X-gray sources based on electron laser-plasma acceleration

Laser-plasma technology promises a drastic reduction of the size of high-energy electron accelerators. It could make free-electron lasers available to a broad scientific community and push further the limits of electron accelerators for high-energy physics.

Furthermore, the unique femtosecond nature of the source makes it a promising tool for the study of ultrafast phenomena. However, applications are hindered by the lack of suitable lens to transport this kind of high-current electron beams mainly due to their divergence. Here we show that this issue can be solved by using a laser-plasma lens in which the field gradients are five order of magnitude larger than in conventional optics. We demonstrate a reduction of the divergence by nearly a factor of three, which should allow for an efficient coupling of the beam with a conventional beam transport line.

Yet, this small emittance is mostly due to a sub-micrometer source size 10while the beams typically have rather large divergence of a few milliradians.

Their energy spread, of a couple of per cents 11is also at least one order of magnitude larger than in linear accelerators. This raises several issues for the beam transport and hence for key applications of laser-plasma accelerators such as free-electron lasers and high-energy colliders 121314 In particular, the transverse emittance tends to increase during a free drift because electrons with different energies rotate with different velocities in the transverse phase space The emittance increase is tolerable 17 if the drift length.

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In other words, electrons must be focused within a few centimeters from the accelerator exit in order to be transported efficiently. Focusing the beam within such a short distance requires very high transverse field gradients. An electron beam transport line based on quadrupole technology will therefore degrade the quality of a laser-plasma electron beam, rendering it useless for most applications.

As they can sustain much higher gradients, plasmas could help to drastically miniaturize focusing optics, similar to the miniaturization achieved by laser-plasma accelerators, and hence to avoid any emittance growth. Incidentally, the idea to use plasma to focus an electron beam 20 is almost as old as the idea to use plasma to accelerate electrons It was proposed to focus an electron beam using the radial fields created in the wake of the electron beam itself, when it propagates in a plasma.

The so-called plasma lens was demonstrated in the context of conventional accelerators 22232425but it has not been considered for focusing electron beams from laser-plasma accelerators owing to the ultrashort length of these beams.

Indeed, there is always a finite length at the bunch head over which the focusing is very non-uniform 2627 ; for ultrashort bunches from laser-plasma accelerators this length is comparable to the bunch length The laser-plasma lens was recently proposed, and validated by three-dimensional particle-in-cell simulations, to solve this issue 29 In the following, we present an experimental demonstration of this concept. First, we explain the principle of the laser-plasma lens.

Then, we show that the strength of the lens can be optimized by tuning both the distance between the accelerator and the lens, and the electron density in the lens. Finally, we analyse the chromaticity of the lens and discuss the results.In this presentation, we show recent progress toward this goal: guiding of 0. This was achieved by increasing the focusing strength of a capillary 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. The single-cycle laser pulses were able to excite nonlinear plasma wakefields and accelerate electrons to MeV Controlling the parameters of a laser plasma accelerated electron beam is a topic of intense research with a particular focus placed on controlling the injection phase of electrons into the accelerating structure from the background plasma.

An essential prerequisite for high-quality beams is dark-current free acceleration i. We report on the generation of quasi-monoenergetic electron beams with up to 1. These high charge densities result in significant beam loading which affects both the final energy and the spectral shape of the electron beam. We confirm and explain the Laser wakefield acceleration LWFA is a candidate to build next generation of electron accelerators due to its huge acceleration field in a plasma medium.

Progresses of intense laser technologies contributed to developments of multi-GeV [1,2] and high repetition-rate electron beams [3] by LWFA. Recently, we accomplished upgrading one of our PW beamlines to 4 PW peak power [4] and started Such pulses Laser Plasma Acceleration LPA enables to generate up to several GeV electron beam with short bunch length and high peak current within centimeters scale.

However, the generated beam quality energy spread, divergence is not sufficient for numerous applications. In view of a Free Electron Laser application, the energy spread has to be adapted to reach the required small slice value while the Focusing petawatt-level laser beams to a variety of spot sizes for different applications is expensive in cost, labor and space.

