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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. 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.

  3. Filamentation in Laser Wakefields

    NASA Astrophysics Data System (ADS)

    Los, Eva; Trines, Raoul; Silva, Luis; Bingham, Robert

    2016-10-01

    Laser filamentation instability is observed in plasma wakefields with sub-critical densities, and in high density inertial fusion plasmas. This leads to non-uniform acceleration or compression respectively. Here, we present simulation results on laser filamentation in plasma wakefields. The 2-D simulations are carried out using the particle-in-cell code Osiris. The filament intensity was found to increase exponentially before saturating. The maximum amplitude to which the highest intensity filament grew for a specific set of parameters was also recorded, and plotted against a corresponding parameter value. Clear, positively correlated linear trends were established between plasma density, transverse wavenumber k, laser pulse amplitude and maximum filament amplitude. Plasma density and maximum filament amplitude also showed a positive correlation, which saturated after a certain plasma density. Pulse duration and interaction length did not affect either filament intensity or transverse k value in a predictable manner. There was no discernible trend between pulse amplitude and filament width.

  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. 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.

  7. 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.

  8. 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.

  9. Stable boosted-frame simulations of laser-wakefield acceleration using Galilean coordinates

    NASA Astrophysics Data System (ADS)

    Lehe, Remi; Kirchen, Manuel; Godfrey, Brendan; Maier, Andreas; Vay, Jean-Luc

    2016-10-01

    While Particle-In-Cell (PIC) simulations of laser-wakefield acceleration are typically very computationally expensive, it is well-known that representing the system in a well-chosen Lorentz frame can reduce the computational cost by orders of magnitude. One of the limitation of this ``boosted-frame'' technique is the Numerical Cherenkov Instability (NCI) - a numerical instability that rapidly grows in the boosted frame and must be eliminated in order to obtain valid physical results. Several methods have been proposed in order to eliminate the NCI, but they introduce additional numerical corrections (e.g. heavy smoothing, unphysical modification of the dispersion relation, etc.) which could potentially alter the physics. By contrast, here we show that, for boosted-frame simulations of laser-wakefield acceleration, the NCI can be eliminated simply by integrating the PIC equations in Galilean coordinates (a.k.a comoving coordinates), without additional numerical correction. Using this technique, we show excellent agreement between simulations in the laboratory frame and Lorentz-boosted frame, with more than 2 orders of magnitude speedup in the latter case. Work supported by US-DOE Contracts DE-AC02-05CH11231.

  10. 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.

  11. Developing high energy, stable laser wakefield accelerators: particle simulations and experiments

    NASA Astrophysics Data System (ADS)

    Geddes, Cameron

    2006-10-01

    Laser driven wakefield accelerators produce accelerating fields thousands of times those achievable in conventional radiofrequency accelerators, and recent experiments have produced high energy electron bunches with low emittance and energy spread. Challenges now include control and reproducibility of the electron beam, further improvements in energy spread, and scaling to higher energies. We present large-scale particle in cell simulations together with recent experiments towards these goals. In LBNL experiments the relativistically intense drive pulse was guided over more than 10 diffraction ranges by plasma channels. Guiding beyond the diffraction range improved efficiency by allowing use of a smaller laser spot size (and hence higher intensities) over long propagation distances. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing > 200pC charge above 80 MeV with normalized emittance estimated at < 2 π-mm-mrad were produced. Energies have now been scaled to 1 GeV using 40 TW of laser power. Particle simulations and data showed that the high quality bunch in recent experiments was formed when beam loading turned off injection after initial self trapping, creating a bunch of electrons isolated in phase space. A narrow energy spread beam was then obtained by extracting the bunch as it outran the accelerating phase of the wake. Large scale simulations coupled with experiments are now under way to better understand the optimization of such accelerators including production of reproducible electron beams and scaling to energies beyond a GeV. Numerical resolution and two and three dimensional effects are discussed as well as diagnostics for application of the simulations to experiments. Effects including injection and beam dynamics as well as pump laser depletion and reshaping will be described, with application to design of future experiments. Supported by DOE grant DE-AC02-05CH11231 and by an INCITE

  12. 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.

  13. Lorentz boosted frame simulation of Laser wakefield acceleration in quasi-3D geometry

    NASA Astrophysics Data System (ADS)

    Yu, Peicheng; Xu, Xinlu; Davidson, Asher; Tableman, Adam; Meyers, Michael; Dalichaouch, Thamine; Tsung, Frank; Decyk, Viktor; Fiuza, Frederico; Vieira, Jorge; Fonseca, Ricardo; Lu, Wei; Silva, Luis; Mori, Warren

    2015-11-01

    We present results on a systematic study of Particle-In-Cell simulation of Laser Wakefield Acceleration (LWFA) by combining the Lorentz boosted frame technique with the quasi-3D algorithm, in which fields are expanded into azimuthal harmonics and solved on an r - z PIC grid keeping only a few harmonics. The studies emphasize on LWFA in the nonlinear blowout regime, which is more challenging from a computational standpoint. We first discuss strategies for eliminating the numerical Cerenkov instability (NCI) that inevitably arises due to the presence of plasma drifting across the grid with relativistic speeds in quasi-3D geometry. These strategies work for FFT based Maxwell solvers. We have incorporated these mitigation strategies into our PIC code OSIRIS by adding a new hybrid Yee-FFT Maxwell solver. With these strategies, OSIRIS can now be used to combine the quasi-3D algorithm and Lorentz boosted frame technique, and carry out high fidelity LWFA boosted frame simulation with no evidence of the NCI in the quasi-3D geometry, leading to unprecedented speedups. Work supported by NSF and DOE.

  14. Photon acceleration in laser wakefield accelerators

    SciTech Connect

    Trines, R. M. G. M.

    2007-07-11

    If the index of a refraction of a dispersive medium, such as a plasma, changes in time, it can be used to change the frequency of light propagating through the medium. This effect is called photon acceleration. It has been predicted in both theory and simulations, and also been demonstrated experimentally for the case of moving ionization fronts in gases (the so-called ionization blueshift) as well as for laser-driven wakefields.Here, we present studies of photon acceleration in laser-driven plasma wakefields. The unique spectral characteristics of this process will be discussed, to distinguish it from e.g. photon acceleration by ionization fronts, frequency domain interferometry or self-phase modulation. The dynamics of the photons in laser-wakefield interaction are studied through both regular particle-in-cell and wave-kinetic simulations. The latter approach provides a powerful, versatile, and easy-to-use method to track the propagation of individual spectral components, providing new insight into the physics of laser-plasma interaction. Theory, simulations and experimental results will be brought together to provide a full understanding of the dynamics of a laser pulse in its own wakefield.Even though the wave-kinetic approach mentioned above has mainly been developed for the description of laser-plasma interaction, it can be applied to a much wider range of fast wave-slow wave interaction processes: Langmuir waves-ion acoustic waves, drift waves-zonal flow, Rossby waves-zonal flow, or even photons-gravitational waves. Several recent results in these areas will be shown, often with surprising results.

  15. 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.

  16. Synchrotron radiation from a curved plasma channel laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Palastro, J. P.; Kaganovich, D.; Hafizi, B.; Chen, Y.-H.; Johnson, L. A.; Peñano, J. R.; Helle, M. H.; Mamonau, A. A.

    2017-03-01

    A laser pulse guided in a curved plasma channel can excite wakefields that steer electrons along an arched trajectory. As the electrons are accelerated along the curved channel, they emit synchrotron radiation. We present simple analytical models and simulations examining laser pulse guiding, wakefield generation, electron steering, and synchrotron emission in curved plasma channels. For experimentally realizable parameters, a ˜2 GeV electron emits 0.1 photons per cm with an average photon energy of multiple keV.

  17. Simulation of 1 GeV laser wakefield accelerator experiments and scaling to 10 GeV

    NASA Astrophysics Data System (ADS)

    Cormier-Michel, Estelle; Geddes, C. G. R.; Isaacs, W. A.; Stinus, N.; Esarey, E.; Schroeder, C. B.; Leemans, W. P.; Bruhwiler, D. L.; Cary, J. R.

    2007-11-01

    Recent laser-plasma accelerator experiments at LBNL have demonstrated the production of high quality 0.5 and 1.0 GeV electron beams.ootnotetextW.P. Leemans et al., Nature Physics 2, 696 (2006) In these experiments, the 10-40 TW laser pulse was guided in a 3 cm long capillary discharge plasma channel. Particle-In-Cell (PIC) simulations provide information not accessible from experiments on the nonlinear laser-plasma interaction that governs the accelerator internal dynamics. Simulations show that high quality electron bunches are formed by self-trapping of electrons in the wake, followed by loading of the wake by the trapped bunch, creating a bunch of electrons isolated in phase space. A narrow energy spread beam is then obtained by extracting the bunch as it outran the accelerating phase of the wake. Simulations in 2D and 3D showing details on the electron bunch, wakefield, and laser evolution are presented and compared to experimental results. Simulations on scaling these experiments to the 10 GeV level are also presented.

  18. Optimization and control of electron beams from laser wakefield accelerations using asymmetric laser pulses

    NASA Astrophysics Data System (ADS)

    Gopal, K.; Gupta, D. N.

    2017-10-01

    Optimization and control of electron beam quality in laser wakefield acceleration are explored by using a temporally asymmetric laser pulse of the sharp rising front portion. The temporally asymmetric laser pulse imparts stronger ponderomotive force on the ambient plasma electrons. The stronger ponderomotive force associated with the asymmetric pulse significantly affects the injection of electrons into the wakefield and consequently the quality of the injected bunch in terms of injected charge, mean energy, and emittance. Based on particle-in-cell simulations, we report to generate a monoenergetic electron beam with reduced emittance and enhanced charge in laser wakefield acceleration using an asymmetric pulse of duration 30 fs.

  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. Role of Direct Laser Acceleration of Electrons in a Laser Wakefield Accelerator with Ionization Injection.

    PubMed

    Shaw, J L; Lemos, N; Amorim, L D; Vafaei-Najafabadi, N; Marsh, K A; Tsung, F S; Mori, W B; Joshi, C

    2017-02-10

    We show the first experimental demonstration that electrons being accelerated in a laser wakefield accelerator operating in the forced or blowout regimes gain significant energy from both the direct laser acceleration (DLA) and the laser wakefield acceleration mechanisms. Supporting full-scale 3D particle-in-cell simulations elucidate the role of the DLA of electrons in a laser wakefield accelerator when ionization injection of electrons is employed. An explanation is given for how electrons can maintain the DLA resonance condition in a laser wakefield accelerator despite the evolving properties of both the drive laser and the electrons. The produced electron beams exhibit characteristic features that are indicative of DLA as an additional acceleration mechanism.

  1. Role of Direct Laser Acceleration of Electrons in a Laser Wakefield Accelerator with Ionization Injection

    NASA Astrophysics Data System (ADS)

    Shaw, J. L.; Lemos, N.; Amorim, L. D.; Vafaei-Najafabadi, N.; Marsh, K. A.; Tsung, F. S.; Mori, W. B.; Joshi, C.

    2017-02-01

    We show the first experimental demonstration that electrons being accelerated in a laser wakefield accelerator operating in the forced or blowout regimes gain significant energy from both the direct laser acceleration (DLA) and the laser wakefield acceleration mechanisms. Supporting full-scale 3D particle-in-cell simulations elucidate the role of the DLA of electrons in a laser wakefield accelerator when ionization injection of electrons is employed. An explanation is given for how electrons can maintain the DLA resonance condition in a laser wakefield accelerator despite the evolving properties of both the drive laser and the electrons. The produced electron beams exhibit characteristic features that are indicative of DLA as an additional acceleration mechanism.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Role of direct laser acceleration of electrons in a laser wakefield accelerator with ionization injection

    NASA Astrophysics Data System (ADS)

    Shaw, Jessica; Lemos, Nuno; Amorim, Ligia Diana; Vafaei-Najafabadi, Navid; Marsh, Ken; Tsung, Frank; Froula, Dustin; Mori, Warren; Josh, Chan

    2016-10-01

    We show through experiments and supporting simulations the role of direct laser acceleration (DLA) of electrons in a laser wakefield accelerator when ionization injection of electrons is employed. The laser pulse is intense enough to create a nonlinear wakefield and long enough to overlap the electrons trapped in the first accelerating potential well (bucket) of the wakefield. The betatron oscillations of the trapped electrons in the plane of the laser polarization in the presence of an ion column lead to an energy transfer from the laser pulse to the electrons through DLA. We show that the produced electron beams exhibit characteristic features that are indicative of DLA as an additional acceleration mechanism when the laser pulse overlaps the trapped electrons. Experimental work supported by NSF Grant PHY-1415306 and DOE Grant DE-SC0010064. Simulation work done on the Fermi Cluster at Cineca.

  7. Dynamics of boundary layer electrons around a laser wakefield bubble

    NASA Astrophysics Data System (ADS)

    Luo, J.; Chen, M.; Zhang, G.-B.; Yuan, T.; Yu, J.-Y.; Shen, Z.-C.; Yu, L.-L.; Weng, S.-M.; Schroeder, C. B.; Esarey, E.

