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Sample records for laser wakefield simulation

  1. Wakefield Simulations for the Laser Acceleration Experiment at SLAC

    SciTech Connect

    Ng, Johnny

    2012-04-18

    Laser-driven acceleration in dielectric photonic band gap structures can provide gradients on the order of GeV/m. The small transverse dimension of the structure, on the order of the laser wavelength, presents interesting wakefield-related issues. Higher order modes can seriously degrade beam quality, and a detailed understanding is needed to mitigate such effects. On the other hand, wakefields also provide a direct way to probe the interaction of a relativistic bunch with the synchronous modes supported by the structure. Simulation studies have been carried out as part of the effort to understand the impact on beam dynamics, and to compare with data from beam experiments designed to characterize candidate structures. In this paper, we present simulation results of wakefields excited by a sub-wavelength bunch in optical photonic band gap structures.

  2. SCALED SIMULATION DESIGN OF HIGH QUALITY LASER WAKEFIELD ACCELERATOR STAGES

    SciTech Connect

    Geddes, C.G.R.; Cormier-Michel, E.; Esarey, E.; Schroeder, C.B.; Leemans, W.P.; Bruhwiler, D.L.; Cowan, B.; Nieter, C.; Paul, K.; Cary, J.R.

    2009-05-04

    Design of efficient, high gradient laser driven wakefield accelerator (LWFA) stages using explicit particle-incell simulations with physical parameters scaled by plasma density is presented. LWFAs produce few percent energy spread electron bunches at 0.1-1 GeV with high accelerating gradients. Design tools are now required to predict and improve performance and efficiency of future LWFA stages. Scaling physical parameters extends the reach of explicit simulations to address applications including 10 GeV stages and stages for radiation sources, and accurately resolves deep laser depletion to evaluate efficient stages.

  3. Automated analysis for detecting beams in laser wakefield simulations

    SciTech Connect

    Ushizima, Daniela M.; Rubel, Oliver; Prabhat, Mr.; Weber, Gunther H.; Bethel, E. Wes; Aragon, Cecilia R.; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Hamann, Bernd; Messmer, Peter; Hagen, Hans

    2008-07-03

    Laser wakefield particle accelerators have shown the potential to generate electric fields thousands of times higher than those of conventional accelerators. The resulting extremely short particle acceleration distance could yield a potential new compact source of energetic electrons and radiation, with wide applications from medicine to physics. Physicists investigate laser-plasma internal dynamics by running particle-in-cell simulations; however, this generates a large dataset that requires time-consuming, manual inspection by experts in order to detect key features such as beam formation. This paper describes a framework to automate the data analysis and classification of simulation data. First, we propose a new method to identify locations with high density of particles in the space-time domain, based on maximum extremum point detection on the particle distribution. We analyze high density electron regions using a lifetime diagram by organizing and pruning the maximum extrema as nodes in a minimum spanning tree. Second, we partition the multivariate data using fuzzy clustering to detect time steps in a experiment that may contain a high quality electron beam. Finally, we combine results from fuzzy clustering and bunch lifetime analysis to estimate spatially confined beams. We demonstrate our algorithms successfully on four different simulation datasets.

  4. Simulation study of wakefield generation by two color laser pulses propagating in homogeneous plasma

    SciTech Connect

    Kumar Mishra, Rohit; Saroch, Akanksha; Jha, Pallavi

    2013-09-15

    This paper deals with a two-dimensional simulation of electric wakefields generated by two color laser pulses propagating in homogeneous plasma, using VORPAL simulation code. The laser pulses are assumed to have a frequency difference equal to the plasma frequency. Simulation studies are performed for two similarly as well as oppositely polarized laser pulses and the respective amplitudes of the generated longitudinal wakefields for the two cases are compared. Enhancement of wake amplitude for the latter case is reported. This simulation study validates the analytical results presented by Jha et al.[Phys. Plasmas 20, 053102 (2013)].

  5. Laser wakefield simulation using a speed-of-light frame envelope model

    SciTech Connect

    Cowan, B.; Bruhwiler, D.; Messmer, P.; Paul, K.; Cormier-Michel, E.; Geddes, C. G. R.; Esarey, E.

    2009-01-22

    Simulation of laser wakefield accelerator (LWFA) experiments is computationally intensive due to the disparate length scales involved. Current experiments extend hundreds of laser wavelengths transversely and many thousands in the propagation direction, making explicit PIC simulations enormously expensive and requiring massively parallel execution in 3D. We can substantially improve the performance of laser wakefield simulations by modeling the envelope modulation of the laser field rather than the field itself. This allows for much coarser grids, since we need only resolve the plasma wavelength and not the laser wavelength, and therefore larger timesteps. Thus an envelope model can result in savings of several orders of magnitude in computational resources. By propagating the laser envelope in a frame moving at the speed of light, dispersive errors can be avoided and simulations over long distances become possible. Here we describe the model and its implementation, and show simulations and benchmarking of laser wakefield phenomena such as channel propagation, self-focusing, wakefield generation, and downramp injection using the model.

  6. Laser wakefield simulation using a speed-of-light frame envelope model

    SciTech Connect

    Cowan, B.; Bruhwiler, D.L.; Cormier-Michel, E.; Esarey, E.; Geddes, C.G.R.; Messmer, P.; Paul, K.

    2008-09-08

    Simulation of laser wakefield accelerator (LWFA) experiments is computationally intensive due to the disparate length scales involved. Current experiments extend hundreds of laser wavelengths transversely and many thousands in the propagation direction, making explicit PIC simulations enormously expensive and requiring massively parallel execution in 3D. We can substantially improve the performance of laser wakefield simulations by modeling the envelope modulation of the laser field rather than the field itself. This allows for much coarser grids, since we need only resolve the plasma wavelength and not the laser wavelength, and therefore larger timesteps. Thus an envelope model can result in savings of several orders of magnitude in computational resources. By propagating the laser envelope in a frame moving at the speed of light, dispersive errors can be avoided and simulations over long distances become possible. Here we describe the model and its implementation, and show simulations and benchmarking of laser wakefield phenomena such as channel propagation, self-focusing, wakefield generation, and downramp injection using the model.

  7. Envelope Model Simulation of Laser Wakefield Acceleration with Realistic Laser Pulses from the Texas Petawatt

    NASA Astrophysics Data System (ADS)

    Weichman, Kathleen; Higuera, Adam; Abell, Dan; Cowan, Ben; Fazel, Neil; Cary, John; Downer, Michael

    2015-11-01

    In a laser wakefield accelerator (LWFA), diffraction of an over-focused laser pulse can provide localized electron injection, leading to the production of a monoenergetic electron bunch. While electron energies up to several GeV have been reported at the Texas Petawatt Laser facility, near-Gaussian beam simulations predict energies higher than have been observed. Experimentally measured laser profiles are non-Gaussian, indicating that closer agreement with experimental conditions is needed to predictively model this experiment. The implementation of the envelope model in the particle-in-cell code VORPAL lowers the computational cost of capturing injection dynamics during the early evolution of laser wakefields. We compare VORPAL envelope model simulations using laser pulses based on experimentally measured profiles versus a corresponding a two-Gaussian approximation. We acknowledge DOE Grants No. DE-SC0011617 and DE-SC0012444, DOE/NSF Grant No. DE-SC0012584, and the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. KW is supported by the DOE CSGF under Grant No. DE-FG02-97ER25308.

  8. Simulation of electron post-acceleration in a two-stage laser Wakefield accelerator

    SciTech Connect

    Reitsma, A.J.W.; Leemans, W.P.; Esarey, E.; Kamp, L.P.J.; Schep, T.J.

    2002-04-01

    Electron bunches produced in self-modulated laser wakefield experiments usually have a broad energy spectrum, with most electrons at low energy (1-3 MeV) and only a small fraction at high energy. We propose and investigate further acceleration of such bunches in a channel-guided resonant laser wakefield accelerator. Two-dimensional simulations with and without the effects of self-consistent beam loading are performed and compared. These results indicate that it is possible to trap about 40 percent of the injected bunch charge and accelerate this fraction to an average energy of about 50 MeV in a plasma channel of a few mn.

  9. Modeling laser wakefield accelerator experiments with ultrafast particle-in-cell simulations in boosted frames

    SciTech Connect

    Martins, S. F.; Fonseca, R. A.; Vieira, J.; Silva, L. O.

    2010-05-15

    The development of new laser systems at the 10 Petawatt range will push laser wakefield accelerators to novel regimes, for which theoretical scalings predict the possibility to accelerate electron bunches up to tens of GeVs in meter-scale plasmas. Numerical simulations will play a crucial role in testing, probing, and optimizing the physical parameters and the setup of future experiments. Fully kinetic simulations are computationally very demanding, pushing the limits of today's supercomputers. In this paper, the recent developments in the OSIRIS framework [R. A. Fonseca et al., Lect. Notes Comput. Sci. 2331, 342 (2002)] are described, in particular the boosted frame scheme, which leads to a dramatic change in the computational resources required to model laser wakefield accelerators. Results from one-to-one modeling of the next generation of laser systems are discussed, including the confirmation of electron bunch acceleration to the energy frontier.

  10. Front-to-end simulations of the design of a laser wakefield accelerator with external injection

    SciTech Connect

    Urbanus, W.H.; Dijk, W. van; Geer, S.B. van der; Brussaard, G.J.H.; Wiel, M.J. van der

    2006-06-01

    We report the design of a laser wakefield accelerator (LWA) with external injection by a rf photogun and acceleration by a linear wakefield in a capillary discharge channel. The design process is complex due to the large number of intricately coupled free parameters. To alleviate this problem, we performed front-to-end simulations of the complete system. The tool we used was the general particle-tracking code, extended with a module representing the linear wakefield by a two-dimensional traveling wave with appropriate wavelength and amplitude. Given the limitations of existing technology for the longest discharge plasma wavelength ({approx}50 {mu}m) and shortest electron bunch length ({approx}100 {mu}m), we studied the regime in which the wakefield acts as slicer and buncher, while rejecting a large fraction of the injected bunch. The optimized parameters for the injected bunch are 10 pC, 300 fs at 6.7 MeV, to be injected into a 70 mm long channel at a plasma density of 7x10{sup 23} m{sup -3}. A linear wakefield is generated by a 2 TW laser focused to 30 {mu}m. The simulations predict an accelerated output of 0.6 pC, 10 fs bunches at 90 MeV, with energy spread below 10%. The design is currently being implemented. The design process also led to an important conclusion: output specifications directly comparable to those reported recently from 'laser-into-gas jet' experiments are feasible, provided the performance of the rf photogun is considerably enhanced. The paper outlines a photogun design providing such a performance level.

  11. Quasi-phase-matched laser wakefield acceleration.

    PubMed

    Yoon, S J; Palastro, J P; Milchberg, H M

    2014-04-01

    The energy gain in laser wakefield acceleration is ultimately limited by dephasing, occurring when accelerated electrons outrun the accelerating phase of the wakefield. We apply quasi-phase-matching, enabled by axially modulated plasma channels, to overcome this limitation. Theory and simulations are presented showing that weakly relativistic laser intensities can drive significant electron energy gains. PMID:24745430

  12. Benchmarking the codes VORPAL, OSIRIS, and QuickPIC with Laser Wakefield Acceleration Simulations

    SciTech Connect

    Paul, Kevin; Huang, C.; Bruhwiler, D.L.; Mori, W.B.; Tsung, F.S.; Cormier-Michel, E.; Geddes, C.G.R.; Cowan, B.; Cary, J.R.; Esarey, E.; Fonseca, R.A.; Martins, S.F.; Silva, L.O.

    2008-09-08

    Three-dimensional laser wakefield acceleration (LWFA) simulations have recently been performed to benchmark the commonly used particle-in-cell (PIC) codes VORPAL, OSIRIS, and QuickPIC. The simulations were run in parallel on over 100 processors, using parameters relevant to LWFA with ultra-short Ti-Sapphire laser pulses propagating in hydrogen gas. Both first-order and second-order particle shapes were employed. We present the results of this benchmarking exercise, and show that accelerating gradients from full PIC agree for all values of a0 and that full and reduced PIC agree well for values of a0 approaching 4.

  13. Benchmarking the codes VORPAL, OSIRIS, and QuickPIC with Laser Wakefield Acceleration Simulations

    SciTech Connect

    Paul, K.; Bruhwiler, D. L.; Cowan, B.; Cary, J. R.; Huang, C.; Mori, W. B.; Tsung, F. S.; Cormier-Michel, E.; Geddes, C. G. R.; Esarey, E.; Fonseca, R. A.; Martins, S. F.; Silva, L. O.

    2009-01-22

    Three-dimensional laser wakefield acceleration (LWFA) simulations have recently been performed to benchmark the commonly used particle-in-cell (PIC) codes VORPAL, OSIRIS, and QuickPIC. The simulations were run in parallel on over 100 processors, using parameters relevant to LWFA with ultra-short Ti-Sapphire laser pulses propagating in hydrogen gas. Both first-order and second-order particle shapes were employed. We present the results of this benchmarking exercise, and show that accelerating gradients from full PIC agree for all values of a{sub 0} and that full and reduced PIC agree well for values of a{sub 0} approaching 4.

  14. Estimation of direct laser acceleration in laser wakefield accelerators using particle-in-cell simulations

    NASA Astrophysics Data System (ADS)

    Shaw, J. L.; Lemos, N.; Marsh, K. A.; Tsung, F. S.; Mori, W. B.; Joshi, C.

    2016-03-01

    Many current laser wakefield acceleration (LWFA) experiments are carried out in a regime where the laser pulse length is on the order of or longer than the wake wavelength and where ionization injection is employed to inject electrons into the wake. In these experiments, the electrons can gain a significant amount of energy from the direct laser acceleration (DLA) mechanism as well as the usual LWFA mechanism. Particle-in-cell (PIC) codes are frequently used to discern the relative contribution of these two mechanisms. However, if the longitudinal resolution used in the PIC simulations is inadequate, it can produce numerical heating that can overestimate the transverse motion, which is important in determining the energy gain due to DLA. We have therefore carried out a systematic study of this LWFA regime by varying the longitudinal resolution of PIC simulations and then examining the energy gain characteristics of both the highest-energy electrons and the bulk electrons. By calculating the contribution of DLA to the final energies of the electrons produced from the LWFA, we find that even at the highest longitudinal resolutions, DLA contributes a significant portion of the energy gained by the highest-energy electrons and also contributes to accelerating the bulk of the charge in the electron beam produced by the LWFA.

  15. Hybrid Envelope Model/Boosted-Frame Simulations of Laser Wakefield Accelerators

    NASA Astrophysics Data System (ADS)

    Higuera, Adam; Weichman, Kathleen; Abell, Dan; Cowan, Ben; Downer, Michael; Cary, John

    2015-11-01

    Laser wakefield accelerators use a high-intensity laser pulse to drive a wave in a plasma that traps, transports, and accelerates electrons. The Texas Petawatt Laser experiment measures different electron energies (2 GeV) than predicted (7 GeV) by computer simulations. We present and analyze a method for efficiently performing higher-fidelity 3-D, particle-in-cell simulations of laser wakefield acceleration. This method combines previous work on a Laser Envelope Model, which resolves electron self-injection, and boosted-frame simulation, which efficiently models beam propagation in the regime where the Envelope Model is no longer valid. This work is supported by the DOE under Grants No. DE-SC0011617 and DE-SC0012444, by DOE/NSF Grant No. DE-SC0012584, and used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  16. Simulation of laser wakefield acceleration of an ultrashort electron bunch.

    PubMed

    Reitsma, A J; Goloviznin, V V; Kamp, L P; Schep, T J

    2001-04-01

    The dynamics of the acceleration of a short electron bunch in a strong plasma wave excited by a laser pulse in a plasma channel is studied both analytically and numerically in slab geometry. In our simulations, a fully nonlinear, relativistic hydrodynamic description for the plasma wave is combined with particle-in-cell methods for the description of the bunch. Collective self-interactions within the bunch are fully taken into account. The existence of adiabatic invariants of motion is shown to have important implications for the final beam quality. Similar to the one-dimensional case, the natural evolution of the bunch is shown to lead, under proper initial conditions, to a minimum in the relative energy spread. PMID:11308961

  17. Self-mode-transition from laser wakefield accelerator to plasma wakefield accelerator of laser-driven plasma-based electron acceleration

    SciTech Connect

    Pae, K. H.; Choi, I. W.; Lee, J.

    2010-12-15

    Via three-dimensional particle-in-cell simulations, the self-mode-transition of a laser-driven electron acceleration from laser wakefield to plasma-wakefield acceleration is studied. In laser wakefield accelerator (LWFA) mode, an intense laser pulse creates a large amplitude wakefield resulting in high-energy electrons. Along with the laser pulse depletion, the electron bunch accelerated in the LWFA mode drives a plasma wakefield. Then, after the plasma wakefield accelerator mode is established, electrons are trapped and accelerated in the plasma wakefield. The mode transition process and the characteristics of the accelerated electron beam are presented.

  18. Simulating the effects of timing and energy stability in a laser wakefield accelerator with external injection

    SciTech Connect

    Dijk, W. van; Corstens, J. M.; Stragier, X. F. D.; Brussaard, G. J. H.; Geer, S. B. van der

    2009-01-22

    One of the most compelling reasons to use external injection of electrons into a laser wakefield accelerator is to improve the stability and reproducibility of the accelerated electrons. We have built a simulation tool based on particle tracking to investigate the expected output parameters. Specifically, we are simulating the variations in energy and bunch charge under the influence of variations in laser power and timing jitter. In these simulations a a{sub 0} = 0.32 to a{sub 0} = 1.02 laser pulse with 10% shot-to-shot energy fluctuation is focused into a plasma waveguide with a density of 1.0x10{sup 24} m{sup -3} and a calculated matched spot size of 50.2 {mu}m. The timing of the injected electron bunch with respect to the laser pulse is varied from up to 1 ps from the standard timing (1 ps ahead or behind the laser pulse, depending on the regime). The simulation method and first results will be presented. Shortcomings and possible extensions to the model will be discussed.

  19. Laser Wakefield experiments at LULI

    NASA Astrophysics Data System (ADS)

    Marquès, J. R.

    1997-11-01

    In the context of Laser Plasma Particle Acceleration, the Laser Wakefield(T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979)) is a very promising scheme for the excitation of a high amplitude Electron Plasma Waves (EPW). In this scheme, the electrons of the plasma are pushed by the radiation pressure associated with the spatio-temporal profile of an ultra-short (< 1 ps), ultra-intense (> 10^16 W/cm^2) laser pulse. In the wake of this pulse, the electrons oscillate (EPW) around their initial positions. The associated electron-ion charge separation generates electric fields that can be over 100 GV/m. These fields can be longitudinal and of relativistic phase velocity, making them very attractive for high energy particle acceleration. We have studied(J. R. Marquès et al, Phys. Rev. Lett. 79 (18) 3463, 1996; J. R. Marquès et al, Phys. Rev. Lett. 76 (19) 3566, 1996.) the transverse electron oscillations excited by laser wakefield. The amplitude, the frequency, and the lifetime of the oscillation have been measured. The quasi-resonant behavior of the oscillation amplitude with the electron density and the increase of the plasma frequency for oscillations in the non-linear regime have been observed. A comparison of our results with 2-D simulations has allowed us to identify a new damping mechanism linked to a transverse gradient of the electron density. At the moment, we are experimentally studying the longitudinal electron oscillations excited by laser wakefield. Two kind of experiments are in progress. The first one is centered on the acceleration of electrons injected in an EPW, while the second one will characterize the EPW. We will present the results of these experiments.

  20. 3D simulations of pre-ionized and two-stage ionization injected laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Davidson, Asher; Zheng, Ming; Lu, Wei; Xu, Xinlu; Joshi, Chang; Silva, Luis O.; Martins, Joana; Fonseca, Ricardo; Mori, Warren B.

    2012-12-01

    In plasma based accelerators (LWFA and PWFA), the methods of injecting high quality electron bunches into the accelerating wakefield is of utmost importance for various applications. To fully understand the numerical effect of simulating the trapping process, numerous numerical convergence tests were performed to ensure the correctness of preionized simulations which confirm the physical picture first proposed in [1]. We Further investigate the use of a two-stage ionization injected LWFA to achieve high quality monoenergetic beams through the use of 3D PIC simulations. The first stage constitutes the Injection Regime, which is 99.5% He and 0.5% N, while the second stage constitutes the Acceleration Regime, which is entirely composed of He. Two of the simulations model the parameters of the LWFA experiments for the LLNL Callisto laser, at laser powers of 90 and 100TW. energies as high as 680MeV were observed in the 90TW simulation, and those as high as 1.44GeV were observed in the 100TW simulation. The affect of the matching condition of the spot size in this LWFA is discussed.

  1. Simulations of laser-wakefield acceleration with external electron-bunch injection for REGAE experiments at DESY

    SciTech Connect

    Grebenyuk, Julia; Mehrling, Timon; Tsung, Frank S.; Floettman, Klaus; Osterhoff, Jens

    2012-12-21

    We present particle-in-cell simulations for future laser-plasma wakefield experiments with external bunch injection at the REGAE accelerator facility at DESY, Hamburg, Germany. Two effects have been studied in detail: emittance evolution of electron bunches externally injected into a wake, and longitudinal bunch compression inside the wakefield. Results show significant transverse emittance growth during the injection process, if the electron bunch is not matched to its intrinsic betatron motion inside the wakefield. This might introduce the necessity to include beam-matching sections upstream of each plasma-accelerator section with fundamental implications on the design of staged laser wakefield accelerators. When externally injected at the zero-field crossing of the laser-driven wake, the electron bunch may undergo significant compression in longitudinal direction and be accelerated simultaneously due to the gradient in the acting force. The mechanism would allow for production of single high-energy, ultra-short (on the order of one femtosecond) bunches at REGAE. The optimal conditions for maximal bunch compression are discussed in the presented studies.

  2. Comparison of quasi-3D and full-3D laser wakefield PIC simulations using azimuthal mode decomposition

    NASA Astrophysics Data System (ADS)

    Dalichaouch, Thamine; Yu, Peicheng; Davidson, Asher; Mori, Warren; Vieira, Jorge; Fonseca, Ricardo

    2015-11-01

    Laser wakefield acceleration (LWFA) has attracted a lot of interest as a possible compact particle accelerator. However, 3D simulations of plasma-based accelerators are computationally intensive, sometimes taking millions of core hours on today's computers. A quasi-3D particle-In-cell (PIC) approach has been developed to take advantage of azimuthal symmetry in LWFA (and PWFA) simulations by using a particle-in-cell description in r-z and a Fourier description in φ. Quasi-3D simulations of LWFA are computationally more efficient and faster than Full-3D simulations because only first few azimuthal harmonics are needed to capture the physics of the problem. We have developed a cylindrical mode decomposition diagnostic for 3D Cartesian geometry simulations to analyze the agreement between full-3D and quasi-3D PIC simulations of laser and beam-plasma interactions. The diagnostic interpolates field data from Full-3D PIC simulations onto an irregular cylindrical grid (r , φ , z). A Fourier decomposition is then performed on the interpolated 3D simulation data along the azimuthal direction. This diagnostic has the added advantage of separating out the wakefields from the laser field. Preliminary results for this diagnostic of LWFA and PWFA simulations with symmetric and nearly symmetric spot sizes as well as of laser-plasma interactions using lasers with orbital angular momentum (higher order Laguerre-Gaussian modes) will be presented.

  3. Current filamentation instability in laser wakefield accelerators.

    PubMed

    Huntington, C M; Thomas, A G R; McGuffey, C; Matsuoka, T; Chvykov, V; Kalintchenko, G; Kneip, S; Najmudin, Z; Palmer, C; Yanovsky, V; Maksimchuk, A; Drake, R P; Katsouleas, T; Krushelnick, K

    2011-03-11

    Experiments using an electron beam produced by laser-wakefield acceleration have shown that varying the overall beam-plasma interaction length results in current filamentation at lengths that exceed the laser depletion length in the plasma. Three-dimensional simulations show this to be a combination of hosing, beam erosion, and filamentation of the decelerated beam. This work suggests the ability to perform scaled experiments of astrophysical instabilities. Additionally, understanding the processes involved with electron beam propagation is essential to the development of wakefield accelerator applications. PMID:21469796

  4. Current Filamentation Instability in Laser Wakefield Accelerators

    SciTech Connect

    Huntington, C. M.; Drake, R. P.; Thomas, A. G. R.; McGuffey, C.; Matsuoka, T.; Chvykov, V.; Kalintchenko, G.; Yanovsky, V.; Maksimchuk, A.; Krushelnick, K.; Kneip, S.; Najmudin, Z.; Palmer, C.; Katsouleas, T.

    2011-03-11

    Experiments using an electron beam produced by laser-wakefield acceleration have shown that varying the overall beam-plasma interaction length results in current filamentation at lengths that exceed the laser depletion length in the plasma. Three-dimensional simulations show this to be a combination of hosing, beam erosion, and filamentation of the decelerated beam. This work suggests the ability to perform scaled experiments of astrophysical instabilities. Additionally, understanding the processes involved with electron beam propagation is essential to the development of wakefield accelerator applications.

  5. Laser-wakefield accelerators for medical phase contrast imaging: Monte Carlo simulations and experimental studies

    NASA Astrophysics Data System (ADS)

    Cipiccia, S.; Reboredo, D.; Vittoria, Fabio A.; Welsh, G. H.; Grant, P.; Grant, D. W.; Brunetti, E.; Wiggins, S. M.; Olivo, A.; Jaroszynski, D. A.

    2015-05-01

    X-ray phase contrast imaging (X-PCi) is a very promising method of dramatically enhancing the contrast of X-ray images of microscopic weakly absorbing objects and soft tissue, which may lead to significant advancement in medical imaging with high-resolution and low-dose. The interest in X-PCi is giving rise to a demand for effective simulation methods. Monte Carlo codes have been proved a valuable tool for studying X-PCi including coherent effects. The laser-plasma wakefield accelerators (LWFA) is a very compact particle accelerator that uses plasma as an accelerating medium. Accelerating gradient in excess of 1 GV/cm can be obtained, which makes them over a thousand times more compact than conventional accelerators. LWFA are also sources of brilliant betatron radiation, which are promising for applications including medical imaging. We present a study that explores the potential of LWFA-based betatron sources for medical X-PCi and investigate its resolution limit using numerical simulations based on the FLUKA Monte Carlo code, and present preliminary experimental results.

  6. Laser Wakefield acceleration with high relativistic pumps

    NASA Astrophysics Data System (ADS)

    Katsouleas, T.; Mori, W. B.; Darrow, C. B.

    1989-10-01

    Preliminary scaling laws are found for the laser wakefield accelerator in the very non-linear regime where the normalized laser pump strengh Voscc=eE0/mω0c≳1. Two important non-linear effects are an increase in the wake phase velocity (and hence the particle dephasing length) and an increase in the laser pulse length for optimal wake excitation. Application of the results to the proposed Livermore High-Brightness Lasers (HBL) is discussed here and in the accompanying paper by C. B. Darrow, et al. A preliminary 1-D PIC simulation is presented.

  7. Simulation of monoenergetic electron generation via laser wakefield accelerators for 5-25 TW lasers

    SciTech Connect

    Tsung, F.S.; Lu, W.; Tzoufras, M.; Mori, W.B.; Joshi, C.; Vieira, J.M.; Silva, L.O.; Fonseca, R.A.

    2006-05-15

    In 2004, using a 3D particle-in-cell (PIC) model [F. S. Tsung et al., Phys. Rev. Lett. 93, 185004 (2004)], it was predicted that a 16.5 TW, 50 fs laser propagating through nearly 0.5 cm of 3x10{sup 18} cm{sup -3} preformed plasma channel would generate a monoenergetic bunch of electrons with a central energy of 240 MeV after 0.5 cm of propagation. In addition, electrons out to 840 MeV were seen if the laser propagated through 0.8 cm of the same plasma. The simulations showed that self-injection occurs after the laser intensity increases due to a combination of photon deceleration, group velocity dispersion, and self-focusing. The monoenergetic beam is produced because the injection process is clamped by beam loading and the rotation in phase space that results as the beam dephases. Nearly simultaneously [S. P. D. Mangles et al., Nature 431, 535 (2004); C. G. R. Geddes et al., ibid. 431, 538 (2004); J. Faure et al., ibid. 431, 541 (2004)] three experimental groups from around the world reported the generation of near nano-Coulomb of low emittance, monoenergetic electron beams using similar laser powers and pulse lengths as those reported in our simulations. Each of these experiments is modeled using the same 3D PIC code OSIRIS. The simulations indicate that although these experiments use a range of plasma parameters, density profiles, laser powers, and spot sizes; there are some commonalities to the mechanism for the generation of monoenergetic beams. Comments are given on how the energy and beam quality can be improved in the future.

  8. Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Masson-Laborde, P. E.; Mo, M. Z.; Ali, A.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.; Rozmus, W.; Teychenné, D.; Fedosejevs, R.

    2014-12-01

    We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional particle-in-cell simulations support this analysis and confirm the scenario.

  9. Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    SciTech Connect

    Masson-Laborde, P. E. Teychenné, D.; Mo, M. Z.; Ali, A.; Fedosejevs, R.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.; Rozmus, W.

    2014-12-15

    We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional particle-in-cell simulations support this analysis and confirm the scenario.

  10. Stimulated Raman side scattering in laser wakefield acceleration.

    PubMed

    Matsuoka, T; McGuffey, C; Cummings, P G; Horovitz, Y; Dollar, F; Chvykov, V; Kalintchenko, G; Rousseau, P; Yanovsky, V; Bulanov, S S; Thomas, A G R; Maksimchuk, A; Krushelnick, K

    2010-07-16

    Stimulated Raman side scattering of an ultrashort high power laser pulse is studied in experiments on laser wakefield acceleration. Experiments and simulations reveal that stimulated Raman side scattering occurs at the beginning of the interaction, that it contributes to the evolution of the pulse prior to wakefield formation, and also that it affects the quality of electron beams generated. The relativistic shift of the plasma frequency is measured. PMID:20867770

  11. Stimulated Raman Side Scattering in Laser Wakefield Acceleration

    SciTech Connect

    Matsuoka, T.; McGuffey, C.; Cummings, P. G.; Horovitz, Y.; Dollar, F.; Chvykov, V.; Kalintchenko, G.; Rousseau, P.; Yanovsky, V.; Bulanov, S. S.; Thomas, A. G. R.; Maksimchuk, A.; Krushelnick, K.

    2010-07-16

    Stimulated Raman side scattering of an ultrashort high power laser pulse is studied in experiments on laser wakefield acceleration. Experiments and simulations reveal that stimulated Raman side scattering occurs at the beginning of the interaction, that it contributes to the evolution of the pulse prior to wakefield formation, and also that it affects the quality of electron beams generated. The relativistic shift of the plasma frequency is measured.

  12. Enhanced Wakefields for the 1D Laser Wakefield Accelerator

    SciTech Connect

    Kingham, R.J.; Bell, A.R.

