Benjamin Cowan
We discuss the potential for using microfabrication techniques for laser-driven accelerator construction. We introduce microfabrication processes in general, and then describe our investigation of a particular trial process. We conclude by considering the issues microfabrication raises for possible future structures.
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In this paper, we use PIC code Vorpal to do the extensive simulation about the laser plasma accelerator in the linear, quasilinear and nonlinear regime respectively. We design the ~100 MeV or so laser plasma accelerator ( LPA ) via Vorpal simulation. Finally, we discuss the application of the designed LPA in the compact light source field.
The spectacular development of Laser-Plasma Accelerators (LPA) appears very promising for a free electron laser application. The handling of the inherent properties of those LPA beams already allowed controlled production of LPA-based spontaneous undulator radiation. Stepping further, we here unveil that the forthcoming LPA-based seeded FELs will present singular spatio-spectral distributions. Relying on numerical simulations and simple analytical models, we show how those interferometric patterns can be exploited to retrieve, in single-shot, the spectro-temporal content and source point prope…
Laser plasma accelerators have the potential to reduce the size of future linacs for high energy physics by more than an order of magnitude, due to their high gradient. Research is in progress at current facilities, including the BELLA PetaWatt laser at LBNL, towards high quality 10 GeV beams and staging of multiple modules, as well as control of injection and beam quality. The path towards high-energy physics applications will likely involve hundreds of such stages, with beam transport, conditioning and focusing. Current research focuses on addressing physics and R&D challenges required for a…
Plasma wakefield accelerators driven by particle beams are capable of providing accelerating gradient several orders of magnitude higher than currently used radio-frequency technology, which could reduce the length of particle accelerators, with drastic influence on the development of future colliders at TeV energies and the minimization of x-ray free-electron lasers. Since inter-plasma components and distances are among the biggest contributors to the total accelerator length, the design of staged plasma accelerators is one of the most important outstanding questions in order to render this t…
The resonant laser cooling of circular accelerator beams of relativistic charged particle is studied. It is shown that in the approximation of the given external electromagnetic wave amplitude (small gain free electron laser) the emittance of a beam of charged particles decreases. In the field of particle energy about 100 in the mass energy units the beam energy losses are negligible. The discovered effect can be used for cooling of charged particle beams in various accelerators. The significant cooling rates are possible to achieve by placing of the cooling device in the appropriate points of…
Using an 800 nm, 45 fs pulse-front-tilted laser we demonstrate a record 315 keV energy gain in a dual grating dielectric laser accelerator (DLA) and average accelerating gradients of 560 MV/m over 0.5 mm. These results open a new regime in DLA characterized by significant evolution of the beam distribution in the longitudinal phase space, corresponding to >1/4 of a synchrotron oscillation. By tilting the laser wavefront we control the resonant velocity of the DLA and observe a net energy gain, indicating that a tapered optical phase could be used to achieve very high energy gain.
Laser-based electron acceleration is attracting strong interest from the conventional accelerator community due to its outstanding characteristics in terms of high initial energy, low emittance and high beam current. Unfortunately, such beams are currently not comparable to those of conventional accelerators, limiting their use for the manifold applications that a traditional accelerator can have. Besides working on the plasma source itself, a promising approach to shape the laser-generated beams is coupling them with conventional accelerator elements in order to benefit from both, a versatile…
In this paper, we simply outline the present status of the free electron laser and the laser plasma based accelerator, and we simply discuss the potential possible roads appearing in the accelerator community to use the laser plasma based accelerator into the field of the free electron laser.
C. B. Schroeder, E. Esarey, C. Benedetti, and W. P. Leemans {Phys. Rev. ST Accel. Beams 13, 101301 (2010) and 15, 051301 (2012)} have proposed a set of parameters for a TeV-scale collider based on plasma wake field accelerator principles. In particular, it is suggested that the luminosities greater than 10^34 cm-2s-1 are attainable for an electron-positron collider. In this comment we dispute this set of parameters on the basis of first principles. The interactions of accelerating beam with plasma impose fundamental limitations on beam properties and, thus, on attainable luminosity values.