In this talk, we present a plasma lens, similar to an adjustable eyepiece in a telescope, to flexibly resize the laser beam by utilizing the laser self-focusing effect.

Using a fixed conventional focusing system to focus the laser a short distance in front of the Plasma beam dump has been recently proposed to absorb the kinetic energy of the spent beam from particle accelerators. In this presentation a passive beam dump with multiple stage plasma cells are investigated. In this new scheme, the stepped plasma densities are required after the first stage so as to maintain a high decelerating gradient compared to a uniform plasma.

Electron spectra were measured and the effect of feedback control of the laser pulse phase front and the laser temporal phase were investigated.

Laser-plasma accelerators and radiation sources by Dino Jaroszynski

The development of liquid targets for high rep rate ion and We will give an overview of the latest commissioning status of the ATLAS laser system at CALA, before reviewing the main results from the laser-wakefield related campaigns with the predecessor TW system. The scaling of their spectral shape I will present an overview the research being undertaken in my group at the Clarendon Laboratory, University of Oxford and with colleagues at the Rutherford Appleton Laboratory.X-ray pulse source for generating X-ray pulses 1 includes electron pulse source device 10 including photo-emitter device 11 being configured for photo-induced creation of free electron pulses 2 and driver device 12 being configured for creating electromagnetic driver pulses 3 accelerating electron pulses 2 along acceleration path 7and electromagnetic interaction device 50 comprising electromagnetic pulse source device 51 being configured for creating electromagnetic pulses 4 in interaction section 5 of electromagnetic interaction device 50wherein electron pulse source device 10 and electromagnetic interaction device 50 are operable for generating X-ray pulses 1 by an interaction of electron pulses 2 and electromagnetic pulses 4and driver device 12 includes THz driver pulse source 13which is configured for creating single cycle or multi cycle THz driver pulses 3.

Furthermore, a method of creating X-ray pulses 1 is described. The invention relates to an X-ray pulse source for generating X-ray pulses, in particular to an X-ray pulse source including an electromagnetic radiation based undulator. Furthermore, the invention relates to a method of creating X-ray pulses, in particular comprising the steps of photo-induced generating electron pulses, accelerating the electron pulses and creating the X-ray pulses by an interaction of the electron pulses and electromagnetic pulses.

Applications of the invention are available in creating X-rays e. For describing the background of the invention, particular reference is made to the following publications: [1] G. Krafft et al. E 72, no. Esarey et al. E 48, no. Jones et al.

Phuoc et al. Powers et al. Chen et al. Maroli, V. Petrillo, L. Serafini, A. Bacci, A. Rossi, and P. Serafini et al. IEEE, ; [11] F. Tran et al. Chang et al. Gea-Banacloche et al. Gallardo et al.Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer.

In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. A Nature Research Journal.

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Femtosecond fs x-ray pulses are a key tool to study the structure and dynamics of matter on its natural length and time scale. To complement radio-frequency accelerator-based large-scale facilities, novel laser-based mechanisms hold promise for compact laboratory-scale x-ray sources.

Laser-plasma driven undulator radiation in particular offers high peak-brightness, optically synchronized few-fs pulses reaching into the few-nanometer nm regime. To date, however, few experiments have successfully demonstrated plasma-driven undulator radiation. Those that have, typically operated at single and comparably long wavelengths. Studying spontaneous undulator radiation is an important step towards a plasma-driven free-electron laser. Our specific setup creates a photon pulse, which closely resembles the plasma electron bunch length and charge profile and thus might enable novel methods to characterize the longitudinal electron phase space.

Since they match the intrinsic length and time scales of matter, femtosecond fs x-ray pulses are ubiquitously applied as an important tool in many scientific disciplines for solving previously unknown structures 123 and accessing atomic and molecular dynamics 45. Today, the required high-brightness x-ray beams are provided to the user community almost exclusively by large-scale synchrotron 67 and free-electron laser facilities 891011which represent mature and highly developed technologies, delivering well-characterized photon beams with exceptional availability and reproducibility.