    1997-12-01

    The amplitudes of wakefields generated by the ponderomotive force of intense pulses much longer than {lambda}{sub p}/2 are determined using nonlinear, relativistic envelope equations and found to be significantly larger than predicted by linear theory. This is relevant to the self-modulated laser wakefield accelerator; under suitable experimental conditions enhanced wakefields should be large enough to act as the dominant source for seeding Raman forward scattering induced {open_quotes}beam breakup.{close_quotes} Consequently the use of other seeding mechanisms such as Raman backscattering, which is unpredictable, can be avoided. The enhancement mechanism is attributed to an effective bandwidth increase of the laser pulse due to nonlinearities in the response of the plasma to the ponderomotive force. {copyright} {ital 1997} {ital The American Physical Society}

  13. Laser Wakefield acceleration with high relativistic pumps

    SciTech Connect

    Katsouleas, T.; Mori, W.B. ); Darrow, C.B. )

    1989-10-15

    Preliminary scaling laws are found for the laser wakefield accelerator in the very non-linear regime where the normalized laser pump strengh {ital V}{sub osc}{ital c}={ital eE}{sub 0}/{ital m}{omega}{sub 0}{ital c}{gt}1. Two important non-linear effects are an increase in the wake phase velocity (and hence the particle dephasing length) and an increase in the laser pulse length for optimal wake excitation. Application of the results to the proposed Livermore High-Brightness Lasers (HBL) is discussed here and in the accompanying paper by C. B. Darrow, {ital et} {ital al}. A preliminary 1-D PIC simulation is presented. {copyright} 1989 American Institute of Physics

  14. Enabling Lorentz boosted frame particle-in-cell simulations of laser wakefield acceleration in quasi-3D geometry

    NASA Astrophysics Data System (ADS)

    Yu, Peicheng; Xu, Xinlu; Davidson, Asher; Tableman, Adam; Dalichaouch, Thamine; Li, Fei; Meyers, Michael D.; An, Weiming; Tsung, Frank S.; Decyk, Viktor K.; Fiuza, Frederico; Vieira, Jorge; Fonseca, Ricardo A.; Lu, Wei; Silva, Luis O.; Mori, Warren B.

    2016-07-01

    When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at βb c towards the laser, which can lead to a computational speedup of ∼ γb2 = (1 - βb2)-1. Meanwhile, when LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields and current are decomposed into a limited number of azimuthal harmonics, speedups are achieved by modeling three dimensional (3D) problems with the computational loads on the order of two dimensional r - z simulations. Here, we describe a method to combine the speedups from the Lorentz boosted frame and quasi-3D algorithms. The key to the combination is the use of a hybrid Yee-FFT solver in the quasi-3D geometry that significantly mitigates the Numerical Cerenkov Instability (NCI) which inevitably arises in a Lorentz boosted frame due to the unphysical coupling of Langmuir modes and EM modes of the relativistically drifting plasma in these simulations. In addition, based on the space-time distribution of the LWFA data in the lab and boosted frame, we propose to use a moving window to follow the drifting plasma, instead of following the laser driver as is done in the LWFA lab frame simulations, in order to further reduce the computational loads. We describe the details of how the NCI is mitigated for the quasi-3D geometry, the setups for simulations which combine the Lorentz boosted frame, quasi-3D geometry, and the use of a moving window, and compare the results from these simulations against their corresponding lab frame cases. Good agreement is obtained among these sample simulations, particularly when there is no self-trapping, which demonstrates it is possible to combine the Lorentz boosted frame and the quasi-3D algorithms when modeling LWFA. We also discuss the preliminary speedups achieved in these sample simulations.

  15. Pulsed mid-infrared radiation from spectral broadening in laser wakefield simulations

    SciTech Connect

    Zhu, W.; Palastro, J. P.; Antonsen, T. M.

    2013-07-15

    Spectral red-shifting of high power laser pulses propagating through underdense plasma can be a source of ultrashort mid-infrared (MIR) radiation. During propagation, a high power laser pulse drives large amplitude plasma waves, depleting the pulse energy. At the same time, the large amplitude plasma wave provides a dynamic dielectric response that leads to spectral shifting. The loss of laser pulse energy and the approximate conservation of laser pulse action imply that spectral red-shifts accompany the depletion. In this paper, we investigate, through simulation, the parametric dependence of MIR generation on pulse energy, initial pulse duration, and plasma density.

  16. Nonlinear Laser Driven Donut Wakefields for Positron and Electron Acceleration

    NASA Astrophysics Data System (ADS)

    Vieira, J.; Mendonça, J. T.

    2014-05-01

    We show analytically and through three-dimensional particle-in-cell simulations that nonlinear wakefields driven by Laguerre-Gaussian laser pulses can lead to hollow electron self-injection and positron acceleration. We find that higher order lasers can drive donut shaped blowout wakefields with strong positron accelerating gradients comparable to those of a spherical bubble. Corresponding positron focusing forces can be more than an order of magnitude stronger than electron focusing forces in a spherical bubble. Required laser intensities and energies to reach the nonlinear donut shaped blowout are within state-of-the-art experimental conditions.

  17. Hybrid Laser-Plasma Wakefield Acceleration

    NASA Astrophysics Data System (ADS)

    Hidding, B.; Königstein, T.; Karsch, S.; Willi, O.; Pretzler, G.; Rosenzweig, J. B.

    2010-11-01

    The concept of driving a driver/witness-type plasma wakefield accelerator (PWFA) with quasimonoenergetic double electron bunches from a laser wakefield accelerator (LWFA) is studied. In the quasimonoenergetic LWFA/SMLWFA (self-modulated LWFA) regime, it is possible to generate multiple quasimonoenergetic electron bunches with durations of only a few fs and distances of only a few tens of fs with a comparably simple experimental setup. In a subsequent high-density plasma afterburner stage the witness bunch energy can be boosted in the plasma wakefield generated by the driver. Such a hybrid system can increase the maximum energy output of a laser wakefield accelerator and is well suited to study driver/witness plasma accelerator phenomena and can be used as a cost-effective test-bed for future high-energy plasma-based accelerators.

  18. Hybrid Laser-Plasma Wakefield Acceleration

    SciTech Connect

    Hidding, B.; Koenigstein, T.; Willi, O.; Pretzler, G.; Karsch, S.; Rosenzweig, J. B.

    2010-11-04

    The concept of driving a driver/witness-type plasma wakefield accelerator (PWFA) with quasimonoenergetic double electron bunches from a laser wakefield accelerator (LWFA) is studied. In the quasimonoenergetic LWFA/SMLWFA (self-modulated LWFA) regime, it is possible to generate multiple quasimonoenergetic electron bunches with durations of only a few fs and distances of only a few tens of fs with a comparably simple experimental setup. In a subsequent high-density plasma afterburner stage the witness bunch energy can be boosted in the plasma wakefield generated by the driver. Such a hybrid system can increase the maximum energy output of a laser wakefield accelerator and is well suited to study driver/witness plasma accelerator phenomena and can be used as a cost-effective test-bed for future high-energy plasma-based accelerators.

  19. Wakefield generation via two color laser pulses

    SciTech Connect

    Jha, Pallavi; Saroch, Akanksha; Kumar Verma, Nirmal

    2013-05-15

    The analytical study for the evolution of longitudinal as well as transverse electric wakefields, generated via passage of two color laser pulses through uniform plasma, has been presented in the mildly relativistic regime. The frequency difference between the two laser pulses is assumed to be equal to the plasma frequency, in the present analysis. The relative angle between the directions of polarization of the two laser pulses is varied and the wakefield amplitudes are compared. Further, the amplitude of the excited wakes by two color pulses are compared with those generated by a single laser pulse.

  20. Laser Wakefield Acceleration Experiments Using HERCULES Laser

    SciTech Connect

    Matsuoka, T.; McGuffey, C.; Dollar, F.; Bulanov, S. S.; Chvykov, V.; Kalintchenko, G.; Rousseau, P.; Yanovsky, V.; Maksimchuk, A.; Krushelnick, K.; Horovitz, Y.

    2009-07-25

    Laser wakefield acceleration (LWFA) in a supersonic gas-jet using a self-guided laser pulse was studied by changing laser power and plasma electron density. The recently upgraded HERCULES laser facility equipped with wavefront correction enables a peak intensity of 6.1x10{sup 19} W/cm{sup 2} at laser power of 80 TW to be delivered to the gas-jet using F/10 focusing optics. We found that electron beam charge was increased significantly with an increase of laser power from 30 TW to 80 TW and showed density threshold behavior at a fixed laser power. We also studied the influence of laser focusing conditions by changing the f-number of the optics to F/15 and found an increase in density threshold for electron production compared to the F/10 configuration. The analysis of different phenomena such as betatron motion of electrons, side scattering of the laser pulse for different focusing conditions, the influence of plasma density down ramp on LWFA are shown.

  1. Laser Wakefield Acceleration in the PetaWatt Regime

    NASA Astrophysics Data System (ADS)

    Katsouleas, Tom; Tsung, Frank; Mori, Warren

    2002-11-01

    Laser wakefield acceleration with multi-terawatt lasers has demonstrated impressive results in experiments around the world-- e.g., energy gains up to 200 MeV in mm-scale gas jets. With the prospects good for a number of petawatt class lasers in the near future, we examine with 2-D and 3-D PIC simulations the potential energy gain and new physics of laser wakefield acceleration in this regime. Prospects for producing GeV electron beams in underdense plasmas will be described. In addition, the differences in physics between terawatt and petawatt regimes will be explored. Preliminary results indicate that there are two acceleration stages in the petawatt regime -- with the early electrons dephasing due to elongation of the laser wake as the laser pump evolves. The later stage produces a long beam of electrons several times the initial plasma wake wavelength with a fairly defined energy in the GeV range.

  2. Three-Dimensional Particle-in-Cell Simulations of Laser WakefieldExperiments

    SciTech Connect

    Tsung, F.S.; Antonsen, T.; Bruhwiler, D.L.; Cary, J.R.; Decyk,V.K.; Esarey, E.; Geddes, C.G.R.; Huang, C.; Hakim, A.; Katsouleas, T.; Lu, W.; Messmer, P.; Mori, W.B.; Tzoufras, M.; Vieira, J.

    2007-06-01

    Plasma accelerator methods offer the potential to reduce thesize of moderate and high energy accelerators by factors of 1000. In thepast few years great advances have been made in the production of lowemittance, high quality (i.e., monoenergetic) electron beams withenergies between .1 and 1 GeV using ultra-fast (<50 femtoseconds),high power (>10TW) lasers. The most noticeable of these advances werethe experimental results presented in the "Dream Beam" issue of Natureand in a recent issues of Physical Review Letters, Nature, and NaturePhysics. The experimental progress have been made due to advances inlasers, diagnostics, plasma sources, and the knowledge of how to controlof this highly nonlinear acceleration process. And this experimentalprogress has occurred simultaneously with and been in part due toadvances in modeling capabilities. Using a hierarchy of particlein-cell(PIC) codes OSIRIS, VORPAL, and QuickPIC, we have performed numerous fullscale 3D simulations using parameters quoted from the Nature and NaturePhysics articles. Our simulations have predicted results, providedagreement between simulations and experiments (within the shot-to-shotvariations of the experiments), and provided insight into the complicatedphysics of the experiments. Most importantly, as our confidence in thefidelity of our methods increases we can now guide the planning of newexperiments, and probe parameters that are not yet available. Therebyproviding a "road map" for generating high quality, high-charge 10 to 100GeV electron beams for use in high-energy physics and lightsources.

  3. Donut wakefields generated by intense laser pulses with orbital angular momentum

    SciTech Connect

    Mendonça, J. T.; Vieira, J.

    2014-03-15

    We study the wakefields produced in a plasma by intense laser pulses carrying a finite amount of orbital angular momentum. We show that these wakefields have new donut-like shapes, different from those usually considered in the literature, and could be used to accelerate hollow electron beams. Wakefields with a more general angular structure were also considered. The analytical solutions are corroborated by relativistic particle-in-cell simulations using OSIRIS.

  4. Relativistic quantum corrections to laser wakefield acceleration.

    PubMed

    Zhu, Jun; Ji, Peiyong

    2010-03-01

    The influence of quantum effects on the interaction of intense laser fields with plasmas is investigated by using a hydrodynamic model based on the framework of the relativistic quantum theory. Starting from the covariant Wigner function and Dirac equation, the hydrodynamic equations for relativistic quantum plasmas are derived. Based on the relativistic quantum hydrodynamic equations and Poisson equation, the perturbations of electron number densities and the electric field of the laser wakefield containing quantum effects are deduced. It is found that the corrections generated by the quantum effects to the perturbations of electron number densities and the accelerating field of the laser wakefield cannot be neglected. Quantum effects will suppress laser wakefields, which is a classical manifestation of quantum decoherence effects, however, the contribution of quantum effects for the laser wakefield correction will been partially counteracted by the relativistic effects. The analysis also reveals that quantum effects enlarge the effective frequencies of plasmas, and the quantum behavior appears a screening effect for plasma electrons. PMID:20365881

  5. Relativistic quantum corrections to laser wakefield acceleration

    SciTech Connect

    Zhu Jun; Ji Peiyong

    2010-03-15

    The influence of quantum effects on the interaction of intense laser fields with plasmas is investigated by using a hydrodynamic model based on the framework of the relativistic quantum theory. Starting from the covariant Wigner function and Dirac equation, the hydrodynamic equations for relativistic quantum plasmas are derived. Based on the relativistic quantum hydrodynamic equations and Poisson equation, the perturbations of electron number densities and the electric field of the laser wakefield containing quantum effects are deduced. It is found that the corrections generated by the quantum effects to the perturbations of electron number densities and the accelerating field of the laser wakefield cannot be neglected. Quantum effects will suppress laser wakefields, which is a classical manifestation of quantum decoherence effects, however, the contribution of quantum effects for the laser wakefield correction will been partially counteracted by the relativistic effects. The analysis also reveals that quantum effects enlarge the effective frequencies of plasmas, and the quantum behavior appears a screening effect for plasma electrons.

  6. Laser Wakefield Acceleration and Fundamental Physics

    SciTech Connect

    Tajima, Toshiki

    2011-06-20

    The laser wakefield acceleration (LWFA) along with the now available laser technology allows us to look at TeV physics both in leptons and hadrons. Near future proof-of-principle experiments for a collider as well as high energy frontier experiments without a collider paradigm are suggested. The intense laser can also contribute to other fundamental physics explorations such as those of dark matter and dark energy candidates. Finally the combination of intense laser and laser-accelerated particles (electrons, hadrons, gammas) provides a further avenue of fundamental research.

  7. 2D hydrodynamic simulations of a variable length gas target for density down-ramp injection of electrons into a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Kononenko, O.; Lopes, N. C.; Cole, J. M.; Kamperidis, C.; Mangles, S. P. D.; Najmudin, Z.; Osterhoff, J.; Poder, K.; Rusby, D.; Symes, D. R.; Warwick, J.; Wood, J. C.; Palmer, C. A. J.

    2016-09-01

    In this work, two-dimensional (2D) hydrodynamic simulations of a variable length gas cell were performed using the open source fluid code OpenFOAM. The gas cell was designed to study controlled injection of electrons into a laser-driven wakefield at the Astra Gemini laser facility. The target consists of two compartments: an accelerator and an injector section connected via an aperture. A sharp transition between the peak and plateau density regions in the injector and accelerator compartments, respectively, was observed in simulations with various inlet pressures. The fluid simulations indicate that the length of the down-ramp connecting the sections depends on the aperture diameter, as does the density drop outside the entrance and the exit cones. Further studies showed, that increasing the inlet pressure leads to turbulence and strong fluctuations in density along the axial profile during target filling, and consequently, is expected to negatively impact the accelerator stability.

  8. Effect of pulse profile and chirp on a laser wakefield generation

    SciTech Connect

    Zhang Xiaomei; Shen Baifei; Ji Liangliang; Wang Wenpeng; Xu Jiancai; Yu Yahong; Yi Longqing; Wang Xiaofeng; Hafz, Nasr A. M.; Kulagin, V.

    2012-05-15

    A laser wakefield driven by an asymmetric laser pulse with/without chirp is investigated analytically and through two-dimensional particle-in-cell simulations. For a laser pulse with an appropriate pulse length compared with the plasma wavelength, the wakefield amplitude can be enhanced by using an asymmetric un-chirped laser pulse with a fast rise time; however, the growth is small. On the other hand, the wakefield can be greatly enhanced for both positively chirped laser pulse having a fast rise time and negatively chirped laser pulse having a slow rise time. Simulations show that at the early laser-plasma interaction stage, due to the influence of the fast rise time the wakefield driven by the positively chirped laser pulse is more intense than that driven by the negatively chirped laser pulse, which is in good agreement with analytical results. At a later time, since the laser pulse with positive chirp exhibits opposite evolution to the one with negative chirp when propagating in plasma, the wakefield in the latter case grows more intensely. These effects should be useful in laser wakefield acceleration experiments operating at low plasma densities.

  9. Laser Wakefield Acceleration in the PetaWatt Regime

    NASA Astrophysics Data System (ADS)

    Joshi, C.; Tsung, F. S.; Mori, W. B.; Katsouleas, T.; Fonseca, R. A.; Silva, L. O.

    2003-10-01

    Laser wakefield acceleration with multi-terawatt lasers has demonstrated impressive results in experiments around the world-- e.g., energy gains up to 700 MeV in mm-scale gas jets has recently been reported. With a number of petawatt class lasers planned for operation in the near future, we examine with 2-D and 3-D PIC simulations the potential energy gain and new physics of laser wakefield acceleration in this regime. These lasers will operated for a variety of pulse lengths. We consider both 35 fs and 600 fs pulses, but will emphasize the 35 fs results for this poster. Prospects for producing GeV electron beams in underdense plasmas will be described. In addition, the differences in physics between terawatt and petawatt regimes will be explored. Preliminary results for the 35 fs class lasers indicate that there are two acceleration stages in the petawatt regime -- with the early electrons dephasing due to elongation of the laser wake as the laser pump evolves. The later stage produces a long beam of electrons several times the initial plasma wake wavelength with a fairly defined energy in the GeV range. For the 600 fs class lasers, 2D simulations indicate that the acceleration process is much more complicated and it involves an interaction between the fields in the wake and the laser.

  10. Two-pulse ionization injection into quasilinear laser wakefields.

    PubMed

    Bourgeois, N; Cowley, J; Hooker, S M

    2013-10-11

    We describe a scheme for controlling electron injection into the quasilinear wakefield driven by a guided drive pulse via ionization of a dopant species by a collinear injection laser pulse with a short Rayleigh range. The scheme is analyzed by particle-in-cell simulations which show controlled injection and acceleration of electrons to an energy of 370 MeV, a relative energy spread of 2%, and a normalized transverse emittance of 2.0 μm. PMID:24160608

  11. Controlled electron injection into laser wakefields with a perpendicular injection laser pulse

    SciTech Connect

    Wang, W.-M.; Sheng, Z.-M.; Zhang, J.

    2008-11-17

    Electron injection into laser wakefields for acceleration by two orthogonally directed laser pulses is investigated theoretically. It is found that efficient injection occurs provided the two pulses are collinearly polarized, even if the injection pulse is much weaker than the pump pulse driving wakefields. Compared with the head-on colliding injection geometry, this scheme allows for a shorter propagation distance less than a Rayleigh length for the injection pulse, before its overlapping with the pump pulse. Moreover, it can generate electron beams stably with comparable low energy spread and emittance, as demonstrated by particle-in-cell simulations. The optimization of laser parameters is also investigated.

  12. Optimization of laser wakefield accelerator parameters

    SciTech Connect

    Pogorelsky, I.V.

    1998-02-01

    The author reveals the dependencies of the laser wakefield accelerator (LWFA) performance upon such basic parameters as laser wavelength, power, and pulse duration and apply them for optimization of the plasma-channeled standard LWFA operating in a linear regime. The maximum energy gain over the dephasing distance scales proportionally to the laser peak power, while the allowed minimum laser pulse duration is proportional to the square root of the energy gain. Electron beam energy spread, emittance and luminosity tend to improve with the laser wavelength increase. These considerations, supported by quantitative examples for the S GeV LWFA stage, favor picosecond CO{sub 2} laser as the optimum choice for future advanced accelerator projects.

  13. Plasma channel guided laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Geddes, Cameron Guy Robinson

    2005-11-01

    High quality electron beams (several 109 electrons above 80 MeV energy with percent energy spread and low divergence) have been produced for the first time in a compact, high gradient, all-optical laser accelerator by extending the interaction distance using a pre-formed plasma density channel to guide the drive laser pulse. Laser-driven accelerators, in which particles are accelerated by the electric field of a plasma wave (wake) driven by the radiation pressure of an intense laser, have over the past decade demonstrated accelerating fields thousands of times greater than those achievable in conventional radio-frequency accelerators. This has spurred interest in them as compact next-generation sources of energetic electrons and radiation. To date, however, acceleration distances have been severely limited by the lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance resulted in low-energy beams with 100 percent electron energy spread, which has limited potential applications. Optical guiding of relativistically intense (>1018 W/cm 2) laser pulses over distances greater than 10 diffraction lengths is demonstrated herein using plasma channels, which have a density minimum on the axis of propagation, formed by hydrodynamic shock. Laser modes with peak powers of up to 4 TW---twice the self-guiding threshold---were guided without aberration by tuning the plasma density profile. The transmitted optical spectrum showed that the pulse remained in the channel over the entire length, and no accelerated electrons were observed at these powers. Simulations indicated that a large plasma wave was driven by the 4 TW pulse, indicating a possible dark current free structure for a laser wakefield accelerator using controlled injection. The presence of a large plasma wave was verified by increasing laser power and observing electron acceleration. At a guided drive pulse power of 9 TW (500 mJ in 50 fs

  14. Generating Ultrarelativistic Attosecond Electron Bunches with Laser Wakefield Accelerators

    SciTech Connect

    Luttikhof, M. J. H.; Khachatryan, A. G.; Goor, F. A. van; Boller, K.-J.

    2010-09-17

    Femtosecond electron bunches with ultrarelativistic energies were recently generated by laser wakefield accelerators. Here we predict that laser wakefield acceleration can generate even attosecond bunches, due to a strong chirp of the betatron frequency. We show how the bunch duration scales with the acceleration parameters and that, after acceleration, the bunches can propagate over many tens of centimeters without a significant increase in duration.

  15. Laser-PlasmaWakefield Acceleration with Higher Order Laser Modes

    SciTech Connect

    Geddes, C.G.R.; Cormier-Michel, E.; Esarey, E.; Schroeder, C.B.; Mullowney, P.; Paul, K.; Cary, J.R.; Leemans, W.P.

    2010-06-01

    Laser-plasma collider designs point to staging of multiple accelerator stages at the 10 GeV level, which are to be developed on the upcoming BELLA laser, while Thomson Gamma source designs use GeV stages, both requiring efficiency and low emittance. Design and scaling of stages operating in the quasi-linear regime to address these needs are presented using simulations in the VORPAL framework. In addition to allowing symmetric acceleration of electrons and positrons, which is important for colliders, this regime has the property that the plasma wakefield is proportional to the transverse gradient of the laser intensity profile. We demonstrate use of higher order laser modes to tailor the laser pulse and hence the transverse focusing forces in the plasma. In particular, we show that by using higher order laser modes, we can reduce the focusing fields and hence increase the matched electron beam radius, which is important to increased charge and efficiency, while keeping the low bunch emittance required for applications.

  16. Laser-Plasma Wakefield Acceleration with Higher Order Laser Modes

    SciTech Connect

    Geddes, C. G. R.; Schroeder, C. B.; Cormier-Michel, E.; Mullowney, P.; Paul, K.; Esarey, E.; Cary, J. R.; Leemans, W. P.

    2010-11-04

    Laser-plasma collider designs point to staging of multiple accelerator stages at the 10 GeV level, which are to be developed on the upcoming BELLA laser, while Thomson Gamma source designs use GeV stages, both requiring efficiency and low emittance. Design and scaling of stages operating in the quasi-linear regime to address these needs are presented using simulations in the VORPAL framework. In addition to allowing symmetric acceleration of electrons and positrons, which is important for colliders, this regime has the property that the plasma wakefield is proportional to the transverse gradient of the laser intensity profile. We demonstrate use of higher order laser modes to tailor the laser pulse and hence the transverse focusing forces in the plasma. In particular, we show that by using higher order laser modes, we can reduce the focusing fields and hence increase the matched electron beam radius, which is important to increased charge and efficiency, while keeping the low bunch emittance required for applications.

  17. Positron generation using laser-wakefield electron sources

    SciTech Connect

    Williams, G. J. Park, J.; Pollock, B. B.; Albert, F.; Chen, Hui

    2015-09-15

    Positron generation, using wakefield-accelerated electrons driven into a converter target, was investigated experimentally and through Monte Carlo simulations. Using experimentally measured initial electron distributions from a 60 fs laser system, modeling shows that a collimated wakefield electron beam of moderate energy (50–200 MeV) produces a large number of positrons (∼10{sup 7}), which are emitted from the rear of a mm-scale, high-Z target with divergence angles between 50 and 150 mrad. The large perpendicular momentum of the positrons was found to be dominated by contributions from multiple small angle Coulomb scattering. Positrons were not observed above background noise for a range of targets where simulations indicate a 5–30× increase in the beam charge was necessary to exceed threshold detection. These results provide new understanding to the fundamental limitations of creating narrow-divergence, high-density positron beams from laser-wakefield platforms for use in future laboratory pair plasma experiments.

  18. Photonuclear fission with quasimonoenergetic electron beams from laser wakefields

    SciTech Connect

    Reed, S. A.; Chvykov, V.; Kalintchenko, G.; Matsuoka, T.; Rousseau, P.; Yanovsky, V.; Vane, C. R.; Beene, J. R.; Stracener, D.; Schultz, D. R.; Maksimchuk, A.

    2006-12-04

    Recent advancements in laser wakefield accelerators have resulted in the generation of low divergence, hundred MeV, quasimonoenergetic electron beams. The bremsstrahlung produced by these highly energetic electrons in heavy converters includes a large number of MeV {gamma} rays that have been utilized to induce photofission in natural uranium. Analysis of the measured delayed {gamma} emission demonstrates production of greater than 3x10{sup 5} fission events per joule of laser energy, which is more than an order of magnitude greater than that previously achieved. Monte Carlo simulations model the generated bremsstrahlung spectrum and compare photofission yields as a function of target depth and incident electron energy.

  19. Laser wakefield and direct acceleration with ionization injection

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Khudik, Vladimir N.; Pukhov, Alexander; Shvets, Gennady

    2016-03-01

    We demonstrate using particle-in-cell simulations that electrons can be injected into a hybrid laser wakefield and direct laser accelerator via ionization injection. We propose an accelerator and injector scenario that utilizes two laser pulses. The first (pump) pulse produces the plasma ‘bubble’ by expelling the plasma electrons generated by its leading edge from the low-Z component of the gas mixture, and then injects electrons into the bubble by ionizing the high-Z component. The second time-delayed laser pulse resonantly interacts with these injected electrons undergoing betatron oscillations inside the bubble. We show that the electrons ionized off-axis and on-axis but off the peak ionization phase possess sufficient transverse energy to undergo efficient direct laser acceleration (DLA). When combined with their acceleration by the bubble’s longitudinal plasma wake, DLA can double the total energy gain and produce a monoenergetic beam.

  20. Positron Production Using a Laser-Wakefield Electron Source

    NASA Astrophysics Data System (ADS)

    Williams, G. Jackson; Albert, Felicie; Chen, Hui; Park, Jaebum; Pollock, Bradley

    2014-10-01

    Positron generation using wakefield-accelerated electrons driven into a second mm-scale target was investigated using the Callisto Laser at the Jupiter Laser Facility at Lawrence Livermore National Laboratory. This technique is in contrast to previous experiments that use direct laser-target interactions to create positron-electron pairs, and has the potential to make laser-produced positron sources widely available to smaller scale laboratories. Monte Carlo simulations show a near-collimated (<10 mrad) wakefield electron beam produces a positron beam with a significantly larger divergence angle (>100 mrad) due to multiple small angle coulomb scattering, resulting in an emitted pair density of 1013 particles/cm3. At the Callisto Laser, we did not observe a signal consistent with positrons using two different charged particle spectrometers. This could be due to a high noise environment and a large detection threshold. This work was performed under the auspices of the U.S. Department of Energy (DOE) by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the LLNL LDRD program under tracking code 13-LW-076 and 12-ERD-062.

  1. Laser wakefield acceleration by petawatt ultrashort laser pulses

    SciTech Connect

    Gorbunov, L.M.; Kalmykov, S.Yu.; Mora, P.

    2004-12-07

    An ultra-short (about 30 fs) petawatt laser pulse focused in a wide focal spot (about 100{mu}m) in rarefied plasma (n0 {approx} 1017cm-3) excites a nonlinear plasma wakefield which can accelerate injected electrons up to a GeV energy without pulse channelling. In these conditions, the laser pulse with an over-critical power for relativistic self-focusing propagates as in vacuum. The nonlinear quasi-plane wake plasma wave, whose amplitude and phase velocity vary along the laser path, effectively traps and accelerates injected electrons with a wide range of initial energies. Electrons accelerated along two Rayleigh lengths (about eight centimeters) gain the energy up to 1 GeV. In particular, the electrons trapped from quite a long ({tau}b {approx} 330 fs) non-resonant electron beamlet of 1 MeV particles eventually form a low emittance bunch with the energies in the range 900 {+-} 50 MeV. All these conclusions follow from the two-dimensional simulations performed in cylindrical geometry by fully relativistic time-averaged particle code WAKE.

  2. On some theoretical problems of laser wake-field accelerators

    NASA Astrophysics Data System (ADS)

    Bulanov, S. V.; Esirkepov, T. Zh.; Hayashi, Y.; Kiriyama, H.; Koga, J. K.; Kotaki, H.; Mori, M.; Kando, M.

    2016-06-01

    > Enhancement of the quality of laser wake-field accelerated (LWFA) electron beams implies the improvement and controllability of the properties of the wake waves generated by ultra-short pulse lasers in underdense plasmas. In this work we present a compendium of useful formulas giving relations between the laser and plasma target parameters allowing one to obtain basic dependences, e.g. the energy scaling of the electrons accelerated by the wake field excited in inhomogeneous media including multi-stage LWFA accelerators. Consideration of the effects of using the chirped laser pulse driver allows us to find the regimes where the chirp enhances the wake field amplitude. We present an analysis of the three-dimensional effects on the electron beam loading and on the unlimited LWFA acceleration in inhomogeneous plasmas. Using the conditions of electron trapping to the wake-field acceleration phase we analyse the multi-equal stage and multiuneven stage LWFA configurations. In the first configuration the energy of fast electrons is a linear function of the number of stages, and in the second case, the accelerated electron energy grows exponentially with the number of stages. The results of the two-dimensional particle-in-cell simulations presented here show the high quality electron acceleration in the triple stage injection-acceleration configuration.

  3. On some theoretical problems of laser wake-field accelerators

    NASA Astrophysics Data System (ADS)

    Bulanov, S. V.; Esirkepov, T. Zh.; Hayashi, Y.; Kiriyama, H.; Koga, J. K.; Kotaki, H.; Mori, M.; Kando, M.

    2016-06-01

    Enhancement of the quality of laser wake-field accelerated (LWFA) electron beams implies the improvement and controllability of the properties of the wake waves generated by ultra-short pulse lasers in underdense plasmas. In this work we present a compendium of useful formulas giving relations between the laser and plasma target parameters allowing one to obtain basic dependences, e.g. the energy scaling of the electrons accelerated by the wake field excited in inhomogeneous media including multi-stage LWFA accelerators. Consideration of the effects of using the chirped laser pulse driver allows us to find the regimes where the chirp enhances the wake field amplitude. We present an analysis of the three-dimensional effects on the electron beam loading and on the unlimited LWFA acceleration in inhomogeneous plasmas. Using the conditions of electron trapping to the wake-field acceleration phase we analyse the multi-equal stage and multiuneven stage LWFA configurations. In the first configuration the energy of fast electrons is a linear function of the number of stages, and in the second case, the accelerated electron energy grows exponentially with the number of stages. The results of the two-dimensional particle-in-cell simulations presented here show the high quality electron acceleration in the triple stage injection-acceleration configuration.