    2016-10-01

    The dynamics of electrons forming the boundary layer of a highly nonlinear laser wakefield driven in the so called bubble or blowout regime is investigated using particle-in-cell simulations. It is shown that when the driver pulse intensity increases or the focal spot size decreases, a significant amount of electrons initially pushed by the laser pulse can detach from the bubble structure at its tail, middle, or front and form particular classes of waves locally with high densities, referred to as the tail wave, lateral wave, and bow wave. The tail wave and bow wave correspond to real electron trajectories, while the lateral wave does not. The detached electrons can be ejected transversely, containing considerable energy, and reducing the efficiency of the laser wakefield accelerator. Some of the transversely emitted electrons may obtain MeV level energy. These electrons can be used for wake evolution diagnosis and producing high frequency radiation.

  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. 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.

  10. Emittance control in Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Cheshkov, S.; Tajima, T.; Chiu, C.; Breitling, F.

    2001-05-01

    In this paper we summarize our recent effort and results in theoretical study of the emittance issues of multistaged Laser Wakefield Accelerator (LWFA) in TeV energy range. In such an energy regime the luminosity and therefore the emittance requirements become very stringent and tantamount to the success or failure of such an accelerator. The system of such a machine is very sensitive to jitters due to misalignment between the beam and the wakefield. In particular, the effect of jitters in the presence of a strong focusing wakefield and initial longitudinal phase space spread of the beam leads to severe transverse emittance degradation of the beam. To improve the emittance we introduce several methods: a mitigated wakefield focusing by working with a plasma channel, an approximately synchronous acceleration in a superunit setup, the "horn" model based on exactly synchronous acceleration achieved through plasma density variation and lastly an algorithm based on minimization of the final beam emittance to actively control the stage displacement of such an accelerator.

  11. Ultrafast science using Laser Wakefield Accelerators

    NASA Astrophysics Data System (ADS)

    Thomas, Alec G. R.

    2016-10-01

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have considerable benefits for ultrafast science. Laser wakefield acceleration provides radiation pulses that have femtosecond duration and intrinsic synchronisation with the laser source, allowing for pump-probe measurements with unprecedented temporal resolution. These pulses can be used to study ultrafast dynamical phenomena in plasma and dense material, such as transient magnetic fields, rapidly evolving plasma dynamics and crystal lattice oscillations. In this talk, I will review recent experiments in laser wakefield acceleration and energetic photon generation using the laser systems HERCULES and Lambda-Cubed at the University of Michigan and their use for capturing the dynamics of laser-pumped samples. Studies of the electron beam hosing instability and the generation of annular phase space distributions increase X-ray flux while maintaining its femtosecond duration. Single-shot, spectrally resolved absorption measurements in laser pumped foils can be made on ultrafast timescales using this broadband photon source. Ultrafast electron radiography is able to temporally resolve relativistically expanding magnetic fields in high-intensity laser-solid interactions and the evolution of electric fields in low density plasma. Time-resolved electron diffraction captures structural dynamics in crystalline silicon. I will also discuss the technological needs for and potential impact of such revolutionary compact radiation sources for ultrafast science in the future. US Air Force Office of Scientific Research under Award Number FA9550-12-1-0310, the US National Science Foundation Grants No. 1054164, 0935197, 1535628 and 0810979, US Department of Energy Grant No. DE-NA0002372 and Army Research Office Grant No. W911NF1.

  12. Numerical studies of density transition injection in laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Massimo, F.; Lifschitz, A. F.; Thaury, C.; Malka, V.

    2017-08-01

    The quality of laser wakefield accelerated electrons beams is strongly determined by the physical mechanism exploited to inject electrons in the wakefield. One of the techniques used to improve the beam quality is the density transition injection, where the electron trapping occurs as the laser pulse passes a sharp density transition created in the plasma. Although this technique has been widely demonstrated experimentally, the literature lacks theoretical and numerical studies on the effects of all the transition parameters. We thus report and discuss the results of a series of particle in cell (PIC) simulations where the density transition height and downramp length are systematically varied, to show how the electron beam parameters and the injection mechanism are affected by the density transition parameters.

  13. Energy spread minimization in a cascaded laser wakefield accelerator via velocity bunching (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhang, Zhijun

    2017-05-01

    We report the observation of energy-spread compensation of electron bunches in a laser wakefield accelerator in experiment. The compensation was caused by the gradient wakefield in plasma wake, and the energy spectra of the bunches evolved during the acceleration so that we propose a new method to diagnose the longitudinal length of the ultrashort electron bunch. By analyzing the energy spectra of electron bunches with different acceleration length, the wakefield gradient difference and the wakefield slope of the bunch could be estimated by combining with the slippage between the plasma wave and the electron bunch, thus the electron bunches' longitudinal length could be estimated. By applying this new method, the longitudinal length of electron bunches with charge of about 40 pC generated from a laser wakefield accelerator was estimated to be (2.4 ± 2.2) μm in experiment, which was in good agreement with three-dimension particle-in-cell simulations.

  14. 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.

  15. Controlled electron injection using nanoparticles in laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Cho, Myung Hoon; Pathak, Vishwa Bandhu; Kim, Hyung Taek; Nakajima, Kazuhisa; Nam, Chang Hee; CenterRelativistic Laser Science Team

    2016-10-01

    Laser wakefield acceleration is one of compact electron acceleration schemes due to its high accelerating gradient. Despite of the great progress of several GeV electron beams with high power lasers, the electron injection to the wakefield is still a critical issue for a very low density plasma 1017 electrons/cc. In this talk a novel method to control the injection using nanoparticles is proposed. We investigate the electron injection by analyzing the interaction of electrons with the two potentials - one created by a nanoparticle and the other by the wakefield. The nanoparticle creates a localized electric potential and this nanoparticle potential just slips the present wake potential. To confirm the Hamiltonian description of the interaction, a test particle calculation is performed by controlling the bubble and the nanoparticle potentials. A multi-dimensional particle-in-cell simulations are also presented as a proof-of-principle. Comparing theoretical estimates and PIC simulation, we suggest nanoparticle parameters of size and electron density depending on the background plasma density. Our scheme can be applicable for low plasma density to break though the limitation of self-injection toward extremely high energy electron energy.

  16. Laser Wakefield diagnostic using holographic longitudinal interferometry

    SciTech Connect

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

    1999-03-26

    We propose a diagnostic technique for wakefield measurement in plasma channels. A new technique for plasma channel creation, the Ignitor Heater scheme was proposed and experimentally tested in hydrogen and nitrogen previously. It makes use of two laser pulses. The Ignitor, an ultrashort (sub 100 fs) laser pulse, is brought to a line focus using a cylindrical lens to ionize the gas. The Heater pulse (160 ps long) is used to heat the existing spark via in-verse Bremsstrahlung. The hydrodynamic shock expansion creates a partially evacuated plasma channel with a density minimum on axis. Such a channel has properties of an optical waveguide. This technique allows creation of plasma channels in low atomic number gases, such as hydrogen, which is of importance for guiding of highly intense laser pulses. Laser pulses injected into such plasma channels produce a plasma wake that has a phase velocity close to the speed of light. A discussion of plasma wake measurements, using a Longitudinal Interferometry Wakefield Diagnostic Based on Time Domain Rayleigh Refractometry with Holographic Inversion, will be presented.

  17. Generation of skewed laser pulses for laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Toth, C.; Faure, J.; Geddes, C. G. R.; van Tilborg, J.; Leemans, W. P.

    2002-11-01

    The effect of asymmetric laser pulses on electron yield from a laser wakefield accelerator has been experimentally studied (W.P. Leemans et al., submitted to Phys. Rev. Lett.) using > 10^19 cm-3 plasmas and a 10 TW, > 45 fs, Ti:Al_2O3 laser. The non-Gaussian laser pulse shapes were controlled through non-linear chirp with a grating pair compressor. Pulses (76 fs FWHM) with a steep rise (positive skew) were found to significantly enhance the electron yield compared to pulses with a gentle rise (negative skew). These results demonstrate that laser wakefield accelerator can be optimized using skewed laser pulses. Controlling the skewness of laser pulses can be done by appropriate choice of the higher order spectral phase coefficients. Details on how this is done using non-linear chirp using grating compressor, as well as an acousto-optic system (DAZZLER) will be presented.

  18. Laser wakefield acceleration of polarized electron beams

    NASA Astrophysics Data System (ADS)

    Pugacheva, D. V.; Andreev, N. E.; Cros, B.

    2016-11-01

    The acceleration of highly polarized electron beams are widely used in state-of-the-art high-energy physics experiments. In this work, a model for investigation of polarization dynamics of electron beams in the laser-plasma accelerator depending on the initial energy of electrons was developed and tested. To obtain the evolution of the trajectory and momentum of the electron for modeling its acceleration the wakefield structure was determined. The spin precession of the beam electron was described by Thomas-Bargman-Michel-Telegdi equations. The evolution of the electron beam polarization was investigated for zero-emittance beams with zero-energy spread.

  19. Observation of laser chirp dependency on electron yield in laser wakefield accelerators.

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

    The effect of laser chirp on laser wakefield acceleration of electrons has been studied experimentally and theoretically. The experiments operated in the self-modulated laser wakefield acceleration regime and used a high density (1-5 × 10^19 cm-3) laser ionized plasma and a Ti:Al_2O3 laser producing up to 10 TW peak power in 45-55 fs duration laser pulses [1]. For the same peak power, positively chirped laser pulse are found to result in significantly higher amounts of charge per bunch than negatively chirped pulses. Simulations using PIC codes indicate that larger amplitude fast phase velocity plasma waves are generated for positively chirped pulses as well as larger amounts of stimulated Raman backscattering (SRS-B). The enhanced SRS-B in turn leads to larger amounts of trapped, high energy electrons, consistent with the experiments. [1] W.P. Leemans et al., Phys. Plasmas 8, 2510(2001)

  20. Two-color hybrid laser wakefield and direct laser accelerator

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Khudik, V.; Bernstein, A.; Downer, M.; Shvets, G.

    2017-03-01

    We propose and investigate the concept of two-color laser wakefield and direct acceleration (LWDA) scheme in the regime of moderate (10 TW scale) laser powers. The concept utilizes two unequal frequency laser pulses: the leading long-wavelength (λ0 = 0.8 µm) wakefield laser pulse driving a nonlinear plasma wake, and a trailing short-wavelength (λDLA = λ0/2) DLA laser pulse. The combination of the large electric field, yet small ponderomotive pressure of the DLA pulse is shown to be advantageous for producing a higher energy and larger charge electron beam compared with the single frequency LWDA. The sensitivity of the dual-frequency LWDA to synchronization time jitter is also reduced.

  1. Simulation and diagnostics of high density plasmas for multiple electron bunch wakefield generation

    NASA Astrophysics Data System (ADS)

    Kallos, Efthymios; Muggli, Patric; Katsouleas, Tom; Yakimenko, Vitaly; Stolyarov, Daniil; Pogorelsky, Igor; Pavlishin, Igor; Kusche, Karl; Babzien, Marcus; Ben-Zvi, Ilan; Kimura, Wayne

    2006-10-01

    The wakefield generated in a plasma from an electron beam can be enhanced if instead of a single bunch the beam is modulated into multiple bunches. Then the wakefields generated from the microbunches can add up in phase if the plasma density is tuned precisely at the separation between them. In the experimental setup at Brookhaven's Accelerator Test Facility the 45MeV electron beam is IFEL modulated into 150 microbunches 10.6μm apart. Here we present plasma simulations that confirm the wakefield enhancement and diagnostics we performed to tune the plasma density (Stark broadening, HeNe laser interferometry).

  2. 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.

  3. 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.

  4. 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.

  5. 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.

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

    SciTech Connect

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

    2016-05-15

    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.

  7. 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.

  8. Resonant Plasma Wakefield Experiment: Plasma Simulations and Multibunched Electron Beam Diagnostics

    NASA Astrophysics Data System (ADS)

    Kallos, Efthymios; Muggli, Patric; Katsouleas, Thomas; Yakimenko, Vitaly; Stolyarov, Daniil; Pogorelsky, Igor; Pavlishin, Igor; Kusche, Karl; Babzien, Marcus; Ben-Zvi, Ilan; Kimura, Wayne D.

    2006-11-01

    In the multibunch plasma wakefield acceleration experiment at the Brookhaven National Lab's Accelerator Test Facility a 45 MeV electron beam is initially modulated through the IFEL interaction with a CO2 laser beam at 10.6 μm into a train of short microbunches, which are spaced at the laser wavelength. It is then fed into a high-density capillary plasma with a density resonant at this spacing (1.0 × 1019cm-3). The microbunched beam can resonantly excite a plasma wakefield much larger than the wakefield excited from the non-bunched beam. Here we present plasma simulations that confirm the wakefield enhancement and the results of a series of CTR measurements performed of the multibunched electron beam.

  9. 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.

  10. Excitation and Control of Plasma Wakefields by Multiple Laser Pulses

    NASA Astrophysics Data System (ADS)

    Cowley, J.; Thornton, C.; Arran, C.; Shalloo, R. J.; Corner, L.; Cheung, G.; Gregory, C. D.; Mangles, S. P. D.; Matlis, N. H.; Symes, D. R.; Walczak, R.; Hooker, S. M.

    2017-07-01

    We demonstrate experimentally the resonant excitation of plasma waves by trains of laser pulses. We also take an important first step to achieving an energy recovery plasma accelerator by showing that a plasma wave can be damped by an out-of-resonance trailing laser pulse. The measured laser wakefields are found to be in excellent agreement with analytical and numerical models of wakefield excitation in the linear regime. Our results indicate a promising direction for achieving highly controlled, GeV-scale laser-plasma accelerators operating at multikilohertz repetition rates.

