current grows linearly along a train. Current of the second train grows linearly along each bunch and train. The length of...
Dielectric wakefield structures driven by relativistic beams have been employed to generate high-gradients for collinear acceleration schemes, as well as for applications in beam phase space manipulations. In simple cylindrical dielectric structures, the longitudinal wakefields are also accompanied by transverse fields. The growth of the transverse fields can severely limit the acceleration...
Laser-plasma accelerators generate ultrarelativistic electron beams over only a few centimeters, making them particularly interesting as drivers for compact next-generation light sources. In order to become applicable for these applications, control of electron beam properties, enhanced stability and reproducibility are crucial.
Here, we demonstrate dedicated tuning of electron beam parameters...
ALEGRO, the Advanced LinEar collider study GROup is an international study group promoting advanced and novel accelerators (ANAs) for high-energy physics applications. ALEGRO organizes one workshop each year as well as meetings at prominent ANAs conferences (EAAC, AAC, etc.). ALEGRO also submitted an input to the European Strategy for Particle Physics Update (ESPPU) process and was represented...
High power laser facilities currently under construction will open up new accelerator applications, which will encounter quantum processes. Experiments such as Compton backscatter sources will require a thorough experimental understanding of non-classical behaviour. Recently, experiments have started to measure these effects in isolation by studying radiation reaction, using the collision...
FACET-II is a new National User Facility at SLAC National Accelerator Laboratory scheduled to begin operating in 2020. The PWFA collaboration has proposed an ambitious series of experiments consistent with the US DOE Advanced Accelerator R&D Roadmap. A photoinjector in a configuration similar to that of LCLS will enable FACET-II to investigate acceleration and beam quality preservation...
We will be summarizing the status of the major parts of the ELI pillars including high intensity laser sources, experimental areas with beamlines and end-stations. Special emphasis will be given to the availability of equipment for the first calls for users and user policy. The next steps of the transformation of ELI–DC (delivery consortium) to ELI-ERIC (European Research Infrastructure...
Laser-driven accelerators drive ultra-short pulse beams of MeV ions and photons that can be utilised as deployable neutron sources for science and industry. This talk will summarise recent results from groups around the world focusing on the optimisation of laser-driven neutron sources for applications relevant to security, industry and science. Topics covered include neutron beam...
Quantum Electrodynamics (QED) represents one of the greatest theoretical achievements in modern physics, able to elegantly combine electromagnetism, quantum mechanics, and special relativity into a unified theory. Its predictions have been tested to a high degree of precision in relatively low fields but, thus far, little is experimentally known about the behaviour of quantum systems in fields...
Laser-driven proton acceleration to high kinetic energies has great potential for applications in e.g. time-resolved radiography or in high-dose radio-biology. To date, however, a strong discrepancy remains between theoretical predictions of the maximum proton energies (Eprot) and the experimental results. Furthermore, a tremendous progress in laser development did not lead to a dramatic...
Laser-wakefield accelerators (LWFAs) are high acceleration-gradient plasma-based particle accelerators capable of producing ultra-relativistic electron beams. Within the strong focusing fields of the wakefield, accelerated electrons undergo betatron oscillations, emitting a bright pulse of X-rays with a micrometer-scale source size that may be used for imaging applications. Non-destructive...
Laser-plasma accelerators are prominent candidates to drive a next generation of high-brightness x-ray sources. The LUX laser-plasma accelerator, driven by the ANGUS 200 TW laser, has recently demonstrated the generation of few-nm-plasma-driven undulator radiation. Long-term operation of the plasma accelerator with reproducible and stable electron beams requires a highly stable drive laser. To...
Today’s laser-plasma accelerators are driven by terawatt-class laser systems at a few-Hz repetition rates and few-Joule pulse energies. Typically, the architecture of these systems includes a compressor based on in-vacuum gold-coated gratings, which absorb a percent-level fraction of the incident laser energy. However, as laser technology pushes the limit towards higher repetition rates and...