Particle acceleration in dielectric microstructures powered by infrared lasers, or "dielectric laser acceleration" (DLA), is a promising area of advanced accelerator research with the potential to enable more affordable and higher-gradient accelerators for energy frontier science and a variety of other applications. DLA leverages well-established industrial fabrication capabilities and the commercial availability of tabletop lasers to reduce cost, with axial accelerating fields in the GV/m range. Desirable luminosities would be obtained by operating with very low charge per bunch but at extrem…
Photonic crystals have great potential for use as laser-driven accelerator structures. A photonic crystal is a dielectric structure arranged in a periodic geometry. Like a crystalline solid with its electronic band structure, the modes of a photonic crystal lie in a set of allowed photonic bands. Similarly, it is possible for a photonic crystal to exhibit one or more photonic band gaps, with frequencies in the gap unable to propagate in the crystal. Thus photonic crystals can confine an optical mode in an all-dielectric structure, eliminating the need for metals and their characteristic losses…
In laser illuminated dielectric accelerators (DLA) high acceleration gradients can be achieved, due to high damage thresholds of the materials at optical frequencies. This is a necessity in developing more compact particle accelerator technologies. The Accelerator on a CHip International Program funded by the Gordon and Betty Moore Foundation is researching such devices. Means to manipulate the beam, i.e. focusing and deflection, are needed for the proper operation of such devices. These means should rely on the same technologies for manufacturing and powering like the accelerating structures.…
Revealing Laser and Electron Beam Evolution in 10-GeV-class Laser-Plasma Accelerators
通过结合纵向分辨的电子束诊断与激光谱演变测量，研究10 GeV级LPA中等离子体密度分布，验证模拟显示延长加速器长度可将电子束能量提升至15 GeV，甚至通过线性匹配实现20 GeV电子束。
In this paper, we get the 1D approximate analytical solution of the plasma electrostatic wake driven by the laser, and get the oscillating frequency of the wake modified by the nonlinear high order terms, and find that the frequency depends on the oscillating amplitudes of the wake and the laser which is the general nonlinear phenomenon. Finally we analyze the longitudinal beam dynamics in this electrostatic wake, and find that the high order terms don't change the topology of the longitudinal phase space.
Dielectric laser accelerators (DLAs) have proven to be good candidates for miniaturized particle accelerators. They rely on micro-fabricated dielectrics which are able to modulate the kinetic energy of the incoming electron beam under a proper laser illumination. In this paper we demonstrate a dual pillar structure with a distributed Bragg reflector to mimic a double sided illumination to the electron path. The structure is fabricated by an electron beam lithography technique followed by a cryogenic reactive ion etching process. Such a structure can accelerate the injected 28 keV electrons by …
We report the initial considerations of using linearly polarized optical transition radiation (OTR) to characterize the electron beams of laser plasma accelerators (LPAs) such as at the Univ. of Texas at Austin. The two LPAs operate at 100 MeV and 2-GeV, and they currently have estimated normalized emittances at ~ 1-mm mrad regime with beam divergences less than 1/γ and beam sizes to be determined at the micron level. Analytical modeling results indicate the feasibility of using these OTR techniques for the LPA applications.
ARES (Accelerator Research Experiment at SINBAD) is a linear accelerator at the SINBAD (Short INnovative Bunches and Accelerators at DESY) facility at DESY. ARES was designed to combine reproducible beams from conventional RF-based accelerator technology with novel but still experimental acceleration techniques. It aims to produce high brightness ultra-short electron bunches in the range of sub fs to few fs, at a beam energy of 100-150 MeV, suitable for injection into novel acceleration experiments like Dielectric Laser Acceleration (DLA) and Laser driven Plasma Acceleration (LPA). This paper …
We report on electron wakefield acceleration in the resonant bubble regime with few-millijoule near-single-cycle laser pulses at a kilohertz repetition rate. Using very tight focusing of the laser pulse in conjunction with microscale supersonic gas jets, we demonstrate a stable relativistic electron source with a high charge per pulse up to 24 pC/shot. The corresponding average current is 24 nA, making this kilohertz electron source useful for various applications.