  4. Modeling beam-driven and laser-driven plasma Wakefield accelerators with XOOPIC

    SciTech Connect

    Bruhwiler, David L.; Giacone, Rodolfo; Cary, John R.; Verboncoeur, John P.; Mardahl, Peter; Esarey, Eric; Leemans, Wim

    2000-06-01

    We present 2-D particle-in-cell simulations of both beam-driven and laser-driven plasma wakefield accelerators, using the object-oriented code XOOPIC, which is time explicit, fully electromagnetic, and capable of running on massively parallel supercomputers. Simulations of laser-driven wakefields with low ({approximately} 10{sup 16} W/cm{sup 2}) and high ({approximately} 10{sup 18} W/cm{sup 2}) peak intensity laser pulses are conducted in slab geometry, showing agreement with theory. Simulations of the E-157 beam wakefield experiment at the Stanford Linear Accelerator Center, in which a 30 GeV electron beam passes through 1 m of preionized lithium plasma, are conducted in cylindrical geometry, obtaining good agreement with previous work. We briefly describe some of the more significant modifications to XOOPIC required by this work, and summarize the issues relevant to modeling electron-neutral collisions in a particle-in-cell code.

  5. Generating ultrarelativistic attosecond electron bunches with laser wakefield accelerators.

    PubMed

    Luttikhof, M J H; Khachatryan, A G; van Goor, F A; Boller, K-J

    2010-09-17

    Femtosecond electron bunches with ultrarelativistic energies were recently generated by laser wakefield accelerators. Here we predict that laser wakefield acceleration can generate even attosecond bunches, due to a strong chirp of the betatron frequency. We show how the bunch duration scales with the acceleration parameters and that, after acceleration, the bunches can propagate over many tens of centimeters without a significant increase in duration. PMID:20867647

  6. Magnetically Controlled Plasma Waveguide For Laser Wakefield Acceleration

    SciTech Connect

    Froula, D H; Divol, L; Davis, P; Palastro, J; Michel, P; Leurent, V; Glenzer, S H; Pollock, B; Tynan, G

    2008-05-14

    An external magnetic field applied to a laser plasma is shown produce a plasma channel at densities relevant to creating GeV monoenergetic electrons through laser wakefield acceleration. Furthermore, the magnetic field also provides a pressure to help shape the channel to match the guiding conditions of an incident laser beam. Measured density channels suitable for guiding relativistic short-pulse laser beams are presented with a minimum density of 5 x 10{sup 17} cm{sup -3} which corresponds to a linear dephasing length of several centimeters suitable for multi-GeV electron acceleration. The experimental setup at the Jupiter Laser Facility, Lawrence Livermore National Laboratory, where a 1-ns, 150 J 1054 nm laser will produce a magnetically controlled channel to guide a < 75 fs, 10 J short-pulse laser beam through 5-cm of 5 x 10{sup 17} cm{sup -3} plasma is presented. Calculations presented show that electrons can be accelerated to 3 GeV with this system. Three-dimensional resistive magneto-hydrodynamic simulations are used to design the laser and plasma parameters and quasi-static kinetic simulations indicate that the channel will guide a 200 TW laser beam over 5-cm.

  7. Generation of electron beams from a laser wakefield acceleration in pure neon gas

    SciTech Connect

    Li, Song; Hafz, Nasr A. M. Mirzaie, Mohammad; Elsied, Ahmed M. M.; Ge, Xulei; Liu, Feng; Sokollik, Thomas; Chen, Min; Sheng, Zhengming; Zhang, Jie; Tao, Mengze; Chen, Liming

    2014-08-15

    We report on the generation of quasimonoenergetic electron beams by the laser wakefield acceleration of 17–50 TW, 30 fs laser pulses in pure neon gas jet. The generated beams have energies in the range 40–120 MeV and up to ∼430 pC of charge. At a relatively high density, we observed multiple electron beamlets which has been interpreted by simulations to be the result of breakup of the laser pulse into multiple filaments in the plasma. Each filament drives its own wakefield and generates its own electron beamlet.

  8. All-Optical Steering of Laser-Wakefield-Accelerated Electron Beams

    SciTech Connect

    Popp, A.; Osterhoff, J.; Major, Zs.; Hoerlein, R.; Fuchs, M.; Weingartner, R.; Krausz, F.; Gruener, F.; Karsch, S.; Vieira, J.; Marti, M.; Fonseca, R. A.; Martins, S. F.; Silva, L. O.

    2010-11-19

    We investigate the influence of a tilted laser-pulse-intensity front on laser-wakefield acceleration. Such asymmetric light pulses may be exploited to obtain control over the electron-bunch-pointing direction and in our case allowed for reproducible electron-beam steering in an all-optical way within an 8 mrad opening window with respect to the initial laser axis. We also discovered evidence of collective electron-betatron oscillations due to off-axis electron injection into the wakefield induced by a pulse-front tilt. These findings are supported by 3D particle-in-cell simulations.

  9. All-optical steering of laser-wakefield-accelerated electron beams.

    PubMed

    Popp, A; Vieira, J; Osterhoff, J; Major, Zs; Hörlein, R; Fuchs, M; Weingartner, R; Rowlands-Rees, T P; Marti, M; Fonseca, R A; Martins, S F; Silva, L O; Hooker, S M; Krausz, F; Grüner, F; Karsch, S

    2010-11-19

    We investigate the influence of a tilted laser-pulse-intensity front on laser-wakefield acceleration. Such asymmetric light pulses may be exploited to obtain control over the electron-bunch-pointing direction and in our case allowed for reproducible electron-beam steering in an all-optical way within an 8 mrad opening window with respect to the initial laser axis. We also discovered evidence of collective electron-betatron oscillations due to off-axis electron injection into the wakefield induced by a pulse-front tilt. These findings are supported by 3D particle-in-cell simulations. PMID:21231309

  10. Multiple pulse resonantly enhanced laser plasma wakefield acceleration

    SciTech Connect

    Corner, L.; Walczak, R.; Nevay, L. J.; Dann, S.; Hooker, S. M.; Bourgeois, N.; Cowley, J.

    2012-12-21

    We present an outline of experiments being conducted at Oxford University on multiple-pulse, resonantly-enhanced laser plasma wakefield acceleration. This method of laser plasma acceleration uses trains of optimally spaced low energy short pulses to drive plasma oscillations and may enable laser plasma accelerators to be driven by compact and efficient fibre laser sources operating at high repetition rates.

  11. Energy boost in laser wakefield accelerators using sharp density transitions

    NASA Astrophysics Data System (ADS)

    Döpp, A.; Guillaume, E.; Thaury, C.; Lifschitz, A.; Ta Phuoc, K.; Malka, V.

    2016-05-01

    The energy gain in laser wakefield accelerators is limited by dephasing between the driving laser pulse and the highly relativistic electrons in its wake. Since this phase depends on both the driver and the cavity length, the effects of dephasing can be mitigated with appropriate tailoring of the plasma density along propagation. Preceding studies have discussed the prospects of continuous phase-locking in the linear wakefield regime. However, most experiments are performed in the highly non-linear regime and rely on self-guiding of the laser pulse. Due to the complexity of the driver evolution in this regime, it is much more difficult to achieve phase locking. As an alternative, we study the scenario of rapid rephasing in sharp density transitions, as was recently demonstrated experimentally. Starting from a phenomenological model, we deduce expressions for the electron energy gain in such density profiles. The results are in accordance with particle-in-cell simulations, and we present gain estimations for single and multiple stages of rephasing.

  12. Laser pulse propagation in inhomogeneous magnetoplasma channels and wakefield acceleration

    SciTech Connect

    Sharma, B. S. Jain, Archana; Jaiman, N. K.; Gupta, D. N.; Jang, D. G.; Suk, H.; Kulagin, V. V.

    2014-02-15

    Wakefield excitation in a preformed inhomogeneous parabolic plasma channel by an intense relativistic (≃10{sup 19} W/cm{sup 2}) circularly polarized Gaussian laser pulse is investigated analytically and numerically in the presence of an external longitudinal magnetic field. A three dimensional envelope equation for the evolution of the laser pulse is derived, which includes the effect of the nonparaxial and applied external magnetic field. A relation for the channel radius with the laser spot size is derived and examines numerically to see the external magnetic field effect. It is observed that the channel radius depends on the applied external magnetic field. An analytical expression for the wakefield is derived and validated with the help of a two dimensional particle in cell (2D PIC) simulation code. It is shown that the electromagnetic nature of the wakes in an inhomogeneous plasma channel makes their excitation nonlocal, which results in change of fields with time and external magnetic field due to phase mixing of the plasma oscillations with spatially varying frequencies. The magnetic field effect on perturbation of the plasma density and decreasing length is also analyzed numerically. In addition, it has been shown that the electron energy gain in the inhomogeneous parabolic magnetoplasma channel can be increased significantly compared with the homogeneous plasma channel.

  13. Laser wakefield acceleration: the injection issue. Overview and latest results.

    PubMed

    van der Wiel, M J; Luiten, O J; Brussaard, G J H; van der Geer, S B; Urbanus, W H; van Dijk, W; van Oudheusden, Th

    2006-03-15

    External injection of electron bunches into laser-driven plasma waves so far has not resulted in 'controlled' acceleration, i.e. production of bunches with well-defined energy spread. Recent simulations, however, predict that narrow distributions can be achieved, provided the conditions for properly trapping the injected electrons are met. Under these conditions, injected bunch lengths of one to several plasma wavelengths are acceptable. This paper first describes current efforts to demonstrate this experimentally, using state-of-the-art radio frequency technology. The expected charge accelerated, however, is still low for most applications. In the second part, the paper addresses a number of novel concepts for significant enhancement of photo-injector brightness. Simulations predict that, once these concepts are realized, external injection into a wakefield accelerator will lead to accelerated bunch specs comparable to those of recent 'laser-into-gasjet' experiments, without the present irreproducibility of charge and final energy of the latter. PMID:16483957

  14. Inverse free electron lasers and laser wakefield acceleration driven by CO2 lasers.

    PubMed

    Kimura, W D; Andreev, N E; Babzien, M; Ben-Zvi, I; Cline, D B; Dilley, C E; Gottschalk, S C; Hooker, S M; Kusche, K P; Kuznetsov, S V; Pavlishin, I V; Pogorelsky, I V; Pogosova, A A; Steinhauer, L C; Ting, A; Yakimenko, V; Zigler, A; Zhou, F

    2006-03-15

    The staged electron laser acceleration (STELLA) experiment demonstrated staging between two laser-driven devices, high trapping efficiency of microbunches within the accelerating field and narrow energy spread during laser acceleration. These are important for practical laser-driven accelerators. STELLA used inverse free electron lasers, which were chosen primarily for convenience. Nevertheless, the STELLA approach can be applied to other laser acceleration methods, in particular, laser-driven plasma accelerators. STELLA is now conducting experiments on laser wakefield acceleration (LWFA). Two novel LWFA approaches are being investigated. In the first one, called pseudo-resonant LWFA, a laser pulse enters a low-density plasma where nonlinear laser/plasma interactions cause the laser pulse shape to steepen, thereby creating strong wakefields. A witness e-beam pulse probes the wakefields. The second one, called seeded self-modulated LWFA, involves sending a seed e-beam pulse into the plasma to initiate wakefield formation. These wakefields are amplified by a laser pulse following shortly after the seed pulse. A second e-beam pulse (witness) follows the seed pulse to probe the wakefields. These LWFA experiments will also be the first ones driven by a CO(2) laser beam. PMID:16483952

  15. Laser red shifting based characterization of wakefield excitation in a laser-plasma accelerator

    SciTech Connect

    Shiraishi, S.; Benedetti, C.; Gonsalves, A. J.; Nakamura, K.; Shaw, B. H.; Sokollik, T.; Tilborg, J. van; Geddes, C. G. R.; Schroeder, C. B.; Tóth, Cs.; Esarey, E.; Leemans, W. P.

    2013-06-15

    Optical spectra of a drive laser exiting a channel guided laser-plasma accelerator (LPA) are analyzed through experiments and simulations to infer the magnitude of the excited wakefields. The experiments are performed at sufficiently low intensity levels and plasma densities to avoid electron beam generation via self-trapping. Spectral redshifting of the laser light is studied as an indicator of the efficiency of laser energy transfer into the plasma through the generation of coherent plasma wakefields. Influences of input laser energy, plasma density, temporal and spatial laser profiles, and laser focal location in a plasma channel are analyzed. Energy transfer is found to be sensitive to details of laser pulse shape and focal location. The experimental conditions for these critical parameters are modeled and included in particle-in-cell simulations. Simulations reproduce the redshift of the laser within uncertainties of the experiments and produce an estimate of the wake amplitudes in the experiments as a function of amount of redshift. The results support the practical use of laser redshifting to quantify the longitudinally averaged accelerating field that a particle would experience in an LPA powered below the self-trapping limit.

  16. Laser wakefield accelerator based light sources: potential applications and requirements

    SciTech Connect

    Albert, F.; Thomas, A. G.; Mangles, S. P.D.; Banerjee, S.; Corde, S.; Flacco, A.; Litos, M.; Neely, D.; Viera, J.; Najmudin, Z.; Bingham, R.; Joshi, C.; Katsouleas, T.

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

  17. Dense attosecond electron sheets from laser wakefields using an up-ramp density transition.

    PubMed

    Li, F Y; Sheng, Z M; Liu, Y; Meyer-ter-Vehn, J; Mori, W B; Lu, W; Zhang, J

    2013-03-29

    Controlled electron injection into a laser-driven wakefield at a well defined space and time is reported based on particle-in-cell simulations. Key novel ingredients are an underdense plasma target with an up-ramp density profile followed by a plateau and a fairly large laser focus diameter that leads to an essentially one-dimensional (1D) regime of laser wakefield, which is different from the bubble (complete blowout) regime occurring for tightly focused drive beams. The up-ramp profile causes 1D wave breaking to occur sharply at the up-ramp-plateau transition. As a result, it generates an ultrathin (few nanometer, corresponding to attosecond duration), strongly overdense relativistic electron sheet that is injected and accelerated in the wakefield. A peaked electron energy spectrum and high charge (∼nC) distinguish the final sheet. PMID:23581329

  18. Emission of electromagnetic pulses from laser wakefields through linear mode conversion.

    PubMed

    Sheng, Zheng-Ming; Mima, Kunioki; Zhang, Jie; Sanuki, Heiji

    2005-03-11

    Powerful coherent emission around the plasma oscillation frequency can be produced from a laser wakefield through linear mode conversion. This occurs when the laser pulse is incident obliquely to the density gradient of inhomogeneous plasmas. The emission spectrum and conversion efficiency are obtained analytically, which are in agreement with particle-in-cell simulations. The emission can be tuned to be a radiation source in the terahertz region and with field strengths as large as a few GV/m, suitable for high-field applications. The emission also provides a simple way to measure the wakefield produced for particle acceleration. PMID:15783972

  19. Plasma Density Tapering for Laser Wakefield Acceleration of Electrons and Protons

    SciTech Connect

    Ting, A.; Gordon, D.; Kaganovich, D.; Sprangle, P.; Helle, M.; Hafizi, B.

    2010-11-04

    Extended acceleration in a Laser Wakefield Accelerator can be achieved by tailoring the phase velocity of the accelerating plasma wave, either through profiling of the density of the plasma or direct manipulation of the phase velocity. Laser wakefield acceleration has also reached a maturity that proton acceleration by wakefield could be entertained provided we begin with protons that are substantially relativistic, {approx}1 GeV. Several plasma density tapering schemes are discussed. The first scheme is called ''bucket jumping'' where the plasma density is abruptly returned to the original density after a conventional tapering to move the accelerating particles to a neighboring wakefield period (bucket). The second scheme is designed to specifically accelerate low energy protons by generating a nonlinear wakefield in a plasma region with close to critical density. The third scheme creates a periodic variation in the phase velocity by beating two intense laser beams with laser frequency difference equal to the plasma frequency. Discussions and case examples with simulations are presented where substantial acceleration of electrons or protons could be obtained.

  20. Emission of strong Terahertz pulses from laser wakefields in weakly coupled plasma

    NASA Astrophysics Data System (ADS)

    Singh, Divya; Malik, Hitendra K.

    2016-09-01

    The present paper discusses the laser plasma interaction for the wakefield excitation and the role of external magnetic field for the emission of Terahertz radiation in a collisional plasma. Flat top lasers are shown to be more appropriate than the conventional Gaussian lasers for the effective excitation of wakefields and hence, the generation of strong Terahertz radiation through the transverse component of wakefield.

  1. Dual effects of stochastic heating on electron injection in laser wakefield acceleration

    SciTech Connect

    Deng, Z. G.; Wang, X. G.; Yang, L.; Zhou, C. T.; Yu, M. Y.; Ying, H. P.

    2014-08-15

    Electron injection into the wakefield of an intense short laser pulse by a weaker laser pulse propagating in the opposite direction is reconsidered using two-dimensional (2D) particle-in-cell simulations as well as analytical modeling. It is found that for linearly polarized lasers the injection efficiency and the quality of the wakefield accelerated electrons increase with the intensity of the injection laser only up to a certain level, and then decreases. Theory and simulation tracking test electrons originally in the beat region of the two laser pulses show that the reduction of the injection efficiency at high injection-laser intensities is caused by stochastic overheating of the affected electrons.

  2. Bunch self-focusing regime of laser wakefield acceleration with reduced emittance growth.

    PubMed

    Reitsma, A J W; Goloviznin, V V; Kamp, L P J; Schep, T J

    2002-01-01

    A new regime of laser wakefield acceleration of an injected electron bunch is described. In this regime, the bunch charge is so high that the bunch wakefields play an important role in the bunch dynamics. In particular, the transverse bunch wakefield induces a strong self-focusing that suppresses the transverse emittance growth arising from misalignment errors. The decelerating longitudinal bunch wakefield, however, is not so strong that it completely cancels the accelerating laser wakefield. In fact, the induced energy spread can be compensated by exploiting phase slippage effects. These features make the new regime interesting for high beam quality laser wakefield acceleration. PMID:11800957

  3. Design of 10 GeV laser wakefield accelerator stages with shaped laser modes

    SciTech Connect

    Cormier-Michel, Estelle; Esarey, E.; Geddes, C.G.R.; Geddes, C.G.R.; Leemans, W.P.; Bruhwiler, D.L.; Cowan, B.; Paul, K.

    2009-09-25

    We present particle-in-cell simulations, using the VORPAL framework, of 10 GeV laser plasma wakefield accelerator stages. Scaling of the physical parameters with the plasma density allows us to perform these simulations at reasonable cost and to design high performance stages. In particular we show that, by choosing to operate in the quasi-linear regime, we can use higher order laser modes to tailor the focusing forces. This makes it possible to increase the matched electron beam radius and hence the total charge in the bunch while preserving the low bunch emittance required for applications.

  4. Probing the laser wakefield in underdense plasmas by induced terahertz emission

    SciTech Connect

    Hu, Z. D.; Wang, W. M.; Chen, L. M.; Li, Y. T.; Sheng, Z. M.; Zhang, J.; Key Laboratory for Laser Plasmas and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240

    2013-08-15

    Terahertz (THz) radiation can be produced from a laser wakefield driven in underdense plasmas in the presence of a transverse DC magnetic field. It is shown that the radiation usually contains a component at the electron plasma frequency and its harmonics when the wakefield is excited at high amplitudes. In the highly nonlinear bubble/blowout regime, the radiation contains a smooth component peaked at the reduced electron plasma frequency and an irregular spectrum extending to tens of the electron plasma frequency. The latter is due to the broken-wave structure behind the bubble. A theoretical model is presented and validated via two-dimensional particle-in-cell simulations. The measurement of such THz emission may provide a diagnostic of the laser wakefield structure.

  5. Quasimonoenergetic electron beams from laser wakefield acceleration in pure nitrogen

    SciTech Connect

    Mo, M. Z.; Ali, A.; Fedosejevs, R.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.

    2012-02-13

    Quasimonoenergetic electron beams with maximum energy >0.5 GeV and 2 mrad divergence have been generated in pure nitrogen gas via wakefield acceleration with 80 TW, 30 fs laser pulses. Long low energy tail features were typically observed due to continuous ionization injection. The measured peak electron energy decreased with the plasma density, agreeing with the predicted scaling for electrons. The experiments showed a threshold electron density of 3x10{sup 18}cm{sup -3} for self-trapping. Our experiments suggest that pure Nitrogen is a potential candidate gas to achieve GeV monoenergetic electrons using the ionization induced injection scheme for laser wakefield acceleration.

  6. Overloading effect of energetic electrons in the bubble regime of laser wakefield acceleration

    SciTech Connect

    Xu Jiancai; Shen Baifei; Zhang Xiaomei; Wen Meng; Ji Liangliang; Wang Wenpeng; Yu Yahong; Li Yuelin

    2010-10-15

    The overloading effect of self-injected high-charge electron bunch in the bubble regime of laser wakefield acceleration is studied. When too many electrons are trapped by the bubble, the wakefield can be strongly modified, preventing further injection of the background electrons. This process is directly observed in two-dimensional particle-in-cell simulation and is explained using a one-dimensional wake model. For obtaining significantly more energetic electrons, the use of a decreasing plasma density profile is proposed.

  7. High quality electron beam acceleration by ionization injection in laser wakefields with mid-infrared dual-color lasers

    NASA Astrophysics Data System (ADS)

    Zeng, Ming; Luo, Ji; Chen, Min; Mori, Warren B.; Sheng, Zheng-Ming; Hidding, Bernhard

    2016-06-01

    For the laser wakefield acceleration, suppression of beam energy spread while keeping sufficient charge is one of the key challenges. In order to achieve this, we propose bichromatic laser ionization injection with combined laser wavelengths of 2.4 μ m and 0.8 μ m for wakefield excitation and triggering electron injection via field ionization, respectively. A laser pulse at 2.4 μ m wavelength enables one to drive an intense acceleration structure with a relatively low laser power. To further reduce the requirement of laser power, we also propose to use carbon dioxide as the working gas medium, where carbon acts as the injection element. Our three dimensional particle-in-cell simulations show that electron beams at the GeV energy level with both low energy spreads (around 1%) and high charges (several tens of picocoulomb) can be obtained by the use of this scheme with laser peak power totaling sub-100 TW.

  8. Effects of Ionization in a Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    McGuffey, C.; Schumaker, W.; Kneip, S.; Matsuoka, T.; Bychenkov, V. Yu.; Glazyrin, I. V.; Karpeev, A. V.; Dollar, F. J.; Chvykov, V.; Kalintchenko, G.; Yanovsky, V.; Thomas, A. G. R.; Maksimchuk, A.; Krushelnick, K.

    2010-11-01

    Experimental results are presented from studies of the ionization injection process in laser wakefield acceleration using the Hercules laser with laser power up to 100 TW. Gas jet targets consisting of gas mixtures reduced the density threshold required for electron injection and increased the maximum beam charge. Gas mixture targets produced smooth beams even at densities which would produce severe beam breakup in pure He targets and the divergence was found to increase with gas mixture pressure.

  9. Effects of Ionization in a Laser Wakefield Accelerator

    SciTech Connect

    McGuffey, C.; Schumaker, W.; Matsuoka, T.; Dollar, F. J.; Chvykov, V.; Kalintchenko, G.; Yanovsky, V.; Thomas, A. G. R.; Maksimchuk, A.; Krushelnick, K.; Kneip, S.; Bychenkov, V. Yu.; Glazyrin, I. V.; Karpeev, A. V.

    2010-11-04

    Experimental results are presented from studies of the ionization injection process in laser wakefield acceleration using the Hercules laser with laser power up to 100 TW. Gas jet targets consisting of gas mixtures reduced the density threshold required for electron injection and increased the maximum beam charge. Gas mixture targets produced smooth beams even at densities which would produce severe beam breakup in pure He targets and the divergence was found to increase with gas mixture pressure.

  10. Enhancement of electron energy to the multi-GeV regime by a dual-stage laser-wakefield accelerator pumped by petawatt laser pulses.

    PubMed

    Kim, Hyung Taek; Pae, Ki Hong; Cha, Hyuk Jin; Kim, I Jong; Yu, Tae Jun; Sung, Jae Hee; Lee, Seong Ku; Jeong, Tae Moon; Lee, Jongmin

    2013-10-18

    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 acceleration. Here, we present a significant increase in laser-driven electron energy to the multi-GeV level by utilizing a 30-fs, 1-PW laser system. In particular, a dual-stage laser-wakefield acceleration scheme (injector and accelerator scheme) was applied to boost electron energies to over 3 GeV with a single PW laser pulse. Three-dimensional particle-in-cell simulations corroborate the multi-GeV electron generation from the dual-stage laser-wakefield accelerator driven by PW laser pulses. PMID:24182273

  11. Efficiency and energy spread in laser-wakefield acceleration.

    PubMed

    Reitsma, A J W; Cairns, R A; Bingham, R; Jaroszynski, D A

    2005-03-01

    The theoretical limits on efficiency and energy spread of the laser-wakefield accelerator are investigated using a one-dimensional model. Modifications, both of the wakefield due to the electron bunch, and of the laser pulse shape due to the varying permittivity of the plasma, are described self-consistently. It is found that a short laser pulse gives a higher efficiency than a long laser pulse with the same initial energy. Energy spread can be minimized by optimizing bunch length and bunch charge such that the variation of the accelerating force along the length of the bunch is minimized. An inherent trade-off between energy spread and efficiency exists. PMID:15783901

  12. Preparation For Laser Wakefield Experiments Driven by the Texas Petawatt Laser System

    SciTech Connect

    Reed, S. A.; Kalmykov, S.; Gaul, E.; Martinez, M.; Henderson, W.; Dong, P.; Gao, X.; Sanders, J. C.; Wang, X.; Shvets, G.; Ditmire, T.; Downer, M.

    2009-01-22

    Laboratories around the world are planning petawatt laser driven experiments. The Texas petawatt laser offers the ability to demonstrate laser wake field acceleration (LWFA) in a unique regime with pulse duration ({approx}160 fs) shorter than other petawatt scale systems currently in operation or under development. By focusing the 1.25 PW, 200 J, 160 fs pulses to peak intensity {approx}10{sup 19} W/cm{sup 2}, multi-GeV electron bunches can be produced from a low density He gas jet. The rarefied plasma density (5x10{sup 16}-10{sup 17} cm{sup -3}) required for near-resonant LWFA minimizes plasma lensing and offers long dephasing length for electron acceleration over distances ({approx}10 cm) exceeding the Rayleigh range. Because of the high power, the laser can be focused to a spot (r{sub 0}{approx}100 microns) greater than the plasma wavelength (r{sub 0}>{lambda}{sub p}), thus minimizing radial propagation effects. Together these properties enable the laser pulse to self-guide without the use of a preformed channel lending simplicity and stability to the overall acceleration process. Particle-in-cell (PIC) simulations show the laser experiences self-focusing which, because of ultrashort pulse duration, does not lead to a collapse of the wakefield and can generate over 3 GeV electron energy. The presented material will include details of initial measurements of the Texas petawatt laser system, simulations of laser wakefield acceleration for the given laser parameters and the experimental setup currently under construction.

  13. Automatic Beam Path Analysis of Laser Wakefield Particle Acceleration Data

    SciTech Connect

    Rubel, Oliver; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Wu, Kesheng; Prabhat,; Weber, Gunther H.; Ushizima, Daniela M.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes

    2009-10-19

    Numerical simulations of laser wakefield particle accelerators play a key role in the understanding of the complex acceleration process and in the design of expensive experimental facilities. As the size and complexity of simulation output grows, an increasingly acute challenge is the practical need for computational techniques that aid in scientific knowledge discovery. To that end, we present a set of data-understanding algorithms that work in concert in a pipeline fashion to automatically locate and analyze high energy particle bunches undergoing acceleration in very large simulation datasets. These techniques work cooperatively by first identifying features of interest in individual timesteps, then integrating features across timesteps, and based on the information derived perform analysis of temporally dynamic features. This combination of techniques supports accurate detection of particle beams enabling a deeper level of scientific understanding of physical phenomena than hasbeen possible before. By combining efficient data analysis algorithms and state-of-the-art data management we enable high-performance analysis of extremely large particle datasets in 3D. We demonstrate the usefulness of our methods for a variety of 2D and 3D datasets and discuss the performance of our analysis pipeline.

  14. Exploring laser-wakefield-accelerator regimes for near-term lasers using particle-in-cell simulation in Lorentz-boosted frames

    NASA Astrophysics Data System (ADS)

    Martins, S. F.; Fonseca, R. A.; Lu, W.; Mori, W. B.; Silva, L. O.

    2010-04-01

    Plasma-based acceleration offers compact accelerators with potential applications for high-energy physics and photon sources. The past five years have seen an explosion of experimental results with monoenergetic electron beams up to 1GeV on a centimetre-scale, using plasma waves driven by intense lasers. The next decade will see tremendous increases in laser power and energy, permitting beam energies beyond 10GeV. Leveraging on the Lorentz transformations to bring the laser and plasma spatial scales together, we have reduced the computational time for modelling laser-plasma accelerators by several orders of magnitude, including all the relevant physics. This scheme enables the first one-to-one particle-in-cell simulations of the next generation of accelerators at the energy frontier. Our results demonstrate that, for a given laser energy, choices in laser and plasma parameters strongly affect the output electron beam energy, charge and quality, and that all of these parameters can be optimized.

  15. Electron yield enhancement in a laser wakefield accelerator driven by asymmetric laser pulses

    SciTech Connect

    Leemans, W.P.; Catravas, P.; Esarey, E.; Geddes, C.G.R.; Toth, C.; Trines, R.; Schroeder, C.B.; Shadwick, B.A.; van Tilborg, J.; Faure, J.

    2002-08-01

    The effect of asymmetric laser pulses on electron yield from a laser wakefield accelerator has been experimentally studied using > 10{sup 19} cm{sup -3} plasmas and a 10 TW, > 45 fs, Ti:Al{sub 2}O{sub 3} laser. Laser pulse shape was controlled through non-linear chirp with a grating pair compressor. Pulses (76 fs FWHM) with a steep rise and positive chirp were found to significantly enhance the electron yield compared to pulses with a gentle rise and negative chirp. Theory and simulation show that fast rising pulses can generate larger amplitude wakes that seed the growth of the self-modulation instability and that frequency chirp is of minimal importance for the experimental parameters.

  16. Beam dynamics and wakefield simulations of the double grating accelerating structure

    SciTech Connect

    Najafabadi, B. Montazeri; Byer, R. L.; Ng, C. K.; England, R. J.; Peralta, E. A.; Soong, K.; Noble, R.; Wu, Z.

    2012-12-21

    Laser-driven acceleration in dielectric structures can provide gradients on the order of GeV/m. The small transverse dimension and tiny feature sizes introduce challenges in design, fabrication, and simulation studies of these structures. In this paper we present the results of beam dynamic simulation and short range longitudinal wakefield simulation of the double grating structure. We show the linear trend of acceleration in a dielectric accelerator design and calculate the maximum achievable gradient equal to 0.47E{sub 0} where E0 is maximum electric field of the laser excitation. On the other hand, using wakefield simulations, we show that the loss factor of the structure with 400nm gap size will be 0.12GV/m for a 10fC, 100as electron bunch which is an order of magnitude less than expected gradient near damage threshold of the device.

  17. Proof-of-principle experiments of laser Wakefield acceleration

    SciTech Connect

    Nakajima, K.; Kawakubo, T.; Nakanishi, H.