Due to their size and cost, however, access to these important resources is very limited. Laser-driven sources of high brightness particle 1213141516 and x-ray beams 17 are promising to complement established facilities by offering easy access to compact, laboratory-scale femtosecond x-rays that are intrinsically synchronized to the optical driver and thus enable sub-fs temporal resolution in pump-probe experiments.

These prospects have motivated a large variety of concepts for laser-driven x-ray sources, including high-harmonic generation 1819 or plasma lasers 20as well as novel acceleration schemes, like THz acceleration 212223dielectric laser acceleration 2425or laser-plasma acceleration 1213which can generate x-rays from laser-driven relativistic electron beams 26272829303132 Laser-plasma acceleration in particular is a promising laboratory-scale technique to generate ultra-relativistic electron beams.

Here, the interaction of a terawatt-class laser with an under-dense plasma creates a density modulation, i. The field gradients supported by the plasma wave are orders of magnitude stronger than in a conventional radio-frequency RF driven cavity and as a result, the acceleration distance required for typical GeV-level electron beams can be as short as a few centimetres 343536Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion.

However, their size and expense now threaten the future of teraelectronvolt-class accelerator research, exemplified by the recent discovery of a Higgs-like boson 2and inhibit wide availability of gigaelectronvolt GeV -class accelerators that underlie coherent X-ray sources used for biological, chemical and condensed matter research.

InTajima and Dawson 3 proposed the idea of accelerating charged particles by surfing them on electron density waves propagating through underdense plasma in the wake of an intense ultrashort laser pulse.

The quest for multi-GeV LPAs is motivated by the possibility of constructing compact linear colliders 9 for future high-energy physics research and table-top sources of ultrashort, coherent hard X-rays 10 for physical, chemical and biological studies of dynamics at the atomic scale. Both numerical modelling 811 and experimental diagnostics 12 have shown that bubble formation is essential for producing collimated, quasi-monoenergetic electron beams. Third, laser peak power P must be kept well above the critical power GW for relativistic self focusing.

This enables the drive pulse to self focus and self compress during its initial non-linear interaction with the plasma, increasing its intensity to a level at which blowout occurs, and helps it to self guide over multiple Rayleigh lengths once acceleration begins, thereby exploiting the increased acceleration length set by L D and L PD.

On the other hand, deviations from a matched geometry—due to the focus geometry or non-Gaussian profile a likely feature of many first-generation PW-class laser systems of the incident laser pulse—cause the laser pulse and bubble profiles to vary as they copropagate.

Such variations profoundly affect self injection in ways not captured by simple scaling laws 1314making self-injection thresholds difficult to predict accurately Moreover, details of bubble evolution dictate the dynamics of self injection, which in turn dictate key beam properties such as energy spread, angular divergence and background current 1314 In view of these uncertainties, previous work provides limited quantitative guidance on self-injection physics and beam properties of multi-GeV LPAs, which must therefore be discovered through laboratory experiments.

At the same time, our results show two features not predicted by any previous simulation or scaling law. First, self-injection and multi-GeV acceleration occur despite a highly irregular focal profile. These last features, along with the quasi-monoenergetic multi-GeV spectral peak, are critical for collider and coherent light source applications.

Our results were obtained with an exceptionally simple target consisting of uniform, undoped He gas, similar to the target used by Osterhoff et al. Our results thus provide a benchmark against which future multi-GeV LPAs employing such methods can be compared. Figure 1 shows a schematic layout of the experiments. Transversely scattered pump light was imaged through a side window in the cell. Accelerated electrons emerged through a 3-mm radius exit aperture and were deflected in a plane perpendicular to the laser polarization by a magnetic field from a permanent dipole magnet.

The electron beam entered the field perpendicular to one edge, aimed nominally at the centre of the plateau. The measured field deflected electrons equivalently to a uniform, fringe-free effective field of 1.