  11. Theory of laser chirp effects on instabilities in laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Schroeder, C.; Esarey, E.; van Tilborg, J.; Leemans, W. P.; Shadwick, B. A.; Trines, R.; Cary, J. R.; Giacone, R.

    2001-10-01

    Experimentally, laser chirp is found to be an important parameter affecting electron output from self-modulated laser wakefield accelerators (SMLWFAs). In SMLWFAs, electrons are accelerated to high energies by plasma wakefields generated by the self-modulation instability and forward Raman scattering, whereas the initial trapping and heating of the electrons is strongly affected by backward and sideways Raman scattering. The effect of laser frequency chirp on self-modulation and Raman instabilities is analyzed theoretically. Expressions for chirp-modified growth rates are presented. Theoretical results are compared to results from various simulation models, including time-averaged quasi-static envelope fluid codes, full fluid codes, and particle-in-cell codes. In addition, comparison is made to recent experimental results obtained at LBNL.(W.P. Leemans et al., Phys. Plasmas 8), 2510 (2001).

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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, ˜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.

  14. 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.

  15. High-flux electron beams from laser wakefield accelerators driven by petawatt lasers

    NASA Astrophysics Data System (ADS)

    Zeng, Ming; Tesileanu, Ovidiu

    2017-07-01

    Laser wakefield accelerators (LWFAs) are considered to be one of the most competitive next-generation accelerator candidates. In this paper, we will study the potential high-flux electron beam production of an LWFA driven by petawatt-level laser pulses. In our three-dimensional particle-in-cell simulations, an optimal set of parameters gives ˜ 40 {nC} of charge with 2 {PW} laser power, thus ˜ 400 {kA} of instantaneous current if we assume the electron beam duration is 100 fs. This high flux and its secondary radiation are widely applicable in nuclear and QED physics, industrial imaging, medical and biological studies.

  16. High-flux electron beams from laser wakefield accelerators driven by petawatt lasers

    NASA Astrophysics Data System (ADS)

    Ming, ZENG; Ovidiu, TESILEANU

    2017-07-01

    Laser wakefield accelerators (LWFAs) are considered to be one of the most competitive next-generation accelerator candidates. In this paper, we will study the potential high-flux electron beam production of an LWFA driven by petawatt-level laser pulses. In our three-dimensional particle-in-cell simulations, an optimal set of parameters gives ∼ 40 {nC} of charge with 2 {PW} laser power, thus ∼ 400 {kA} of instantaneous current if we assume the electron beam duration is 100 fs. This high flux and its secondary radiation are widely applicable in nuclear and QED physics, industrial imaging, medical and biological studies.

  17. 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.

  18. 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.

  19. Laser Wakefield Accelerator Injection Control and X-Ray Sources

    NASA Astrophysics Data System (ADS)

    Geddes, C. G. R.; Cormier-Michel, E.; Esarey, E. H.; Le Corre, T.; Lin, C.; Matlis, N. H.; Nakamura, K.; Plateau, G. R.; Schroeder, C. B.; van Mourik, R. A.; Leemans, W. P.; Thorn, D. B.; Bruhwiler, D. L.; Cowan, B.; Paul, K.; Cary, J. R.

    2009-11-01

    Reduced beam energy spread, fluctuation, and emittance are important to applications of compact, high gradient laser-plasma wakefield accelerators including Thomson gamma sources and high energy colliders. Experiments and simulations will be presented on control of injection to improve beam quality compared to use of self-injection by the wake. Trapping of electrons in the wake can be controlled using the beat between multiple laser pulses to via kick electrons in momentum and phase into the wake accelerating phase. Laser and gas target shaping and control are used to further control the accelerator structure. Simulations demonstrate the tuning of accelerator structure required to accelerate such bunches to high energies while retaining high bunch quality. Electron beam source size and position are measured using betatron X-ray emission produced when electrons oscillate in the focusing field of the wake to improve understanding of beam emittance and stability, while also producing a broadband, synchronized fs source of keV X-rays. Supported by US DOE NA-22 and HEP including DE-AC02-05CH11231, SciDAC, and SBIR.

  20. 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.

  1. Particle-in-cell simulation of x-ray wakefield acceleration and betatron radiation in nanotubes

    SciTech Connect

    Zhang, Xiaomei; Tajima, Toshiki; Farinella, Deano; Shin, Youngmin; Mourou, Gerard; Wheeler, Jonathan; Taborek, Peter; Chen, Pisin; Dollar, Franklin; Shen, Baifei

    2016-10-18

    Though wakefield acceleration in crystal channels has been previously proposed, x-ray wakefield acceleration has only recently become a realistic possibility since the invention of the single-cycled optical laser compression technique. We investigate the acceleration due to a wakefield induced by a coherent, ultrashort x-ray pulse guided by a nanoscale channel inside a solid material. By two-dimensional particle-in-cell computer simulations, we show that an acceleration gradient of TeV/cm is attainable. This is about 3 orders of magnitude stronger than that of the conventional plasma-based wakefield accelerations, which implies the possibility of an extremely compact scheme to attain ultrahigh energies. In addition to particle acceleration, this scheme can also induce the emission of high energy photons at ~O(10–100) MeV. Here, our simulations confirm such high energy photon emissions, which is in contrast with that induced by the optical laser driven wakefield scheme. In addition to this, the significantly improved emittance of the energetic electrons has been discussed.

  2. Particle-in-cell simulation of x-ray wakefield acceleration and betatron radiation in nanotubes

    DOE PAGES

    Zhang, Xiaomei; Tajima, Toshiki; Farinella, Deano; ...

    2016-10-18

    Though wakefield acceleration in crystal channels has been previously proposed, x-ray wakefield acceleration has only recently become a realistic possibility since the invention of the single-cycled optical laser compression technique. We investigate the acceleration due to a wakefield induced by a coherent, ultrashort x-ray pulse guided by a nanoscale channel inside a solid material. By two-dimensional particle-in-cell computer simulations, we show that an acceleration gradient of TeV/cm is attainable. This is about 3 orders of magnitude stronger than that of the conventional plasma-based wakefield accelerations, which implies the possibility of an extremely compact scheme to attain ultrahigh energies. In additionmore » to particle acceleration, this scheme can also induce the emission of high energy photons at ~O(10–100) MeV. Here, our simulations confirm such high energy photon emissions, which is in contrast with that induced by the optical laser driven wakefield scheme. In addition to this, the significantly improved emittance of the energetic electrons has been discussed.« less

  3. Particle-in-cell simulation of x-ray wakefield acceleration and betatron radiation in nanotubes

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaomei; Tajima, Toshiki; Farinella, Deano; Shin, Youngmin; Mourou, Gerard; Wheeler, Jonathan; Taborek, Peter; Chen, Pisin; Dollar, Franklin; Shen, Baifei

    2016-10-01

    Though wakefield acceleration in crystal channels has been previously proposed, x-ray wakefield acceleration has only recently become a realistic possibility since the invention of the single-cycled optical laser compression technique. We investigate the acceleration due to a wakefield induced by a coherent, ultrashort x-ray pulse guided by a nanoscale channel inside a solid material. By two-dimensional particle-in-cell computer simulations, we show that an acceleration gradient of TeV /cm is attainable. This is about 3 orders of magnitude stronger than that of the conventional plasma-based wakefield accelerations, which implies the possibility of an extremely compact scheme to attain ultrahigh energies. In addition to particle acceleration, this scheme can also induce the emission of high energy photons at ˜O (10 - 100 ) MeV . Our simulations confirm such high energy photon emissions, which is in contrast with that induced by the optical laser driven wakefield scheme. In addition to this, the significantly improved emittance of the energetic electrons has been discussed.

  4. Electron Rephasing in a Laser-Wakefield Accelerator.

    PubMed

    Guillaume, E; Döpp, A; Thaury, C; Ta Phuoc, K; Lifschitz, A; Grittani, G; Goddet, J-P; Tafzi, A; Chou, S W; Veisz, L; Malka, V

    2015-10-09

    An important limit for energy gain in laser-plasma wakefield accelerators is the dephasing length, after which the electron beam reaches the decelerating region of the wakefield and starts to decelerate. Here, we propose to manipulate the phase of the electron beam in the wakefield, in order to bring the beam back into the accelerating region, hence increasing the final beam energy. This rephasing is operated by placing an upward density step in the beam path. In a first experiment, we demonstrate the principle of this technique using a large energy spread electron beam. Then, we show that it can be used to increase the energy of monoenergetic electron beams by more than 50%.

  5. 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.

  6. Dynamics of boundary layer electrons in laser driven wakefields (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Chen, Min

    2017-05-01

    The dynamics of electrons forming the boundary layer of a highly nonlinear laser wakefield is investigated using computational simulations. It is shown that when the driver pulse intensity increases or the focal spot size decreases, a significant amount of electrons initially pushed by the laser pulse can detach from the bubble structure at its tail, middle, or front and form particular classes of waves locally with high densities, referred to as the tail wave, lateral wave, and bow wave. Simulation results show that the tail and bow waves correspond to real electron trajectories, while the lateral wave does not. The detached electrons can be ejected transversely, containing considerable energy, and reducing the efficiency of the laser wakefield accelerator. Some of the transversely emitted electrons may obtain MeV level energy. These electrons can be used for wake evolution diagnosis and producing high frequency radiation.

  7. 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.

  8. Backward Raman Amplifier for Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Ludwig, Joshua; Masson-Laborde, Paul-Edouard; Huller, Stefan; Rozmus, Wojciech; Wilks, Scott C.

    2016-10-01

    Particle in cell simulations via SCPIC and theoretical work on Raman amplification and laser wake field acceleration will be presented. Laser energy depletion has been shown to be a limiting factor during wake field acceleration. This work focuses on optimizing parameters for Raman amplification to work in conjunction with wake field acceleration in order in order to sustain an accelerating laser pulse as it generates plasma waves. It has been shown that laser pulses undergo red shifting during wake generation. Our work demonstrates that this red shifting results in a detuning between pump and seed in the backward Raman Amplifier. This detuning limits the amount of energy that can be transferred from the pump to the seed, and places new limits on backward Raman amplification. To overcome this limiting factor, this study makes use of a chirped pump allowing for extended coupling to the accelerating pulse. Three wave coupling model of Raman amplifier with a frequency shift term due to wake field will also be discussed and compared with PIC simulations.

  9. 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.

  10. 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.

  11. SU-E-T-472: Characterization of the Very High Energy Electrons, ISO - 250 MeV (VHEE) Beam Generated by ALPHA-X Laser Wakefield Accelerator Beam Line for Utilization in Monte Carlo Simulation for Biomedical Experiment Planning.

    PubMed

    Moskvin, V; Subiel, A; Desrosiers, C; Wiggins, M; Maryanski, M; Mendonca, M; Boyd, M; Sorensen, A; Cipiccia, S; Issac, R; Welsh, G; Brunetti, E; Aniculaesei, C; Jaroszynski, D A

    2012-06-01

    Progress in the development of compact high-energy pulsed laser- plasma wakefield accelerators is opening up the potential for using Very High Energy Electron (VHEEs) beams in the range of 150 - 250 MeV for biomedical studies. Initial experiments using VHEE for this purpose have been carried out using the ALPHA-X laser-plasma wakefield accelerator beam line at the University of Strathclyde, Glasgow, UK. The purpose of this investigation is to use Monte Carlo simulations to plan experiments and compare with characterization of the interaction of the VHEE beam using a dosimeter. An experiment using the VHEE beam to irradiate a muscle-equivalent BANG polymer gel dosimeter has been carried out. Simulations have been used to prepare for the experiments. These were undertaken using the expected average energy for a pulse set and an energy spread approximated by Gaussian distribution. The model was implemented in FLUKA Monte Carlo code with follow up modeling using the Geant4 toolkit. The results have been compared with 1mm̂3 voxel laser CT based measurements of the dose deposited in the BANG dosimeter and with measurement of the induced radioactivity. The results of the measured dose from induced radioactivity have been compared with data from the FLUKA simulations. The beam model based on an average energy of particles in irradiation gives an acceptable estimate of the induced radioactivity and the dose deposited in the BANG dosimeter. Comparison with the dosimeter scanned profiles shows that the structure of the spectra of VHEE beams in the experiment and secondary scattered particles in the beam line should be accounted for in any model. Such model description of the VHEE beam for the ALPHA-X beam line has been developed. Monte Carlo simulations using the FLUKA code is an efficient way to plan a VHEE experiment and analyze data from measurements. © 2012 American Association of Physicists in Medicine.

  12. Laser wakefield signatures: from gas plasma to nanomaterials

    NASA Astrophysics Data System (ADS)

    Farinella, Deano; Zhang, Xiaomei; Shin, Youngmin; Tajima, Toshiki

    2016-10-01

    The signatures of laser wakefields have become increasingly important in recent years due to the invention of a novel laser compression technique that may enable the creation of single cycle x-ray pulses. This x-ray driver may be able to utilize solid density targets to create acceleration gradients of up to TeV/cm. On the other hand, Laser Wakefield Acceleration (LWFA) has been identified as a potential mechanism for the generation of Extreme High Energy Cosmic Rays (EHECR) in Active Galactic Nuclei (AGN). Though these disparate density regimes may include different physics, by investigating scalings of the ratio ncr/ne we are able to survey a wide range of parameters to gain insight into particle acceleration and photon emission properties. The scaling of electron acceleration and photon radiation from wakefields as a function of the parameter ncr/ne has been studied. Further, acceleration gradient as well as other scalings were investigated in solid density channels and compared to gas plasma. Funded in part by the Norman Rostoker Fund.