    1994-04-01

    Recently there has been a great interest in laser-plasma accelerators as possible next-generation particle accelerators because of their potential for ultra high accelerating gradients and compact size compared with conventional accelerators. It is known that the laser pulse is capable of exciting a plasma wave propagating at a phase velocity close to the velocity of light by means of beating two-frequency lasers or an ultra short laser pulse. These schemes came to be known as the Beat Wave Accelerator (BWA) for beating lasers or as the Laser Wakefield Accelerator (LWFA) for a short pulse laser. In this paper, the principle of laser wakefield particle acceleration has been tested by the Nd:glass laser system providing a short pulse with a power of 10 TW and a duration of 1 ps. Electrons accelerated up to 18 MeV/c have been observed by injecting 1 MeV/c electrons emitted from a solid target by an intense laser impact. The accelerating field gradient of 30 GeV/m is inferred.

  18. Radio-isotope production using laser Wakefield accelerators

    SciTech Connect

    Leemans, W.P.; Rodgers, D.; Catravas, P.E.; Geddes, C.G.R.; Fubiani, G.; Toth, C.; Esarey, E.; Shadwick, B.A.; Donahue, R.; Smith, A.; Reitsma, A.

    2001-07-27

    A 10 Hz, 10 TW solid state laser system has been used to produce electron beams suitable for radio-isotope production. The laser beam was focused using a 30 cm focal length f/6 off-axis parabola on a gas plume produced by a high pressure pulsed gas jet. Electrons were trapped and accelerated by high gradient wakefields excited in the ionized gas through the self-modulated laser wakefield instability. The electron beam was measured to contain excesses of 5 nC/bunch. A composite Pb/Cu target was used to convert the electron beam into gamma rays which subsequently produced radio-isotopes through (gamma, n) reactions. Isotope identification through gamma-ray spectroscopy and half-life time measurements demonstrated that Cu{sup 61} was produced which indicates that 20-25 MeV gamma rays were produced, and hence electrons with energies greater than 25-30 MeV. The production of high energy electrons was independently confirmed using a bending magnet spectrometer. The measured spectra had an exponential distribution with a 3 MeV width. The amount of activation was on the order of 2.5 uCi after 3 hours of operation at 1 Hz. Future experiments will aim at increasing this yield by post-accelerating the electron beam using a channel guided laser wakefield accelerator.

  19. Supersonic jets of hydrogen and helium for laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Svensson, K.; Hansson, M.; Wojda, F.; Senje, L.; Burza, M.; Aurand, B.; Genoud, G.; Persson, A.; Wahlström, C.-G.; Lundh, O.

    2016-05-01

    The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ˜30 % higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

  20. Laser wakefield acceleration experiments at the University of Michigan

    SciTech Connect

    Matsuoka, T.; McGuffey, C.; Horovitz, Y.; Dollar, F.; Bulanov, S. S.; Chvykov, V.; Kalintchenko, G.; Reed, S.; Rousseau, P.; Yanovsky, V.; Maksimchuk, A.; Krushelnick, K.; Huntington, C. M.; Drake, R. P.; Levin, M.; Zigler, A.

    2009-01-22

    Laser wakefield acceleration (LWFA) in a supersonic gas-jet using a self-guided laser pulse was studied by changing the laser power and electron density. The recently upgraded HERCULES laser facility equipped with wavefront correction enables a peak intensity of 8x10{sup 19} W/cm{sup 2} at laser power of 100 TW to be delivered to the gas-jet using f/10 focusing optics. We found that electron beam charge was increased significantly with an increase of the laser power from 30 TW to 80 TW and showed density threshold behavior at a fixed laser power. Betatron motion of electrons was also observed depending on laser power and electron density.

  1. Simulation of Wakefield Effect in ILC IR Chamber

    SciTech Connect

    Pei, S; Seryi, A.; Raubenheimer, T.O.; /SLAC

    2008-06-26

    To achieve super high luminosity, high current beams with very short bunch length are needed, which carry high intensity EM fields. For ILC, two bunch trains with bunch length of 300 {micro}m and bunch charge of 3.2nC are needed to collide at the IR to achieve the ILC luminosity goals. When the 300 {micro}m bunches pass through the IR chamber, wakefields will be excited, which will cause HOM power flowing through the IR chamber beam pipe to the final doublets due to the high frequency characteristic of the induced wakefields. Since superconducting technology is adopted for the final doublets of ILC BDS, whose operation stability might be affected by the HOM power produced at the IR chamber, quench might happen. In this paper, we did some analytical estimation and numerical simulation on the wakefield effects in ILC IR chamber.

  2. The phase-lock dynamics of the laser wakefield acceleration with an intensity-decaying laser pulse

    SciTech Connect

    Li, Wentao; Liu, Jiansheng Wang, Wentao; Zhang, Zhijun; Chen, Qiang; Tian, Ye; Qi, Rong; Yu, Changhai; Wang, Cheng; Li, Ruxin Xu, Zhizhan; Tajima, T.

    2014-03-03

    An electron beam with the maximum energy extending up to 1.8 GeV, much higher than the dephasing limit, is experimentally obtained in the laser wakefield acceleration with the plasma density of 3.5 × 10{sup 18} cm{sup −3}. With particle in cell simulations and theoretical analysis, we find that the laser intensity evolution plays a major role in the enhancement of the electron energy gain. While the bubble length decreases due to the intensity-decay of the laser pulse, the phase of the electron beam in the wakefield can be locked, which contributes to the overcoming of the dephasing. Moreover, the laser intensity evolution is described for the phase-lock acceleration of electrons in the uniform plasma, confirmed with our own simulation. Since the decaying of the intensity is unavoidable in the long distance propagation due to the pump depletion, the energy gain of the high energy laser wakefield accelerator can be greatly enhanced if the current process is exploited.

  3. Laser-Driven Coherent Betatron Oscillation in a Laser-Wakefield Cavity: Formation of Sinusoid Beam Shapes and Coherent Trajectories

    SciTech Connect

    Nemeth, Karoly; Li Yuelin; Shang Hairong; Harkay, Katherine C.; Shen Baifei; Crowell, Robert; Cary, John R.

    2009-01-22

    High amplitude coherent electron-trajectories have been seen in 3D particle-in-cell simulations of the colliding pulse injection scheme of laser-wakefield accelerators in the bubble regime, and explained as a consequence of laser-driven coherent betatron oscillation in our recent paper [K. Nemeth et al., Phys. Rev. Lett. 100, 095002 (2008)]. In the present paper we provide more details on the shape of the trajectories, their relationship to the phase velocity of the laser and indicate the dependence of the phenomenon on the accuracy of the numerical representation and choice of laser/plasma parameters.

  4. Ultra-bright XUV emission from laser wakefields in underdense plasma

    SciTech Connect

    Liu Yue; Sheng, Z. M.; Zheng, J.; Li, F. Y.; Xu, X. L.; Lu, W.; Mori, W. B.; Liu, C. S.; Zhang, J.

    2012-12-21

    By use of particle-in-cell (PIC) simulation, we observe ultra-bright XUV radiation pulses emerging from a laser wakefield driven above the wave-breaking threshold in underdense plasma, which is as short as a few hundred attoseconds in one-dimentsional simulations and a few femtoseconds in two-dimensional simulations. It is concerned with the formation of a transverse narrow current layer co-moving with the intense laser pulse. This current layer is formed by an electron density spike with trapped electrons in the wakefield with certain transverse kinetic momentum of electrons left behind the laser pulse. This net momentum appears when the driving laser pulse undergoes strong selfmodulation and subsequent pulse steepening at the front. In the multi-dimensional simulations, the XUV emission is found only near the laser axis with a much smaller spot size than the laser pulse due to the transverse dynamics of the trapped electrons. The present scheme provides an alternative method to produce ultra-bright XUV pulses for ultrafast applications.

  5. First measurement of laser Wakefield oscillations by longitudinal interferometry

    SciTech Connect

    Siders, C.W.; Le Blanc, S.P.; Rau, B.; Fisher, D.; Tajima, T.; Downer, M.C.; Babine, A.; Stepanov, A.; Sergeev, A.

    1996-12-31

    Because the electrostatic fields present in plasma waves can exceed those achievable in conventional accelerators and approach atomic scale values (E{sub a} {approximately} 500 GV/m), plasma based accelerators have received considerable attention as compact sources of high-energy electron pulses. Although stimulated Raman scattering or terahertz radiation at {ital w{sub p}} provided spatially averaged optical signatures of the plasma wave`s existence, new diagnostic techniques are required to map the the temporal and spatial structure of the plasma wave directly since such information is vital for addressing fundamental issues of wakefield generation and propagation. In this paper, we report femtosecond time resolved measurements of the longitudinal and radial structure of laser wakefield oscillations using an all optical technique known as interferometric ``photon acceleration`` or Longitudinal Interferometry.

  6. Laser Triggered Electron Injection into a Channel Guided Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Filip, C.

    2005-10-01

    Laser-plasma accelerators have demonstrated the generation of narrow energy spread (˜ few %) electron beams with considerable amount of charge (>100 pC). Stability of laser-plasma accelerators, as in the conventional accelerators, requires highly synchronized injection of electrons into the structured accelerating field. The Colliding Pulse Method[1] with pre-formed plasma channel guiding [2] can result in jitter-free injection in a dark-current-free accelerating structure. We report on experimental progress of laser triggered injection of electrons into a laser wakefield, where an intense laser pulse is guided by a pre-formed plasma channel. The experiments use the multi-beam, multi-terawatt Ti:Al2O3 laser at LOASIS facility of LBNL. The ignitor-heater method is used to first produce a pre-formed plasma channel in a hydrogen gas jet. Two counter propagating beams (wakefield driver:100-500mJ-50fs, injector:50-300mJ-50fs) then are focused onto the entrance of the channel. Preliminary results indicate that electron beam properties are affected by the second beam. Details of the experiment will be presented. [1]G.Fubiani, et al, Phys. Rev. E 70, 016402 (2004). [2]C.G.R. Geddes et al, Nature 431, 538 (2004). This work is supported by DoE under contract DE-AC02-05CH11231.

  7. Transverse effects in plasma wakefield acceleration at FACET - Simulation studies

    SciTech Connect

    Adli, E.; Hogan, M.; Frederico, J.; Litos, M. D.; An, W.; Mori, W.

    2012-12-21

    We investigate transverse effects in the plasma-wakefield acceleration experiments planned and ongoing at FACET. We use PIC simulation tools, mainly QuickPIC, to simulate the interaction of the drive electron beam and the plasma. In FACET a number of beam dynamics knobs, including dispersion and bunch length knobs, can be used to vary the beam transverse characteristics in the plasma. We present simulation results and the status of the FACET experimental searches.

  8. Modeling laser wakefield accelerators in a Lorentz boosted frame

    SciTech Connect

    Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E.; Grote, D.P.

    2010-09-15

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [1] is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing theframe of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.

  9. Modeling laser wakefield accelerators in a Lorentz boosted frame

    SciTech Connect

    Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E.; Grotec, D. P.

    2010-06-15

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high-frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing the frame of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.

  10. Laser wakefield acceleration of electrons with ionization injection in a pure N{sup 5+} plasma waveguide

    SciTech Connect

    Goers, A. J.; Yoon, S. J.; Elle, J. A.; Hine, G. A.; Milchberg, H. M.

    2014-05-26

    Ionization injection-assisted laser wakefield acceleration of electrons up to 120 MeV is demonstrated in a 1.5 mm long pure helium-like nitrogen plasma waveguide. The guiding structure stabilizes the high energy electron beam pointing and reduces the beam divergence. Our results are confirmed by 3D particle-in-cell simulations.

  11. Beam manipulation for compact laser wakefield accelerator based free-electron lasers

    NASA Astrophysics Data System (ADS)

    Loulergue, A.; Labat, M.; Evain, C.; Benabderrahmane, C.; Malka, V.; Couprie, M. E.

    2015-02-01

    Free-electron lasers (FELs) are a unique source of light, particularly in the x-ray domain. After the success of FELs based on conventional acceleration using radio-frequency cavities, an important challenge is the development of FELs based on electron bunching accelerated by a laser wakefield accelerator (LWFA). However, the present LWFA electron bunch properties do not permit use directly for a significant FEL amplification. It is known that longitudinal decompression of electron beams delivered by state-of-the-art LWFA eases the FEL process. We propose here a second order transverse beam manipulation turning the large inherent transverse chromatic emittances of LWFA beams into direct FEL gain advantage. Numerical simulations are presented showing that this beam manipulation can further enhance by orders of magnitude the peak power of the radiation.

  12. Charge Accretion Rate and Injection Radius of Ionized-Induced Injections in Laser Wakefield Accelerators

    NASA Astrophysics Data System (ADS)

    Zeng, Ming; Chen, Min; Sheng, Zheng-Ming

    2016-03-01

    Ionization-induced injection has recently been proved to be a stable injection method with several advantages in laser wakefield accelerators. However, the controlling of this injection process aiming at producing high quality electron beams is still challenging. In this paper, we examine the ionization injection processes and estimate the injection rate with two-dimensional particle-in-cell simulations. The injection rate is shown to increase linearly with the high-Z gas density as long as its ratio is smaller than some threshold in the mix gases. It is also shown that by changing the transverse mode of the driving lasers one can control the injection rate.

  13. Positron acceleration in plasma bubble wakefield driven by an ultraintense laser

    NASA Astrophysics Data System (ADS)

    Hou, Ya-Juan; Wan, Feng; Sang, Hai-Bo; Xie, Bai-Song

    2016-01-01

    The dynamics of positrons accelerating in electron-positron-ion plasma bubble fields driven by an ultraintense laser is investigated. The bubble wakefield is obtained theoretically when laser pulses are propagating in the electron-positron-ion plasma. To restrict the positrons transversely, an electron beam is injected. Acceleration regions and non-acceleration ones of positrons are obtained by the numerical simulation. It is found that the ponderomotive force causes the fluctuation of the positrons momenta, which results in the trapping of them at a lower ion density. The energy gaining of the accelerated positrons is demonstrated, which is helpful for practical applications.

  14. Observation of large-angle quasimonoenergetic electrons from a laser wakefield.

    PubMed

    Kaganovich, D; Gordon, D F; Ting, A

    2008-05-30

    A relativistically intense laser pulse is focused into a helium jet and quasimonoenergetic electrons emitted at a 40 degrees angle with respect to the laser axis are observed. The average electron energy is between 1 and 2 MeV and the total accelerated charge is about 1 nC emitted in a 10 degrees cone angle. Three dimensional particle-in-cell simulations reproduce key features of the experimental results and show that the interaction between ionization heating and nonlinear cavitation wakefields is responsible for the acceleration. PMID:18518612

  15. Numerical modeling of multi-GeV laser wakefield electron acceleration inside a dielectric capillary tube

    SciTech Connect

    Paradkar, B. S.; Cros, B.; Maynard, G.; Mora, P.

    2013-08-15

    Numerical modeling of laser wakefield electron acceleration inside a gas filled dielectric capillary tube is presented. Guiding of a short pulse laser inside a dielectric capillary tube over a long distance (∼1 m) and acceleration of an externally injected electron bunch to ultra-relativistic energies (∼5-10 GeV) are demonstrated in the quasi-linear regime of laser wakefield acceleration. Two dimensional axisymmetric simulations were performed with the code WAKE-EP (Extended Performances), which allows computationally efficient simulations of such long scale plasma. The code is an upgrade of the quasi-static particle code, WAKE [P. Mora and T. M. Antonsen, Jr., Phys. Plasmas 4, 217 (1997)], to simulate the acceleration of an externally injected electron bunch (including beam loading effect) and propagation of the laser beam inside a dielectric capillary. The influence of the transverse electric field of the plasma wake on the radial loss of the accelerated electrons to the dielectric wall is investigated. The stable acceleration of electrons to multi-GeV energy with a non-resonant laser pulse with a large spot-size is demonstrated.

  16. Increasing energy coupling into plasma waves by tailoring the laser radial focal spot distribution in a laser wakefield accelerator

    SciTech Connect

    Genoud, G.; Burza, M.; Persson, A.; Svensson, K.; Wahlström, C.-G.; Bloom, M. S.; Najmudin, Z.; Mangles, S. P. D.; Vieira, J.; Silva, L. O.

    2013-06-15

    By controlling the focal spot quality with a deformable mirror, we are able to show that increasing the fraction of pulse energy contained within the central part of the focal spot, while keeping the total energy and central spot size constant, significantly increases the amount of energy transferred to the wakefield: Our measurements show that the laser loses significantly more laser energy and undergoes greater redshifting and that more charge is produced in the accelerated beam. Three dimensional particle in cell simulations performed with accurate representations of the measured focal spot intensity distribution confirm that energy in the wings of the focal spot is effectively wasted. Even though self-focusing occurs, energy in the wings of the focal spot distribution is not coupled into the wakefield, emphasising the vital importance of high quality focal spot profiles in experiments.

  17. Radially polarized, half-cycle, attosecond pulses from laser wakefields through coherent synchrotronlike radiation.

    PubMed

    Li, F Y; Sheng, Z M; Chen, M; Yu, L L; Meyer-ter-Vehn, J; Mori, W B; Zhang, J

    2014-10-01

    Attosecond bursts of coherent synchrotronlike radiation are found when driving ultrathin relativistic electron disks in a quasi-one-dimensional regime of wakefield acceleration, in which the laser waist is larger than the wake wavelength. The disks of overcritical density shrink radially due to focusing wakefields, thus providing the transverse currents for the emission of an intense, radially polarized, half-cycle pulse of about 100 attoseconds in duration. The electromagnetic pulse first focuses to a peak intensity (7×10(20)W/cm(2)) 10 times larger than the driving pulse and then emerges as a conical beam. Basic dynamics of the radiative process are derived analytically and in agreement with particle-in-cell simulations. By making use of gas targets instead of solids to form the ultrathin disks, this method allows for high repetition rates required for applications. PMID:25375611

  18. Controlling the betatron oscillations of a wakefield-accelerated electron beam by temporally asymmetric laser pulses

    SciTech Connect

    Nam, Inhyuk; Hur, Min Sup; Uhm, Han Sup; Hafz, Nasr A. M.; Suk, Hyyong

    2011-04-15

    Based on two-dimensional particle-in-cell simulations, we investigated the electron beam's transverse oscillations by temporally asymmetric laser pulses in laser wakefield acceleration. Of particular interest in this article are the effects of ultrashort laser pulses having sharp rising and slow falling time scales. In this situation, the accelerated electron beam interacts directly with the laser field and undergoes transverse oscillations due to a phase-slip with the laser field. This oscillation can be matched with the betatron oscillation due to the focusing force of the ions, which can lead to a large transverse oscillation amplitude due to the resonance between them. Furthermore, in this case, the electron beam can be microbunched at the laser wavelength, which may provide the possibility for generation of a coherent synchrotron radiation.

  19. Ionization Induced Trapping in a Laser Wakefield Accelerator

    SciTech Connect

    McGuffey, C.; Thomas, A. G. R.; Schumaker, W.; Matsuoka, T.; Chvykov, V.; Dollar, F. J.; Kalintchenko, G.; Yanovsky, V.; Maksimchuk, A.; Krushelnick, K.; Bychenkov, V. Yu.; Glazyrin, I. V.; Karpeev, A. V.

    2010-01-15

    Experimental studies of electrons produced in a laser wakefield accelerator indicate trapping initiated by ionization of target gas atoms. Targets composed of helium and controlled amounts of various gases were found to increase the beam charge by as much as an order of magnitude compared to pure helium at the same electron density and decrease the beam divergence from 5.1+-1.0 to 2.9+-0.8 mrad. The measurements are supported by particle-in-cell modeling including ionization. This mechanism should allow generation of electron beams with lower emittance and higher charge than in preionized gas.

  20. Femtosecond x-rays from Thomson scattering using laser wakefield accelerators

    SciTech Connect

    Catravas, P.; Esarey, E.; Leemans, W.P.

    2001-03-01

    The possibility of producing femtosecond x-rays through Thomson scattering high power laser beams off laser wakefield generated relativistic electron beams is discussed. The electron beams are produced with either a self-modulated laser wakefield accelerator (SM-LWFA) or through a standard laser wakefield accelerator (LWFA) with optical injection. For a SM-LWFA (LWFA) produced electron beam, a broad (narrow) energy distribution is assumed, resulting in X-ray spectra that are broadband (monochromatic). Designs are presented for 3-100 fs x-ray pulses and the expected flux and brightness of these sources are compared.

  1. Experimental validation of a radio frequency photogun as external electron injector for a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Stragier, X. F. D.; Luiten, O. J.; van der Geer, S. B.; van der Wiel, M. J.; Brussaard, G. J. H.

    2011-07-01

    A purpose-built RF-photogun as external electron injector for a laser wakefield accelerator has been thoroughly tested. Different properties of the RF-photogun have been measured such as energy, energy spread and transverse emittance. The focus of this study is the investigation of the smallest possible focus spot and focus stability at the entrance of the plasma channel. For an electron bunch with 10 pC charge and 3.7 MeV kinetic energy, the energy spread was 0.5% with a shot-to-shot stability of 0.05%. After focusing the bunch by a pulsed solenoid lens at 140 mm from the middle of the lens, the focal spot was 40 μm with a shot-to-shot stability of 5 μm. Higher charge leads to higher energy spread and to a larger spot size, due to space charge effects. All properties were found to be close to design values. Given the limited energy of 3.7 MeV, the properties are sufficient for this gun to serve as injector for one particular version of laser wakefield acceleration, i.e., injection ahead of the laser pulse. These measured electron bunch properties were then used as input parameters for simulations of electron bunch injection in a laser wakefield accelerator. The arrival time jitter was deduced from measurements of the energy fluctuation, in combination with earlier measurements using THz coherent transition radiation, and is around 150 fs in the present setup. The bunch length in the focus, simulated using particle tracking, depends on the accelerated charge and goes from 100 fs at 0.1 pC to 1 ps at 50 pC. When simulating the injection of the 3.7 MeV electron bunch of 10 pC in front of a 25 TW laser pulse with a waist of 30 μm in a plasma with a density of 0.7 × 1024 m-3, the maximum accelerated charge was found to be 1.2 pC with a kinetic energy of ˜900 MeV and an energy spread of ˜5%. The experiments combined with the simulations show the feasibility of external injection and give a prediction of the output parameters that can be expected from a laser

  2. Experimental validation of a radio frequency photogun as external electron injector for a laser wakefield accelerator

    SciTech Connect

    Stragier, X. F. D.; Luiten, O. J.; Geer, S. B. van der; Wiel, M. J. van der; Brussaard, G. J. H.

    2011-07-15

    A purpose-built RF-photogun as external electron injector for a laser wakefield accelerator has been thoroughly tested. Different properties of the RF-photogun have been measured such as energy, energy spread and transverse emittance. The focus of this study is the investigation of the smallest possible focus spot and focus stability at the entrance of the plasma channel. For an electron bunch with 10 pC charge and 3.7 MeV kinetic energy, the energy spread was 0.5% with a shot-to-shot stability of 0.05%. After focusing the bunch by a pulsed solenoid lens at 140 mm from the middle of the lens, the focal spot was 40 {mu}m with a shot-to-shot stability of 5 {mu}m. Higher charge leads to higher energy spread and to a larger spot size, due to space charge effects. All properties were found to be close to design values. Given the limited energy of 3.7 MeV, the properties are sufficient for this gun to serve as injector for one particular version of laser wakefield acceleration, i.e., injection ahead of the laser pulse. These measured electron bunch properties were then used as input parameters for simulations of electron bunch injection in a laser wakefield accelerator. The arrival time jitter was deduced from measurements of the energy fluctuation, in combination with earlier measurements using THz coherent transition radiation, and is around 150 fs in the present setup. The bunch length in the focus, simulated using particle tracking, depends on the accelerated charge and goes from 100 fs at 0.1 pC to 1 ps at 50 pC. When simulating the injection of the 3.7 MeV electron bunch of 10 pC in front of a 25 TW laser pulse with a waist of 30 {mu}m in a plasma with a density of 0.7 x 10{sup 24} m{sup -3}, the maximum accelerated charge was found to be 1.2 pC with a kinetic energy of {approx}900 MeV and an energy spread of {approx}5%. The experiments combined with the simulations show the feasibility of external injection and give a prediction of the output parameters that can

  3. Experimental laser wakefield acceleration scalings exceeding 100 TW

    SciTech Connect

    McGuffey, C.; Matsuoka, T.; Schumaker, W.; Dollar, F.; Zulick, C.; Chvykov, V.; Kalintchenko, G.; Yanovsky, V.; Maksimchuk, A.; Thomas, A. G. R.; Krushelnick, K.; Kneip, S.; Najmudin, Z.

    2012-06-15

    Understanding the scaling of laser wakefield acceleration (LWFA) is crucial to the design of potential future systems. A number of computational and theoretical studies have predicted scalings with laser power for various parameters, but experimental studies have typically been limited to small parameter ranges. Here, we detail extensive measurements of LWFA experiments conducted over a considerable range in power from 20 to 110 TW, which allows for a greater plasma density range and for a large number of data points. These measurements include scalings of the electron beam charge and maximum energy as functions of density as well as injection threshold density, beam charge, and total beam energy as functions of laser power. The observed scalings are consistent with theoretical understandings of operation in the bubble regime.

  4. Acceleration and evolution of a hollow electron beam in wakefields driven by a Laguerre-Gaussian laser pulse

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Bo; Chen, Min; Schroeder, C. B.; Luo, Ji; Zeng, Ming; Li, Fei-Yu; Yu, Lu-Le; Weng, Su-Ming; Ma, Yan-Yun; Yu, Tong-Pu; Sheng, Zheng-Ming; Esarey, E.

    2016-03-01

    We show that a ring-shaped hollow electron beam can be injected and accelerated by using a Laguerre-Gaussian laser pulse and ionization-induced injection in a laser wakefield accelerator. The acceleration and evolution of such a hollow, relativistic electron beam are investigated through three-dimensional particle-in-cell simulations. We find that both the ring size and the beam thickness oscillate during the acceleration. The beam azimuthal shape is angularly dependent and evolves during the acceleration. The beam ellipticity changes resulting from the electron angular momenta obtained from the drive laser pulse and the focusing forces from the wakefield. The dependence of beam ring radius on the laser-plasma parameters (e.g., laser intensity, focal size, and plasma density) is studied. Such a hollow electron beam may have potential applications for accelerating and collimating positively charged particles.

  5. Electron Injection into Laser Wakefields by the Two-Beam Colliding Pulse Scheme

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Michel, P.; Toth, C. S.; Geddes, C. G. R.; van Tilborg, J.; Fubiani, G.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.; Cary, J. R.; Giacone, R.; Bruhwiler, D.

    2004-11-01

    Laser driven acceleration in plasmas has succeeded in producing electron beams containing considerable amount of charge (> 100 pC) at energies in excess of 100 MeV. Control of the trapping process is needed to generate monoenergetic electron beams in a reproducible manner. We report on experimental progress of laser triggered injection of electrons into laser wakefields with a two-pulse colliding laser scheme[1]. The experiments use the multi-beam, multi-terawatt Ti:Al_2O3 laser at the l'OASIS facility of LBNL. In the experiments, two counter propagating beams 30^rc angle are focused onto a high density ( ˜10^19/cm^3) gas jet. Preliminary results indicate that electron beam properties are affected by the second beam. Details of the experiments will be shown as well as comparisons with simulations. [1] G. Fubiani, et., al, Phys. Rev. E 70, 016402 (2004).

  6. Influence of a strong longitudinal magnetic field on laser wakefield acceleration

    SciTech Connect

    Rassou, S.; Bourdier, A.; Drouin, M.

    2015-07-15

    Optimization of the beam quality and electronic trapped charge in the cavity are key issues of laser wake field acceleration. The effect of an initially applied uniform magnetic field, parallel to the direction of propagation of the pump pulse, on the laser wakefield is explored. First, an analytic model for the laser wakefield is built up in the case when such an external magnetic field is applied. Then, simulations are performed with a 3D quasi-cylindrical particle in cell code in the blowout (or bubble) regime. Transverse currents are generated at the rear of the bubble which amplify the longitudinal magnetic field. For several plasma and laser parameters, the wake shape is altered and trapping can be reduced or cancelled by the magnetic field. When considering optical injection, and when two counterpropagating waves interact with a rather high plasma density, trapping is not affected by the magnetic field. In this range of plasma and laser parameters, it is shown that the longitudinal magnetic field can reduce or even prevent self-injection and enhance beam quality.

  7. UNDULATOR-BASED LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC

    SciTech Connect

    Bakeman, M.S.; Fawley, W.M.; Leemans, W. P.; Nakamura, K.; Robinson, K.E.; Schroeder, C.B.; Toth, C.

    2009-05-04

    to couple the THUNDER undulator to the LOASIS Lawrence Berkeley National Laboratory (LBNL) laser wakefield accelerator (LWFA). Currently the LWFA has achieved quasi-monoenergetic electron beams with energies up to 1 GeV. These ultra-short, high-peak-current, electron beams are ideal for driving a compact XUV free electron laser (FEL). Understanding the electron beam properties such as the energy spread and emittance is critical for achieving high quality light sources with high brightness. By using an insertion device such as an undulator and observing changes in the spontaneous emission spectrum, the electron beam energy spread and emittance can be measured with high precision. The initial experiments will use spontaneous emission from 1.5 m of undulator. Later experiments will use up to 5 m of undulator with a goal of a high gain, XUV FEL.

  8. Optimization of THz Radiation Generation from a Laser Wakefield Accelerator

    SciTech Connect

    Plateau, G. R.; Matlis, N. H.; Toth, C.; Geddes, C. G. R.; Schroeder, C. B.; Tilborg, J. van; Albert, O.; Esarey, E.; Leemans, W. P.

    2009-01-22

    Ultrashort terahertz pulses with energies in the {mu}J range can be generated with laser wakefield accelerators (LWFA), which are novel, compact accelerators that produce ultrashort electron bunches with energies up to 1 GeV and energy spreads of a few-percent. Laser pulses interacting with a plasma create accelerated electrons which upon exiting the plasma emit terahertz pulses via transition radiation. Because these electron bunches are ultrashort (<50 fs), they can radiate coherently (coherent transition radiation--CTR) in a wide bandwidth ({approx}1-10 THz) yielding high intensity terahertz pulses. In addition to providing a non-invasive bunch-length diagnostic and thus feedback for the LWFA, these high peak power THz pulses are suitable for high field (MV/cm) pump-probe experiments. Here we present energy-based measurements using a Golay cell and an electro-optic technique which were used to characterize these THz pulses.

  9. Summary of Working Group 1: Laser Plasma Wakefield Accelerators

    SciTech Connect

    Krushelnick, Karl; Kaganovich, Dmitri; Gonsalves, Anthony

    2009-01-22

    There have been many significant experimental and theoretical advances recently with regard to the production of relativistic electron beams using laser wakefield accelerators (LWFA) driven by high power short pulse lasers. In particular, there has been an explosion of interest in this field following the discovery of methods to generate such beams with low energy spread. In recent work by many groups around the world the energy and quality of these beams has been improved and a more complete understanding of the 'bubble' regime of electron acceleration has been obtained, enabling a significant improvement in the output electron beam stability. The 2008 Advanced Accelerator Concepts workshop in Santa Cruz CA brought together the leading groups engaged in this research from around the world. This paper will summarize the major results presented at the conference. Further details on the work described here can be found in the other related papers in these proceedings.