High-intensity laser facilities can now routinely generate GeV electron bunches and broadband multi-keV X-rays using laser-driven wakefield accelerators. These energetic sources are ultra-short in duration (femtoseconds) with a small source size (microns) and low divergence (miliradians). They are also inherently synchronised to the drive laser itself, making pump-probe setups possible.
The...
Laser-driven ion acceleration promises to provide a compact solution for demanding applications like radio-biology experiments. For that, controlling particle beam parameters particularly in experiments with high energy Petawatt class ultra-short pulse systems with high repetition rate is a mandatory, yet challenging task. The performance of the plasma acceleration is strongly dependent on the...
Hosing instability is the most important instability needs to be controlled when building a future linear collider using plasma based acceleration. The normal method for mitigating the hosing instability requires energy chirps on the beam or longitudinally varying focusing force. However, these methods require additional manipulation on the witness beam, and the beam centroid oscillation...
The realization of compact positron source is of great importance for a wide range of applications such as positron annihilation spectroscopy for material science. Moreover, a number of applications could benefit from short pulse duration (sub-100 ps) positron beams.
The interaction of a high-intensity laser with high-Z solid targets can be used to produce a population of relativistic...
When a multi-terawatt laser pulse is incident onto a nanometer-scale target, strong electron heating and plasma expansion occurs. As the plasma expands, the target experiences a change in electron density which affects the type of interaction occurring. Of particular interest is the regime of relativistic transparency, when the target density drops below the relativistic critical density,...
One of the main challenges for the development of 10 Hz petawatt-class lasers is the avoidance of grating heating in the compressor [1,2]. Beam distortions appear even at low average power [3], meaning mitigation strategies must be adopted for smaller scale systems. In this paper we describe detailed measurements of the compressor parameters in TA2 of the Gemini laser at the Central Laser...
During the interaction of ultra-intense laser pulses with ultrathin foils, advanced mechanisms of ion acceleration take place which can be controlled and optimized in view of further progress towards high energy ranges of medical relevance on upcoming multi-PW facilities.
In the framework of the activities of the UK-wide A-SAIL project, recent campaigns at the ASTRA GEMINI laser facility...
While laser-plasma accelerators provide multi-GeV electron beams today, the acceleration to higher energies is limited. The sub-luminal group-velocity of plasma waves let electrons outrun the accelerating field. We present Traveling-Wave Electron Acceleration, a novel compact laser-plasma accelerator scheme which circumvents the LWFA constraints of electron beam dephasing, laser pulse...
In the framework of the Compact Light XLS project, we have performed a possible RF design on the 35 GHz accelerating structure in order to linearize the longitudinal phase space. Detailed RF estimations and the wake-field effects on the beam dynamics are also reported. The numerical electromagnetic simulations have been carried out by using the code HFSS in the frequency domain and CST...
Plasma based electron acceleration is widely considered as a promising concept for compact electron accelerators with broad range of applications. These accelerators can be driven by either ultra-intense laser beams (LWFA) or high-current particle beams (PWFA).
Here, we report on a novel approach to combine both schemes in a compact experimental setup. In our “LWFA + PWFA” hybrid accelerator,...
A Laser Wakefield Accelerator producing two distinct electron populations: a 2 GeV component that was self-injected early in the interaction, and a sub-GeV component injected close to the laser depletion length, was shown to be an intense source of betatron x-rays. The x-rays were predominantly generated by the sub-GeV bunch.
Simultaneous measurements of the electron and x-ray spectra...
With the trend towards higher repetition rate laser systems for applications, there is a demand for new, high repetition rate target solutions. This talk will look at efforts to develop shaped, thin, near-critical density gas targets for radiation pressure driven ion acceleration experiments using the high power, $\mathrm{10.6}{\mu m}$ $\mathrm{CO_2}$ laser at Brookhaven National Laboratory....
A new multi-dimensional solver for Maxwell equations will be presented. It rips the volumetric Yee lattice to a transverse plane. The fields locations become Lorentz-invariant. The solver alleviates numerical dispersion for plane waves running along the selected axis and perfectly fits for problems of particle acceleration in plasmas. The solver has a compact local stencil and allows for...