  13. Measurement of magnetic-field structures in a laser-wakefield accelerator.

    PubMed

    Kaluza, M C; Schlenvoigt, H-P; Mangles, S P D; Thomas, A G R; Dangor, A E; Schwoerer, H; Mori, W B; Najmudin, Z; Krushelnick, K M

    2010-09-10

    Experimental measurements of magnetic fields generated in the cavity of a self-injecting laser-wakefield accelerator are presented. Faraday rotation is used to determine the existence of multimegagauss fields, constrained to a transverse dimension comparable to the plasma wavelength ∼λp and several λp longitudinally. The fields are generated rapidly and move with the driving laser. In our experiment, the appearance of the magnetic fields is correlated with the production of relativistic electrons, indicating that they are inherently tied to the growth and wave breaking of the nonlinear plasma wave. This evolution is confirmed by numerical simulations, showing that these measurements provide insight into the wakefield evolution with high spatial and temporal resolution.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Applications of laser wakefield accelerator-based light sources

    DOE PAGES

    Albert, Felicie; Thomas, Alec G. R.

    2016-10-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons inmore » the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.« less

  20. Applications of laser wakefield accelerator-based light sources

    SciTech Connect

    Albert, Felicie; Thomas, Alec G. R.

    2016-10-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons in the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.

  1. Applications of laser wakefield accelerator-based light sources

    NASA Astrophysics Data System (ADS)

    Albert, Félicie; Thomas, Alec G. R.

    2016-11-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons in the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. We first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.

  2. Applications of laser wakefield accelerator-based light sources

    SciTech Connect

    Albert, Felicie; Thomas, Alec G. R.

    2016-10-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons in the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.

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

    SciTech Connect

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

    2016-01-15

    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.

  4. Enhanced x-rays from resonant betatron oscillations in laser wakefield with external wigglers

    NASA Astrophysics Data System (ADS)

    Zhang, Z. M.; Zhang, B.; Hong, W.; Yu, M. Y.; Deng, Z. G.; Teng, J.; He, S. K.; Gu, Y. Q.

    2016-11-01

    Generation of ultra-short betatron x-rays by laser-accelerated electron beams is of great research interest as it has many applications. In this paper, we propose a scheme for obtaining bright betatron x-rays by applying external wiggler magnetic field in the laser wakefield to resonantly drive the betatron oscillations of the accelerated electrons therein. This results in a significant enhancement of the betatron oscillation amplitude and generation of bright x-rays with high photon energy. The scheme is demonstrated using two-dimensional particle-in-cell simulation and discussed using a simple analytical model.

  5. Preformed transient gas channels for laser wakefield particle acceleration

    SciTech Connect

    Wood, W.M.

    1994-11-01

    Acceleration of electrons by laser-driven plasma wake fields is limited by the range over which a laser pulse can maintain its intensity. This distance is typically given by the Rayleigh range for the focused laser beam, usually on the order of 0.1 mm to 1 mm. For practical particle acceleration, interaction distances on the order of centimeters are required. Therefore, some means of guiding high intensity laser pulses is necessary. Light intensities on the order of a few times 10{sup 17} W/cm{sup 2} are required for laser wakefield acceleration schemes using near IR radiation. Gas densities on the order of or greater than 10{sup 17} cm{sup {minus}3} are also needed. Laser-atom interaction studies in this density and intensity regime are generally limited by the concomitant problems in beam propagation introduced by the creation of a plasma. In addition to the interaction distance limit imposed by the Rayleigh range, defocusing of the high intensity laser pulse further limits the peak intensity which can be achieved. To solve the problem of beam propagation limitations in laser-plasma wakefield experiments, two potential methods for creating transient propagation channels in gaseous targets are investigated. The first involves creation of a charge-neutral channel in a gas by an initial laser pulse, which then is ionized by a second, ultrashort, high-intensity pulse to create a waveguide. The second method involves the ionization of a gas column by an ultrashort pulse; a transient waveguide is formed by the subsequent expansion of the heated plasma into the neutral gas.

  6. Optimization of positrons generation based on laser wakefield electron acceleration

    NASA Astrophysics Data System (ADS)

    Wu, Yuchi; Han, Dan; Zhang, Tiankui; Dong, Kegong; Zhu, Bin; Yan, Yonghong; Gu, Yuqiu

    2016-08-01

    Laser based positron represents a new particle source with short pulse duration and high charge density. Positron production based on laser wakefield electron acceleration (LWFA) has been investigated theoretically in this paper. Analytical expressions for positron spectra and yield have been obtained through a combination of LWFA and cascade shower theories. The maximum positron yield and corresponding converter thickness have been optimized as a function of driven laser power. Under the optimal condition, high energy (>100 MeV ) positron yield up to 5 ×1011 can be produced by high power femtosecond lasers at ELI-NP. The percentage of positrons shows that a quasineutral electron-positron jet can be generated by setting the converter thickness greater than 5 radiation lengths.

  7. Hybrid Laser Wakefield and Direct Laser Plasma Accelerator in the Plasma Bubble Regime

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    The concept of hybrid laser wakefield and direct laser plasma accelerator in plasma bubble regime was recently proposed. The advantage of this approach is two-fold: (a) electrons' energy gains from the laser and from the wake add up, and (b) dephasing is slowed down. Using 2D VLPL simulations, we will demonstrate that two conditions must be met by the electrons injected into the hybrid accelerator: (1) strong spatial overlap with the laser field, and (2) large initial transverse energy. The firstcondition is met by employing two laser pulses: one to produce a plasma bubble, and the second time-delayed pulse to interact with the injected electrons. We will show that there are two approaches to meeting the second condition: self-injection using an engineered density bump and ionization-injection. The criteria for direct laser acceleration of ionization-injected electrons will be discussed. Combinations of laser pulses with different wavelengths will also be considered. This work is supported by the US DOE grant DE-SC0007889 and the AFOSR grant FA9550-14-1-0045.

  8. 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.

  9. 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.

  10. Wakefield evolution and electron acceleration in interaction of frequency-chirped laser pulse with inhomogeneous plasma

    NASA Astrophysics Data System (ADS)

    Rezaei-Pandari, M.; Niknam, A. R.; Massudi, R.; Jahangiri, F.; Hassaninejad, H.; Khorashadizadeh, S. M.

    2017-02-01

    The nonlinear interaction of an ultra-short intense frequency-chirped laser pulse with an underdense plasma is studied. The effects of plasma inhomogeneity and laser parameters such as chirp, pulse duration, and intensity on plasma density and wakefield evolutions, and electron acceleration are examined. It is found that a properly chirped laser pulse could induce a stronger laser wakefield in an inhomogeneous plasma and result in higher electron acceleration energy. It is also shown that the wakefield amplitude is enhanced by increasing the slope of density in the inhomogeneous plasma.

  11. 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

  12. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question.

    PubMed

    Yang, X; Brunetti, E; Gil, D Reboredo; Welsh, G H; Li, F Y; Cipiccia, S; Ersfeld, B; Grant, D W; Grant, P A; Islam, M R; Tooley, M P; Vieux, G; Wiggins, S M; Sheng, Z M; Jaroszynski, D A

    2017-03-10

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5-10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°-60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators.

  13. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

    PubMed Central

    Yang, X.; Brunetti, E.; Gil, D. Reboredo; Welsh, G. H.; Li, F. Y.; Cipiccia, S.; Ersfeld, B.; Grant, D. W.; Grant, P. A.; Islam, M. R.; Tooley, M. P.; Vieux, G.; Wiggins, S. M.; Sheng, Z. M.; Jaroszynski, D. A.

    2017-01-01

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5–10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°–60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators. PMID:28281679

  14. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

    NASA Astrophysics Data System (ADS)

    Yang, X.; Brunetti, E.; Gil, D. Reboredo; Welsh, G. H.; Li, F. Y.; Cipiccia, S.; Ersfeld, B.; Grant, D. W.; Grant, P. A.; Islam, M. R.; Tooley, M. P.; Vieux, G.; Wiggins, S. M.; Sheng, Z. M.; Jaroszynski, D. A.

    2017-03-01

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5-10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°-60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators.

  15. Experimental Studies of Self-Modulated and Standard Laser Wakefield Accelerators

    NASA Astrophysics Data System (ADS)

    Leemans, W. P.

    2000-10-01

    Experimental results will be presented on the self-modulated (in which the laser pulse length is much greater than the plasma wavelength) and the standard (in which the laser pulse length is matched to the plasma wavelength) laser wakefield accelerator,(E. Esarey et al., IEEE Trans. Plasma Sci. 24), 252 (1996). as well as on colliding pulse injection.(E. Esarey et al., Phys. Rev. Lett. 79), 2682 (1997); C.B. Schroeder et al., Phys. Rev. E 59, 6037 (1999). LBNL has an ongoing experimental program on these topics using a 12 TW, 10 Hz laser system in which the pulse length can be readily scanned from 50 fs to over 200 fs, thus allowing the transition from the self-modulated to the standard regime to be readily studied.(W.P. Leemans et al., Phys. Rev. Lett., submitted.) In the self-modulated regime, plasma electrons are self-trapped and accelerated to multi-MeV energies. In the standard regime, electrons are injected into the wakefield by two additional colliding laser pulses. Experimental results, including electron beam charge, emittance, energy, laser spectra, and plasma interferometry, as well as simulations, will be presented.

  16. X-ray beam source from a Self-modulated laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Lemos, Nuno; Albert, Felicie; Marsh, K. A.; Shaw, J. L.; King, P.; Patankar, S.; Ralph, J.; Pollock, B. B.; Martins, J. L.; Amorim, L. D.; Tsung, F. S.; Goyon, C.; Pak, A.; Moody, J. D.; Schumaker, W.; Fiuza, F.; Glenzer, S. H.; Hegelichand, B. M.; Saunders, A.; Flacone, R. W.; Joshi, C.

    2016-10-01

    To diagnose material properties under extreme conditions of temperature and pressure the development of a directional, small-divergence, small source size and short pulse duration x-ray source has become essential. In this work we explore through experiments and PIC simulations the betatron radiation generated in self-modulated laser-wakefield accelerators. The experiment was preformed at the Jupiter Laser Facility, LLNL where electrons with energies up to 200 MeV and Betatron x-rays with critical energies >10 keV were observed. OSIRIS 2D PIC simulations indicate that the x-ray critical energy directly scales with the a0 of the laser and can easily be increased to critical energies exceeding 50 keV using a laser with a0 of 3.

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

    SciTech Connect

    Zhang, Guo-Bo; Chen, Min E-mail: yanyunma@126.com; Luo, Ji; Zeng, Ming; Yu, Lu-Le; Weng, Su-Ming; Schroeder, C. B.; Esarey, E.; Li, Fei-Yu; Ma, Yan-Yun E-mail: yanyunma@126.com; Yu, Tong-Pu; Sheng, Zheng-Ming

    2016-03-15

    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.

  18. Generation of 20 kA electron beam from a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Li, Y. F.; Li, D. Z.; Huang, K.; Tao, M. Z.; Li, M. H.; Zhao, J. R.; Ma, Y.; Guo, X.; Wang, J. G.; Chen, M.; Hafz, N.; Zhang, J.; Chen, L. M.

    2017-02-01

    We present the experimentally generated electron bunch from laser-wakefield acceleration (LWFA) with a charge of 620 pC and a maximum energy up to 0.6 GeV by irradiating 80 TW laser pulses at a 3 mm Helium gas jet. The charge of injected electrons is much larger than the normal scaling laws of LWFA in bubble regime. We also got a quasi-monoenergetic electron beam with energy peaked at 249 MeV and a charge of 68 pC with the similar laser conditions but lower plasma density. As confirmed by 2D particle-in-cell simulations, the boosted bunch charge is due to the continuous injection caused by the self-steepening and self-compression of a laser pulse. During the nonlinear evolution of the laser pulse, the bubble structure broadens and stretches, leading to a longer dephasing length and larger beam charge.

  19. 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).

  20. Numerical investigation of the influence of laser chirp on electron yield in laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Trines, R. M. G. M.; Kamp, L. P. J.; Schep, T. J.; Leemans, W. P.; Esarey, E. H.

    2001-10-01

    An important phenomenon in laser wakefield acceleration is the production of fast electrons by intense laser pulses. In recent experiments [1], an influence of the laser chirp on the fast electron yield has been observed. For the same peak power, the electron yield of a positively chirped pulse was significantly higher than that of a negatively chirped pulse. Numerical simulations have been performed using the particle-in-cell code XOOPIC [2] to investigate this influence and to reveal the mechanism behind it. Parametric studies of the dependence of the growth of plasma waves through the Raman forward and backward scattering, and the yield of accelerated electrons on the amount of chirp will be presented. These simulations indicate that enhanced excitation of fast and slow phase velocity plasma waves does indeed occur when using positively chirped laser pulses, in agreement with the experiments. Negatively chirped pulses could be used to suppress instabilities for intense pulses propagating through dense plasmas. [1] W.P. Leemans et al., Phys. Plasmas 8, 2510 (2001); W. P. Leemans et al., in preparation [2] J.P. Verboncoeur, A.B. Langdon and N.T. Gladd, Comp. Phys. Comm. 87, 199 (1995)

  1. 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.