Laser powered dielectric structures achieve high-gradient particle acceleration by taking advantage of modern laser technology capable of producing electric fields in excess of 10GV/m. These fields can drive the bulk dielectric beyond its linear response, and break the phase synchronicity between the accelerating field and the electrons. We show how control of the pulse dispersion can be used to compensate the effect of self-phase modulation and maximize the energy gain in the laser accelerator.In our experiment, a high brightness 8MeV e-beam is used to probe accelerating fields of 1.8GV/m in …
Development of an achromatic spectrometer for a laser-wakefield-accelerator experiment
本文提出了一种色散谱仪的设计，用于诊断和优化等离子体相互作用，通过非线性等离子体透镜实现高发散和能量分散电子束的高分辨率分析。
We describe a new approach for driving GeV-scale plasma accelerators with long laser pulses. We show that the temporal phase of a long, high-energy driving laser pulse can be modulated periodically by co-propagating it with low-amplitude plasma wave driven by a short, low-energy seed pulse. Compression of the modulated driver by a dispersive optic generates a train of short pulses suitable for resonantly driving a plasma accelerator. Modulation of the driver occures via well-controlled linear process, as confirmed by good agreement between particle-in-cell (PIC) simulations and an analytic mod…
The Extreme Light Infrastructure (ELI) Beamlines is a laser driven accelerator facility located in the outskirts of the city of Prague. With its state-of-the-art lasers, it will carry out an ambitious and diverse research program. Activities at ELI Beamlines can be broken down in complementary areas of scientific interest: development and testing of novel technologies for multi-PW laser systems, plasma physics, high field physics experiments, production of femtosecond secondary sources of ionizing radiation (extreme ultraviolet radiation, X rays, gamma, electrons, and protons)to be used in int…
In order to demonstrate acceleration of electrons to relativistic scales by an on chipdielectric laser accelerator (DLA), a ponderomotive focusing scheme capable of capturingand transporting electrons through nanometer-scale apertures over extended interactionlengths has been proposed. We present a Matlab-based numerical code (SHarD) utilizinga spatial harmonic expansion of the fields within the dielectric structure to simulate theevolution of the beam phase space distribution in this scheme. The code can be usedto optimize key-parameters for the accelerator performance such as the final energ…
The widespread use of high energy particle beams in basic research, medicine and coherent X-ray generation coupled with the large size of modern radio frequency (RF) accelerator devices and facilities has motivated a strong need for alternative accelerators operating in regimes outside of RF. Working at optical frequencies, dielectric laser accelerators (DLAs) - transparent laser-driven nanoscale dielectric structures whose near fields can synchronously accelerate charged particles - have demonstrated high-gradient acceleration with a variety of laser wavelengths, materials, and electron beam …
Accelerator-based light sources such as storage rings and free-electron lasers use relativistic electron beams to produce intense radiation over a wide spectral range for fundamental research in physics, chemistry, materials science, biology and medicine. More than a dozen such sources operate worldwide, and new sources are being built to deliver radiation that meets with the ever increasing sophistication and depth of new research. Even so, conventional accelerator techniques often cannot keep pace with new demands and, thus, new approaches continue to emerge. In this article, we review a var…
In this paper we discuss the possibility to generate and accelerate proton nanobeams in fully dielectric laser-driven accelerators (p-DLAs). High gradient on-chip optical-power dielectric laser accelerators (DLAs) could represent one of the most promising way towards future miniaturized particle accelerator. A primary challenge for DLAs are small beam apertures having a size of the order of the driving laser wavelength where low charge high-repetition (or also CW) ultralow emittance nanobeams have to be transported. For electrons beams generation and acceleration, intense research activities a…
Dielectric laser-driven accelerators (DLAs) can provide high accelerating gradients in the GV/m range due to their having higher breakdown thresholds than metals, which opens the way for the miniaturization of the next generation of particle accelerator facilities. Two kinds of scheme, the addition of a Bragg reflector and the use of pulse-front-tilted (PFT) laser illumination, have been studied separately to improve the energy efficiency for dual-grating DLAs. The Bragg reflector enhances the accelerating gradient of the structure, while the PFT increases the effective interaction length. In …
We report observations of coherent optical transition radiation interferometry (COTRI) patterns generated by microbunched ~200-MeV electrons as they emerge from a laser-plasma accelerator. The divergence of the microbunched portion of electrons, deduced by comparison to an analytical COTRI model, is ~6x smaller than the ~3 mrad ensemble beam divergence, while the radius of the microbunched beam, obtained from COTR images on the same shot, is < 3 microns. The combined results show that the microbunched distribution has estimated transverse normalized emittance ~0.5 mm mrad.