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This effective field was used in calculating electron trajectories. Between magnet and detectors, electrons and X-rays passed through two arrays of thin, precisely positioned tungsten-wire fiducials, which cast identifying shadows on the detectors. With this information, complete electron trajectories from source to detector were recovered from shadows in the electron spectrum. Undeflected X-rays and energy-dispersed electrons above 0.

The laser-plasma conditions for these shots are given in the top two rows of Table 1. Spectra recorded by other detectors corroborated the position and spectral shape of the main peaks precisely. The high-energy tails, highlighted in the third column, indicated some electrons accelerated to 2. Trajectories of a 2-GeV electron for shots a and b are plotted in Fig.

Similar analysis for all energies established the energy scale of Fig. This signifies that electrons were injected closer to the axis of the accelerator structure in a pure He plasma than electrons injected by ionizing K -shell electrons of a high- Z dopant gas species 20216.

x-gray sources based on electron laser-plasma acceleration

On the other hand, when this divergence is scaled to sub-GeV electron energy, it signifies transverse electron momentum similar to that obtained in the lowest-divergence sub-GeV beams from uniform undoped gas targets for example, 2. Analysis of the shape of the fiducial shadows shows that divergence in the horizontal that is, energy dispersion plane is similar in magnitude, facilitating accurate energy analysis.

In fact, the quasi-monoenergetic peaks in Fig.Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer.

Water-Window X-Ray Pulses from a Laser-Plasma Driven Undulator

In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. A Nature Research Journal.

x-gray sources based on electron laser-plasma acceleration

This approach has the drawback of requiring very high energy, up to the multi-GeV-scale, electron beams, to obtain the required photon energy. Compact, less costly, monochromatic X-ray sources based on very high field acceleration and very short period undulators, however, may enable diverse, paradigm-changing X-ray applications ranging from novel X-ray therapy techniques to active interrogation of sensitive materials, by making them accessible in energy reach, cost and size.

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Such compactness and enhanced energy reach may be obtained by an all-optical approach, which employs a laser-driven high gradient accelerator based on inverse free electron laser IFELfollowed by a collision point for inverse Compton scattering ICSa scheme where a laser is used to provide undulator fields.

These results demonstrate the feasibility of this scheme, which can be joined with other techniques such as laser recirculation to yield very compact photon sources, with both high peak and average brilliance, and with energies extending from the keV to MeV scale.

Further, use of the IFEL acceleration with the ICS interaction produces a train of high intensity X-ray pulses, thus enabling a unique tool synchronized with a laser pulse for ultra-fast strobe, pump-probe experimental scenarios.

x-gray sources based on electron laser-plasma acceleration

The rapid progress in X-ray science over the last century, beginning with cathode ray tubes and arriving at 4 th generation light sources — in the form of the X-ray free-electron laser, or XFEL — has been driven by many breakthroughs in the fields of electron acceleration and synchrotron radiation generation. Dramatic advances in these techniques have fueled many discoveries across a wide swath of scientific disciplines ranging from physics 12to chemistry 3biology 4and material science 5.

The main drawback of modern high brightness X-ray sources is their large size and cost, driven both by the size and complexity of the high energy particle accelerators and the elaborate undulator magnets used. In an attempt to create a more compact, high flux, high brilliance X-ray source, 5 th generation X-ray sources based on all-optical schemes involving laser-driven accelerators and laser-enabled undulators have been the subject of intensive study 678910 This change, to a relativistic electron-intense laser radiative interaction, is termed inverse Compton scattering ICSallows one to reach similar photon energies as reached by magnetostatic undulators with two orders of magnitude lower energy electron beams.

Further, the ICS approach is uniquely suitable for the production of very high-energy photons.

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Given such possibilities, an ICS-based X-ray source possesses desirable characteristics for many X-ray applications that demand narrow bandwidth, short pulse, and directional high-flux X-ray beams. To this end, it is possible to use the same laser pulse utilized for the Compton interaction to enable a compact, high-gradient electron accelerator based on the inverse free-electron laser IFEL scheme. An IFEL has the demonstrated capability to produce notably higher than state-of-the-art acceleration gradients in a material free interaction region It thus permits use of the laser for acceleration without the conventional limitations arising from nearby matter in accelerators, i.