  2. Merging conventional and laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Zeitler, Benno; Dornmair, Irene; Gehrke, Tim; Titberidze, Mikheil; Maier, Andreas R.; Hidding, Bernhard; Flöttmann, Klaus; Grüner, Florian

    2013-05-01

    Laser wake field accelerators deliver high quality electron beams in terms of emittance and bunch length. However, there are also parameters which cannot compete with conventional machines, namely the spectral width as well as the shot-to-shot stability in terms of energy and pointing. The bunch formation in this new type of accelerators happens in a highly non-linear plasma wave and is a statistical process based on Coulomb scattering. However, there is no direct access to the injection mechanism of electrons into that plasma wake field. Injecting a well-characterized electron beam produced by a conventional accelerator into a plasma wake field could help to solve this problem: Measuring the difference in the electron spectrum in such a pump-probe type experiment should yield the possibility to directly reconstruct the electric field distribution. From that point on, comparisons with theoretical models as well as results from particle-in-cell (PIC) codes could lead to a better understanding of the injection process. At DESY in Hamburg there is a conventional accelerator suited for such a type of experiment: the Relativistic Electron Gun for Atomic Exploration (REGAE). We report on the status of the beam line extension to REGAE and the plans of the external injection project, with the goal to directly measure the wake field and further improve the stability of laser wake field accelerators.

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

    NASA Astrophysics Data System (ADS)

    Krushelnick, Karl; Kaganovich, Dmitri; Gonsalves, Anthony

    2009-01-01

    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.

  4. 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.

  5. 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.

  6. 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.

  7. Laser plasma wakefield acceleration gain enhancement by means of accelerating Bessel pulses

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Parola, A.; Di Trapani, P.; Jedrkiewicz, O.

    2017-06-01

    In this paper, we propose an approach to enhance the electron energy gain in standard laser-driven plasma wakefield accelerators, using accelerating Bessel pulses with tunable group velocity so to avoid electron dephasing. We use in the numerical simulations a one-dimensional theoretical model in the linear regime, taking advantage of the "diffraction-free" properties of the localized Bessel beam and thus neglecting transverse effects during the acceleration process. With a multistage tailoring approach, we show a gain enhancement of more than 100 with electron energies that may reach the GeV range over distances shorter than 1 m.

  8. Dynamics of electron injection in a laser-wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Xu, J.; Buck, A.; Chou, S.-W.; Schmid, K.; Shen, B.; Tajima, T.; Kaluza, M. C.; Veisz, L.

    2017-08-01

    The detailed temporal evolution of the laser-wakefield acceleration process with controlled injection, producing reproducible high-quality electron bunches, has been investigated. The localized injection of electrons into the wakefield has been realized in a simple way—called shock-front injection—utilizing a sharp drop in plasma density. Both experimental and numerical results reveal the electron injection and acceleration process as well as the electron bunch's temporal properties. The possibility to visualize the plasma wave gives invaluable spatially resolved information about the local background electron density, which in turn allows for an efficient suppression of electron self-injection before the controlled process of injection at the sharp density jump. Upper limits for the electron bunch duration of 6.6 fs FWHM, or 2.8 fs (r.m.s.) were found. These results indicate that shock-front injection not only provides stable and tunable, but also few-femtosecond short electron pulses for applications such as ultrashort radiation sources, time-resolved electron diffraction or for the seeding of further acceleration stages.

  9. Intense γ ray generated by refocusing laser pulse on wakefield accelerated electrons

    NASA Astrophysics Data System (ADS)

    Feng, Jie; Wang, Jinguang; Li, Yifei; Zhu, Changqing; Li, Minghua; He, Yuhang; Li, Dazhang; Wang, Weimin; Chen, Liming

    2017-09-01

    Ultrafast x/γ ray emission from the combination of laser wake-field acceleration and plasma mirror has been investigated as a promising Thomson scattering source. However, the photon energy and yield of radiation are limited to the intensity of reflected laser pulses. We use the 2D particle in cell simulation to demonstrate that a 75TW driven laser pulse can be refocused on the accelerated electron bunches through a hemispherical plasma mirror with a small f number of 0.25. The energetic electrons with the maximum energy about 350 MeV collide with the reflected laser pulse of a0 = 3.82 at the focal spot, producing high order multi-photon Thomson scattering, and resulting in the scattering spectrum which extends up to 21.2 MeV. Such a high energy γ ray source could be applied to photonuclear reaction and materials science.

  10. 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

    2006-06-02

    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.

  11. Wakefield in a waveguide

    NASA Astrophysics Data System (ADS)

    Bliokh, Y. P.; Leopold, J. G.; Shafir, G.; Shlapakovski, A.; Krasik, Ya. E.

    2017-06-01

    The feasibility of an experiment which is being set up in our plasma laboratory to study the effect of a wakefield formed by an ultra-short (≤10-9 s) high-power (˜1 GW) microwave (10 GHz) pulse propagating in a cylindrical waveguide filled with an under-dense [(2-5) × 1010 cm-3] plasma is modeled theoretically and simulated by a particle in cell code. It is shown that the radial ponderomotive force plays a circular key role in the wakefield formation by the TM mode waveguide. The model and the simulations show that powerful microwave pulses produce a wakefield at lower plasma density and electric field gradients but larger space and time scales compared to the laser produced wakefield in plasmas, thus providing a more accessible platform for the experimental study.

  12. 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.

  13. 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.

  14. 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

  15. Laser Wakefield Acceleration Driven by ATF CO2 Laser (STELLA-LW)

    NASA Astrophysics Data System (ADS)

    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.; Pantell, R. H.; Pavlishin, I. V.; Pogorelsky, I. V.; Pogosova, A. A.; Steinhauer, L. C.; Ting, A.; Yakimenko, V.; Zigler, A.; Zhou, F.

    2004-12-01

    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 CO2 laser beam. This will be the first time LWFA is conducted at 10.6-μm 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.

  16. 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.

  17. 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)

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

    SciTech Connect

    Zeng, Ming; Zhang, Jie; Chen, Min; Sheng, Zheng-Ming; 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.

  19. Multichromatic Narrow-Energy-Spread Electron Bunches from Laser-Wakefield Acceleration with Dual-Color Lasers

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  20. Simulations of a meter-long plasma wakefield accelerator.

    PubMed

    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.

  1. Wakefield effects and solitary waves of an intense short laser pulse propagation in a plasma channel

    SciTech Connect

    Hong Xueren; Xie Baisong; Zhao Xueyan; Zhang Shan; Wu Haicheng

    2011-10-15

    In the presence of relativistic and channel-coupling nonlinearity and wakefield effects, the propagation characteristics and solitary waves of an intense short laser pulse in a preformed plasma channel are investigated. The evolution equation of the laser spot size is derived by using variational technique, the initial laser and plasma parameters for propagation with constant spot size, periodic defocusing and focusing oscillations, and solitary waves are identified. For illustration, some numerical results are also presented. It is found that the laser focusing is enhanced by the wakefield effects that result in a significant reduced focusing power.

  2. 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.

  3. 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.

  4. Laser wakefield acceleration at reduced density in the self-guided regime

    SciTech Connect

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

    2010-05-15

    Experiments conducted using a 200 TW 60 fs laser have demonstrated up to 720 MeV electrons in the self-guided laser wakefield regime using pure helium gas jet targets. The self-trapped charge in a helium plasma was shown to fall off with decreasing electron density with a threshold at 2.5x10{sup 18} cm{sup -3}, below which no charge is measured above 100 MeV. Self-guiding, however, is shown to continue below this density limitation over distances of 14 mm with an exit spot size of 25 {mu}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.

  5. Dynamics of electron injection and acceleration driven by laser wakefield in tailored density profiles

    NASA Astrophysics Data System (ADS)

    Lee, P.; Maynard, G.; Audet, T. L.; Cros, B.; Lehe, R.; Vay, J.-L.

    2016-11-01

    The dynamics of electron acceleration driven by laser wakefield is studied in detail using the particle-in-cell code WARP with the objective to generate high-quality electron bunches with narrow energy spread and small emittance, relevant for the electron injector of a multistage accelerator. Simulation results, using experimentally achievable parameters, show that electron bunches with an energy spread of ˜11 % can be obtained by using an ionization-induced injection mechanism in a mm-scale length plasma. By controlling the focusing of a moderate laser power and tailoring the longitudinal plasma density profile, the electron injection beginning and end positions can be adjusted, while the electron energy can be finely tuned in the last acceleration section.

  6. Dynamics of electron injection and acceleration driven by laser wakefield in tailored density profiles

    DOE PAGES

    Lee, Patrick; Maynard, G.; Audet, T. L.; ...

    2016-11-16

    The dynamics of electron acceleration driven by laser wakefield is studied in detail using the particle-in-cell code WARP with the objective to generate high-quality electron bunches with narrow energy spread and small emittance, relevant for the electron injector of a multistage accelerator. Simulation results, using experimentally achievable parameters, show that electron bunches with an energy spread of ~11% can be obtained by using an ionization-induced injection mechanism in a mm-scale length plasma. By controlling the focusing of a moderate laser power and tailoring the longitudinal plasma density profile, the electron injection beginning and end positions can be adjusted, while themore » electron energy can be finely tuned in the last acceleration section.« less

  7. Development of 873 nm Raman Seed Pulse for Raman-seeded Laser Wakefield Acceleration

    NASA Astrophysics Data System (ADS)

    Grigsby, F.; Peng, D.; Downer, M. C.

    2004-12-01

    By using a Raman-shifted seed pulse coincident with a main driving pulse, laser wakefields can be generated with sub-relativistic intensity, coherent control and high repetition rate in the self-modulated regime. Experimentally, the generation of a chirped Stokes laser pulse by inserting a solid state Raman shifter, Ba(NO3)2, into a CPA system before the compressor (to suppress self-phase modulation) will be described. We will also report on design, modeling and experimental demonstration of a novel compressor for the Stokes pulse that uses a mismatched grating pair to achieve a near transform-limited seed pulse. Finally, we will describe the design, simulation and current status of Raman-seeded LWFA experiments that use this novel source.

  8. Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator.

    PubMed

    He, Z-H; Beaurepaire, B; Nees, J A; Gallé, G; Scott, S A; Pérez, J R Sánchez; Lagally, M G; Krushelnick, K; Thomas, A G R; Faure, J

    2016-11-08

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scale by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-diffraction schemes.

  9. Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    He, Z.-H.; Beaurepaire, B.; Nees, J. A.; Gallé, G.; Scott, S. A.; Pérez, J. R. Sánchez; Lagally, M. G.; Krushelnick, K.; Thomas, A. G. R.; Faure, J.

    2016-11-01

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scale by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-diffraction schemes.

  10. 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.

  11. 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.

  12. 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.

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

    SciTech Connect

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

    2016-05-15

    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.

  14. 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.

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

    DOE PAGES

    Zhang, C. J.; Hua, J. F.; Wan, Y.; ...

    2016-06-17

    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. Sincemore » 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. Lastly, this method is demonstrated through particle-in-cell simulations and experiment.« less

  16. 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.}

  17. 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.

  18. 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.

  19. 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.

  20. Applications of the wave kinetic approach: from laser wakefields to drift wave turbulence

    NASA Astrophysics Data System (ADS)

    Trines, R. M. G. M.; Bingham, R.; Silva, L. O.; Mendonça, J. T.; Shukla, P. K.; Murphy, C. D.; Dunlop, M. W.; Davies, J. A.; Bamford, R.; Vaivads, A.; Norreys, P. A.

    2010-12-01

    Nonlinear wave-driven processes in plasmas are normally described by either a monochromatic pump wave that couples to other monochromatic waves, or as a random phase wave coupling to other random phase waves. An alternative approach involves a random or broadband pump coupling to monochromatic and/or coherent structures in the plasma. This approach can be implemented through the wave-kinetic model. In this model, the incoming pump wave is described by either a bunch (for coherent waves) or a sea (for random phase waves) of quasi-particles. This approach has been applied to both photon acceleration in laser wakefields and drift wave turbulence in magnetized plasma edge configurations. Numerical simulations have been compared to experiments, varying from photon acceleration to drift mode-zonal flow turbulence, and good qualitative correspondences have been found in all cases.

  1. 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.

  2. Analysis of x-ray emission and electron dynamics in a capillary-guided laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Ju, J.; Genoud, G.; Ferrari, H. E.; Dadoun, O.; Paradkar, B.; Svensson, K.; Wojda, F.; Burza, M.; Persson, A.; Lundh, O.; Andreev, N. E.; Wahlström, C.-G.; Cros, B.

    2014-05-01

    The dynamics of electron acceleration driven by laser wakefield inside a 30.5 mm long dielectric capillary tube is analyzed using radiation emitted in the x-ray range. 3D particle-in-cell simulations, performed with parameters close to the experimental ones, show that in long plasmas, the accelerated electrons catch up and finally overrun the driving laser owing to a higher velocity of the electrons in the plasma. The electrons are then transversely scattered by the laser pulse, and penetrate the capillary wall where they generate bremsstrahlung radiation, modeled using geant4 simulations. The signature of bremsstrahlung radiation is detected using an x-ray camera, together with the betatron radiation emitted during electron acceleration in the plasma bubble. The reflection of betatron radiation from the inner capillary surface also accounts for a fraction of the observed signal on the x-ray camera. The simulation results are in agreement with the experimental ones and provide a detailed description of the electron and radiation properties, useful for the design of laser wakefield accelerators or radiation sources using long plasma media.

  3. 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.

  4. 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.