A Compact laser plasma accelerator (CLAPA) is being built in Peking University, which is based on RPA-PSA mechanism or other acceleration mechanisms. According to the beam parameters from preparatory experiments and theoretical simulations, the beam line is preliminarily designed. The beam line is mainly constituted by common transport elements to deliver proton beam with the energy of 1~50MeV, energy spread of 0~1% and current of 0~108 proton per pulse to satisfy the requirement of different experiments. The simulation result of 15MeV proton beam with an energy spread of 1%, current of 1x108 …
Laser-Plasma Accelerator Beams in Light Sources: Femtosecond High-Brightness Radiation through Chirped Pulse Injection
该研究提出啁啾脉冲注入方案，将激光等离子体电子束注入PETRA IV等硬X射线同步光源，可提供千安级短脉冲并产生飞秒相干辐射，为光源领域提供新方案。
Subrelativistic Alternating Phase Focusing Dielectric Laser Accelerators
该研究提出两种硅基交替相位聚焦介质激光加速器设计，通过分数周期漂移段调整相位实现电子长程加速与约束，实验验证了亚相对论条件下的显著能量增益。
In dielectric laser-driven accelerators (DLA), careful tuning of drive-laser wavelength and structure periodicity is typically required in order to hit the resonant condition and match the phase velocity of the accelerating wave to the electron beam velocity. By aggressively detuning (up to 30 mrad) the angle of incidence of the drive laser on a double grating DLA structure, we show that it is possible to recover resonant phase matching and maximize the energy modulation of an externally injected 6 MeV beam in a 800 nm period structure driven using a 780 nm laser. These results show that it is…
The concept of dielectric-laser acceleration (DLA) provides the highest gradients among breakdown-limited (nonplasma) particle accelerators and thus the potential of miniaturization. The implementation of a fully scalable electron accelerator on a microchip by twodimensional alternating phase focusing (APF), which relies on homogeneous laser fields and external magnetic focusing in the third direction, was recently proposed. In this Letter, we generalize the APF for DLA scheme to 3D, such that stable beam transport and acceleration is attained without any external equipment, while the structur…
White paper to the Proceedings of the U.S. Particle Physics Community Planning Exercise (Snowmass 2021): Linear colliders based on laser-plasma accelerators
It is reported that [Z. Huang et al., Phys. Rev. Lett. 109, 204801 (2012)], high-gain free-electron laser (FEL) can be generated by transverse-dispersed electron beams from laser-plasma accelerators (LPAs) using transverse-gradient undulator (TGU) assuming an ideal constant dispersion function without focusing optics. The constant dispersion function keeps electrons beyond the resonant energy bandwidth still being on resonant with the FEL radiation. Instead, in this paper, the case with focusing optics in an LPA-driven FEL using TGU is numerically studied, in which the dispersion function shou…
Laser wakefield acceleration offers the promise of a compact electron accelerator for generating a multi-GeV electron beam using the huge field gradient induced by an intense laser pulse, compared to conventional rf accelerators. However, the energy and quality of the electron beam from the laser wakefield accelerator have been limited by the power of the driving laser pulses and interaction properties in the target medium. Recent progress in laser technology has resulted in the realization of a petawatt (PW) femtosecond laser, which offers new capabilities for research on laser wakefield acce…
The use of dielectric microstructures driven by solid state lasers to accelerate charged particles or to transversely deflect them is a growing area of scientific interest with an international collaboration of researchers working to develop this concept. Many experimental efforts and new designs use a planar symmetric geometry with sub-micron apertures for the particle beam. We provide a general theoretical framework for the electromagnetic fields in this type of geometry, including derivation of the TE and TM modes supported, and examine the transverse force components exerted on the beam, w…
Dielectric laser acceleration (DLA) is one of the advanced concepts for more compact accelerators. DLA gratings have apertures and period lengths within the range of optical wavelengths. Phase stability and wakefield effects are thus crucial for upcoming experiments with relativistic electrons. For this, we present a method to analytically calculate energy spectra for comparison with measurements in order to reconstruct the phase of injection into the DLA grating structure. Knowing the injection phase is important for both alignment and interpretation of measured data. Furthermore, we estimate…
This paper presents the pre-experiment plan and prediction of the first stage of Vacuum Laser Acceleration (VLA) collaborating by UCLA, Fudan University and ATF-BNL. This first stage experiment is a Proof-of-Principle to support our previously posted novel VLA theory. Simulations show that based on ATF's current experimental conditions, the electron beam with initial energy of 15MeV can get net energy gain from intense CO2 laser beam. The difference of electron beam energy spread is observable by ATF beam line diagnostics system. Further this energy spread expansion effect increases along with…
Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our pro…