  10. Direct Observation of the Injection Dynamics of a Laser Wakefield Accelerator Using Few-Femtosecond Shadowgraphy.

    PubMed

    Sävert, A; Mangles, S P D; Schnell, M; Siminos, E; Cole, J M; Leier, M; Reuter, M; Schwab, M B; Möller, M; Poder, K; Jäckel, O; Paulus, G G; Spielmann, C; Skupin, S; Najmudin, Z; Kaluza, M C

    2015-07-31

    We present few-femtosecond shadowgraphic snapshots taken during the nonlinear evolution of the plasma wave in a laser wakefield accelerator with transverse synchronized few-cycle probe pulses. These snapshots can be directly associated with the electron density distribution within the plasma wave and give quantitative information about its size and shape. Our results show that self-injection of electrons into the first plasma-wave period is induced by a lengthening of the first plasma period. Three-dimensional particle-in-cell simulations support our observations. PMID:26274425

  11. Laser triggered injection of electrons in a laser wakefield accelerator with the colliding pulse method

    SciTech Connect

    Nakamura, K.; Fubiani, G.; Geddes, C.G.R.; Michel, P.; van Tilborg, J.; Toth, C.; Esarey, E.; Schroeder, C.B.; Leemans, W.P.

    2004-10-22

    An injection scheme for a laser wakefield accelerator that employs a counter propagating laser (colliding with the drive laser pulse, used to generate a plasma wake) is discussed. The threshold laser intensity for electron injection into the wakefield was analyzed using a heuristic model based on phase-space island overlap. Analysis shows that the injection can be performed using modest counter propagating laser intensity a{sub 1} < 0.5 for a drive laser intensity of a{sub 0} = 1.0. Preliminary experiments were preformed using a drive beam and colliding beam. Charge enhancement by the colliding pulse was observed. Increasing the signal-to-noise ratio by means of a preformed plasma channel is discussed.

  12. Self-guided laser wakefield acceleration beyond 1 GeV using ionization-induced injection.

    PubMed

    Clayton, C E; Ralph, J E; Albert, F; Fonseca, R A; Glenzer, S H; Joshi, C; Lu, W; Marsh, K A; Martins, S F; Mori, W B; Pak, A; Tsung, F S; Pollock, B B; Ross, J S; Silva, L O; Froula, D H

    2010-09-01

    The concepts of matched-beam, self-guided laser propagation and ionization-induced injection have been combined to accelerate electrons up to 1.45 GeV energy in a laser wakefield accelerator. From the spatial and spectral content of the laser light exiting the plasma, we infer that the 60 fs, 110 TW laser pulse is guided and excites a wake over the entire 1.3 cm length of the gas cell at densities below 1.5 × 10(18) cm(-3). High-energy electrons are observed only when small (3%) amounts of CO2 gas are added to the He gas. Computer simulations confirm that it is the K-shell electrons of oxygen that are ionized and injected into the wake and accelerated to beyond 1 GeV energy. PMID:20867526

  13. Laser-wakefield acceleration of monoenergetic electron beams in the first plasma-wave period.

    PubMed

    Mangles, S P D; Thomas, A G R; Kaluza, M C; Lundh, O; Lindau, F; Persson, A; Tsung, F S; Najmudin, Z; Mori, W B; Wahlström, C-G; Krushelnick, K

    2006-06-01

    Beam profile measurements of laser-wakefield accelerated electron bunches reveal that in the monoenergetic regime the electrons are injected and accelerated at the back of the first period of the plasma wave. With pulse durations ctau >or= lambda(p), we observe an elliptical beam profile with the axis of the ellipse parallel to the axis of the laser polarization. This increase in divergence in the laser polarization direction indicates that the electrons are accelerated within the laser pulse. Reducing the plasma density (decreasing ctau/lambda(p)) leads to a beam profile with less ellipticity, implying that the self-injection occurs at the rear of the first period of the plasma wave. This also demonstrates that the electron bunches are less than a plasma wavelength long, i.e., have a duration <25 fs. This interpretation is supported by 3D particle-in-cell simulations. PMID:16803242

  14. Plasma wakefields driven by an incoherent combination of laser pulses: a path towards high-average power laser-plasma accelerators

    SciTech Connect

    Benedetti, C.; Schroeder, C.B.; Esarey, E.; Leemans, W.P.

    2014-05-01

    he wakefield generated in a plasma by incoherently combining a large number of low energy laser pulses (i.e.,without constraining the pulse phases) is studied analytically and by means of fully-self-consistent particle-in-cell simulations. The structure of the wakefield has been characterized and its amplitude compared with the amplitude of the wake generated by a single (coherent) laser pulse. We show that, in spite of the incoherent nature of the wakefield within the volume occupied by the laser pulses, behind this region the structure of the wakefield can be regular with an amplitude comparable or equal to that obtained from a single pulse with the same energy. Wake generation requires that the incoherent structure in the laser energy density produced by the combined pulses exists on a time scale short compared to the plasma period. Incoherent combination of multiple laser pulses may enable a technologically simpler path to high-repetition rate, high-average power laser-plasma accelerators and associated applications.

  15. Plasma wakefields driven by an incoherent combination of laser pulses: A path towards high-average power laser-plasma accelerators

    SciTech Connect

    Benedetti, C.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2014-05-15

    The wakefield generated in a plasma by incoherently combining a large number of low energy laser pulses (i.e., without constraining the pulse phases) is studied analytically and by means of fully self-consistent particle-in-cell simulations. The structure of the wakefield has been characterized and its amplitude compared with the amplitude of the wake generated by a single (coherent) laser pulse. We show that, in spite of the incoherent nature of the wakefield within the volume occupied by the laser pulses, behind this region, the structure of the wakefield can be regular with an amplitude comparable or equal to that obtained from a single pulse with the same energy. Wake generation requires that the incoherent structures in the laser energy density produced by the combined pulses exist on a time scale short compared to the plasma period. Incoherent combination of multiple laser pulses may enable a technologically simpler path to high-repetition rate, high-average power laser-plasma accelerators, and associated applications.

  16. GEANT4 simulations for beam emittance in a linear collider based on plasma wakefield acceleration

    SciTech Connect

    Mete, O. Xia, G.; Hanahoe, K.; Labiche, M.

    2015-08-15

    Alternative acceleration technologies are currently under development for cost-effective, robust, compact, and efficient solutions. One such technology is plasma wakefield acceleration, driven by either a charged particle or laser beam. However, the potential issues must be studied in detail. In this paper, the emittance evolution of a witness beam through elastic scattering from gaseous media and under transverse focusing wakefields is studied.

  17. Laser Guiding at Relativistic Intensities and Wakefield ParticleAcceleration in Plasma Channels

    SciTech Connect

    Geddes, C.G.R.; Toth, Cs.; van Tilborg, J.; Esarey, E.; Schroeder, C.B.; Bruhwiler, D.; Nieter, C.; Cary, J.; Leemans, W.P.

    2005-05-01

    High quality electron beams with hundreds of picoCoulombs ofcharge inpercent energy spread above 80 MeV were produced for the firsttime in high gradient laser wakefield accelerators by guiding the drivelaser pulse.

  18. Laser Wakefield Acceleration Driven by a CO2 Laser (STELLA-LW) - Final Report

    SciTech Connect

    Kimura, Wayne D

    2008-06-27

    The original goals of the Staged Electron Laser Acceleration – Laser Wakefield (STELLA-LW) program were to investigate two new methods for laser wakefield acceleration (LWFA). In pseudo-resonant LWFA (PR-LWFA), a laser pulse experiences nonlinear pulse steepening while traveling through the plasma. This steepening allows the laser pulse to generate wakefields even though the laser pulse length is too long for resonant LWFA to occur. For the conditions of this program, PR-LWFA requires a minimum laser peak power of 3 TW and a low plasma density (10^16 cm^-3). Seeded self-modulated LWFA (seeded SM-LWFA) combines LWFA with plasma wakefield acceleration (PWFA). An ultrashort (~100 fs) electron beam bunch acts as a seed in a plasma to form a wakefield via PWFA. This wakefield is subsequently amplified by the laser pulse through a self-modulated LWFA process. At least 1 TW laser power and, for a ~100-fs bunch, a plasma density ~10^17 cm^-3 are required. STELLA-LW was located on Beamline #1 at the Brookhaven National Laboratory (BNL) Accelerator Test Facility (ATF). The ATF TW CO2 laser served as the driving laser beam for both methods. For PR-LWFA, a single bunch was to probe the wakefield produced by the laser beam. For seeded SM-LWFA, the ATF linac would produce two bunches, where the first would be the seed and the second would be the witness. A chicane would compress the first bunch to enable it to generate wakefields via PWFA. The plasma source was a short-length, gas-filled capillary discharge with the laser beam tightly focused in the center of the capillary, i.e., no laser guiding was used, in order to obtain the needed laser intensity. During the course of the program, several major changes had to be made. First, the ATF could not complete the upgrade of the CO2 laser to the 3 TW peak power needed for the PR-LWFA experiment. Therefore, the PR-LWFA experiment had to be abandoned leaving only the seeded SM-LWFA experiment. Second, the ATF discovered that the

  19. Electron acceleration in a two-stage laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Li, Ruxin; Liu, Jiansheng; Xia, Changquan; Wang, Wentao; Lu, Haiyang; Wang, Cheng; Deng, Aihua; Li, Wentao; Zhang, Hui; Liang, Xiaoyan; Leng, Yuxin; Lu, Xiaoming; Wang, Cheng; Wang, Jianzhou; Shen, Baifei; Nakajima, Kazuhisa; Xu, Zhizhan

    2012-07-01

    Near-GeV electron beam generation from a two-stage laser wakefield accelerator (LWFA) is reported. Electron injection and acceleration are separated into two distinct LWFA stages and controlled independently from each other by employing two gas cells filled with a He/O2 mixture and pure He gas, respectively. Electrons with a Maxwellian spectrum, generated from the injection stage assisted by ionization-induced injection, are seeded into the acceleration stage with a 3-mm long gas cell and accelerated to produce a 0.8-GeV quasimonoenergetic electron beam for a 45 TW 40 fs laser pulse, corresponding to an acceleration gradient of 187 GV/m. In the injection stage, the produced electron beam properties can be optimized by adjusting the input laser intensity and the plasma density so that quasimonoenergetic electron beams are obtained owing to the self-focusing effects of the laser beam. The ionization-induced injection scheme has been extensively employed for a capillary discharge plasma waveguide to demonstrate channel-guided LWFA beyond 1 GeV. Using a 4-cm capillary made of oxygen containing acrylic resin results in optically guiding 130 TW 55 fs laser pulse that accelerates electrons up to 1.8 GeV in contrast with no electron acceleration in a polyethylene capillary free of oxygen.

  20. LASER WAKEFIELD ACCELERATION DRIVEN BY ATF CO2 LASER (STELLA-LW).

    SciTech Connect

    KIMURA,W.D.; ANDREEV,N.E.; BABZIEN,M.; BEN-ZVI,I.; ET AL.

    2004-09-25

    A new experiment has begun that builds upon the successful Staged Electron Laser Acceleration (STELLA) experiment, which demonstrated high-trapping efficiency and narrow energy spread in a staged laser-driven accelerator. STELLA was based upon inverse free electron lasers (IFEL); the new experiment, called STELLA-LW, is based upon laser wakefield acceleration (LWFA). The first phase of STELLA-LW will be to demonstrate LWFA in a capillary discharge driven by the Brookhaven National Laboratory Accelerator Test Facility (ATF) terawatt CO{sub 2} laser beam. This will be the first time LWFA is conducted at 10.6-{micro}m laser wavelength. It will also be operating in an interesting pseudo-resonant regime where the laser pulse length is too long for resonant LWFA, but too short for self-modulated LWFA. Analysis has shown that in pseudo-resonant LWFA, pulse-steepening effects occur on the laser pulse that permits generation of strong wakefields. Various approaches are being explored for the capillary discharge including polypropylene and hydrogen-filled capillaries. Planned diagnostics for the experiment include coherent Thomson scattering (CTS) to detect the wakefield generation. This will be one of the first times CTS is used on a capillary discharge.

  1. Self-truncated ionization injection and consequent monoenergetic electron bunches in laser wakefield acceleration

    SciTech Connect

    Zeng, Ming; Zhang, Jie; Chen, Min; Department of Mathematics, Institute of Natural Sciences, and MOE-LSC, Shanghai Jiao Tong University, Shanghai 20040 ; Sheng, Zheng-Ming; SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG ; Mori, Warren B.

    2014-03-15

    The ionization-induced injection in laser wakefield acceleration has been recently demonstrated to be a promising injection scheme. However, the energy spread controlling in this mechanism remains a challenge because continuous injection in a mixed gas target is usually inevitable. Here, we propose that by use of certain initially unmatched laser pulses, the electron injection can be constrained to the very front region of the mixed gas target, typically in a length of a few hundreds micrometers determined by the laser self-focusing and the wake deformation. As a result, the produced electron beam has narrow energy spread and meanwhile contains tens of pC in charge. Both multidimensional simulations and theoretical analysis illustrate the effectiveness of this scheme.

  2. Nonlinear laser-seeded modulation instability in a proton driver plasma wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Siemon, Carl; Khudik, Vladimir; Yi, S. Austin; Pukhov, Alexander; Shvets, Gennady

    2013-10-01

    A new method for seeding the modulation instability (MI) in a proton driver plasma wakefield accelerator (PDPWA) using a CO2 laser pulse is presented. The proton beam's envelope equation is used to analytically compare the laser seed with previously suggested seeding methods. Simulations demonstrate that a laser pulse placed ahead of a proton beam with a realistic longitudinal density profile leads to peak accelerating gradients that are comparable to those produced by other seeding methods. The nonlinear BNS damping of the MI is analytically shown to lead to instability saturation. The envelope equation is Fourier expanded into a set of coupled, nonlinear equations that describe the evolution of the beam's Fourier components. Peak beam density and peak accelerating gradient during the beam's evolution are estimated.

  3. Measurements of the Critical Power for Self-Injection of Electrons in a Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Froula, D. H.; Clayton, C. E.; Döppner, T.; Marsh, K. A.; Barty, C. P. J.; Divol, L.; Fonseca, R. A.; Glenzer, S. H.; Joshi, C.; Lu, W.; Martins, S. F.; Michel, P.; Mori, W. B.; Palastro, J. P.; Pollock, B. B.; Pak, A.; Ralph, J. E.; Ross, J. S.; Siders, C. W.; Silva, L. O.; Wang, T.

    2009-11-01

    A laser wakefield acceleration study has been performed in the matched, self-guided, blowout regime producing 720±50MeV quasimonoenergetic electrons with a divergence ΔθFWHM of 2.85±0.15mrad using a 10 J, 60 fs 0.8μm laser. While maintaining a nearly constant plasma density (3×1018cm-3), the energy gain increased from 75 to 720 MeV when the plasma length was increased from 3 to 8 mm. Absolute charge measurements indicate that self-injection of electrons occurs when the laser power P exceeds 3 times the critical power Pcr for relativistic self-focusing and saturates around 100 pC for P/Pcr>5. The results are compared with both analytical scalings and full 3D particle-in-cell simulations.

  4. Measurements of the critical power for self-injection of electrons in a laser wakefield accelerator.

    PubMed

    Froula, D H; Clayton, C E; Döppner, T; Marsh, K A; Barty, C P J; Divol, L; Fonseca, R A; Glenzer, S H; Joshi, C; Lu, W; Martins, S F; Michel, P; Mori, W B; Palastro, J P; Pollock, B B; Pak, A; Ralph, J E; Ross, J S; Siders, C W; Silva, L O; Wang, T

    2009-11-20

    A laser wakefield acceleration study has been performed in the matched, self-guided, blowout regime producing 720 +/- 50 MeV quasimonoenergetic electrons with a divergence Deltatheta_{FWHM} of 2.85 +/- 0.15 mrad using a 10 J, 60 fs 0.8 microm laser. While maintaining a nearly constant plasma density (3 x 10{18} cm{-3}), the energy gain increased from 75 to 720 MeV when the plasma length was increased from 3 to 8 mm. Absolute charge measurements indicate that self-injection of electrons occurs when the laser power P exceeds 3 times the critical power P{cr} for relativistic self-focusing and saturates around 100 pC for P/P{cr} > 5. The results are compared with both analytical scalings and full 3D particle-in-cell simulations. PMID:20366048

  5. Laser-seeded modulation instability in a proton driver plasma wakefield accelerator

    SciTech Connect

    Siemon, Carl; Khudik, Vladimir; Austin Yi, S.; Shvets, Gennady; Pukhov, Alexander

    2013-10-15

    A new method for initiating the modulation instability (MI) of a proton beam in a proton driver plasma wakefield accelerator using a short laser pulse preceding the beam is presented. A diffracting laser pulse is used to produce a plasma wave that provides a seeding modulation of the proton bunch with the period equal to that of the plasma wave. Using the envelope description of the proton beam, this method of seeding the MI is analytically compared with the earlier suggested seeding technique that involves an abrupt truncation of the proton bunch. The full kinetic simulation of a realistic proton bunch is used to validate the analytic results. It is further used to demonstrate that a plasma density ramp placed in the early stages of the laser-seeded MI leads to its stabilization, resulting in sustained accelerating electric fields (of order several hundred MV/m) over long propagation distances (∼100–1000 m)

  6. Undulator radiation driven by laser-wakefield accelerator electron beams

    NASA Astrophysics Data System (ADS)

    Wiggins, S. M.; Anania, M. P.; Welsh, G. H.; Brunetti, E.; Cipiccia, S.; Grant, P. A.; Reboredo, D.; Manahan, G.; Grant, D. W.; Jaroszynski, D. A.

    2015-05-01

    The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laserplasma accelerators for the production of ultra-short electron bunches with subsequent generation of coherent, bright, short-wavelength radiation pulses. The new Scottish Centre for the Application of Plasma-based Accelerators (SCAPA) will develop a wide range of applications utilising such light sources. Electron bunches can be propagated through a magnetic undulator with the aim of generating fully coherent free-electron laser (FEL) radiation in the ultra-violet and Xrays spectral ranges. Demonstration experiments producing spontaneous undulator radiation have been conducted at visible and extreme ultra-violet wavelengths but it is an on-going challenge to generate and maintain electron bunches of sufficient quality in order to stimulate FEL behaviour. In the ALPHA-X beam line experiments, a Ti:sapphire femtosecond laser system with peak power 20 TW has been used to generate electron bunches of energy 80-150 MeV in a 2 mm gas jet laser-plasma wakefield accelerator and these bunches have been transported through a 100 period planar undulator. High peak brilliance, narrow band spontaneous radiation pulses in the vacuum ultra-violet wavelength range have been generated. Analysis is provided with respect to the magnetic quadrupole beam transport system and subsequent effect on beam emittance and duration. Requirements for coherent spontaneous emission and FEL operation are presented.

  7. Trapping, compression, and acceleration of an electron bunch in the nonlinear laser wakefield.

    PubMed

    Khachatryan, Arsen G

    2002-04-01

    A scheme of laser wakefield acceleration, when a relatively rare and long bunch of nonrelativistic or weakly relativistic electrons is initially in front of the laser pulse, is suggested and considered. The motion of test electrons is studied both in the one-dimensional (1D) case (1D wakefield) and in the case of three-dimensional laser wakefield excited in a plasma channel. It is shown that for definite parameters of the problem the bunch can be trapped, effectively compressed both in longitudinal and transverse directions, and accelerated to ultra-relativistic energies in the region of first accelerating maximum of the wakefield. The accelerated bunch has sizes much less than the plasma wavelength and relatively small energy spread. PMID:12006039

  8. Multichromatic narrow-energy-spread electron bunches from laser-wakefield acceleration with dual-color lasers.

    PubMed

    Zeng, M; Chen, M; Yu, L L; Mori, W B; Sheng, Z M; Hidding, B; Jaroszynski, D A; Zhang, J

    2015-02-27

    A method based on laser wakefield acceleration with controlled ionization injection triggered by another frequency-tripled laser is proposed, which can produce electron bunches with low energy spread. As two color pulses copropagate in the background plasma, the peak amplitude of the combined laser field is modulated in time and space during the laser propagation due to the plasma dispersion. Ionization injection occurs when the peak amplitude exceeds a certain threshold. The threshold is exceeded for limited duration periodically at different propagation distances, leading to multiple ionization injections and separated electron bunches. The method is demonstrated through multidimensional particle-in-cell simulations. Such electron bunches may be used to generate multichromatic x-ray sources for a variety of applications. PMID:25768765

  9. Observation of strong correlation between quasimonoenergetic electron beam generation by laser wakefield and laser guiding inside a preplasma cavity.

    PubMed

    Hosokai, Tomonao; Kinoshita, Kenichi; Ohkubo, Takeru; Maekawa, Akira; Uesaka, Mitsuru; Zhidkov, Alexei; Yamazaki, Atsushi; Kotaki, Hideyuki; Kando, Masaki; Nakajima, Kazuhisa; Bulanov, Sergei V; Tomassini, Paolo; Giulietti, Antonio; Giulietti, Danilo

    2006-03-01

    We use a one-shot measurement technique to study effects of laser prepulses on the electron laser wakefield acceleration driven by relativistically intense laser pulses (lambda=790 nm, 11 TW, 37 fs) in dense helium gas jets. A quasimonoenergetic electron bunch with an energy peak approximately 11.5 MeV[DeltaE/E approximately 10% (FWHM)] and with a narrow-cone angle (0.04pi mm mrad) of ejection is detected at a plasma density of 8 x 10(19) cm(-3). A strong correlation between the generation of monoenergetic electrons and optical guiding of the pulse in a thin channel produced by picosecond laser prepulses is observed. This generation mechanism is well corroborated by two-dimensional particle-in-cell simulations. PMID:16605668

  10. Simulations of a meter-long plasma wakefield accelerator

    SciTech Connect

    Lee, S.; Katsouleas, T.; Hemker, R.; Mori, W. B.

    2000-06-01

    Full-scale particle-in-cell simulations of a meter-long plasma wakefield accelerator (PWFA) are presented in two dimensions. The results support the design of a current PWFA experiment in the nonlinear blowout regime where analytic solutions are intractable. A relativistic electron bunch excites a plasma wake that accelerates trailing particles at rates of several hundred MeV/m. A comparison is made of various simulation codes, and a parallel object-oriented code OSIRIS is used to model a full meter of acceleration. Excellent agreement is obtained between the simulations and analytic expressions for the transverse betatron oscillations of the beam. The simulations are used to develop scaling laws for designing future multi-GeV accelerator experiments. (c) 2000 The American Physical Society.

  11. First demonstration of a staged all-optical laser wakefield acceleration

    SciTech Connect

    Kaganovich, D.; Ting, A.; Gordon, D.F.; Hubbard, R.F.; Jones, T.G.; Zigler, A.; Sprangle, P.

    2005-10-01

    A proof-of-principle experiment on staged all-optical laser wakefield acceleration was performed at the Naval Research Laboratory. Electrons with <1 MeV energy created by the interaction of a 2 TW laser beam with a nitrogen gas jet were injected and accelerated to more than 20 MeV in a plasma wakefield generated by a 10 TW laser beam in a helium gas jet. The energy gain occurred in a narrow time window of 3 ps between the injection and acceleration laser beams, and within a tight spatial alignment of {approx}10 {mu}m.

  12. An ultrashort pulse ultra-violet radiation undulator source driven by a laser plasma wakefield accelerator

    SciTech Connect

    Anania, M. P.; Brunetti, E.; Wiggins, S. M.; Grant, D. W.; Welsh, G. H.; Issac, R. C.; Cipiccia, S.; Shanks, R. P.; Manahan, G. G.; Aniculaesei, C.; Jaroszynski, D. A.; Geer, S. B. van der; Loos, M. J. de; Poole, M. W.; Shepherd, B. J. A.; Clarke, J. A.; Gillespie, W. A.; MacLeod, A. M.

    2014-06-30

    Narrow band undulator radiation tuneable over the wavelength range of 150–260 nm has been produced by short electron bunches from a 2 mm long laser plasma wakefield accelerator based on a 20 TW femtosecond laser system. The number of photons measured is up to 9 × 10{sup 6} per shot for a 100 period undulator, with a mean peak brilliance of 1 × 10{sup 18} photons/s/mrad{sup 2}/mm{sup 2}/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has energy of 120–130 MeV with the radiation pulse duration in the range of 50–100 fs.

  13. Measurements of the critical power for self-injection of electrons in a laser wakefield accelerator

    SciTech Connect

    Froula, D H; Clayton, C E; Doppner, T; Fonseca, R A; Marsh, K A; Barty, C J; Divol, L; Glenzer, S H; Joshi, C; Lu, W; Martins, S F; Michel, P; Mori, W; Palastro, J P; Pollock, B B; Pak, A; Ralph, J E; Ross, J S; Siders, C; Silva, L O; Wang, T

    2009-06-02

    A laser wakefield acceleration study has been performed in the matched, self-guided, blow-out regime where a 10 J, 60 fs laser produced 720 {+-} 50 MeV quasi-monoenergetic electrons with a divergence of {Delta}{theta} = 2.85 {+-} 0.15 mRad. While maintaining a nearly constant plasma density (3 x 10{sup 18} cm{sup -3}), a linear electron energy gain was measured from 100 MeV to 700 MeV when the plasma length was scaled from 3 mm to 8 mm. Absolute charge measurements indicate that self-injection occurs when P/P{sub cr} > 4 and saturates around 100 pC for P/P{sub cr} > 12. The results are compared with both analytical scalings and full 3D particle-in-cell simulations.

  14. Laser Wakefield Acceleration at Reduced Density in the Self-Guided Regime

    SciTech Connect

    Ralph, J E; Albert, F; Glenzer, S H; Palastro, J P; Pollock, B B; Shaw, J L; Till, A; Froula, D H; Clayton, C E; Lu, W; Mori, W B; Pak, A E; Joshi, C; Martin, S; Silva, L O

    2009-11-18

    Experiments conducted using a 200TW 60 fs laser have demonstrated up to 720 MeV electrons in the self-guided laser wakefield regime using pure Helium gas jet targets. Charge and energy of the accelerated electrons was measured using an electron spectrometer with a 0.5T magnet and charge callibrated image plates. The self-trapped charge in a helium plasma was shown to fall off with decreasing electron density with a threshold at 2.5 x 10{sup 18} (cm{sup -3}) below which no charge is trapped. Self-guiding however is shown to continue below this density limitation over distances of 14 mm with an exit spot size of 25{micro}m. Simulations show that injection of electrons at these densities can be assisted through ionization induced trapping in a mix of Helium with 3% Oxygen.

  15. Control and optimization of a staged laser-wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Golovin, G.; Banerjee, S.; Chen, S.; Powers, N.; Liu, C.; Yan, W.; Zhang, J.; Zhang, P.; Zhao, B.; Umstadter, D.

    2016-09-01

    We report results of an experimental study of laser-wakefield acceleration of electrons, using a staged device based on a double-jet gas target that enables independent injection and acceleration stages. This novel scheme is shown to produce stable, quasi-monoenergetic, and tunable electron beams. We show that optimal accelerator performance is achieved by systematic variation of five critical parameters. For the injection stage, we show that the amount of trapped charge is controlled by the gas density, composition, and laser power. For the acceleration stage, the gas density and the length of the jet are found to determine the final electron energy. This independent control over both the injection and acceleration processes enabled independent control over the charge and energy of the accelerated electron beam while preserving the quasi-monoenergetic character of the beam. We show that the charge and energy can be varied in the ranges of 2-45 pC, and 50-450 MeV, respectively. This robust and versatile electron accelerator will find application in the generation of high-brightness and controllable x-rays, and as the injector stage for more conventional devices.

  16. Simulation of ultrashort electron pulse generation from optical injection into wake-field plasma waves

    SciTech Connect

    Dodd, E.S.; Kim, J.K.; Umstadter, D.

    2004-11-01

    A laser-plasma-based source of relativistic electrons is described in detail, and analyzed in two dimensions using theoretical and numeric techniques. Two laser beams are focused in a plasma, one exciting a wake-field electron plasma wave while another locally alters some electron trajectories in such a way that they can be trapped and accelerated by the wave. Previous analyses dealt only with one-dimensional models. In this paper two-dimensional particle-in-cell simulations and analysis of single particle trajectories show that the radial wake field plays an important role. The simulation results are interpreted to evaluate the accelerated electron beam's properties and compared with existing devices.

  17. Simulation of ultrashort electron pulse generation from optical injection into wake-field plasma waves.

    PubMed

    Dodd, E S; Kim, J K; Umstadter, D

    2004-11-01

    A laser-plasma-based source of relativistic electrons is described in detail, and analyzed in two dimensions using theoretical and numeric techniques. Two laser beams are focused in a plasma, one exciting a wake-field electron plasma wave while another locally alters some electron trajectories in such a way that they can be trapped and accelerated by the wave. Previous analyses dealt only with one-dimensional models. In this paper two-dimensional particle-in-cell simulations and analysis of single particle trajectories show that the radial wake field plays an important role. The simulation results are interpreted to evaluate the accelerated electron beam's properties and compared with existing devices. PMID:15600768

  18. Synergistic laser-wakefield and direct-laser acceleration in the plasma-bubble regime.

    PubMed

    Zhang, Xi; Khudik, Vladimir N; Shvets, Gennady

    2015-05-01

    The concept of a hybrid laser plasma accelerator is proposed. Relativistic electrons undergoing resonant betatron oscillations inside the plasma bubble created by a laser pulse are accelerated by gaining energy directly from the laser pulse and from its plasma wake. The resulting phase space of self-injected plasma electrons is split into two, containing a subpopulation that experiences wakefield acceleration beyond the standard dephasing limit because of the multidimensional nature of its motion that reduces the phase slippage between the electrons and the wake. PMID:26001005

  19. Bubble shape and electromagnetic field in the nonlinear regime for laser wakefield acceleration

    SciTech Connect

    Li, X. F.; Yu, Q.; Huang, S.; Kong, Q.; Gu, Y. J.; Kawata, S.

    2015-08-15

    The electromagnetic field in the electron “bubble” regime for ultra-intense laser wakefield acceleration was solved using the d'Alembert equations. Ignoring the residual electrons, we assume an ellipsoidal bubble forms under ideal conditions, with bubble velocity equal to the speed of light in vacuum. The general solution for bubble shape and electromagnetic field were obtained. The results were confirmed in 2.5D PIC (particle-in-cell) simulations. Moreover, slopes for the longitudinal electric field of larger than 0.5 were found in these simulations. With spherical bubbles, this slope is always smaller than or equal to 0.5. This behavior validates the ellipsoid assumption.

  20. Characteristics of a tapered capillary plasma waveguide for laser wakefield acceleration

    SciTech Connect

    Kim, M. S.; Jang, D. G.; Lee, T. H.; Nam, I. H.; Lee, I. W.; Suk, H.

    2013-05-20

    We developed a gas-filled capillary with a tapered density for laser wakefield acceleration, of which the tapering was realized by employing gas feed-lines with different cross-sections. Plasma diagnostics show that the capillary plasma has a significant longitudinal density tapering and a transverse parabolic profile. By using the tapered capillary plasma, high transmission (over 90%) of laser beams, meaning good optical guiding, was observed. These results demonstrate the potential of the tapered plasma source for high-energy laser wakefield acceleration, where the dephasing problem is minimized.

  1. Energy spread minimization in a cascaded laser wakefield accelerator via velocity bunching

    NASA Astrophysics Data System (ADS)

    Zhang, Zhijun; Li, Wentao; Liu, Jiansheng; Wang, Wentao; Yu, Changhai; Tian, Ye; Nakajima, Kazuhisa; Deng, Aihua; Qi, Rong; Wang, Cheng; Qin, Zhiyong; Fang, Ming; Liu, Jiaqi; Xia, Changquan; Li, Ruxin; Xu, Zhizhan

    2016-05-01

    We propose a scheme to minimize the energy spread of an electron beam (e-beam) in a cascaded laser wakefield accelerator to the one-thousandth-level by inserting a stage to compress its longitudinal spatial distribution. In this scheme, three-segment plasma stages are designed for electron injection, e-beam length compression, and e-beam acceleration, respectively. The trapped e-beam in the injection stage is transferred to the zero-phase region at the center of one wakefield period in the compression stage where the length of the e-beam can be greatly shortened owing to the velocity bunching. After being seeded into the third stage for acceleration, the e-beam can be accelerated to a much higher energy before its energy chirp is compensated owing to the shortened e-beam length. A one-dimensional theory and two-dimensional particle-in-cell simulations have demonstrated this scheme and an e-beam with 0.2% rms energy spread and low transverse emittance could be generated without loss of charge.