The gas-foil target combines two domains in laser-plasma acceleration which are normally separate: gas targets are usually used for electron acceleration and solid targets for ion acceleration. The combination of the two thus provides a system of rich physics to explore. We are experimentally investigating this type of target with a focus on ion acceleration. The experiment is done under...
A new take on ionization-assisted shock-front injection was used to create spectrally two-component beams in a laser-wakefield accelerator, with the goal of investigating the possibilities for such an injection scheme for beam-driven plasma-wakefield acceleration. Ionization injection was combined with shock-front injection to provide characteristic spectra with a broadband, continuous part...
Technological advancements are strongly required to fulfil demands for new accelerators devices from the compact or portable devices for radiotherapy to mobile cargo inspections and security, biology, energy and environmental applications, and ultimately for the next generation of colliders. New manufacturing techniques for hard-copper structures are being investigated in order to determine...
Multi-pulse laser wakefield acceleration (MP-LWFA) is a promising scheme for increasing the repetition rate of LWFAs to to the kHz range [1-2] In this approach the laser wakefield is driven by a train of laser pulses spaced by the plasma wavelength such that the wakefields driven by each pulse interfere coherently.
A major consideration for MP-LWFA is the decay time of the wakefield, since...
Intense laser irradiation experiments of sub-micrometer scale targets are currently performed at slow shot rates. This limitation is the result of the inability to place such targets quickly and accurately in the focus of the laser. I will present a target setup that enables irradiation at a high rate and sub-wavelength positioning accuracy. Three hundred targets were micro machined and...
We report on optical probing results using few-cycle microscopy obtained during a laser wakefield acceleration experiment carried out with the JETI-200 laser system at the Helmholtz-Institute Jena. When traveling through the plasma and exciting a plasma wave, the pump pulse can get scattered at plasma structures depending on the pump pulse’s evolution inside the plasma, its chirp and the...
Recent studies and investigations show the possibility to increase the cathode peak field, using normal conducting structures with a reduced RF pulse duration or using copper structures operated at cryogenic temperatures. In this context we studied the beam dynamics advantages using a 1.6 cells C-band gun operated at the gradient of 240 MV/m, in order to set the photo-injector layout for the...
During its Run 1, AWAKE has very successfully demonstrated the self-modulation of long SPS proton bunches in plasma, as well as the acceleration of externally injected, 19MeV electrons up to 2GeV. The goal of Run 2 is to accelerate an externally injected electron bunch, i.e. charge >100pC to GeV energy with a narrow final energy spread and preservation of its incoming emittance. To achieve...
Photoionization by a femtosecond TW laser pulse generates a plasma column in a neutral ambient gas.The 3D laser wake wave extends through the column surface, generating an azimuthally polarized rotational current within a micron-thin shell. This current supports a broad-band, evanescent THz signal accompanying the wake, detectable at a distance orders of magnitude larger than the column...
The beam-driven plasma photocathode wakefield acceleration concept [1] allows decoupled laser injection of electron bunches with emittance and brightness reach many orders of magnitude better than state-of-the-art [2]. After successful proof-of-concept demonstration at SLAC FACET in the “E-210: Trojan Horse” project [3], we now embark on the next experimental phase around the “E-310:...
The research activities in the field of plasma-based particle acceleration is shifting from the investigation of fundamental processes to the actual practical implementation of such promising technology. Laser wake-field acceleration is foreseen to be implemented in user oriented facility expected to deliver high-quality GeV electron bunches suitable for injection in a free-electron laser...
Beam-driven plasma-wakefield accelerators(PWFAs) offer a unique regime for the generation and acceleration of high-quality electron beams to multi-GeV energies. Here we present an innovative hybrid staging approach, deploying electron beams generated from a compact laser-driven wakefield-accelerator(LWFA) as drivers for a PWFA. This scenario exploits the capability of LWFAs to deliver...
Extreme field gradients intrinsic to relativistic laser-interactions with thin solid targets enable compact multi-MeV proton accelerators. The initial µm-scale acceleration phase is followed by ballistic proton propagation with negligible space-charge effects over millimeters to hundreds of centimeters to a site of analysis/application. The detected proton distribution can be influenced by the...