  5. Two-Color Laser High-Harmonic Generation in Cavitated Plasma Wakefields

    SciTech Connect

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2016-10-03

    A method is proposed for producing coherent x-rays via high-harmonic generation using a laser interacting with highly-stripped ions in cavitated plasma wakefields. Two laser pulses of different colors are employed: a long-wavelength pulse for cavitation and a short-wavelength pulse for harmonic generation. This method enables efficient laser harmonic generation in the sub-nm wavelength regime.

  6. 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.

  7. 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.

  8. Probing lattice dynamics in silicon with laser-wakefield accelerated electrons

    NASA Astrophysics Data System (ADS)

    Nees, John; He, Z.-H.; Thomas, A. G. R.; Krushelnick, Karl; Scott, S.; Legally, M.; Beaurepaire, B.; Gallé, G.; Faure, J.

    2016-10-01

    Laser wakefield acceleration is the key technology in a new breed of electron and photon beam sources that operate in the ultrafast domain. We show that the spatial and temporal properties of wakefield-generated electron beams can be manipulated to enable them interrogate ultrafast lattice dynamics in freestanding single-crystal silicon membranes, while maintaining spatial resolution on the atomic scale. In particular, picosecond resolution of Si lattice dynamics is obtained by recording streaked electron diffraction peaks using static magnetic fields. We will also discuss the role of wave front control in establishing optimal beam characteristics and the significance of single-shot measurements. Michigan support from NSF PHY-1535628.

  9. 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.

  10. 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.

  11. Methods of Generating High-Quality Beams in Laser Wakefield Accelerators through Self-Injection

    NASA Astrophysics Data System (ADS)

    Davidson, Asher Warren

    In the pursuit of discovering the fundamental laws and particles of nature, physicists have been colliding particles at ever increasing energy for almost a century. Lepton (electrons and positrons) colliders rely on linear accelerators (LINACS) because leptons radiate copious amounts of energy when accelerated in a circular machine. The size and cost of a linear collider is mainly determined by the acceleration gradient. Modern linear accelerators have gradients limited to 20-100 MeV/m because of the breakdown of the walls of the accelerator. Plasma based acceleration is receiving much attention because a plasma wave with a phase velocity near the speed of light can support acceleration gradients at least three orders of magnitude larger than those in modern accelerators. There is no breakdown limit in a plasma since it is already ionized. Such a plasma wave can be excited by the radiation pressure of an intense short pulse laser. This is called laser wakefield acceleration (LWFA). Much progress has been made in LWFA research in the past 30 years. Particle-in-cell (PIC) simulations have played a major part in this progress. The physics inherent in LWFA is nonlinear and three-dimensional in nature. Three-dimensional PIC simulations are computationally intensive. In this dissertation, we present and describe in detail a new algorithm that was introduced into the Particle-In-Cell Simulation Framework. We subsequently use this new quasi three-dimensional algorithm to efficiently explore the parameter regimes of LWFA that are accessible for existing and near term lasers. This regimes cannot be explored using full three-dimensional simulations even on leadership class computing facilities. The simulations presented in this dissertation show that the nonlinear, self-guided regime of LWFA described through phenomenological scaling laws by Lu et al., in 2007 is still useful for accelerating electrons to energies greater than 10 GeV. (Abstract shortened by ProQuest.).

  12. 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.

  13. Wakefield-acceleration of relativistic electrons with few-cycle laser pulses at kHz-repetition-rate

    NASA Astrophysics Data System (ADS)

    Guenot, Diego; Gustas, Dominykas; Vernier, Aline; Boehle, Frederik; Beaurepaire, Benoit; Lopez-Martens, Rodrigo; Faure, Jerome; Appli Team

    2016-10-01

    The generation of relativistic electron beams using laser wakefield acceleration has become a standard technique, providing low emittance electron bunches with femtosecond durations. However, this technique usually requires multi-ten-terawatt lasers and is thus limited to low repetition-rate (typically 10 Hz or less). We have recently demonstrated the generation of few MeV electrons using 2.5-mJ, 4-fs, 1-kHz repetition-rate laser pulses, focused to relativistic intensity onto a gas jet with electron density 1020 cm-3. We have investigated the influence of the pulse duration, the gas density. We demonstrated that an electron beam with a charge in the range of 10-fC/shot, with a divergence of 20-mrad and a peaked spectrum with energies between 2 and 4 MeV can be generated at kHz repetition-rate. These results confirm the possibility of using few-cycle laser pulses with very low energy for exciting wakefields in the bubble regime and for trapping electrons, as predicted by PIC simulations. This kHz electron source is ideally suited for performing electron diffraction experiments with very high temporal resolution. Our results also open the way to other applications, such as the generation of a kHz ultrafast X-ray source. ERC femtoelec.

  14. Summary report of working group 1: Laser-plasma wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Gonsalves, Anthony; Pollock, Bradley; Lu, Wei

    2017-03-01

    The work presented in the laser-plasma acceleration working group at the 2016 Advanced Accelerator Concepts (AAC) Workshop is summarized. Some of the highlights include: direct visualization of the electric and magnetic fields using a LPA (laser plasma accelerator) electron probe, offering transverse snapshots of the wakefield even for very low density; first demonstration of multi-pulse LPA and wakefield cancellation with a trailing pulse (first step to energy recovery); and control over the shock front angle to optimize density transition injection, which provides stable and low-energy-spread beams that are critical for increasing the efficiency of the recently presented staged LPA. Interesting ongoing and future work discussed included LPAs driven by CO2 lasers and scaling to 10 GeV with and without optical guiding. Further details on each of these topics can be found in the respective papers in these Proceedings.

  15. Exploiting multi-scale parallelism for large scale numerical modelling of laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Fonseca, R. A.; Vieira, J.; Fiuza, F.; Davidson, A.; Tsung, F. S.; Mori, W. B.; Silva, L. O.

    2013-12-01

    A new generation of laser wakefield accelerators (LWFA), supported by the extreme accelerating fields generated in the interaction of PW-Class lasers and underdense targets, promises the production of high quality electron beams in short distances for multiple applications. Achieving this goal will rely heavily on numerical modelling to further understand the underlying physics and identify optimal regimes, but large scale modelling of these scenarios is computationally heavy and requires the efficient use of state-of-the-art petascale supercomputing systems. We discuss the main difficulties involved in running these simulations and the new developments implemented in the OSIRIS framework to address these issues, ranging from multi-dimensional dynamic load balancing and hybrid distributed/shared memory parallelism to the vectorization of the PIC algorithm. We present the results of the OASCR Joule Metric program on the issue of large scale modelling of LWFA, demonstrating speedups of over 1 order of magnitude on the same hardware. Finally, scalability to over ˜106 cores and sustained performance over ˜2 P Flops is demonstrated, opening the way for large scale modelling of LWFA scenarios.

  16. 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.

  17. 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.

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

    PubMed

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

    2015-12-01

    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.

  20. 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.

  1. Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator

    PubMed Central

    He, Z.-H.; Beaurepaire, B.; Nees, J. A.; Gallé, G.; Scott, S. A.; Pérez, J. R. Sánchez; Lagally, M. G.; Krushelnick, K.; Thomas, A. G. R.; Faure, J.

    2016-01-01

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scale by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-diffraction schemes. PMID:27824086

  2. 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.

  3. Measurements and simulations of wakefields at the Accelerator Test Facility 2

    NASA Astrophysics Data System (ADS)

    Snuverink, J.; Ainsworth, R.; Boogert, S. T.; Cullinan, F. J.; Lyapin, A.; Kim, Y. I.; Kubo, K.; Kuroda, S.; Okugi, T.; Tauchi, T.; Terunuma, N.; Urakawa, J.; White, G. R.

    2016-09-01

    Wakefields are an important factor in accelerator design, and are a real concern when preserving the low beam emittance in modern machines. Charge dependent beam size growth has been observed at the Accelerator Test Facility (ATF2), a test accelerator for future linear collider beam delivery systems. Part of the explanation of this beam size growth is wakefields. In this paper we present numerical calculations of the wakefields produced by several types of geometrical discontinuities in the beam line as well as tracking simulations to estimate the induced effects. We also discuss precision beam kick measurements performed with the ATF2 cavity beam position monitor system for a test wakefield source in a movable section of the vacuum chamber. Using an improved model independent method we measured a wakefield kick for this movable section of about 0.49 V /pC /mm , which, compared to the calculated value from electromagnetic simulations of 0.41 V /pC /mm , is within the systematic error.

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

    SciTech Connect

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

    2016-02-17

    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. As a result, 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.

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

    DOE PAGES

    Lemos, N.; Martins, J. L.; Tsung, F. S.; ...

    2016-02-17

    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) ismore » 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. As a result, 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.« less

  6. 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.

  7. Laser-driven plasma wakefield electron acceleration and coherent femtosecond pulse generation in X-ray and gamma ranges

    NASA Astrophysics Data System (ADS)

    Trunov, V. I.; Lotov, K. V.; Gubin, K. V.; Pestryakov, E. V.; Bagayev, S. N.; Logachev, P. V.

    2017-01-01

    The laser wakefield acceleration (LWFA) of electrons in capillaries and gas jets followed by inverse Compton scattering of high intensity femtosecond laser pulses is discussed. The drive and scattered pulses will be produced by the two-channel multi-terawatt laser system developed in ILP SB RAS.

  8. 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.

  9. 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.

  10. An Undulator-Based Laser Wakefield Accelerator Electron Beam Diagnostic

    NASA Astrophysics Data System (ADS)

    Bakeman, Michael S.

    Currently particle accelerators such as the Large Hadron Collider use RF cavities with a maximum field gradient of 50-100 MV/m to accelerate particles over long distances. A new type of plasma based accelerator called a Laser Plasma Accelerator (LPA) is being investigated at the LOASIS group at Lawrence Berkeley National Laboratory which can sustain field gradients of 10-100 GV/m. This new type of accelerator offers the potential to create compact high energy accelerators and light sources. In order to investigate the feasibility of producing a compact light source an undulator-based electron beam diagnostic for use on the LOASIS LPA has been built and calibrated. This diagnostic relies on the principal that the spectral analysis of synchrotron radiation from an undulator can reveal properties of the electron beam such as emittance, energy and energy spread. The effects of electron beam energy spread upon the harmonics of undulator produced synchrotron radiation were derived from the equations of motion of the beam and numerically simulated. The diagnostic consists of quadrupole focusing magnets to collimate the electron beam, a 1.5 m long undulator to produce the synchrotron radiation, and a high resolution high gain XUV spectrometer to analyze the radiation. The undulator was aligned and tuned in order to maximize the flux of synchrotron radiation produced. The spectrometer was calibrated at the Advanced Light Source, with the results showing the ability to measure electron beam energy spreads at resolutions as low as 0.1% rms, a major improvement over conventional magnetic spectrometers. Numerical simulations show the ability to measure energy spreads on realistic LPA produced electron beams as well as the improvements in measurements made with the quadrupole magnets. Experimentally the quadrupoles were shown to stabilize and focus the electron beams at specific energies for their insertion into the undulator, with the eventual hope of producing an all optical

  11. 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.

  12. Laser wakefield acceleration research by using a tapered capillary waveguide at GIST

    NASA Astrophysics Data System (ADS)

    Kim, Minseok; Jang, Donggyu; Nam, Inhyuk; Lee, Taehee; Suk, Hyyong

    2012-10-01

    The tapered plasma density in a gas-filled capillary waveguide can suppress the dephasing problem in laser wakefield acceleration (LWFA). As a result, the acceleration distance and the gained electron energy are expected to be increased significantly. For this purpose, we recently developed a tapered capillary waveguide, which can produce a plasma density of 10^18 cm-3. This capillary plasma waveguide will be used for high-energy electron generation experiment together with a 20 TW/35 fs Ti:sapphire laser system that will be completed by this summer. In this presentation, the ongoing experiments will be reported.

  13. Laser-induced wakefield acceleration by using density-tapered gas-cell

    NASA Astrophysics Data System (ADS)

    Kim, Minseok; Nam, Inhyuk; Lee, Seungwoo; Suk, Hyyong

    2015-11-01

    The plasma sources with upward density gradient can be used to increase a dephasing length and an accelerating field in laser wakefield acceleration (LWFA) mechanism. As a result, the electron energy accelerated is expected to be increased and we developed a density-tapered gas-cell on this account. Using a 20 TW Ti:Sapphire laser constructed at GIST, we performed the acceleration experiments with the gas-cell and gas-jet with density-gradient. In this presentation, the results of acceleration experiments will be presented in detail.