  2. High-efficiency acceleration in the laser wakefield by a linearly increasing plasma density

    SciTech Connect

    Dong, Kegong; Wu, Yuchi; Zhu, Bin; Zhang, Zhimeng; Zhao, Zongqing; Zhou, Weimin; Hong, Wei; Cao, Leifeng; Gu, Yuqiu

    2014-12-15

    The acceleration length and the peak energy of the electron beam are limited by the dephasing effect in the laser wakefield acceleration with uniform plasma density. Based on 2D-3V particle in cell simulations, the effects of a linearly increasing plasma density on the electron acceleration are investigated broadly. Comparing with the uniform plasma density, because of the prolongation of the acceleration length and the gradually increasing accelerating field due to the increasing plasma density, the electron beam energy is twice higher in moderate nonlinear wakefield regime. Because of the lower plasma density, the linearly increasing plasma density can also avoid the dark current caused by additional injection. At the optimal acceleration length, the electron energy can be increased from 350 MeV (uniform) to 760 MeV (linearly increasing) with the energy spread of 1.8%, the beam duration is 5 fs and the beam waist is 1.25 μm. This linearly increasing plasma density distribution can be achieved by a capillary with special gas-filled structure, and is much more suitable for experiment.

  3. Temporal characterization of ultrashort linearly chirped electron bunches generated from a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Zhang, C. J.; Hua, J. F.; Wan, Y.; Guo, B.; Pai, C.-H.; Wu, Y. P.; Li, F.; Chu, H.-H.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Wang, J.; Lu, W.

    2016-06-01

    A new method for diagnosing the temporal characteristics of ultrashort electron bunches with linear energy chirp generated from a laser wakefield accelerator is described. When the ionization-injected bunch interacts with the back of the drive laser, it is deflected and stretched along the direction of the electric field of the laser. Upon exiting the plasma, if the bunch goes through a narrow slit in front of the dipole magnet that disperses the electrons in the plane of the laser polarization, it can form a series of bunchlets that have different energies but are separated by half a laser wavelength. Since only the electrons that are undeflected by the laser go through the slit, the energy spectrum of the bunch is modulated. By analyzing the modulated energy spectrum, the shots where the bunch has a linear energy chirp can be recognized. Consequently, the energy chirp and beam current profile of those bunches can be reconstructed. This method is demonstrated through particle-in-cell simulations and experiment.

  4. PROPOSAL FOR A PRE-BUNCHED LASER WAKEFIELD ACCELERATION EXPERIMENT AT THE BNL DUV FEL FACILITY.

    SciTech Connect

    WANG,X.J.SHEEHY,B.WU,Z.GAI,W.TING,A.

    2003-05-12

    We propose a pre-bunched Laser Wakefield Acceleration (LWFA) experiment in a plasma channel at the BNL DUV-FEL Facility. BNL DUV-FEL facility is uniquely qualified to carry out the proposed experiment because of the high-brightness' electron beam and RF synchronized TW Ti:Sapphire laser system. The DUV-FEL is a 200 MeV linac facility equipped with a photocathode RF gun injector, a 100 fs Ti:Sapphire laser system and a magnetic bunch compressor. The proposed LWFA will inject a 150 MeV, 10 fs electron bunch into a centimeters long plasma channel. Simulation and preliminary experiment showed that, high-brightness 10 fs electron bunch with 20 pC charge could be produced using the technique of longitudinal emittance compensation. The initial experiment will be performed using the existing Ti:Sapphire laser system (50mJ, 100 fs) with 30 {micro}m spot and 4 cm channel, the maximum energy gain will be about 15 MeV. We propose to upgrade the existing SDL laser output to 500 mJ with a shorter pulse length (50 fs). For an electron beam spot size of 20 um, the expected energy gain is about 100 MeV for a 5 TW, 50 fs laser pulse.

  5. Observation of Betatron radiation in the self-modulated regime of laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Albert, Felicie; Pollock, Bradley; Goyon, Clement; Pak, Arthur; Moody, John; Shaw, Jessica; Lemos, Nuno; Marsh, Ken; Clayton, Christopher; Schumaker, William; Glenzer, Siegfried; Saunders, Alison; Falcone, Roger; Fiuza, Frederico; Joshi, Chan

    2015-11-01

    We observed multi keV Betatron x-rays from a self-modulated laser wakefield accelerator. The experiment was performed at the Jupiter Laser Facility, LLNL, by focusing the Titan short pulse beam (4-150 J, 1 ps) onto the edge of a Helium gas jet at electronic densities around 1019 cm-3. For the first time on this laser system, we used a long focal length optic, which produced a laser normalized potential a0 in the range 1-3. Under these conditions, electrons are accelerated by the plasma wave created in the wake of the light pulse. As a result, intense Raman satellites, which measured shifts depend on the electron plasma density, were observed on the laser spectrum transmitted through the target. Electrons with energies up to 200 MeV, as well as Betatron x-rays with critical energies around 20 keV, were measured. OSIRIS 2D PIC simulations confirm that the electrons gain energy both from the plasma wave and from their interaction with the laser field. This work was performed under the auspices of the U.S. Department of Energy under contract DE-AC52- 07NA27344, and supported by the Laboratory Directed Research and Development (LDRD) Program under tracking code 13-LW-076.

  6. Temporal Evolution of Self-Modulated Laser Wakefields Measured by Coherent Thomson Scattering

    SciTech Connect

    Ting, A.; Krushelnick, K.; Moore, C.I.; Burris, H.R.; Esarey, E.; Krall, J.; Sprangle, P. |

    1996-12-01

    Coherent Thomson scattering of a picosecond probe laser was used to measure the time evolution of plasma wakefields produced by a high intensity laser pulse (7{times}10{sup 18} W/cm{sup 2}) in an underdense plasma ({ital n}{sub {ital e}}{approx_equal}10{sup 19} cm{sup {minus}3}) in the self-modulated laser wakefield accelerator configuration. Large amplitude plasma wakefields which lasted less than 5ps were observed to decay into ion acoustic waves. The time scales associated with these measurements were consistent with the effects of the modulational instability and the enhancement of scattered signal from plasma channel formation. {copyright} {ital 1996 The American Physical Society.}

  7. Applications of laser wakefield accelerators for biomedical imaging

    NASA Astrophysics Data System (ADS)

    Najmudin, Zulfikar

    2014-10-01

    Laser-wakefield accelerators driven by high-intensity short-pulse lasers are a proven compact source of high-energy electron beams, with energy gains of ~GeV energy in centimetres of plasma demonstrated. One of the main proposed applications for these accelerators is to drive synchrotron light sources, in particular for x-ray applications. It has also been shown that the same plasma accelerator can also act as a wigglers, capable of the production of high brightness and spatially coherent hard x-ray beams. In this latest work, we demonstrate the application of these unique light-sources for biological and medical applications. The experiments were performed with the Astra Gemini laser at the Rutherford Appleton Laboratory in the UK. Gemini produces laser pulses with energy exceeding 10 J in pulse lengths down to 40 fs. A long focal length parabola (f / 20) is used to focus the laser down to a spot of size approximately 25 μ m (fwhm) into a gas-cell of variable length. Electrons are accelerated to energies up to 1 GeV and a bright beam of x-rays is observed simultaneously with the accelerated beam. The length of the gas cell was optimised to produce high contrast x-ray images of radiographed test objects. This source was then used for imaging a number of interesting medical and biological samples. Full tomographic imaging of a human trabecular bone sample was made with resolution easily exceeding the ~100 μm level required for CT applications. Phase-contrast imaging of human prostrate and mouse neonates at the micron level was also demonstrated. These studies indicate the usefulness of these sources in research and clinical applications. They also show that full 3D imaging can be made possible with this source in a fraction of the time that it would take with a corresponding x-ray tube. The JAI is funded by STFC Grant ST/J002062/1.

  8. A table-top x-ray FEL based on a laser wakefield accelerator-undulator system

    SciTech Connect

    Nakajima, K.; Kawakubo, T.; Nakanishi, H.

    1995-12-31

    Ultrahigh-gradient electron acceleration has been confirmed owing to the laser wakefield acceleration mechanism driven by an intense short laser wakefield acceleration mechanism driven by an intense short laser pulse in an underdense plasma. The laser wakefield acceleration makes it possible to build a compact electron linac capable of producing an ultra-short bunched electron beam. While the accelerator is attributed to longitudinal wakefields, transverse wakefields simultaneously generated by a short laser pulse can serve as a plasma undulator with a very short wavelength equal to a half of the plasma wavelength. We propose a new FEL concept for X-rays based on a laser wakefield accelerator-undulator system driven by intense short laser pulses delivered from table-top terawatt lasers. The system is composed of the accelerator stage and the undulator stage in a table-top size. A low energy electron beam is accelerated an bunched into microbunches due to laser wakefields in the accelerator stage. A micro-bunched beam travelling to the opposite direction of driving laser pulses produces coherent X-ray radiation in the undulator stage. A practical configuration and its analyses are presented.

  9. Application of High-performance Visual Analysis Methods to Laser Wakefield Particle Acceleration Data

    SciTech Connect

    Rubel, Oliver; Prabhat, Mr.; Wu, Kesheng; Childs, Hank; Meredith, Jeremy; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Ahern, Sean; Weber, Gunther H.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes

    2008-08-28

    Our work combines and extends techniques from high-performance scientific data management and visualization to enable scientific researchers to gain insight from extremely large, complex, time-varying laser wakefield particle accelerator simulation data. We extend histogram-based parallel coordinates for use in visual information display as well as an interface for guiding and performing data mining operations, which are based upon multi-dimensional and temporal thresholding and data subsetting operations. To achieve very high performance on parallel computing platforms, we leverage FastBit, a state-of-the-art index/query technology, to accelerate data mining and multi-dimensional histogram computation. We show how these techniques are used in practice by scientific researchers to identify, visualize and analyze a particle beam in a large, time-varying dataset.

  10. Compton Scattering X-Ray Sources Driven by Laser Wakefield Acceleration

    SciTech Connect

    Hartemann, F V; Gibson, D J; Brown, W J; Rousse, A; Phuoc, K T; Pukhov, A

    2005-10-19

    Recent laser wakefield acceleration experiments have demonstrated the generation of femtosecond, nano-Coulomb, low emittance, nearly monokinetic relativistic electron bunches of sufficient quality to produce bright, tunable, ultrafast x-rays via Compton scattering. Design parameters for a proof-of-concept experiment are presented using a three-dimensional Compton scattering code and a laser-plasma interaction particle-in-cell code modeling the wakefield acceleration process; x-ray fluxes exceeding 10{sup 22} s{sup -1} are predicted, with a peak brightness > 10{sup 20} photons/(mm{sup 2} x mrad{sup 2} x s x 0.1% bandwidth).

  11. Tomography of injection and acceleration of monoenergetic electrons in a laser-wakefield accelerator.

    PubMed

    Hsieh, C-T; Huang, C-M; Chang, C-L; Ho, Y-C; Chen, Y-S; Lin, J-Y; Wang, J; Chen, S-Y

    2006-03-10

    A tomographic diagnosis method was developed to systematically resolve the injection and acceleration processes of a monoenergetic electron beam in a laser-wakefield accelerator. It was found that all the monoenergetic electrons are injected at the same location in the plasma column and accelerated from 5 to 55 MeV energy in 200 microm distance. This is a direct measurement of the real acceleration gradient in a laser-wakefield accelerator, and the experimental data are consistent with the model of transverse wave breaking and beam loading for monoenergetic electron injection. PMID:16606269

  12. Generation of laser pulse trains for tests of multi-pulse laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Shalloo, R. J.; Corner, L.; Arran, C.; Cowley, J.; Cheung, G.; Thornton, C.; Walczak, R.; Hooker, S. M.

    2016-09-01

    In multi-pulse laser wakefield acceleration (MP-LWFA) a plasma wave is driven by a train of low-energy laser pulses separated by the plasma period, an approach which offers a route to driving plasma accelerators with high efficiency and at high pulse repetition rates using emerging technologies such as fibre and thin-disk lasers. Whilst these laser technologies are in development, proof-of-principle tests of MP-LWFA require a pulse train to be generated from a single, high-energy ultrafast pulse. Here we demonstrate the generation of trains of up to 7 pulses with pulse separations in the range 150-170 fs from single 40 fs pulses produced by a Ti:sapphire laser.

  13. Injection and acceleration of electron bunch in a plasma wakefield produced by a chirped laser pulse

    SciTech Connect

    Afhami, Saeedeh; Eslami, Esmaeil

    2014-06-15

    An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can trap and accelerate charged particles up to GeV. One-dimensional analysis of electron injection, trapping, and acceleration by different chirped pulses propagating in plasma is investigated numerically. In this paper, we inject electron bunches in front of the chirped pulses. It is indicated that periodical chirped laser pulse can trap electrons earlier than other pulses. It is shown that periodical chirped laser pulses lead to decrease the minimum momentum necessary to trap the electrons. This is due to the fact that periodical chirped laser pulses are globally much efficient than nonchirped pulses in the wakefield generation. It is found that chirped laser pulses could lead to much larger electron energy than that of nonchirped pulses. Relative energy spread has a lower value in the case of periodical chirped laser pulses.

  14. Modeling of Laser wakefield acceleration in the Lorentz boosted frame using UPIC-EMMA and OSIRIS

    NASA Astrophysics Data System (ADS)

    Yu, Peicheng; Xu, Xinlu; Decyk, Viktor; Tsung, Frank; Vieira, Jorge; Fonseca, Ricardo; Lu, Wei; Silva, Luis; Mori, Warren; UCLA Team; Tsinghua University Beijing Team; IST Portugal Team

    2014-10-01

    We present the capability of investigating physics of laser wakefield accelerator (LWFA) in nonlinear regimes using various approaches. This includes simulating the physics using OSIRIS 3D code in the lab and boosted frame. We also implemented hybrid 3D algorithm into OSIRIS which uses an algorithm with a PIC description in r-z and a gridless description in phi [A. F. Lifschitz et al., JCP. 228, 1803 (2009)]. This algorithm greatly reduce the computation load by describing the three-dimensional (3D) physics problem of laser-plasma interaction with essentially two-dimensional if the expansion is truncated. The hybrid 3D OSIRIS code can be used to simulate the nonlinear physics in LWFA in both lab and boosted frames. Combining the hybrid 3D and boosted frame approaches potentially provides unprecedented speedups. Furthermore, we can simulate the same problems in a boosted frame using the spectral EM-PIC code UPIC-EMMA which solves the Maxwell's equation in Fourier space. By applying a recipe to systematically reduce the numerical Cerenkov instability (NCI) in the spspectral code, we are able to conduct LWFA Lorentz boosted frame simulation at arbitrary gamma with no signs of NCI.

  15. Progress in Laser Wakefield Acceleration with Few-Cycle Lasers

    SciTech Connect

    Veisz, Laszlo; Schmid, Karl; Sears, Chris; Buck, Alexander; Krausz, Ferenc; Mikhailova, Julia; Tautz, Raphael; Herrmann, Daniel; Geissler, Michael

    2010-11-04

    We present a novel method of controlled electron injection from the background plasma into a laser driven plasma wave using a {mu}m--scale density transition. Substantial quality improvements on the monoenergetic electron beam are demonstrated. Furthermore we discuss the rms transverse emittance measurement results of the generated electron bunch.

  16. Multiple quasi-monoenergetic electron beams from laser-wakefield acceleration with spatially structured laser pulse

    SciTech Connect

    Ma, Y.; Li, M. H.; Li, Y. F.; Wang, J. G.; Tao, M. Z.; Han, Y. J.; Zhao, J. R.; Huang, K.; Yan, W. C.; Ma, J. L.; Li, Y. T.; Chen, L. M.; Li, D. Z.; Chen, Z. Y.; Sheng, Z. M.; Zhang, J.

    2015-08-15

    By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal in energy and size and intense enough to form their own filaments, two electron beams were produced. Moreover, with a proper distance between those two focal spots, three electron beams emerged with a certain probability owing to the superposition of the diffractions of those two spots. The energy spectra of the multiple electron beams are quasi-monoenergetic, which are different from that of the large energy spread beams produced due to the longitudinal multiple-injection in the single bubble.

  17. High-quality electron beam from laser wake-field acceleration in laser produced plasma plumes

    SciTech Connect

    Sanyasi Rao, Bobbili; Moorti, Anand; Rathore, Ranjana; Ali Chakera, Juzer; Anant Naik, Prasad; Dass Gupta, Parshotam

    2013-06-10

    Generation of highly collimated ({theta}{sub div}{approx}10 mrad), quasi-monoenergetic electron beam with peak energy 12 MeV and charge {approx}50 pC has been experimentally demonstrated from self-guided laser wake-field acceleration (LWFA) in a plasma plume produced by laser ablation of solid nylon (C{sub 12}H{sub 22}N{sub 2}O{sub 2}){sub n} target. A 7 TW, 45 fs Ti:sapphire laser system was used for LWFA, and the plasma plume forming pulse was derived from the Nd:YAG pump laser of the same system. The results show that a reproducible, high quality electron beam could be produced from this scheme which is simple, low cost and has the capability for high repetition rate operation.

  18. Observation of laser multiple filamentation process and multiple electron beams acceleration in a laser wakefield accelerator

    SciTech Connect

    Li, Wentao; Liu, Jiansheng; Wang, Wentao; Chen, Qiang; Zhang, Hui; Tian, Ye; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2013-11-15

    The multiple filaments formation process in the laser wakefield accelerator (LWFA) was observed by imaging the transmitted laser beam after propagating in the plasma of different density. During propagation, the laser first self-focused into a single filament. After that, it began to defocus with energy spreading in the transverse direction. Two filaments then formed from it and began to propagate independently, moving away from each other. We have also demonstrated that the laser multiple filamentation would lead to the multiple electron beams acceleration in the LWFA via ionization-induced injection scheme. Besides, its influences on the accelerated electron beams were also analyzed both in the single-stage LWFA and cascaded LWFA.

  19. Generation and analysis of quasimonoenergetic electron beams by laser-plasma interaction in transitional region from the self-modulated laser wakefield to bubble acceleration regime

    SciTech Connect

    Masuda, S.; Miura, E.

    2009-09-15

    Generation of quasimonoenergetic electron beams in a transitional region from the self-modulated laser wakefield to bubble acceleration regime is reported. Quasimonoenergetic electron beams containing more than 3x10{sup 8} electrons in the monoenergetic peak with energies of 40-60 MeV have been obtained from a plasma with an electron density of 1.6x10{sup 19} cm{sup -3} produced by an 8 TW, 50 fs laser pulse. The generation of quasimonoenergetic electron beams is investigated by two-dimensional particle-in-cell simulations. Few periods of the plasma wave are located inside the laser pulse, because the laser pulse duration is longer than the wavelength of the plasma wave. Electrons trapped in the first period of the plasma wave can form the monoenergetic bunch, even though the trapped electrons interact directly with the laser field. The quasimonoenergetic electron beam can be obtained due to the small contribution of the direct acceleration by the laser field. This type of monoenergetic electron acceleration is different from that of both the self-modulated laser wakefield and bubble acceleration regimes, in which the trapped electrons in the plasma wave are located behind the laser pulse due to the pulse compression or fragmentation and free from the laser electric field. This result suggests a new regime for the quasimonoenergetic electron acceleration in the region between the self-modulation and bubble regime.

  20. Study of Laser Wakefield Accelerators as injectors for Synchrotron light sources

    NASA Astrophysics Data System (ADS)

    Hillenbrand, Steffen; Assmann, Ralph; Müller, Anke-Susanne; Jansen, Oliver; Judin, Vitali; Pukhov, Alexander

    2014-03-01

    Laser WakeField Accelerators (LWFA) feature short bunch lengths and high peak currents, combined with a small facility footprint. This makes them very interesting as injectors for Synchrotron light sources. Using the ANKA Synchrotron as an example, we investigate the possibility to inject a LWFA bunch into an electron storage ring. Particular emphasis is put on the longitudinal evolution of the bunch.

  1. Measuring the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator

    SciTech Connect

    Albert, F.; Pollock, B. B.; Shaw, J. L.; Marsh, K. A.; Ralph, J. E.; Chen, Y. -H.; Alessi, D.; Pak, A.; Clayton, C. E.; Glenzer, S. H.; Joshi, C.

    2014-07-22

    This paper presents a new technique to measure the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator. Measurements are performed with a stacked image plates spectrometer, capable of detecting broadband x-ray radiation up to 1 MeV. It can provide measurements of the betatron x-ray spectrum at any angle of observation (within a 40 mrad cone) and of the beam profile. A detailed description of our data analysis is given, along with comparison for several shots. As a result, these measurements provide useful information on the dynamics of the electrons are they are accelerated and wiggled by the wakefield.

  2. Diagnosis of bubble evolution in laser-wakefield acceleration via angular distributions of betatron x-rays

    SciTech Connect

    Ma, Y.; Chen, L. M. Huang, K.; Yan, W. C.; Hafz, N. A. M.; Zhang, J.; Li, D. Z.; Dunn, J.; Sheng, Z. M.

    2014-10-20

    We present an indirect method to diagnose the electron beam behaviors and bubble dynamic evolution in a laser-wakefield accelerator. Four kinds of typical bubble dynamic evolution and, hence, electron beam behaviors observed in Particle-In-Cell simulations are identified correspondingly by simultaneous measurement of distinct angular distributions of the betatron radiation and electron beam energy spectra in experiment. The reconstruction of the bubble evolution may shed light on finding an effective way to better generate high-quality electron beams and enhanced betatron X-rays.

  3. Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator.

    PubMed

    Chang, C-L; Hsieh, C-T; Ho, Y-C; Chen, Y-S; Lin, J-Y; Wang, J; Chen, S-Y

    2007-03-01

    Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator is investigated with a tomographic method which resolves the electron injection and acceleration processes. It is found that all the electrons in the monoenergetic electron bunch are injected at the same location in the plasma column and then accelerated with an acceleration gradient exceeding 2 GeV/cm. The injection position shifts with the position of pump-pulse focus, and no significant deceleration is observed for the monoenergetic electron bunch after it reaches the maximum energy. The results are consistent with the model of transverse wave breaking and beam loading for the injection of monoenergetic electrons. The tomographic method adds a crucial dimension to the whole array of existing diagnostics for laser beams, plasma waves, and electron beams. With this method the details of the underlying physical processes in laser-plasma interactions can be resolved and compared directly to particle-in-cell simulations. PMID:17500801

  4. Formation of Ultrarelativistic Electron Rings from a Laser-Wakefield Accelerator.

    PubMed

    Pollock, B B; Tsung, F S; Albert, F; Shaw, J L; Clayton, C E; Davidson, A; Lemos, N; Marsh, K A; Pak, A; Ralph, J E; Mori, W B; Joshi, C

    2015-07-31

    Ultrarelativistic-energy electron ring structures have been observed from laser-wakefield acceleration experiments in the blowout regime. These electron rings had 170-280 MeV energies with 5%-25% energy spread and ∼10  pC of charge and were observed over a range of plasma densities and compositions. Three-dimensional particle-in-cell simulations show that laser intensity enhancement in the wake leads to sheath splitting and the formation of a hollow toroidal pocket in the electron density around the wake behind the first wake period. If the laser propagates over a distance greater than the ideal dephasing length, some of the dephasing electrons in the second period can become trapped within the pocket and form an ultrarelativistic electron ring that propagates in free space over a meter-scale distance upon exiting the plasma. Such a structure acts as a relativistic potential well, which has applications for accelerating positively charged particles such as positrons. PMID:26274427

  5. Tailoring the laser pulse shape to improve the quality of the self-injected electron beam in laser wakefield acceleration

    SciTech Connect

    Upadhyay, Ajay K.; Samant, Sushil A.; Krishnagopal, S.

    2013-01-15

    In laser wakefield acceleration, tailoring the shape of the laser pulse is one way of influencing the laser-plasma interaction and, therefore, of improving the quality of the self-injected electron beam in the bubble regime. Using three-dimensional particle-in-cell simulations, the evolution dynamics of the laser pulse and the quality of the self-injected beam, for a Gaussian pulse, a positive skew pulse (i.e., one with sharp rise and slow fall), and a negative skew pulse (i.e., one with a slow rise and sharp fall) are studied. It is observed that with a negative skew laser pulse there is a substantial improvement in the emittance (by around a factor of two), and a modest improvement in the energy-spread, compared to Gaussian as well as positive skew pulses. However, the injected charge is less in the negative skew pulse compared to the other two. It is also found that there is an optimal propagation distance that gives the best beam quality; beyond this distance, though the energy increases, the beam quality deteriorates, but this deterioration is least for the negative skew pulse. Thus, the negative skew pulse gives an improvement in terms of beam quality (emittance and energy spread) over what one can get with a Gaussian or positive skew pulse. In part, this is because of the lesser injected charge, and the strong suppression of continuous injection for the negative skew pulse.

  6. Low-energy-spread laser wakefield acceleration using ionization injection with a tightly focused laser in a mismatched plasma channel

    NASA Astrophysics Data System (ADS)

    Li, F.; Zhang, C. J.; Wan, Y.; Wu, Y. P.; Xu, X. L.; Hua, J. F.; Pai, C. H.; Lu, W.; Gu, Y. Q.; Mori, W. B.; Joshi, C.

    2016-03-01

    An improved ionization injection scheme for laser wakefield acceleration using a tightly focused laser pulse, with intensity near the ionization threshold to trigger the injection in a mismatched plasma channel, has been proposed and examined via 3D particle-in-cell (PIC) simulations. In this scheme, the key to achieving a very low energy spread is shortening the injection distance through the fast diffraction of the tightly focused laser. Furthermore, the oscillation of the laser envelope in the mismatched plasma channel can induce multiple low-energy-spread injections with an even distribution in both space and energy. The envelope oscillation can also significantly enhance the energy gain of the injected beams compared to the standard non-evolving wake scenario due to the rephasing between the electron beam and the laser wake. A theoretical model has been derived to precisely predict the injection distance, the ionization degree of injection atoms/ions, the electron yield as well as the ionized charge for given laser-plasma parameters, and such expressions can be directly utilized for optimizing the quality of the injected beam. Through 3D PIC simulations, we show that an injection distance as short as tens of microns can be achieved, which leads to ultrashort fs, few pC electron bunches with a narrow absolute energy spread around 2 MeV (rms). Simulations also show that the initial absolute energy spread remains nearly constant during the subsequent acceleration due to the very short bunch length, and this indicates that further acceleration of the electron bunches up to the GeV level may lead to an electron beam with an energy spread well below 0.5%. Such low-energy-spread electron beams may have potential applications for future coherent light sources driven by laser-plasma accelerators.

  7. Modeling laser-plasma acceleration in the wakefield frame

    SciTech Connect

    2011-01-01

    A simulation of laser-plasma acceleration in the boosted frame of the wake, moving at near lightspeed. Space has contracted and time has stretched, separating events in time. Relatively few time steps are needed to model them, requiring less computer time.

  8. A bremsstrahlung gamma-ray source based on stable ionization injection of electrons into a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Döpp, A.; Guillaume, E.; Thaury, C.; Lifschitz, A.; Sylla, F.; Goddet, J.-P.; Tafzi, A.; Iaquanello, G.; Lefrou, T.; Rousseau, P.; Conejero, E.; Ruiz, C.; Ta Phuoc, K.; Malka, V.

    2016-09-01

    Laser wakefield acceleration permits the generation of ultra-short, high-brightness relativistic electron beams on a millimeter scale. While those features are of interest for many applications, the source remains constraint by the poor stability of the electron injection process. Here we present results on injection and acceleration of electrons in pure nitrogen and argon. We observe stable, continuous ionization-induced injection of electrons into the wakefield for laser powers exceeding a threshold of 7 TW. The beam charge scales approximately with the laser energy and is limited by beam loading. For 40 TW laser pulses we measure a maximum charge of almost 1 nC per shot, originating mostly from electrons of less than 10 MeV energy. The relatively low energy, the high charge and its stability make this source well-suited for applications such as non-destructive testing. Hence, we demonstrate the production of energetic radiation via bremsstrahlung conversion at 1 Hz repetition rate. In accordance with GEANT4 Monte-Carlo simulations, we measure a γ-ray source size of less than 100 μm for a 0.5 mm tantalum converter placed at 2 mm from the accelerator exit. Furthermore we present radiographs of image quality indicators.

  9. Density profile of a line plasma generated by laser ablation for laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Kim, J.; Hwangbo, Y.; Ryu, W.-J.; Kim, K. N.; Park, S. H.

    2016-03-01

    An elongated line plasma generated by a laser ablation of an aluminum target was investigated, which can be used in the laser wakefield acceleration (LWFA) by employing ultra-intense laser pulse through the longitudinal direction of the plasma. To generate a uniform and long plasma channel along the propagation of ultra-intense laser pulse (main pulse), a cylindrical lens combined with a biprism was used to shape the intensity of a ns Nd:YAG laser (pre-pulse) on the Al target. A uniformity of laser intensity can be manipulated by changing the distance between the biprism and the target. The density profile of the plasma generated by laser ablation was measured using two interferometers, indicating that a 3-mm long uniform line plasma with a density of 6 × 1017 cm-3 could be generated. The density with main pulse was also measured and the results indicated that the density would increase further due to additional ionization of the plasma by the main ultra-intense laser pulse. The resulting plasma density, which is a crucial parameter for the LWFA, can be controlled by the intensity of the pre-pulse, the time delay between the pre- and main pulse, and the distance of the main pulse from the target surface.

  10. Plasma Wakefield Acceleration Simulations with Multiple Electron Bunches

    NASA Astrophysics Data System (ADS)

    Kallos, Efthymios; Muggli, Patric; Yakimenko, Vitaly; Kusche, Karl; Park, Jangho; Babzien, Marcus; Lichtl, Adam

    2008-11-01

    In the multibunch plasma wakefield accelerator, a train of electron bunches is utilized to excite a high gradient wakefield in a plasma which can be sampled by a trailing short witness bunch. We show that for five drive bunches with 150 pC total charge which can be generated in the Accelerator Test Facility of the Brookhaven National Lab, a wakefield of 140 MV/m can be generated if the plasma density is matched to the bunch train period. In addition, the possibility of ramping the charge per bunch in order to achieve high transformer ratios (>5) is examined, a scenario that is of great interest for a future afterburner collider. The work was supported by the US Department of Energy.

  11. Dynamics of ionization-induced electron injection in the high density regime of laser wakefield acceleration

    SciTech Connect

    Desforges, F. G.; Paradkar, B. S. Ju, J.; Audet, T. L.; Maynard, G.; Cros, B.; Hansson, M.; Senje, L.; Persson, A.; Lundh, O.; Wahlström, C.-G.; Dobosz-Dufrénoy, S.; Monot, P.; Vay, J.-L.

    2014-12-15

    The dynamics of ionization-induced electron injection in high density (∼1.2 × 10{sup 19} cm{sup −3}) regime of laser wakefield acceleration is investigated by analyzing the betatron X-ray emission. In such high density operation, the laser normalized vector potential exceeds the injection-thresholds of both ionization-injection and self-injection due to self-focusing. In this regime, direct experimental evidence of early on-set of ionization-induced injection into the plasma wave is given by mapping the X-ray emission zone inside the plasma. Particle-In-Cell simulations show that this early on-set of ionization-induced injection, due to its lower trapping threshold, suppresses the trapping of self-injected electrons. A comparative study of the electron and X-ray properties is performed for both self-injection and ionization-induced injection. An increase of X-ray fluence by at least a factor of two is observed in the case of ionization-induced injection due to increased trapped charge compared to self-injection mechanism.