Laser recirculation, paired with an electron beam pulse train, has been demonstrated for an ICS source by Ovodenko et al. There is strong global interest in the development of 5 th generation light sources — the use of advanced accelerators to obtain high brilliance keV-to-MeV photon beams, with many projects now being initiated In this paper, we show the use of an IFEL that produces a high quality, micro-bunched accelerated electron beam which in turn feeds a Compton scattering interaction point IP based on the same laser system, for the production of a narrow bandwidth, directional, pulsed X-rays.

We thus demonstrate a unique all-optically driven, electron beam-based X-ray source. This is an important step forward in the burgeoning research into advanced accelerators and their use in real world applications, in particular compact light sources. The experimental challenges encountered required addressing frontier demands in accelerator physics concerning beam quality 19 and have pushed forward experimental techniques needed to arrive at yet higher energy applications of advanced accelerators We first review some basic properties of the ICS process.

In practice, the scattering takes place in the context of a highly focused, short pulse beam of electrons colliding with a laser pulse of similar spatio-temporal characteristics. There are a number of aspects of the interaction arising from the distribution of electron and photon angles in the beams, as well as the influence of the finite time of laser-electron interaction, that affect the flux, bandwidth, and divergence of the X-ray photon distribution generated The most basic of these considerations is that the total number of generated X-rays is proportional to the number of electrons and laser photons available for interaction as well as the cross-sectional overlap of the two beams, i.Thank you for visiting nature.

You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. A Nature Research Journal. With gigaelectron-volts per centimetre energy gains and femtosecond electron beams, laser wakefield acceleration LWFA is a promising candidate for applications, such as ultrafast electron diffraction, multistaged colliders and radiation sources betatron, compton, undulator, free electron laser.

However, for some of these applications, the beam performance, for example, energy spread, divergence and shot-to-shot fluctuations, need a drastic improvement.

Here, we show that, using a dedicated transport line, we can mitigate these initial weaknesses. We demonstrate that we can manipulate the beam longitudinal and transverse phase-space of the presently available LWFA beams. Indeed, we separately correct orbit mis-steerings and minimise dispersion thanks to specially designed variable strength quadrupoles, and select the useful energy range passing through a slit in a magnetic chicane.

These results pave the way to applications demanding in terms of beam quality.

x-gray sources based on electron laser-plasma acceleration

The capacity of plasma waves to produce and sustain extremely strong electric fields gave rise to a high interest for plasma-based electron acceleration 1.

In the past decade, the concept of laser wakefield acceleration LWFA has become a reality 234. Worldwide efforts presently aim at improving LWFA performance, targeting applications, such as undulator synchrotron radiation 56free electron lasers 789intrinsic betatron radiation 10ultrafast electron diffraction sources 11 and even high-energy colliders In modern LWFA schemes, a high-power femtosecond laser is focused into a gas target and resonantly drives a nonlinear plasma wave.

The charge-separation fields in such waves are much larger than in the radio-frequency cavities of conventional accelerators. Being able to trap the ambient plasma electrons, plasma fields accelerate them to hundreds of megaelectron-volts over few millimetre distances 1314 The characteristics of the produced electron beams strongly depend on how they are injected into the accelerating plasma structures.

Depending on the desired application, the LWFA can be based on self injection 2341617on triggering local injection using an auxiliary laser pulse 1819 or by creating sharp plasma density transitions 2021 The localised injection requires more complicated setups but can significantly improve beam quality in terms of energy spread and divergence.

In both configurations, the ionisation injection 2223242526which uses a gas with a mixture of low and high atomic number ions, enables an improvement in the source stability 2227but may also lead to a higher energy spread. By guiding the laser pulse at high intensity over a longer distance, high-energy electrons are obtained


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