  14. Noise effects, emittance control, and luminosity issues in laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Cheshkov, Sergey Valeriev

    2001-09-01

    To reach the new high energy frontiers (higher than a TeV center of mass energy) new acceleration methods seem to be needed. Plasma based wakefield accelerator is one possible candidate which can provide an ultra high gradient acceleration and thus make the total acceleration distance reasonable. However, the final energy is not the only requirement. The accelerator should maintain an excellent beam quality to meet the luminosity requirements at the Inter action Point (IP). One of the most important figures of merit which describe the quality of the beam is its emittance. We study the particle dynamics in laser pulse-driven wakefields over multi-stages in a several TeV range center of mass energy e+e - collider. The approach is based on a map of phase space dynamics over a stage of wakefield acceleration induced by a laser pulse (or electron beam). The entire system of the collider is generated with a product of multiple maps of wakefields, drifts, and magnets, etc. This systems map may include offsets of various elements of the accelerator, representing noise and errors arising from the operation of such a complex device. We find that an unmitigated strong focusing of the wakefield coupled with the alignment errors of the position (or laser beam aiming) of each Wakefield stage and the unavoidable dispersion in individual particle betatron frequencies leads to a phase space mixing and causes a transverse emittance degradation. The rate of the emittance increase in the limit of constant energy is proportional to the number of stages, the energy of the particles, the betatron frequency, the square of the misalignment amplitude, and the square of the betatron phase shift over a single stage. The accelerator with a weakened focusing force in a channel can, therefore, largely suppress the emittance degradation. To improve the emittance we introduce several methods: a mitigated wakefield focusing by working with a plasma channel, an approximately synchronous acceleration

  15. Wakefield Simulation of CLIC PETS Structure Using Parallel 3D Finite Element Time-Domain Solver T3P

    SciTech Connect

    Candel, A.; Kabel, A.; Lee, L.; Li, Z.; Ng, C.; Schussman, G.; Ko, K.; Syratchev, I.; /CERN

    2009-06-19

    In recent years, SLAC's Advanced Computations Department (ACD) has developed the parallel 3D Finite Element electromagnetic time-domain code T3P. Higher-order Finite Element methods on conformal unstructured meshes and massively parallel processing allow unprecedented simulation accuracy for wakefield computations and simulations of transient effects in realistic accelerator structures. Applications include simulation of wakefield damping in the Compact Linear Collider (CLIC) power extraction and transfer structure (PETS).

  16. Laser Wakefield Acceleration Experiments in the Self Modulated Regime at Titan

    NASA Astrophysics Data System (ADS)

    King, Paul; Albert, Felicie; Lemos, Nuno; Patankar, Siddarth; Ralph, Joseph; Shaw, Jessica; Hegelich, Manuel; Moody, John; Joshi, Chan

    2016-10-01

    Picosecond laser plasma interaction has been studied as a novel source of producing betatron x-rays. In this regime, electrons are accelerated through the interplay of two mechanisms: self-modulated laser wakefield acceleration and direct laser acceleration. The experiment, conducted on the Titan laser system (1 ps and 150 Joules) at Lawrence Livermore National Lab, using electron densities of 0.5 - 1.5 ×1019cm-3 , found electrons accelerated to energies of up to 250 MeV with divergence half angles on order of 10s of milliradians. Corresponding to the electron densities above, frequency shifts of laser light on order ωp 1.5 - 2 ×1014 rad/sec were measured using Raman forward scattering diagnostics.

  17. Density-transition based electron injector for laser driven wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Schmid, K.; Buck, A.; Sears, C. M. S.; Mikhailova, J. M.; Tautz, R.; Herrmann, D.; Geissler, M.; Krausz, F.; Veisz, L.

    2010-09-01

    We demonstrate a laser wakefield accelerator with a novel electron injection scheme resulting in enhanced stability, reproducibility, and ease of use. In order to inject electrons into the accelerating phase of the plasma wave, a sharp downward density transition is employed. Prior to ionization by the laser pulse this transition is formed by a shock front induced by a knife edge inserted into a supersonic gas jet. With laser pulses of 8 fs duration and with only 65 mJ energy on target, the accelerator produces a monoenergetic electron beam with tunable energy between 15 and 25 MeV and on average 3.3 pC charge per electron bunch. The shock-front injector is a simple and powerful new tool to enhance the reproducibility of laser-driven electron accelerators, is easily adapted to different laser parameters, and should therefore allow scaling to the energy range of several hundred MeV.

  18. Short-pulse, high-energy radiation generation from laser-wakefield accelerated electron beams

    NASA Astrophysics Data System (ADS)

    Schumaker, Will

    2013-10-01

    Recent experimental results of laser wakefield acceleration (LWFA) of ~GeV electrons driven by the 200TW HERCULES and the 400TW ASTRA-GEMINI laser systems and their subsequent generation of photons, positrons, and neutrons are presented. In LWFA, high-intensity (I >1019 W /cm2), ultra-short (τL < 1 / (2 πωpe)) laser pulses drive highly nonlinear plasma waves which can trap ~ nC of electrons and accelerate them to ~GeV energies over ~cm lengths. These electron beams can then be converted by a high-Z target via bremsstrahlung into low-divergence (< 20 mrad) beams of high-energy (<600 MeV) photons and subsequently into positrons via the Bethe-Heitler process. By increasing the material thickness and Z, the resulting Ne+ /Ne- ratio can approach unity, resulting in a near neutral density plasma jet. These quasi-neutral beams are presumed to retain the short-pulse (τL < 40 fs) characteristic of the electron beam, resulting in a high peak density of ne- /e+ ~ 1016 cm-3 , making the source an excellent candidate for laboratory study of astrophysical leptonic jets. Alternatively, the electron beam can be interacted with a counter-propagating, ultra-high intensity (I >1021 W /cm2) laser pulse to undergo inverse Compton scattering and emit a high-peak brightness beam of high-energy photons. Preliminary results and experimental sensitivities of the electron-laser beam overlap are presented. The high-energy photon beams can be spectrally resolved using a forward Compton scattering spectrometer. Moreover, the photon flux can be characterized by a pixelated scintillator array and by nuclear activation and (γ,n) neutron measurements from the photons interacting with a secondary solid target. Monte-Carlo simulations were performed using FLUKA to support the yield estimates. This research was supported by DOE/NSF-PHY 0810979, NSF CAREER 1054164, DARPA AXiS N66001-11-1-4208, SF/DNDO F021166, and the Leverhulme Trust ECF-2011-383.

  19. GeV electron beams from a centimeter-scale channel guided laser wakefield acceleratora)

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Nagler, B.; Tóth, Cs.; Geddes, C. G. R.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.; Gonsalves, A. J.; Hooker, S. M.

    2007-05-01

    Laser wakefield accelerators can produce electric fields of order 10-100GV/m, suitable for acceleration of electrons to relativistic energies. The wakefields are excited by a relativistically intense laser pulse propagating through a plasma and have a phase velocity determined by the group velocity of the light pulse. Two important effects that can limit the acceleration distance and hence the net energy gain obtained by an electron are diffraction of the drive laser pulse and particle-wake dephasing. Diffraction of a focused ultrashort laser pulse can be overcome by using preformed plasma channels. The dephasing limit can be increased by operating at a lower plasma density, since this results in an increase in the laser group velocity. Here we present detailed results on the generation of GeV-class electron beams using an intense femtosecond laser beam and a 3.3cm long preformed discharge-based plasma channel [W. P. Leemans et al., Nature Physics 2, 696 (2006)]. The use of a discharge-based waveguide permitted operation at an order of magnitude lower density and 15 times longer distance than in previous experiments that relied on laser preformed plasma channels. Laser pulses with peak power ranging from 10-40TW were guided over more than 20 Rayleigh ranges and high quality electron beams with energy up to 1GeV were obtained by channeling a 40TW peak power laser pulse. The dependence of the electron beam characteristics on capillary properties, plasma density, and laser parameters are discussed.

  20. 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; Zhang, Jie

    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.

  1. 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.

  2. 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.

  3. 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.

  4. Experimental Demonstration of 1 GeV Energy Gain and Stable Self Trapping in a Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Panasenko, D.; Gonsalves, A. J.; Nakamura, K.; Toth, C.; Geddes, C. G. R.; Cormier-Michel, E.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.; Hooker, S. M.; Cary, J.; Bruhwiler, D.

    2007-11-01

    GeV-class electron accelerators have broad applications, including synchrotron facilities, free electron lasers, and high-energy physics (HEP). Laser-wakefield accelerators (LWFAs) may reduce cost and size of such accelerators (and push the HEP energy frontier), since LWFAs sustain electric fields of hundreds of GV/m, thousands of times those achievable in RF accelerators. Results will be presented on production of GeV-class beams using LWFAs^*. Laser pulses with peak power ranging from 10-40TW were guided in gas-filled capillary discharge waveguides of length 15mm and 33mm, allowing the production of high-quality electron beams with energy up to 1 GeV. Stable self trapping and acceleration of beams to 500 MeV with few percent energy spread was also demonstrated. Electron beam characteristics and laser guiding, and their dependence on laser and plasma parameters will be discussed and compared to simulations. ^*Leemans et al., Nature Physics, 2006

  5. Density characterization of tapered super-sonic gas jet targets for laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Golovin, Gregory; Grace, Emily; Banerjee, Sudeep; Petersen, Chad; Brown, Kevin; Mills, Jared; Chen, Shouyuan; Liu, Cheng; Umstadter, Donald

    2012-10-01

    Phase slippage between plasma wave and electron bunch limits maximum energy gain in laser-wakefield acceleration. Plasma-density spatial tailoring has been proposed as a way to overcome this dephasing problem [1]. In practice, such tailoring can be achieved in super-sonic gas jets by use of a nozzle with a tapered orifice. We have developed a 3-D temporally-resolved interferometric tomography technique to characterize dynamical density distribution of such gas jets. The SIRT (Simultaneous Iterative Reconstructive Technique) algorithm [2] was implemented. We also present preliminarily results on laser wakefield acceleration in the tailored gradient density profiles resulting from use of the characterized jets as targets. [4pt] [1] W. Rittershofer, C. B. Schroeder, E. Esarey, F. J. Gr"uner, and W. P. Leemans, ``Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators,'' Physics of Plasmas 17, 063104, (2010). [0pt] [2] P. Gilbert, ``Iterative methods for the three-dimensional reconstruction of an object from projections,'' Journal of Theoretical Biology 36, 105 (1972).

  6. 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.

  7. 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.

  8. 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.

  9. Laser Guiding and Wakefield Excitation in Plasma Channels.

    NASA Astrophysics Data System (ADS)

    Volfbeyn, Paul

    1998-11-01

    Laser driven plasma waves have been experimentally shown to sustain electric field gradients in excess of 10 GV/m. (For a review see E. Esarey et al., IEEE Trans. Plasma Sci. PS-24), 252 (1996). Laser diffraction limits the distance over which the high gradients are excited, thus placing a severe limit on the energy gain achievable in a laser plasma accelerating stage. To overcome the limitation on the acceleration distance due to laser beam diffraction, plasma channel guiding has been proposed in which, plasma channels with density minimum on axis can serve as optical guides. An overview is given of various techniques for plasma channel creation, relying on hydrodynamic shock expansion in laser heated plasmas (C.G. Durfee III and H. M. Milchberg, Phys. Rev. Lett., vol. 71, pp. 2409, (1993).) and capillary discharges. ( Y. Ehrlich, et al. Phys. Rev. Lett., vol.77, (no.20), p.4186-9 (1996).) Details of the dual laser pulse Ignitor - Heater scheme (P. Volfbeyn and W. P. Leemans, Phys. Rev. Lett., to be submitted.) will be presented, which allows creation of plasma channels in low atomic number gases, such as hydrogen. The current status of experiments on characterization of the plasma channel density profile and guiding of high intensity laser pulses will then be reviewed. These measurements are important since the density profile of plasma channels defines the modes of plasma oscillations and, therefore both the transverse (focusing) and longitudinal (accelerating) properties of the wake modes. Results of theoretical calculations of the wake modes for various plasma channel density profiles are presented, and their significance for the laser-plasma accelerator design is discussed.

  10. Enhancement of x-rays generated by a guided laser wakefield accelerator inside capillary tubes

    SciTech Connect

    Ju, J.; Doepp, A.; Cassou, K.; Neveu, O.; Cros, B.; Svensson, K.; Genoud, G.; Wojda, F.; Burza, M.; Persson, A.; Lundh, O.; Wahlstroem, C.-G.; Ferrari, H. E.

    2012-05-07

    Electrons accelerated in the nonlinear regime in a laser wakefield accelerator experience transverse oscillations inside the plasma cavity, giving rise to ultra-short pulsed x-rays, also called the betatron radiation. We show that the fluence of x-ray can be enhanced by more than one order of magnitude when the laser is guided by a 10 mm long capillary tube instead of interacting with a 2 mm gas jet. X-rays with a synchrotron-like spectrum and associated critical energy {approx}5 keV, with a peak brightness of {approx}1x10{sup 21} ph/s/mm{sup 2}/mrad{sup 2}/0.1%BW, were achieved by employing 16 TW laser pulses.

  11. 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.

  12. 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.

  13. Laser wakefield accelerated electron beam monitoring and control

    SciTech Connect

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

    2016-03-25

    We will discuss our participation in the ImPACT project, which has as one of its goals the development of an ultra-compact electron accelerator using lasers (< 1 GeV, < 10   m) and the generation of an x-ray beam from the accelerated electrons. Within this context we will discuss our investigation into electron beam monitoring and control. Since laser accelerated electrons will be used for x-ray beam generation combined with an undulator, we will present investigation into the possibilities of the improvement of electron beam emittance through cooling.

  14. 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.

  15. 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.

  16. Innovative single-shot diagnostics for electrons from laser wakefield acceleration at FLAME

    NASA Astrophysics Data System (ADS)

    Bisesto, F. G.; Anania, M. P.; Cianchi, A.; Chiadroni, E.; Curcio, A.; Ferrario, M.; Pompili, R.; Zigler, A.