  12. Development of High Gradient Laser Wakefield Accelerators Towards Nuclear Detection Applications at LBNL

    SciTech Connect

    Geddes, Cameron G. R.; Gonsalves, Anthony J.; Lin Chen; Cormier-Michel, Estelle; Matlis, Nicholas H.; Panasenko, Dmitriy; Plateau, Guillaume R.; Schroeder, Carl B.; Toth, Csaba; Bruhwiler, David L.; Cary, John R.; Esarey, Eric H.; Nakamura, Kei; Bakeman, Mike; Leemans, Wim P.

    2009-03-10

    Compact high-energy linacs are important to applications including monochromatic gamma sources for nuclear material security applications. Recent laser wakefield accelerator experiments at LBNL demonstrated narrow energy spread beams, now with energies of up to 1 GeV in 3 cm using a plasma channel at low density. This demonstrates the production of GeV beams from devices much smaller than conventional linacs, and confirms the anticipated scaling of laser driven accelerators to GeV energies. Stable performance at 0.5 GeV was demonstrated. Experiments and simulations are in progress to control injection of particles into the wake and hence to improve beam quality and stability. Using plasma density gradients to control injection, stable beams at 1 MeV over days of operation, and with an order of magnitude lower absolute momentum spread than previously observed, have been demonstrated. New experiments are post-accelerating the beams from controlled injection experiments to increase beam quality and stability. Thomson scattering from such beams is being developed to provide collimated multi-MeV monoenergetic gamma sources for security applications from compact devices. Such sources can reduce dose to target and increase accuracy for applications including photofission and nuclear resonance fluorescence.

  13. Development of high gradient laser wakefield accelerators towards nuclear detection applications at LBNL

    SciTech Connect

    Geddes, Cameron GR; Bruhwiler, David L.; Cary, John R.; Esarey, Eric H.; Gonsalves, Anthony J.; Lin, Chen; Cormier-Michel, Estelle; Matlis, Nicholas H.; Nakamura, Kei; Bakeman, Mike; Panasenko, Dmitriy; Plateau, Guillaume R.; Schroeder, Carl B.; Toth, Csaba; Leemans, Wim P.

    2008-09-08

    Compact high-energy linacs are important to applications including monochromatic gamma sources for nuclear material security applications. Recent laser wakefield accelerator experiments at LBNL demonstrated narrow energy spread beams, now with energies of up to 1 GeV in 3 cm using a plasma channel at low density. This demonstrates the production of GeV beams from devices much smaller than conventional linacs, and confirms the anticipated scaling of laser driven accelerators to GeV energies. Stable performance at 0.5 GeV was demonstrated. Experiments and simulations are in progress to control injection of particles into the wake and hence to improve beam quality and stability. Using plasma density gradients to control injection, stable beams at 1 MeV over days of operation, and with an order of magnitude lower absolute momentum spread than previously observed, have been demonstrated. New experiments are post-accelerating the beams from controlled injection experiments to increase beam quality and stability. Thomson scattering from such beams is being developed to provide collimated multi-MeV monoenergetic gamma sources for security applications from compact devices. Such sources can reduce dose to target and increase accuracy for applications including photofission and nuclear resonance fluorescence.

  14. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    SciTech Connect

    Makito, K.; Shin, J.-H.; Zhidkov, A.; Hosokai, T.; Masuda, S.; Kodama, R.

    2012-10-15

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of {approx}3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  15. Plasma undulator based on laser excitation of wakefields in a plasma channel.

    PubMed

    Rykovanov, S G; Schroeder, C B; Esarey, E; Geddes, C G R; Leemans, W P

    2015-04-10

    An undulator is proposed based on the plasma wakefields excited by a laser pulse in a plasma channel. Generation of the undulator fields is achieved by inducing centroid oscillations of the laser pulse in the channel. The period of such an undulator is proportional to the Rayleigh length of the laser pulse and can be submillimeter, while preserving high undulator strength. The electron trajectories in the undulator are examined, expressions for the undulator strength are presented, and the spontaneous radiation is calculated. Multimode and multicolor laser pulses are considered for greater tunability of the undulator period and strength. PMID:25910131

  16. Plasma Undulator Based on Laser Excitation of Wakefields in a Plasma Channel

    NASA Astrophysics Data System (ADS)

    Rykovanov, S. G.; Schroeder, C. B.; Esarey, E.; Geddes, C. G. R.; Leemans, W. P.

    2015-04-01

    An undulator is proposed based on the plasma wakefields excited by a laser pulse in a plasma channel. Generation of the undulator fields is achieved by inducing centroid oscillations of the laser pulse in the channel. The period of such an undulator is proportional to the Rayleigh length of the laser pulse and can be submillimeter, while preserving high undulator strength. The electron trajectories in the undulator are examined, expressions for the undulator strength are presented, and the spontaneous radiation is calculated. Multimode and multicolor laser pulses are considered for greater tunability of the undulator period and strength.

  17. High Quality Electron Bunches up to 1 GeV from Laser WakefieldAcceleration at LBNL

    SciTech Connect

    Esarey, E.; Nagler, B.; Gonsalves, A.J.; Toth, Cs.; Nakamura, K.; Geddes, C.G.R.; Schroeder, C.B.; van Tilborg, J.; Hooker, S.; Leemans,W.P.; Michel, E.; Cary, J.; Bruhwiler, D.

    2006-07-01

    Experiments at the LOASIS laboratory of LBNL havedemonstrated production of 100 MeV to 1 GeV electron bunches with lowenergy spread and low divergence from laser wakefield acceleration. Theradiation pressure of a 10 TW laser pulse, guided over 10 diffractionranges by a few-mm long plasma density channel, was used to drive anintense plasma wave (wakefield), producing electron bunches with energieson the order of 100 MeV and acceleration gradients on the order of 100GV/m. Beam energy was increased from 100 MeV to 1 GeV by using a few-cmlong guiding channel at lower density, driven by a 40 TW laser,demonstrating the anticipated scaling to higher beam energies. Particlesimulations indicate that the low energy spread beams were produced fromself-trapped electrons through the interplay of trapping, loading, anddephasing. Other experiments and simulations are also underway to controlinjection of particles into the wake, and hence improve beam quality andstability further.

  18. A broadband gamma-ray spectrometry using novel unfolding algorithms for characterization of laser wakefield-generated betatron radiation

    SciTech Connect

    Jeon, Jong Ho Nakajima, Kazuhisa Pathak, Vishwa Bandhu; Cho, Myung Hoon; Yoo, Byung Ju; Shin, Kang Woo; Kim, Hyung Taek; Sung, Jae Hee; Lee, Seung Ku; Choi, Il Woo; Rhee, Yong Joo; Shin, Jung Hun; Jo, Sung Ha; Hojbota, Calin; Cho, Byeoung Ick; Nam, Chang Hee

    2015-12-15

    We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime.

  19. Laser Wakefield Structures and Electron Acceleration in Gas Jet and Capillary Discharge Plasmas

    NASA Astrophysics Data System (ADS)

    Maksimchuk, Anatoly

    2007-11-01

    Laser-driven plasma wakefield accelerators have the potential to become the next generation of particle accelerators because of the very high acceleration gradients. The beam quality from such accelerators depends critically on the details plasma wave spatial structures. In experiments at the University of Michigan it was possible in a single shot by frequency domain holography (FDH) to visualize individual plasma waves produced by the 40 TW, 30 fs Hercules laser focused to the intensity of 10^19 W/cm^2 onto a supersonic He gas jet [1]. These holographic ``snapshots'' capture the evolution of multiple wake periods, and resolve wavefront curvature seen previously only in simulations. High-energy quasi-monoenergetic electron beams for plasma density in the specific range 1.5x10^19<=ne<=3.5x10^19 cm-3 were generated [2]. The experiments show that the energy, charge, divergence and pointing stability of the beam can be controlled by changing ne, and that higher electron energies and more stable beams are produced for lower densities. An optimized quasi-monoenergetic beam of over 300 MeV and 10 mrad angular divergence is demonstrated at a plasma density of ne=1.5x10^19 cm-3. The resulted relativistic electron beams have been used to perform gamma-neutron activation of ^12C and ^63Cu and photo-fission of ^238U with a record high reaction yields of ˜5x10^5/Joule [3]. Experiments performed with ablative capillary discharge plasma demonstrate stable guiding for laser power up to 10 TW with the transmission of 50% and guided intensity of ˜10^17 W/cm^2. Study of the staged electron acceleration have been performed which uses ablated plasma in front of the capillary to inject electrons into the wakefield structures. [1] N. H. Matlis et. al., Nature Physics 2, 749 (2006). [2] A. Maksimchuk et. al., Journal de Physique IV 133, 1123 (2006). [3] S. A. Reed et. al., Appl. Phys. Lett. 89, 231107 (2006).

  20. Stable Electron Beams With Low Absolute Energy Spread From a LaserWakefield Accelerator With Plasma Density Ramp Controlled Injection

    SciTech Connect

    Geddes, Cameron G.R.; Cormier-Michel, E.; Esarey, E.; Leemans,W.P.; Nakamura, K.; Panasenko, D.; Plateau, Guillaume R.; Schroeder, CarlB.; Toth, Csaba; Cary, J.R.

    2007-06-25

    Laser wakefield accelerators produce accelerating gradientsup to hundreds of GeV/m, and recently demonstrated 1-10 MeV energy spreadat energies up to 1 GeV using electrons self-trapped from the plasma.Controlled injection and staging may further improve beam quality bycircumventing tradeoffs between energy, stability, and energyspread/emittance. We present experiments demonstrating production of astable electron beam near 1 MeV with hundred-keV level energy spread andcentral energy stability by using the plasma density profile to controlselfinjection, and supporting simulations. Simulations indicate that suchbeams can be post accelerated to high energies,potentially reducingmomentum spread in laser acceleratorsby 100-fold or more.

  1. Single-shot betatron source size measurement from a laser-wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Köhler, A.; Couperus, J. P.; Zarini, O.; Jochmann, A.; Irman, A.; Schramm, U.

    2016-09-01

    Betatron radiation emitted by accelerated electrons in laser-wakefield accelerators can be used as a diagnostic tool to investigate electron dynamics during the acceleration process. We analyze the spectral characteristics of the emitted Betatron pattern utilizing a 2D x-ray imaging spectroscopy technique. Together with simultaneously recorded electron spectra and x-ray images, the betatron source size, thus the electron beam radius, can be deduced at every shot.

  2. Two-Screen Method for Determining Electron Beam Energy and Deflection from Laser Wakefield Acceleration

    SciTech Connect

    Pollock, B B; Ross, J S; Tynan, G R; Divol, L; Glenzer, S H; Leurent, V; Palastro, J P; Ralph, J E; Froula, D H; Clayton, C E; Marsh, K A; Pak, A E; Wang, T L; Joshi, C

    2009-04-24

    Laser Wakefield Acceleration (LWFA) experiments have been performed at the Jupiter Laser Facility, Lawrence Livermore National Laboratory. In order to unambiguously determine the output electron beam energy and deflection angle at the plasma exit, we have implemented a two-screen electron spectrometer. This system is comprised of a dipole magnet followed by two image plates. By measuring the electron beam deviation from the laser axis on each plate, both the energy and deflection angle at the plasma exit are determined through the relativistic equation of motion.

  3. Simulations of a High-Transformer-Ratio Plasma Wakefield Accelerator Using Multiple Electron Bunches

    SciTech Connect

    Kallos, Efthymios; Muggli, Patric; Katsouleas, Thomas; Yakimenko, Vitaly; Park, Jangho

    2009-01-22

    Particle-in-cell simulations of a plasma wakefield accelerator in the linear regime are presented, consisting of four electron bunches that are fed into a high-density plasma. It is found that a high transformer ratio can be maintained over 43 cm of plasma if the charge in each bunch is increased linearly, the bunches are placed 1.5 plasma wavelengths apart and the bunch emmitances are adjusted to compensate for the nonlinear focusing forces. The generated wakefield is sampled by a test witness bunch whose energy gain after the plasma is six times the energy loss of the drive bunches.

  4. Overcomingthe Dephasing Limit in the Bubble Regime by Synergybetween Direct Laser Acceleration and Laser Wakefield Acceleration

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Khudik, Vladimir; Shvets, Gennady

    2014-10-01

    Direct Laser Acceleration (DLA) in the bubble regime is an acceleration mechanism that combines the traditional plasma wakefield acceleration inside the plasma bubble with energy gain directly from the laser pulse. Recent experiments demonstrated one of the signatures of the DLA: highly efficient gamma-rays from resonantly excited betatron oscillations of accelerated electrons inside the plasma bubble. Here we propose another potential benefit of DLA: the reduction of dephasing between the accelerated electrons and accelerating field of the bubble. A simple semi-analytic model is developed to investigate the synergy between DLA and LWA acceleration mechanisms. We propose to enhance the DLA by adding a second time-delayed weak laser pulse capable of interacting with bubble electrons right after self-injection. This scenario is validated by direct PIC modeling using the 2D VLPL code. The prospects for achieving high-energy electrons at the Texas Petawatt laser are discussed. This work is supported by the US DOE grant DE-SC0007889.

  5. Injection of electrons by colliding laser pulses in a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Hansson, M.; Aurand, B.; Ekerfelt, H.; Persson, A.; Lundh, O.

    2016-09-01

    To improve the stability and reproducibility of laser wakefield accelerators and to allow for future applications, controlling the injection of electrons is of great importance. This allows us to control the amount of charge in the beams of accelerated electrons and final energy of the electrons. Results are presented from a recent experiment on controlled injection using the scheme of colliding pulses and performed using the Lund multi-terawatt laser. Each laser pulse is split into two parts close to the interaction point. The main pulse is focused on a 2 mm diameter gas jet to drive a nonlinear plasma wave below threshold for self-trapping. The second pulse, containing only a fraction of the total laser energy, is focused to collide with the main pulse in the gas jet under an angle of 150°. Beams of accelerated electrons with low divergence and small energy spread are produced using this set-up. Control over the amount of accelerated charge is achieved by rotating the plane of polarization of the second pulse in relation to the main pulse. Furthermore, the peak energy of the electrons in the beams is controlled by moving the collision point along the optical axis of the main pulse, and thereby changing the acceleration length in the plasma.

  6. Compton Backscattered X-rays from Self-Generated Laser Wiggler in a Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Ting, Antonio; Kaganovich, Dmitri; Hafizi, Bahman; Palastro, John; Helle, Michael; Gordon, Daniel; Chen, Yu-Hsin; Seely, John

    2014-10-01

    A unique Compton backscattering configuration for generating monochromatic, short pulse, and potentially coherent x-rays in a Laser Wakefield Accelerator (LWFA) is being studied at the Naval Research Laboratory. Reflection mechanisms such as stimulated Raman scattering and shock-created density gradients in a plasma can generate the required backward-travelling laser pulse directly from the same laser pulse used in the LWFA, i.e., the high energy electron beam and the counter-propagating photon beam are both self-generated by an ultrashort laser pulse in plasma. The automatic alignment of the counter-propagating electrons and photons together with the extended interaction distance and tightly guided beam sizes in a LWFA can lead to a high-gain situation for the Doppler upshifted forward propagating x-rays. Possibilities for exponential gain to achieve coherent generation of the x-rays are under investigation. Theoretical, numerical, and preliminary experimental results will be presented. This work is supported by DOE and NRL 6.1 funding.

  7. Self-modulated laser wakefield acceleration as a X-ray source

    NASA Astrophysics Data System (ADS)

    Lemos, Nuno; Tsung, Frank; Shaw, Jessica; Marsh, Ken; Albert, Felicie; Pollock, Brad; Joshi, Chan

    2015-11-01

    Understanding material properties under extreme conditions of temperature and pressure is critical for different fields of physics such as astrophysics and high energy density (HED) science. The HED science facilities such as OMEGA and the National Ignition Facility are now uniquely able to recreate in the laboratory conditions of temperature and pressure that were thought to be only attainable in the interiors of stars and planets. To diagnose such extreme states of matter, the development of efficient, versatile and fast (sub-picosecond scale) x-ray probes with energies larger than 50 kilo-electronvolts has become essential for HED science experiments on these specific facilities. In this work we explore the betatron radiation generated in self-modulated laser-wakefield accelerators to probe HED plasmas with unprecedented time resolution. Through Osiris 2D particle-in-cell simulations we we will show that this acceleration scheme can produce radiation with energies exceeding 50keV. The work at UCLA was supported by DOE grant # DE/SC0010064 and NSF grant # PHY/1415386.

  8. Plasma undulator based on laser excitation of wakefields in a plasma channel

    NASA Astrophysics Data System (ADS)

    Schroeder, Carl; Rykovanov, Sergey; Esarey, Eric; Geddes, Cameron; Leemans, Wim

    2015-11-01

    A novel plasma undulator based on the wakefields excited by a laser pulse in a plasma channel is described. Generation of the undulator fields is achieved by inducing centroid oscillations of the laser pulse in the channel. The period of such a plasma undulator is proportional to the Rayleigh length of the laser pulse and can be sub-millimeter, with an effective undulator strength parameter of order unity. The undulator period can further be controlled and reduced by beating laser modes or using multiple colors. Analytic expressions for the electron trajectories in the plasma undulator and the synchrotron radiation are compared to numerical modeling. Examples of short-period laser-driven plasma undulators are presented based on available laser and plasma channel parameters. Work supported by the U.S. DOE under Contract No. DE-AC02-05CH11231.

  9. Unphysical kinetic effects in particle-in-cell modeling of laser wakefield accelerators.

    PubMed

    Cormier-Michel, Estelle; Shadwick, B A; Geddes, C G R; Esarey, E; Schroeder, C B; Leemans, W P

    2008-07-01

    Unphysical heating and macroparticle trapping that arise in the numerical modeling of laser wakefield accelerators using particle-in-cell codes are investigated. A dark current free laser wakefield accelerator stage, in which no trapping of background plasma electrons into the plasma wave should occur, and a highly nonlinear cavitated wake with self-trapping, are modeled. Numerical errors can lead to errors in the macroparticle orbits in both phase and momentum. These errors grow as a function of distance behind the drive laser and can be large enough to result in unphysical trapping in the plasma wake. The resulting numerical heating in intense short-pulse laser-plasma interactions grows much faster and to a higher level than the known numerical grid heating of an initially warm plasma in an undriven system. The amount of heating, at least in the region immediately behind the laser pulse, can, in general, be decreased by decreasing the grid size, increasing the number of particles per cell, or using smoother interpolation methods. The effect of numerical heating on macroparticle trapping is less severe in a highly nonlinear cavitated wake, since trapping occurs in the first plasma wave period immediately behind the laser pulse. PMID:18764064

  10. Temporal evolution of longitudinal bunch profile in a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Heigoldt, M.; Popp, A.; Khrennikov, K.; Wenz, J.; Chou, S. W.; Karsch, S.; Bajlekov, S. I.; Hooker, S. M.; Schmidt, B.

    2015-12-01

    We present single-shot measurements of the longitudinal bunch profile from a laser-wakefield accelerator with sub-fs resolution, based on detection of coherent transition radiation in a broad spectral range. A previously developed phase retrieval algorithm enables reconstruction of the bunch profile without prior assumptions about its shape. In this study, a variable-length gas target is used to explore the dynamics of bunch evolution. Our results show that once the laser energy is depleted the time structure of the generated electron beam changes from a single bunch to a double bunch structure, well suited for driver-witness type experiments.

  11. Complete temporal characterization of asymmetric pulse compression in a laser wakefield.

    PubMed

    Schreiber, J; Bellei, C; Mangles, S P D; Kamperidis, C; Kneip, S; Nagel, S R; Palmer, C A J; Rajeev, P P; Streeter, M J V; Najmudin, Z

    2010-12-01

    We present complete experimental characterization of the temporal shape of an intense ultrashort 200-TW laser pulse driving a laser wakefield. The phase of the pulse was uniquely measured by using (second-order) frequency-resolved optical gating. The pulses are asymmetrically compressed and exhibit a positive chirp consistent with the expected asymmetric self-phase-modulation due to photon acceleration or deceleration in a relativistic plasma wave. The measured pulse duration decreases linearly with increasing length and density of the plasma, in quantitative agreement with the intensity-dependent group velocity variation in the plasma wave. PMID:21231474

  12. Measurements of wave-breaking radiation from a laser-wakefield accelerator.

    PubMed

    Thomas, A G R; Mangles, S P D; Najmudin, Z; Kaluza, M C; Murphy, C D; Krushelnick, K

    2007-02-01

    Spectral analysis of radiation emitted transverse to laser propagation in laser-wakefield acceleration experiments shows broadband emission when electrons are accelerated to relativistic energies. The region over which emission occurs is short compared with the overall interaction length. The energy of the emission and location along the interaction length both vary with plasma density. A model for the radiation from self-trapped electrons indicates that the emission is a signature of the violent initial acceleration, and hence can be used as a diagnostic of the self-injection mechanism. PMID:17358867

  13. Controlled injection and acceleration of electrons in plasma wakefields by colliding laser pulses.

    PubMed

    Faure, J; Rechatin, C; Norlin, A; Lifschitz, A; Glinec, Y; Malka, V

    2006-12-01

    In laser-plasma-based accelerators, an intense laser pulse drives a large electric field (the wakefield) which accelerates particles to high energies in distances much shorter than in conventional accelerators. These high acceleration gradients, of a few hundreds of gigavolts per metre, hold the promise of compact high-energy particle accelerators. Recently, several experiments have shown that laser-plasma accelerators can produce high-quality electron beams, with quasi-monoenergetic energy distributions at the 100 MeV level. However, these beams do not have the stability and reproducibility that are required for applications. This is because the mechanism responsible for injecting electrons into the wakefield is based on highly nonlinear phenomena, and is therefore hard to control. Here we demonstrate that the injection and subsequent acceleration of electrons can be controlled by using a second laser pulse. The collision of the two laser pulses provides a pre-acceleration stage which provokes the injection of electrons into the wakefield. The experimental results show that the electron beams obtained in this manner are collimated (5 mrad divergence), monoenergetic (with energy spread <10 per cent), tuneable (between 15 and 250 MeV) and, most importantly, stable. In addition, the experimental observations are compatible with electron bunch durations shorter than 10 fs. We anticipate that this stable and compact electron source will have a strong impact on applications requiring short bunches, such as the femtolysis of water, or high stability, such as radiotherapy with high-energy electrons or radiography for materials science. PMID:17151663

  14. All-Optical Laser-Wakefield Electron Injector

    SciTech Connect

    Umstadter, Donald P.

    2003-07-01

    Demonstrated the principle of optical control of laser accelerators, namely, that one laser pulse could modify the properties (e.g., emittance and electron number) of an electron beam accelerated by a separate but synchronized laser pulse. Another recent highlight was that, using our new 30-fs 10-TW laser system, we accelerated with a laser accelerator an electron beam with a record low divergence (0.2 degrees). This is more than 100 times lower than the 30-degree divergence that was reported recently by a French group using a laser with similar parameters.

  15. Effects of self-focusing on tunnel-ionization-induced injection in a laser wakefield accelerator

    SciTech Connect

    Xia Changquan; Liu Jiansheng; Wang Wentao; Lu Haiyang; Cheng Wang; Deng Aihua; Li Wentao; Zhang Hui; Liang Xiaoyan; Leng Yuxin; Lu Xiaoming; Wang Cheng; Wang Jianzhou; Li Ruxin; Xu Zhizhan; Nakajima, Kazuhisa

    2011-11-15

    We report on the study of the self-focusing effects on the tunnel-ionization-induced injection in a laser wakefield accelerator. Targets composed of a gas mixture of 94% helium and 6% oxygen were used. The energy, energy spread, and charge of the generated electron beams can be adjusted by changing the input laser intensity and the plasma density, but the different aspects of the properties of the electron beams were not independent. It was inferred that the K-shell electrons of oxygen were ionized and injected into the plasma wake for acceleration when the laser intensity was increased beyond the threshold for generating O{sup 7+} by tunnel-ionization, due to the relativistic self-focusing in the propagation. Controlling the self-focusing of the laser beam by adjusting the input laser energy to shorten the distance over which the electrons were injected into the wake, quasi-monoenergetic electron beams were observed.

  16. Model experiment of cosmic ray acceleration due to an incoherent wakefield induced by an intense laser pulse

    SciTech Connect

    Kuramitsu, Y.; Sakawa, Y.; Takeda, K.; Tampo, M.; Takabe, H.; Nakanii, N.; Kondo, K.; Tsuji, K.; Kimura, K.; Fukumochi, S.; Kashihara, M.; Tanimoto, T.; Nakamura, H.; Ishikura, T.; Kodama, R.; Mima, K.; Tanaka, K. A.; Mori, Y.; Miura, E.; Kitagawa, Y.

    2011-01-15

    The first report on a model experiment of cosmic ray acceleration by using intense laser pulses is presented. Large amplitude light waves are considered to be excited in the upstream regions of relativistic astrophysical shocks and the wakefield acceleration of cosmic rays can take place. By substituting an intense laser pulse for the large amplitude light waves, such shock environments were modeled in a laboratory plasma. A plasma tube, which is created by imploding a hollow polystyrene cylinder, was irradiated by an intense laser pulse. Nonthermal electrons were generated by the wakefield acceleration and the energy distribution functions of the electrons have a power-law component with an index of {approx}2. The maximum attainable energy of the electrons in the experiment is discussed by a simple analytic model. In the incoherent wakefield the maximum energy can be much larger than one in the coherent field due to the momentum space diffusion or the energy diffusion of electrons.

  17. Modeling of Laser wakefield accelerator in Lorentz boosted frame using EM-PIC code with spectral solver

    NASA Astrophysics Data System (ADS)

    Yu, Peicheng; Xu, Xinlu; Decyk, Viktor; An, Weiming; Vieira, Jorge; Tsung, Frank; Fonseca, Ricardo; Lu, Wei; Silva, Luis; Mori, Warren; UCLA Collaboration; Tsinghua University Collaboration; IST Portugal Collaboration

    2013-10-01

    Simulating laser wakefield acceleration (LWFA) in a Lorentz boosted frame can reduce the computational time over existing fully explicit methods tremendously. In these simulations the relativistic drifting plasma inevitably induces a high frequency numerical instability that contaminates the interested physics, which we mitigate by solve Maxwell equations in Fourier space (a spectral solver) plus using a low pass or ring filter in Fourier space. We describe the development of UPIC-EMMA that uses a spectral solver and that includes the ability to launch a laser using a moving antenna. We show that using UPIC-EMMA LWFA simulations in boosted frames with arbitrary γb can be conducted without any evidence on the numerical instability. We also benchmark the results with lab frame simulations using OSIRIS. These simulations include the modeling cases where there are no self-trapped electrons, and modeling the self-trapped regime. Detailed comparison among Lorentz boost ed frame results and lab frame results obtained from OSIRIS shows the feasibility of using UPIC-EMMA to conduct LWFA simulation at high γb.

  18. Self-modulated laser wakefield accelerators as x-ray sources

    NASA Astrophysics Data System (ADS)

    Lemos, N.; Martins, J. L.; Tsung, F. S.; Shaw, J. L.; Marsh, K. A.; Albert, F.; Pollock, B. B.; Joshi, C.

    2016-03-01

    The development of a directional, small-divergence, and short-duration picosecond x-ray probe beam with an energy greater than 50 keV is desirable for high energy density science experiments. We therefore explore through particle-in-cell (PIC) computer simulations the possibility of using x-rays radiated by betatron-like motion of electrons from a self-modulated laser wakefield accelerator as a possible candidate to meet this need. Two OSIRIS 2D PIC simulations with mobile ions are presented, one with a normalized vector potential a 0  =  1.5 and the other with an a 0  =  3. We find that in both cases direct laser acceleration (DLA) is an important additional acceleration mechanism in addition to the longitudinal electric field of the plasma wave. Together these mechanisms produce electrons with a continuous energy spectrum with a maximum energy of 300 MeV for a 0  =  3 case and 180 MeV in the a 0  =  1.5 case. Forward-directed x-ray radiation with a photon energy up to 100 keV was calculated for the a 0  =  3 case and up to 12 keV for the a 0  =  1.5 case. The x-ray spectrum can be fitted with a sum of two synchrotron spectra with critical photon energies of 13 and 45 keV for the a 0 of 3 and critical photon energies of 0.3 and 1.4 keV for a 0 of 1.5 in the plane of polarization of the laser. The full width at half maximum divergence angle of the x-rays was 62  ×  1.9 mrad for a 0  =  3 and 77  ×  3.8 mrad for a 0  =  1.5.

  19. Compton X-rays from Self-Generated Backscattered Radiation in a Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Ting, Antonio; Kaganovich, Dmitri; Helle, Michael; Chen, Yu-Hsin; Palastro, John; Hafizi, Bahman; Gordon, Daniel

    2015-11-01

    A unique Compton scattering configuration for generating monochromatic, short pulse, and potentially coherent x-rays in a Laser Wakefield Accelerator (LWFA) is being studied at the Naval Research Laboratory. Reflection mechanisms such as stimulated Raman scattering and shock-created density gradients in a plasma can generate the required backward-travelling laser pulse directly from the same laser pulse used in the LWFA, i.e., the high energy electron beam and the counter-propagating photon beam are both self-generated by an ultrashort laser pulse in plasma. Extended interaction distance and automatic alignment of electron beam and backscattered radiation could be beneficial to the amplification of the Doppler upshifted Compton X-rays. Preliminary experiments are ongoing with measurement of Raman backscattering and reflection off a plasma density gradient. Energy resolved X-ray results are also anticipated. This work is supported by NRL Base Program and DOE.

  20. Quasimonoenergetic electron beam generation by using a pinholelike collimator in a self-modulated laser wakefield acceleration.

    PubMed

    Hafz, N; Hur, M S; Kim, G H; Kim, C; Ko, I S; Suk, H

    2006-01-01

    A relativistic electron bunch with a large charge (>2 nC) was produced from a self-modulated laser wakefield acceleration configuration. For this experiment, an intense laser beam with a peak power of 2 TW and a duration of 700 fs was focused in a supersonic He gas jet, and relativistic high-energy electrons were observed from the strong laser-plasma interaction. By passing the electron bunch through a small pinholelike collimator, we could generate a quasimonoenergetic high-energy electron beam, in which electrons within a cone angle of 0.25 mrad (f/70) were selected. The beam clearly showed a narrow-energy-spread behavior with a central energy of 4.3 MeV and a charge of 200 pC. The acceleration gradient was estimated to be about 30 GeV/m. Particle-in-cell simulations were performed for comparison study and the result shows that both the experimental and simulation results are in good agreement and the electron trapping is initiated by the slow beat wave of the Raman backward wave and the incident laser pulse. PMID:16486286

  1. Spectrum bandwidth narrowing of Thomson scattering X-rays with energy chirped electron beams from laser wakefield acceleration

    SciTech Connect

    Xu, Tong; Chen, Min Li, Fei-Yu; Yu, Lu-Le; Sheng, Zheng-Ming; SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG ; Zhang, Jie; Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190

    2014-01-06

    We study incoherent Thomson scattering between an ultrashort laser pulse and an electron beam accelerated from a laser wakefield. The energy chirp effects of the accelerated electron beam on the final radiation spectrum bandwidth are investigated. It is found that the scattered X-ray radiation has the minimum spectrum width and highest intensity as electrons are accelerated up to around the dephasing point. Furthermore, it is proposed that the electron acceleration process inside the wakefield can be studied by use of 90° Thomson scattering. The dephasing position and beam energy chirp can be deduced from the intensity and bandwidth of the scattered radiation.