Particle acceleration in microstructures driven by ultrafast solid state lasers is a rapidly evolving area of advanced accelerator research, leading to a variety of concepts based on planar-symmetric dielectric gratings, hollow core fibers, photonic crystals, and plasmonic meta-surfaces. This approach leverages well-established industrial fabrication capabilities and the commercial availability of tabletop lasers to reduce cost, with demonstrated axial accelerating fields in the GV/m range. Wide-ranging international efforts have significantly improved understanding of gradient limits, structu…
In order to study the dynamic response of the material and the physical mechanism of the fluid dynamics, an accelerator scenario which can be applied to hard X-ray free electron laser and high energy electron radiography was proposed. This accelerator is mainly composed of a 12GeV linac, an undulator branch and an eRad beamline. In order to characterize sample's dynamic behavior in situ and real-time with XFEL and eRad simultaneously, the linac should be capable of accelerating the two kinds of beam within the same operation mode. Combining with in-vacuum and tapering techniques, the undulator…
Dielectric laser accelerators (DLAs) use the nearfields created when a laser pulse impinges on a dielectric structure to accelerate charged particles. We provide an overview of the theory of operation of photon driven accelerators, from photons interacting with charged particles in a vacuum, to the advantages gained by introducing dielectric structures, with a discussion of their advantages and limitations. Furthermore we show the state of the art of the current development of dielectric laser accelerators, including acceleration, focusing, deflection, beam position monitoring, and advanced to…
Radio frequency particle accelerators are ubiquitous in ultra-small and ultrafast science, but their size and cost has prompted exploration of compact and scalable alternatives like the dielectric laser accelerator. We present the first demonstration of high gradient laser acceleration and deflection of electrons with a silicon structure. Driven by a five nanojoule, 130 fs mode-locked Ti:Sapphire laser at 907 nm wavelength, our devices achieve accelerating gradients in excess of 200 MeV/m and sub-optical cycle streaking of 96.30 keV electrons. These results pave the way for high gradient silic…
We study the energetics of wake excitation during the laser-plasma interaction in application to laser wakefield accelerators. We find that both the wake amplitude and the accelerating efficiency (transformer ratio) can be maximized by properly shaping the longitudinal profile of the driving laser pulse. The corresponding family of laser pulse shapes is derived in the nonlinear regime of laser-plasma interaction. Such shapes provide theoretical upper limit on the magnitude of the wakefield and efficiency by allowing for uniform photon deceleration inside the laser pulse. We also construct real…
The question of suitability of transfer matrix description of electrons traversing grating-type dielectric laser acceleration (DLA) structures is addressed. It is shown that although matrix considerations lead to interesting insights, the basic transfer properties of DLA cells cannot be described by a matrix. A more general notion of a transfer function is shown to be a simple and useful tool for formulating problems of particle dynamics in DLA. As an example, a focusing structure is proposed which works simultaneously for all electron phases.
X-ray Free-Electron Laser accelerator to study on Quantum Electro-Dynamics
本研究利用X射线自由电子激光产生的高能电子束与反射X射线脉冲碰撞，研究电子-正电子对产生过程，提出成本效益高的实验方案并估算参数。
The notions of acceleration gradient and deflection gradient are generalized to phasor quantities (complex-valued functions) in the context of dielectric laser acceleration (DLA). It is shown that the electromagnetic forces imparted on a near-resonant particle traversing a unit cell of a grating-type DLA can be conveniently described by generalized acceleration and deflection gradients. A~simple formulation of the Panofsky-Wenzel theorem in terms of the generalized gradients is given. It is shown that all particle transfer properties of a DLA unit cell can be derived from a single, complex-val…
We convert a GeV laser-plasma electron accelerator into a compact femtosecond-pulsed $γ$-ray source by inserting a $100 μ$m-thick glass plate $\sim3$ cm after the accelerator exit. With near-unity reliability, and requiring only crude alignment, this glass plasma mirror retro-reflected spent drive laser pulses (photon energy $\hbarω_L = 1.17$ eV) with $>50\%$ efficiency back onto trailing electrons (peak Lorentz factor $1000 < γ_e < 4400$), creating an optical undulator that generated $\sim10^8 γ$-ray photons with sub-mrad divergence, estimated peak brilliance $\sim10^{21}$ photons/s/mm$^2$/mr…
We access the possibility of using the conventional RF accelerator as an injector for the plasma driven wakefield accelerator. Conventional accelerators deliver high quality beams with low emittance and low energy spread. Once injected into the plasma wake, the emittance may be preserved upon proper beam matching while the energy spread may not due to long beam duration delivered by the conventional accelerators. Parameters of the overall accelerator system and the free electron laser based on such an accelerator are estimated.