  2. Ionization injection effects in x-ray spectra generated by betatron oscillations in a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Behm, K. T.; Zhao, T. Z.; Cole, J. M.; Maksimchuk, A.; Mangles, S. P. D.; Nees, J.; Wood, J. C.; Yanovsky, V.; Krushelnick, K.; Thomas, A. G. R.

    2016-05-01

    Single photon counting techniques were used with an x-ray CCD camera to measure features of synchrotron-like x-ray spectra generated by betatron oscillations of electrons in a laser wakefield accelerator (LWFA) with different injection techniques. Measurements were made using the Hercules laser system at the University of Michigan. With a single stage gas cell, we demonstrate that pure helium gas in our wakefield accelerator will produce spectra with higher critical energies than when helium mixed with nitrogen is used. This result was not evident when a two stage gas cell was used.

  3. Monoenergetic Energy Doubling in a Hybrid Laser-Plasma Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Hidding, B.; Königstein, T.; Osterholz, J.; Karsch, S.; Willi, O.; Pretzler, G.

    2010-05-01

    An ultracompact laser-plasma-generated, fs-scale electron double bunch system can be injected into a high-density driver/witness-type plasma wakefield accelerator afterburner stage to boost the witness electrons monoenergetically to energies far beyond twice their initial energy on the GeV scale. The combination of conservation of monoenergetic phase-space structure and fs duration with radial electric plasma fields Er˜100GV/m leads to dramatic transversal witness compression and unprecedented charge densities. It seems feasible to upscale and implement the scheme to future accelerator systems.

  4. Control of seeding phase for a cascaded laser wakefield accelerator with gradient injection

    SciTech Connect

    Wang, Wentao; Li, Wentao; Liu, Jiansheng; Wang, Cheng; Chen, Qiang; Zhang, Zhijun; Qi, Rong; Leng, Yuxin; Liang, Xiaoyan; Liu, Yanqi; Lu, Xiaoming; Wang, Cheng; Li, Ruxin; Xu, Zhizhan

    2013-12-09

    We demonstrated experimentally the seeding-phase control for a two-stage laser wakefield accelerator with gradient injection. By optimizing the seeding phase of electrons into the second stage, electron beams beyond 0.5 GeV with a 3% rms energy spread were produced over a short acceleration distance of ∼2 mm. Peak energy of the electron beam was further extended beyond 1 GeV by lengthening the second acceleration stage to 5 mm. Time-resolved magnetic field measurements via magneto-optical Faraday polarimetry allowed us to monitor the processes of electron seeding and acceleration in the second stage.

  5. Monoenergetic energy doubling in a hybrid laser-plasma wakefield accelerator.

    PubMed

    Hidding, B; Königstein, T; Osterholz, J; Karsch, S; Willi, O; Pretzler, G

    2010-05-14

    An ultracompact laser-plasma-generated, fs-scale electron double bunch system can be injected into a high-density driver/witness-type plasma wakefield accelerator afterburner stage to boost the witness electrons monoenergetically to energies far beyond twice their initial energy on the GeV scale. The combination of conservation of monoenergetic phase-space structure and fs duration with radial electric plasma fields E(r)∼100  GV/m leads to dramatic transversal witness compression and unprecedented charge densities. It seems feasible to upscale and implement the scheme to future accelerator systems. PMID:20866970

  6. Monoenergetic Energy Doubling in a Hybrid Laser-Plasma Wakefield Accelerator

    SciTech Connect

    Hidding, B.; Koenigstein, T.; Osterholz, J.; Willi, O.; Pretzler, G.; Karsch, S.

    2010-05-14

    An ultracompact laser-plasma-generated, fs-scale electron double bunch system can be injected into a high-density driver/witness-type plasma wakefield accelerator afterburner stage to boost the witness electrons monoenergetically to energies far beyond twice their initial energy on the GeV scale. The combination of conservation of monoenergetic phase-space structure and fs duration with radial electric plasma fields E{sub r{approx}}100 GV/m leads to dramatic transversal witness compression and unprecedented charge densities. It seems feasible to upscale and implement the scheme to future accelerator systems.

  7. Two-screen single-shot electron spectrometer for laser wakefield accelerated electron beams.

    PubMed

    Soloviev, A A; Starodubtsev, M V; Burdonov, K F; Kostyukov, I Yu; Nerush, E N; Shaykin, A A; Khazanov, E A

    2011-04-01

    The laser wakefield acceleration electron beams can essentially deviate from the axis of the system, which distinguishes them greatly from beams of conventional accelerators. In case of energy measurements by means of a permanent-magnet electron spectrometer, the deviation angle can affect accuracy, especially for high energies. A two-screen single-shot electron spectrometer that correctly allows for variations of the angle of entry is considered. The spectrometer design enables enhancing accuracy of measuring narrow electron beams significantly as compared to a one-screen spectrometer with analogous magnetic field, size, and angular acceptance. PMID:21529002

  8. Experimental study of self-trapping in capillary discharge guided laser wakefield acceleration

    SciTech Connect

    Panasenko, D.; Esarey, E.; Geddes, C. G. R.; Gonsalves, A. J.; Leemans, W. P.; Lin, C.; Nakamura, K.; Schroeder, C. B.; Toth, C.

    2009-05-04

    Laser wakefield acceleration experiments were carried out using hydrogen-filled capillary discharge waveguides. For a 33 mm long, 300 mu m capillary, parameter regimes with high energy electron beams (up to 1 GeV) and stable 0.5 GeV were found. In the high energy regime, the electron beam peak energy was correlated with the number of trapped electrons. For a 15 mm long, 200 mu m diameter capillary, quasi-monoenergetic e beams up to 300 MeV were observed. By de-tuning discharge delay from optimum guiding performance, self-trapping was found to be stabilized.

  9. Enhanced electron yield from laser-driven wakefield acceleration in high-Z gas jets

    NASA Astrophysics Data System (ADS)

    Mirzaie, Mohammad; Hafz, Nasr A. M.; Li, Song; Liu, Feng; He, Fei; Cheng, Ya; Zhang, Jie

    2015-10-01

    An investigation of the electron beam yield (charge) form helium, nitrogen, and neon gas jet plasmas in a typical laser-plasma wakefield acceleration experiment is carried out. The charge measurement is made by imaging the electron beam intensity profile on a fluorescent screen into a charge coupled device which was cross-calibrated with an integrated current transformer. The dependence of electron beam charge on the laser and plasma conditions for the aforementioned gases are studied. We found that laser-driven wakefield acceleration in low Z-gas jet targets usually generates high-quality and well-collimated electron beams with modest yields at the level of 10-100 pC. On the other hand, filamentary electron beams which are observed from high-Z gases at higher densities reached much higher yields. Evidences for cluster formation were clearly observed in the nitrogen gas jet target, where we received the highest electron beam charge of ˜1.7 nC. Those intense electron beams will be beneficial for the applications on the generation of bright X-rays, gamma rays radiations, and energetic positrons via the bremsstrahlung or inverse-scattering processes.

  10. Power Spectrum of Cerenkov Radiation from Laser Wakefield in Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Gao, Hong; Higashiguchi, Takeshi; Yugami, Noboru; Ito, Hiroaki; Nishida, Yasushi

    2000-10-01

    An angle and radiation frequecy distribution of the output power of the electromagnetic wave radiation from the laser wakefield in a magnetized plasma (Cerenkov wakes radiaiton) have been calculated. The magnetic field here is applied for the far field electromagnetic wave radiation = requirement. The radiation frequency is confined from ωp to = ω_h. The electromagnetic wave generation originates from the coupling between the DC perpendicular magnetic field and the plasma electron longitudinal = disturbance caused by the laser ponderomotive force. Under Coulomb gauge condition, the wave equation can be completely partitioned for the scale potential = and the vector field, so it can be easily obtained from the near zone static = field and far zone radiation field. The former has well been studied as the = static wakefield acceleration. Here we wish to present the detailed study on = the feature of the radiated electromagnetic field for the later case. The radiation = power spectrum which depends on the magnetic field, the laser pulse length, = the radiation frequency and the corresponding refraction index have been = given. The analysis shows that at the direction of \\cos θ= c=3D1/β n, where n is the refraction index of the magnetized plasma, the output = power has the maximum which satisfies the Cerenkov radiation angle condition, = so that the output power for the radiation frequency of ωp = is mainly located at the forward direction.

  11. Enhanced electron yield from laser-driven wakefield acceleration in high-Z gas jets

    SciTech Connect

    Mirzaie, Mohammad; Hafz, Nasr A. M. Li, Song; Liu, Feng; Zhang, Jie; He, Fei; Cheng, Ya

    2015-10-15

    An investigation of the electron beam yield (charge) form helium, nitrogen, and neon gas jet plasmas in a typical laser-plasma wakefield acceleration experiment is carried out. The charge measurement is made by imaging the electron beam intensity profile on a fluorescent screen into a charge coupled device which was cross-calibrated with an integrated current transformer. The dependence of electron beam charge on the laser and plasma conditions for the aforementioned gases are studied. We found that laser-driven wakefield acceleration in low Z-gas jet targets usually generates high-quality and well-collimated electron beams with modest yields at the level of 10-100 pC. On the other hand, filamentary electron beams which are observed from high-Z gases at higher densities reached much higher yields. Evidences for cluster formation were clearly observed in the nitrogen gas jet target, where we received the highest electron beam charge of ∼1.7 nC. Those intense electron beams will be beneficial for the applications on the generation of bright X-rays, gamma rays radiations, and energetic positrons via the bremsstrahlung or inverse-scattering processes.

  12. Study of x-ray radiation from a laser wakefield accelerator

    SciTech Connect

    Leurent, V.; Pollock, B. B.; Michel, P.; Divol, L.; Doeppner, T.; Glenzer, S. H.; Palastro, J. P.; Froula, D. H.; Clayton, C. E.; Joshi, C.; Marsh, K. A.; Pak, A.; Ralph, J.; Wang, T. L.; Tynan, G.

    2009-01-22

    A Laser Wakefield Accelerator (LWFA) is under development at Lawrence Livermore National Laboratory (LLNL) to produce electron bunches with GeV class energy and energy spreads of a few-percent. The interaction of a high power (200 TW), short pulse (50 fs) laser with neutral He gas can generate quasi-monoenergetic electron beams at energies up to 1 GeV [1]. The laser pulse can be self-guided over 1 cm overcoming the limitation of vacuum diffraction. X-ray betatron radiation is emitted while the accelerated electrons undergo oscillations in the wakefield electrostatic field. Here we present electron spectra measurements with a two screen spectrometer allowing to measure both the electron energy and the transverse deflection at the plasma exit. We have measured monoenergetic electron beams above 300 MeV. Furthermore a forward directed x-ray beam is observed. Preliminary measurements of the spectrum are in reasonable agreement with the calculated betatron spectrum in the synchrotron asymptotic limit using the measured electron beam parameters.

  13. ULTRA-SHORT X-RAY RADIATION COMING FROM A LASER WAKEFIELD ACCELERATOR

    SciTech Connect

    Leurent, V; Michel, P; Clayton, C E; Pollock, B; Doeppner, T; Wang, T L; Ralph, J; Pak, A; Joshi, C; Tynan, G; Divol, L; Palastro, J P; Glenzer, S H; Froula, D H

    2008-06-17

    A Laser Wakefield Accelerator (LWFA) is under development at Lawrence Livermore National Laboratory (LLNL) to produce electron bunches with GeV class energy and energy spreads of a few-percent. The ultimate goal is to provide a bright and compact photon source for high energy density physics. The interaction of a high power (200 TW), short pulse (50 fs) laser with neutral He gas can generate quasi-monoenergetic electrons beams at energies up to 1 GeV [1]. The laser pulse can be self-guided over a dephasing length of 1 cm (for a plasma density of 1.5 x 10{sup 18} cm{sup -3}) overcoming the limitation of vacuum diffraction. Betatron radiation is emitted while the accelerated electrons undergo oscillations in the wakefield electrostatic field. Here we present electron spectrum measurements with a two screen spectrometer allowing to fix the ambiguities due to unknown angle at the plasma exit. We have measured monoenergetic electron beams at energies around 110 MeV. Furthermore a forward directed x-ray beam is observed. The peak energy of the measured synchrotron spectrum is reconstructed based on the energy deposited after different sets of filters, assuming x-ray radiation described in the synchrotron asymptotic limit (SAL) and is found around 6 keV.

  14. Enhanced electron yield from laser-driven wakefield acceleration in high-Z gas jets.

    PubMed

    Mirzaie, Mohammad; Hafz, Nasr A M; Li, Song; Liu, Feng; He, Fei; Cheng, Ya; Zhang, Jie

    2015-10-01

    An investigation of the electron beam yield (charge) form helium, nitrogen, and neon gas jet plasmas in a typical laser-plasma wakefield acceleration experiment is carried out. The charge measurement is made by imaging the electron beam intensity profile on a fluorescent screen into a charge coupled device which was cross-calibrated with an integrated current transformer. The dependence of electron beam charge on the laser and plasma conditions for the aforementioned gases are studied. We found that laser-driven wakefield acceleration in low Z-gas jet targets usually generates high-quality and well-collimated electron beams with modest yields at the level of 10-100 pC. On the other hand, filamentary electron beams which are observed from high-Z gases at higher densities reached much higher yields. Evidences for cluster formation were clearly observed in the nitrogen gas jet target, where we received the highest electron beam charge of ∼1.7 nC. Those intense electron beams will be beneficial for the applications on the generation of bright X-rays, gamma rays radiations, and energetic positrons via the bremsstrahlung or inverse-scattering processes. PMID:26520950

  15. A method of determining narrow energy spread electron beams from a laser plasma wakefield accelerator using undulator radiation

    SciTech Connect

    Gallacher, J. G.; Anania, M. P.; Brunetti, E.; Ersfeld, B.; Islam, M. R.; Reitsma, A. J. W.; Shanks, R. P.; Wiggins, S. M.; Jaroszynski, D. A.; Budde, F.; Debus, A.; Haupt, K.; Schwoerer, H.; Jaeckel, O.; Pfotenhauer, S.; Rohwer, E.; Schlenvoigt, H.-P.

    2009-09-15

    In this paper a new method of determining the energy spread of a relativistic electron beam from a laser-driven plasma wakefield accelerator by measuring radiation from an undulator is presented. This could be used to determine the beam characteristics of multi-GeV accelerators where conventional spectrometers are very large and cumbersome. Simultaneous measurement of the energy spectra of electrons from the wakefield accelerator in the 55-70 MeV range and the radiation spectra in the wavelength range of 700-900 nm of synchrotron radiation emitted from a 50 period undulator confirm a narrow energy spread for electrons accelerated over the dephasing distance where beam loading leads to energy compression. Measured energy spreads of less than 1% indicates the potential of using a wakefield accelerator as a driver of future compact and brilliant ultrashort pulse synchrotron sources and free-electron lasers that require high peak brightness beams.

  16. A computational investigation of the impact of aberrated Gaussian laser pulses on electron beam properties in laser-wakefield acceleration experiments

    SciTech Connect

    Cummings, P.; Thomas, A. G. R.

    2011-05-15

    Critical to the performance of any future accelerator based on the laser wakefield accelerator is the response of the system to perturbations from ideal. In this paper, we use particle-in-cell simulation using a modified version of the OSIRIS 2.0 framework to demonstrate that comatic optical aberrations in a nominally Gaussian laser pulse are self-corrected by the plasma response, leading to stable propagation and therefore little variation in peak energy, energy spread, or peak current of the accelerated bunch, even for serious aberrations. However, the comatic aberration does lead to enhanced transverse beam emittance in the direction of the coma. Although this may be deleterious to the performance of an accelerator, one useful outcome is that the increased oscillation amplitude of electrons in the wake structure may lead to increased synchrotron radiation emission, which would be partially polarized in the direction of coma.

  17. Start-to-end beam dynamics simulation of double triangular current profile generation in Argonne Wakefield Accelerator

    SciTech Connect

    Ha, G.; Power, J.; Kim, S. H.; Gai, W.; Kim, K.-J.; Cho, M. H.; Namkung, W.

    2012-12-21

    Double triangular current profile (DT) gives a high transformer ratio which is the determining factor of the performance of collinear wakefield accelerator. This current profile can be generated using the emittance exchange (EEX) beam line. Argonne Wakefield Accelerator (AWA) facility plans to generate DT using the EEX beam line. We conducted start-to-end simulation for the AWA beam line using PARMELA code. Also, we discuss requirements of beam parameters for the generation of DT.

  18. Time-resolved measurements with streaked diffraction patterns from electrons generated in laser plasma wakefield

    NASA Astrophysics Data System (ADS)

    He, Zhaohan; Nees, John; Hou, Bixue; Krushelnick, Karl; Thomas, Alec; Beaurepaire, Benoît; Malka, Victor; Faure, Jérôme

    2013-10-01

    Femtosecond bunches of electrons with relativistic to ultra-relativistic energies can be robustly produced in laser plasma wakefield accelerators (LWFA). Scaling the electron energy down to sub-relativistic and MeV level using a millijoule laser system will make such electron source a promising candidate for ultrafast electron diffraction (UED) applications due to the intrinsic short bunch duration and perfect synchronization with the optical pump. Recent results of electron diffraction from a single crystal gold foil, using LWFA electrons driven by 8-mJ, 35-fs laser pulses at 500 Hz, will be presented. The accelerated electrons were collimated with a solenoid magnetic lens. By applying a small-angle tilt to the magnetic lens, the diffraction pattern can be streaked such that the temporal evolution is separated spatially on the detector screen after propagation. The observable time window and achievable temporal resolution are studied in pump-probe measurements of photo-induced heating on the gold foil.

  19. Efficient initiation of photonuclear reactions using quasimonoenergetic electron beams from laser wakefield acceleration

    SciTech Connect

    Reed, S. A.; Chvykov, V.; Kalintchenko, G.; Matsuoka, T.; Yanovsky, V.; Vane, C. R.; Beene, J. R.; Stracener, D.; Schultz, D. R.; Maksimchuk, A.

    2007-10-01

    Pulses of nearly monoenergetic relativistic electrons have been generated by laser wakefield acceleration and used to perform photonuclear activation of carbon, copper, and photofission in uranium. Using bremsstrahlung converter targets, the electron beams generated by this technique have been shown to be effective in producing high energy {gamma}-rays (tens of MeV) that are necessary to efficiently induce photonuclear reactions. Quantitative {gamma}-ray spectroscopy of the irradiated C, Cu, and U samples indicates that more than 10{sup 5} reactions were produced per joule of laser energy. The activation yield measurements have been compared with Monte Carlo modeling of electromagnetic cascade and photonuclear processes occurring in the targets to infer the characteristics of the laser accelerated electron beams.

  20. Control of laser-wakefield acceleration by the plasma-density profile.

    PubMed

    Pukhov, A; Kostyukov, I

    2008-02-01

    We show that both the maximum energy gain and the accelerated beam quality can be efficiently controlled by the plasma-density profile. Choosing a proper density gradient one can uplift the dephasing limitation and keep the phase synchronism between the bunch of relativistic particles and the plasma wave over extended distances. Putting electrons into the n th wake period behind the driving laser pulse, the maximum energy gain is increased by the factor, which is proportional to n, over that in the case of uniform plasma. Layered plasma is suggested to keep the resonant condition for laser-wakefield excitation. The acceleration is limited then by laser depletion rather than by dephasing. Further, we show that the natural energy spread of the particle bunch acquired at the acceleration stage can be effectively removed by a matched deceleration stage, where a larger plasma density is used. PMID:18352081

  1. Narrow spread electron beams from a laser-plasma wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Wiggins, S. M.; Anania, M. P.; Brunetti, E.; Cipiccia, S.; Ersfeld, B.; Islam, M. R.; Issac, R. C.; Raj, G.; Shanks, R. P.; Vieux, G.; Welsh, G. H.; Gillespie, W. A.; MacLeod, A. M.; Jaroszynski, D. A.

    2009-05-01

    The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laserplasma accelerators for the production of ultra-short electron bunches with subsequent generation of incoherent radiation pulses from plasma and coherent short-wavelength radiation pulses from a free-electron laser (FEL). The first quantitative measurements of the electron energy spectra have been made on the University of Strathclyde ALPHA-X wakefield acceleration beam line. A high peak power laser pulse (energy 900 mJ, duration 35 fs) is focused into a gas jet (nozzle length 2 mm) using an F/16 spherical mirror. Electrons from the laser-induced plasma are self-injected into the accelerating potential of the plasma density wake behind the laser pulse. Electron beams emitted from the plasma have been imaged downstream using a series of Lanex screens positioned along the beam line axis and the divergence of the electron beam has been measured to be typically in the range 1-3 mrad. Measurements of the electron energy spectrum, obtained using the ALPHA-X high resolution magnetic dipole spectrometer, are presented. The maximum central energy of the monoenergetic beam is 90 MeV and r.m.s. relative energy spreads as low as 0.8% are measured. The mean central energy is 82 MeV and mean relative energy spread is 1.1%. A theoretical analysis of this unexpectedly high electron beam quality is presented and the potential impact on the viability of FELs driven by electron beams from laser wakefield accelerators is examined.

  2. Simulations of Jitter Coupling due to Wakefields in the FACET Linac

    SciTech Connect

    Molloy, Stephen

    2009-10-30

    Facilities for Accelerator Science and Experimental Test Beams (FACET) is a proposed facility at SLAC that would use the initial two-thirds of the linac to transport e{sup +} and e{sup -} beams to an experimental region. A principal use of this facility is to identify the optimum method for accelerating positrons in a beam driven plasma wakefield accelerator. To study this, a positron bunch, followed an RF-cycle later by an electron bunch, will be accelerated to an asymmetric chicane designed to move the positrons behind the electrons, and then on to the plasma wakefield test stand. A major focus of study was the coupling of jitter of the positron bunch to the electron bunch via linac wakes. Lucretia is a Matlab toolbox for the simulation of electron beam transport systems, capable of multi-bunch tracking and wakefield calculations. With the exception of the lack of support for tracking of electrons and positrons within a single bunch train, it was well suited to the jitter coupling studies. This paper describes the jitter studies, including modifications made to Lucretia to correctly simulate tracking of mixed-species bunch trains through a lattice of magnetic elements and EM wakes.

  3. A high resolution, broad energy acceptance spectrometer for laser wakefield acceleration experiments

    SciTech Connect

    Sears, Christopher M. S.; Cuevas, Sofia Benavides; Veisz, Laszlo; Schramm, Ulrich; Schmid, Karl; Buck, Alexander; Habs, Dieter; Krausz, Ferenc

    2010-07-15

    Laser wakefield experiments present a unique challenge in measuring the resulting electron energy properties due to the large energy range of interest, typically several 100 MeV, and the large electron beam divergence and pointing jitter >1 mrad. In many experiments the energy resolution and accuracy are limited by the convolved transverse spot size and pointing jitter of the beam. In this paper we present an electron energy spectrometer consisting of two magnets designed specifically for laser wakefield experiments. In the primary magnet the field is produced by permanent magnets. A second optional electromagnet can be used to obtain better resolution for electron energies above 75 MeV. The spectrometer has an acceptance of 2.5-400 MeV (E{sub max}/E{sub min}>100) with a resolution of better than 1% rms for electron energies above 25 MeV. This high resolution is achieved by refocusing electrons in the energy plane and without any postprocessing image deconvolution. Finally, the spectrometer employs two complimentary detection mechanisms: (1) absolutely calibrated scintillation screens imaged by cameras outside the vacuum chamber and (2) an array of scintillating fibers coupled to a low-noise charge-coupled device.

  4. A high resolution, broad energy acceptance spectrometer for laser wakefield acceleration experiments.

    PubMed

    Sears, Christopher M S; Cuevas, Sofia Benavides; Schramm, Ulrich; Schmid, Karl; Buck, Alexander; Habs, Dieter; Krausz, Ferenc; Veisz, Laszlo

    2010-07-01

    Laser wakefield experiments present a unique challenge in measuring the resulting electron energy properties due to the large energy range of interest, typically several 100 MeV, and the large electron beam divergence and pointing jitter >1 mrad. In many experiments the energy resolution and accuracy are limited by the convolved transverse spot size and pointing jitter of the beam. In this paper we present an electron energy spectrometer consisting of two magnets designed specifically for laser wakefield experiments. In the primary magnet the field is produced by permanent magnets. A second optional electromagnet can be used to obtain better resolution for electron energies above 75 MeV. The spectrometer has an acceptance of 2.5-400 MeV (E(max)/E(min)>100) with a resolution of better than 1% rms for electron energies above 25 MeV. This high resolution is achieved by refocusing electrons in the energy plane and without any postprocessing image deconvolution. Finally, the spectrometer employs two complimentary detection mechanisms: (1) absolutely calibrated scintillation screens imaged by cameras outside the vacuum chamber and (2) an array of scintillating fibers coupled to a low-noise charge-coupled device. PMID:20687714

  5. Laser wakefield excitation and measurement by femtosecond longitudinal interferometry

    SciTech Connect

    Siders, C.W.; Le Blanc, S.P.; Fisher, D.; Tajima, T.; Downer, M.C.; Babine, A.; Stepanov, A.; Sergeev, A.

    1996-04-01

    Plasma density oscillations (Langmuir waves) in the wake of an intense (I{sub peak} {approximately} 3 {times} 10{sup 17}W/cm{sup 2}) laser pulse (100 fs) are measured with ultrafast time resolution using a longitudinal interferometric technique. Phase shifts consistent with large amplitude ({delta}n{sub e}/n{sub e} {approximately} 1) density waves at the electron plasma frequency were observed in a fully tunnel-ionized He plasma, corresponding to longitudinal electric fields of {approximately} 10 GV/m. Strong radial ponderomotive forces enhance the density oscillations. As this technique utilizes a necessary component of any laser-based plasma accelerator, it promises to be a powerful tool for on-line monitoring and control of future plasma-based particle accelerators.

  6. Modeling of laser wakefield acceleration in Lorentz boosted frame using EM-PIC code with spectral solver

    NASA Astrophysics Data System (ADS)

    Yu, Peicheng; Xu, Xinlu; Decyk, Viktor K.; An, Weiming; Vieira, Jorge; Tsung, Frank S.; Fonseca, Ricardo A.; Lu, Wei; Silva, Luis O.; Mori, Warren B.

    2014-06-01

    Simulating laser wakefield acceleration (LWFA) in a Lorentz boosted frame in which the plasma drifts towards the laser with vb can speed up the simulation by factors of γb2=(1. In these simulations the relativistic drifting plasma inevitably induces a high frequency numerical instability that contaminates the interesting physics. Various approaches have been proposed to mitigate this instability. One approach is to solve Maxwell equations in Fourier space (a spectral solver) as this has been shown to suppress the fastest growing modes of this instability in simple test problems using a simple low pass or "ring" or "shell" like filters in Fourier space. We describe the development of a fully parallelized, multi-dimensional, particle-in-cell code that uses a spectral solver to solve Maxwell's equations and that includes the ability to launch a laser using a moving antenna. This new EM-PIC code is called UPIC-EMMA and it is based on the components of the UCLA PIC framework (UPIC). We show that by using UPIC-EMMA, LWFA simulations in the boosted frames with arbitrary γb can be conducted without the presence of the numerical instability. We also compare the results of a few LWFA cases for several values of γb, including lab frame simulations using OSIRIS, an EM-PIC code with a finite-difference time domain (FDTD) Maxwell solver. These comparisons include cases in both linear and nonlinear regimes. We also investigate some issues associated with numerical dispersion in lab and boosted frame simulations and between FDTD and spectral solvers.

  7. Colliding pulse injection experiments in non-collinear geometryfor controlled laser plasma wakefield acceleration of electrons

    SciTech Connect

    Toth, Carl B.; Esarey, Eric H.; Geddes, Cameron G.R.; Leemans,Wim P.; Nakamura, Kei; Panasenko, Dmitriy; Schroeder, Carl B.; Bruhwiler,D.; Cary, J.R.

    2007-06-25

    An optical injection scheme for a laser-plasma basedaccelerator which employs a non-collinear counter-propagating laser beamto push background electrons in the focusing and acceleration phase viaponderomotive beat with the trailing part of the wakefield driver pulseis discussed. Preliminary experiments were performed using a drive beamof a_0 = 2.6 and colliding beam of a_1 = 0.8 both focused on the middleof a 200 mu m slit jet backed with 20 bar, which provided ~; 260 mu mlong gas plume. The enhancement in the total charge by the collidingpulse was observed with sharp dependence on the delay time of thecolliding beam. Enhancement of the neutron yield was also measured, whichsuggests a generation of electrons above 10 MeV.

  8. High-Field, {mu}J-Class THz Pulses from a Laser Wakefield Accelerator

    SciTech Connect

    Matlis, N. H.; Tilborg, J. van; Geddes, C. G. R.; Toth, Cs.; Schroeder, C. B.; Plateau, G. R.; Esarey, E.; Leemans, W. P.

    2009-01-22

    We present observation and characterization of microjoule-MV/cm-level THz pulses from a laser wakefield accelerator. THz emitted as coherent transition radiation from the plasma-vacuum boundary is collected and refocused by off-axis parabolas to a test stand where a suite of diagnostics is performed, including energy measurement by a Golay cell and electro-optic sampling of the spatio-temporal electric field using a probe pulse split from the main laser. Frequency Domain Holography is also implemented for the first time to capture spatio-temporal field distributions in a single shot. The four techniques strongly corroborate detection of THz pulses of {approx}0.4 ps duration, with peak fields of several hundred kV/cm and energies of 5-10 {mu}J. The advantages and disadvantages of each technique are discussed.

  9. All-optical cascaded laser wakefield accelerator using ionization-induced injection.

    PubMed

    Liu, J S; Xia, C Q; Wang, W T; Lu, H Y; Wang, Ch; Deng, A H; Li, W T; Zhang, H; Liang, X Y; Leng, Y X; Lu, X M; Wang, C; Wang, J Z; Nakajima, K; Li, R X; Xu, Z Z

    2011-07-15

    We report on near-GeV electron beam generation from an all-optical cascaded laser wakefield accelerator (LWFA). Electron injection and acceleration are successfully separated and controlled in different LWFA stages by employing two gas cells filled with a He/O2 mixture and pure He gas, respectively. Electrons with a Maxwellian spectrum, generated from the first LWFA assisted by ionization-induced injection, were seeded into the second LWFA with a 3-mm-thick gas cell and accelerated to be a 0.8-GeV quasimonoenergetic electron beam, corresponding to an acceleration gradient of 187  GV/m. The demonstrated scheme paves the way towards the multi-GeV laser accelerators. PMID:21838367

  10. Measurements of high-energy radiation generation from laser-wakefield accelerated electron beams

    SciTech Connect

    Schumaker, W. Vargas, M.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Maksimchuk, A.; Nees, J.; Yanovsky, V.; Thomas, A. G. R.; Krushelnick, K.; Sarri, G.; Dromey, B.; Zepf, M.

    2014-05-15

    Using high-energy (∼0.5 GeV) electron beams generated by laser wakefield acceleration (LWFA), bremsstrahlung radiation was created by interacting these beams with various solid targets. Secondary processes generate high-energy electrons, positrons, and neutrons, which can be measured shot-to-shot using magnetic spectrometers, short half-life activation, and Compton scattering. Presented here are proof-of-principle results from a high-resolution, high-energy gamma-ray spectrometer capable of single-shot operation, and high repetition rate activation diagnostics. We describe the techniques used in these measurements and their potential applications in diagnosing LWFA electron beams and measuring high-energy radiation from laser-plasma interactions.