The laser invention more than fifty years ago was a major scientific revolution. Among the different possible gain media, the Free Electron Lasers (FEL) uses free electrons in the periodic permanent magnetic field of an undulator, covering wavelengths from far infrared to X-ray, with easy tuneability and high peak power. Nowadays, the advent of tuneable intense (mJ level) short pulse FELs with record peak power (GW level) in the X-ray domain sets a major step in laser development, and enables to explore new scientific areas, such as deciphering molecular reactions in real time, understanding f…
The one-dimensional wakefield generation equations are solved for increasing levels of non-linearity, to demonstrate how they contribute to the overall behaviour of a non-linear wakefield in a plasma. The effect of laser guiding is also studied as a way to increase the interaction length of a laser wakefield accelerator.
We investigate the effects of a Stern-Gerlach-type addition to the Lorentz force on electrons in a laser wakefield accelerator. The Stern-Gerlach-type terms are found to generate a family of trajectories describing electrons that surf along the plasma density wave driven by a laser pulse. Such trajectories could lead to an increase in the size of an electron bunch, which may have implications for attempts to exploit such bunches in future free electron lasers.
We present methods and preliminary observations of two pulse Direct Laser Acceleration in a Laser-Driven Plasma Accelerator. This acceleration mechanism uses a second co-propagating laser pulse to overlap and further accelerate electrons in a wakefield bubble, increasing energy at the cost of emittance when compared to traditional laser wakefield acceleration (LWFA). To this end, we introduce a method of femtosecond scale control of time delay between two co-propagating pulses. We show energy enhancement when the separation between the two pulses approaches the bubble radius.
Large scale laser facilities are needed to advance the energy frontier in high energy physics and accelerator physics. Laser plasma accelerators are core to advanced accelerator concepts aimed at reaching TeV electron electron colliders. In these facilities, intense laser pulses drive plasmas and are used to accelerate electrons to high energies in remarkably short distances. A laser plasma accelerator could in principle reach high energies with an accelerating length that is 1000 times shorter than in conventional RF based accelerators. Notionally, laser driven particle beam energies could sc…
Research activities on laser plasma accelerators are paved by many significant breakthroughs. This review article provides an opportunity to show the incredible evolution of this field of research which has, in record time, allowed physicists to produce high quality electron beams at the GeV level using compact laser systems. I will show the scientific path that led us to explore different injection schemes and to produce stable, high peak current and high quality electron beams with control of the charge, of the relative energy spread, and of the electron energy.
We present a methodology for designing and measuring pulse front tilt in an ultrafast laser for use in dielectric laser acceleration. Previous research into dielectric laser accelerating modules has focused on measuring high accelerating gradients in novel structures, but has done so only for short electron-laser coupling lengths. Here we demonstrate an optical design to extend the laser-electron interaction to 1mm.
Single cycle laser pulse propagating inside a plasma causes controllable asymmetric plasma electron expulsion from laser according to laser carrier envelope phase (CEP) and forms an oscillating plasma bubble. Bubble's transverse wakefield is modified, exhibiting periodic modulation. Injection scheme for a laser wakefield accelerator combining a single cycle low frequency laser pulse and a many cycle high frequency laser pulse is proposed. The co-propagating laser pulses form a transversely oscillating wakefield which efficiently traps and accelerates electrons from background plasma. By tuning…
A high repetition rate electron source was generated by tightly focusing kHz, few-mJ laser pulses into an underdense plasma. This high intensity laser-plasma interaction led to stable electron beams over several hours but with strikingly complex transverse distributions even for good quality laser focal spots. Analysis of the experimental data, along with results of PIC simulations demonstrate the role of the laser wavefront on the acceleration of electrons. Distortions of the laser wavefront cause spatial inhomogeneities in the out-of-focus laser distribution and consequently, the laser pulse…
Laser-driven plasma accelerators provide acceleration gradients three orders of magnitude greater than conventional machines, offering the potential to shrink the length of accelerators by the same factor. To date, laser-acceleration of electron beams to particle energies comparable to those offered by synchrotron light sources has been demonstrated with plasma acceleration stages only a few centimetres long. This article describes the principles of operation of laser-driven plasma accelerators, and reviews their development from their proposal in 1979 to recent demonstrations. The potential a…
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