    2017-07-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (> 100 GV/m), enabling acceleration of electrons to GeV energy in few centimeters. Here we present all the plasma related activities currently underway at SPARC_LAB exploiting the high power laser FLAME. In particular, we will give an overview of the single shot diagnostics employed: Electro Optic Sampling (EOS) for temporal measurement and Optical Transition Radiation (OTR) for an innovative one shot emittance measurements. In detail, the EOS technique has been employed to measure for the first time the longitudinal profile of electric field of fast electrons escaping from a solid target, driving the ions and protons acceleration, and to study the impact of using different target shapes. Moreover, a novel scheme for one shot emittance measurements based on OTR, developed and tested at SPARC_LAB LINAC, used in an experiment on electrons from laser wakefield acceleration still undergoing, will be shown.

  17. A Stable High-Energy Electron Source from Laser Wakefield Acceleration

    NASA Astrophysics Data System (ADS)

    Zhang, Ping; Zhao, Baozhen; Liu, Cheng; Yan, Wenchao; Golovin, Grigory; Banerjee, Sudeep; Chen, Shouyuan; Haden, Daniel; Fruhling, Colton; Umstadter, Donald

    2016-10-01

    The stability of the electron source from laser wake-field acceleration (LWFA) is essential for applications, such as novel x-ray sources and fundamental experiments in high field physics. To obtain such a stable source, we used an optimal laser pulse and a novel gas nozzle. The high-power laser pulse on target was focused to a diffraction-limited spot by the use of adaptive wavefront correction and the pulse duration was transform limited by the use of spectral feedback control. An innovative design for the nozzle led to a stable, flat-top profile with diameters of 4 mm and 8 mm with a high Mach-number ( 6). In experiments to generate high-energy electron beams by LWFA, we were able to obtain reproducible results with beam energy of 800 MeV and charge >10 pC. Higher charge but broader energy spectrum resulted when the plasma density was increased. These developments have resulted in a laser-driven wakefield accelerator that is stable and robust. With this device, we show that narrowband high-energy x-rays beams can be generated by the inverse-Compton scattering process. This accelerator has also been used in recent experiments to study nonlinear effects in the interaction of high-energy electron beams with ultraintense laser pulses. This material is based upon work supported by NSF No. PHY-153700; US DOE, Office of Science, BES, # DE-FG02-05ER15663; AFOSR # FA9550-11-1-0157; and DHS DNDO # HSHQDC-13-C-B0036.

  18. Kilohertz laser wakefield accelerator using near critical density plasmas and millijoule-level drive pulses

    NASA Astrophysics Data System (ADS)

    Goers, Andy

    2016-10-01

    Laser wakefield accelerators operating in the so-called bubble or blowout regime are typically driven by Joule-class femtosecond laser systems driving plasma waves in highly underdense plasmas (1017 -1019cm-3). While these accelerators are very promising for accelerating GeV scale, low emittance electron beams, the large energy requirements of the laser systems have so far limited them to repetition rates below 10 Hz. However, there are a variety of applications, such as ultrafast electron diffraction or high repetition rate gamma ray sources for materials characterization or medical radiography, which would benefit from lower energy (1-10 MeV) but higher repetition rate ( 1 kHz) sources of relativistic electrons. This talk will describe relativistic wakefield acceleration of electron bunches in the range 1-10 MeV, driven by a 1 kHz, 30 fs, 1-12 mJ laser system. Our results are made possible by the use of very high density cryogenic H2 and He gas jet targets yielding electron densities >1021cm-3 in thin 100 μm gas flows. At these high densities the critical power for relativistic self-focusing and the plasma wave phase velocity are greatly reduced, leading to pulse collapse and self-injection even with 1 mJ drive laser pulses. Applications of this source to ultrafast electron diffraction and gamma ray radiography will be discussed. This research supported by the U.S. Department of Energy, National Science Foundation, and Air Force Office of Scientific Research.

  19. 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.

  20. External injection and acceleration of electron bunch in front of the plasma wakefield produced by a periodic chirped laser pulse

    NASA Astrophysics Data System (ADS)

    Eslami, Esmaeil; Afhami, Saeedeh

    2017-01-01

    Herein, we present the analytical results on the behavior of the electron bunch injected in front of the plasma wakefield produced by a chirped laser pulse. In particular, a periodic chirped pulse may produce an ultra-relativistic electron bunch with a relatively small energy spread. The electrons are trapped near the region of the first accelerating maximum of the wakefield and are compressed in both the longitudinal and transverse directions (betatron oscillation). Our results are in good agreement with the one-dimensional results recently published.

  1. Focusing Betatron Radiation Produced by Laser Wakefield Accelerated Electrons with a Spherically Curved Crystal

    NASA Astrophysics Data System (ADS)

    Vargas, M.; Schumaker, W.; Dollar, F.; Chvykov, V.; Kalintchenko, G.; Yanovsky, V.; Maksimchuk, A.; Krushelnick, K.; Thomas, A. G. R.

    2011-10-01

    Laser Wakefield Acceleration in the bubble regime can be used to accelerate electrons to GeV energies while simultaneously wiggling them to produce a synchotron like x-ray radiation. Using HERCULES, a 100TW TiSapphire laser, 30fs pulses are focused onto a 5mm He gas jet to accelerate electrons in the bubble regime. The betatron x-rays produced by the transverse motion of the accelerated electrons are focused onto a detector by a spherically curved quartz, and other crystals. This result shows the feasibility of dynamic studies of crystal diffraction, with femtosecond level accuracy, using pump probe techniques. This work was supported by NSF FOCUS Grant No. PHY-0114336, and NRC Grant No. 38-09-953.

  2. 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.

  3. 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.

  4. OPTIMIZATION AND SINGLE-SHOT CHARACTERIZATION OF ULTRASHORT THz PULSES FROM A LASER WAKEFIELD ACCELERATOR

    SciTech Connect

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

    2009-05-04

    We present spatiotemporal characterization of J-class ultrashort THz pulses generated from a laser wakefield accelerator (LWFA). Accelerated electrons, resulting from the interaction of a high-intensity laser pulse with a plasma, emit high-intensity THz pulses as coherent transition radiation. Such high peak-power THz pulses, suitable for high-field (MV/cm) pump-probe experiments, also provide a non-invasive bunch-length diagnostic and thus feedback for the accelerator. The characterization of the THz pulses includes energy measurement using a Golay cell, 2D sign-resolved electro-optic measurement and single-shot spatiotemporal electric-field distribution retrieval using a new technique, coined temporal electric-field cross-Correlation (TEX). All three techniques corroborate THz pulses of 5 muJ, with peak fields of 100's of kV/cm and ~;;0:4 ps rms duration.

  5. Optimization of the LBNL Laser Wakefield Accelerator as a Compact, Powerful Terahertz Source

    NASA Astrophysics Data System (ADS)

    Plateau, Guillaume; Matlis, Nicholas; van Tilborg, Jeroen; Nakamura, Kei; Geddes, Cameron; Toth, Csaba; Schroeder, Carl; Esarey, Eric; Leemans, Wim

    2007-11-01

    At LBNL, laser wakefield accelerators (LWFA) routinely produce ultrashort electron bunches with energies up to 1 GeV [1]. As femtosecond electron bunches exit the plasma they radiate a strong burst in the terahertz range [2,3] via coherent transition radiation (CTR). Measuring the CTR properties allows non-invasive bunch-length diagnostics [4], a key to continuing rapid advance in LWFA technology. We present measurements demonstrating both the shot-to-shot stability of bunch parameters, and femtosecond synchronization between the bunch, the THz pulse, and the laser beam. In addition we present a technique for enhancing CTR generation from LWFA-produced electron beams, increasing its suitability for applications. [1] W.P. Leemans et al., Nature Physics 2, 696 (2006); [2] W.P. Leemans et al., PRL 91, 074802 (2003); [3] C.B. Schroeder et al., PRE 69, 016501 (2004); [4] J. van Tilborg et al., PRL 96, 014801 (2006)

  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. Challenges in plasma and laser wakefield accelerated beams diagnostic

    NASA Astrophysics Data System (ADS)

    Cianchi, A.; Anania, M. P.; Bellaveglia, M.; Castellano, M.; Chiadroni, E.; Ferrario, M.; Gatti, G.; Marchetti, B.; Mostacci, A.; Pompili, R.; Ronsivalle, C.; Rossi, A. R.; Serafini, L.

    2013-08-01

    The new frontier in the particle beam accelerator is the so called plasma acceleration. Using the strong electric field inside a plasma it is possible to achieve accelerating gradients in the order of magnitude larger with respect to the actual technologies. Different schemes have been proposed and several already tested, producing beams of energy of several GeV. Mainly two approaches are followed: either the beam is directly produced by the interaction of a TW/PW class laser with a gas jet or a preexisting particle beam is accelerated in a plasma channel. In both cases a precise determination of the emerging beam parameters is mandatory for the fine tuning of the devices. The measurement of these parameters, in particular the emittance, is not trivial, mainly due to the large energy spread and to the tight focusing of these beams or to the background noise produced in the plasma channel. We show the problems related to the diagnostic of this kind of beams and the proposed or already realized solutions.

  8. High-quality electron beams from a laser wakefield accelerator using plasma-channel guiding.

    PubMed

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

    2004-09-30

    Laser-driven accelerators, in which particles are accelerated by the electric field of a plasma wave (the wakefield) driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV m(-1) (refs 1-3). These fields are thousands of times greater than those achievable in conventional radio-frequency accelerators, spurring interest in laser accelerators 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 results in low-energy beams with 100 per cent electron energy spread, which limits potential applications. Here we demonstrate a laser accelerator that produces electron beams with an energy spread of a few per cent, low emittance and increased energy (more than 10(9) electrons above 80 MeV). Our technique involves the use of a preformed plasma density channel to guide a relativistically intense laser, resulting in a longer propagation distance. The results open the way for compact and tunable high-brightness sources of electrons and radiation.

  9. Investigation of electron dynamics in an ionization-injection laser-wakefield accelerator via betatron radiation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Koehler, Alexander; Couperus, Jurjen P.; Zarini, Omid; Pausch, Richard; Krämer, Jakob M.; Debus, Alexander; Bussmann, Michael; Irman, Arie; Schramm, Ulrich

    2017-05-01

    The injection process of electrons into the plasma cavity in laser-wakefield accelerators is a nonlinear process that strongly influences the property of the accelerated electrons. During the acceleration electrons perform transverse (betatron) oscillations around the axis. This results in the emission of hard x-ray radiation (betatron radiation) whose characteristics depend directly on the dynamic of the accelerated electrons. Thus, betatron radiation can be utilized as a powerful diagnostic tool to investigate the acceleration process inside the wakefield. Here we describe our recent LWFA experiments deploying ionization induced injection technique carried out with the Draco Ti:Sapphire laser. We focused 30 fs short pulses down to a FWHM spot size of 19 μm resulting in a normalized vacuum laser intensity a0 = 3.3 on a gas target. The target, which was a supersonic gas jet, provided a flat plasma profile of 3mm length. By varying the plasma density from 2x10^18 cm^-3 to 5x10^18 cm^-3 and the laser pulse energy from 1.6 J to 3.4 J we were able to tune the electron bunch and betatron parameters. Electron spectra were obtained by acquiring an energy resolved and charge calibrated electron profile after detection from the beam axis by a permanent magnetic dipole. Simultaneously, a back-illuminated and deep-depleted CCD placed on axis recorded the emitted x-ray photons with energies up to 20keV. Equipped with an 2D spectroscopy technique based on single pixel absorption events, we reconstructed the corresponding energy resolved x-ray spectrum for every shot and deduced the betatron source size at the plasma exit. Combining the data of the electron and betatron spectrum, we compare the characteristics of the betatron spectra for different electron bunches. In our experiments we recorded a total number of 25x10^4 photons per shot within a divergence angle of 1 mrad and betatron radii in the order of 1 μm. Finally, we compare our results with simulated spectra from the

  10. Tomography of human trabecular bone with a laser-wakefield driven x-ray source

    NASA Astrophysics Data System (ADS)

    Cole, J. M.; Wood, J. C.; Lopes, N. C.; Poder, K.; Abel, R. L.; Alatabi, S.; Bryant, J. S. J.; Jin, A.; Kneip, S.; Mecseki, K.; Parker, S.; Symes, D. R.; Sandholzer, M. A.; Mangles, S. P. D.; Najmudin, Z.

    2016-01-01

    A laser-wakefield driven x-ray source is used for the radiography of human bone. The betatron motion of accelerated electrons generates x-rays which are hard (critical energy {{E}\\text{crit}}>30 keV), have small source size (<3 μm) and high average brightness. The x-rays are generated from a helium gas cell which is near-instantly replenishable, and thus the average photon flux is limited by the repetition rate of the driving laser rather than the breakdown of the x-ray source. A tomograph of a human bone sample was recorded with a resolution down to 50 μm. The photon flux was sufficiently high that a radiograph could be taken with each laser shot, and the fact that x-ray beams were produced on 97% of shots minimised failed shots and facilitated full micro-computed tomography in a reasonable time scale of several hours, limited only by the laser repetition rate. The x-ray imaging beamline length (not including the laser) is shorter than that of a synchrotron source due to the high accelerating fields and small source size. Hence this interesting laboratory-based source may one day bridge the gap between small microfocus x-ray tubes and large synchrotron facilities.

  11. Numerical simulations of optical guiding of laser pulses in a plasma

    SciTech Connect

    Krall, J.; Joyce, G.; Sprangle, P.; Esarey, E. )

    1992-07-01

    In the laser wakefield accelerator, a short ([tau][sub L][lt]1 ps), high power (P[gt]10[sup 12] W) laser pulse propagates in plasma to generate a large amplitude (E[gt]1 GV/m) wakefield. We present an axisymmetric nonlinear fluid model that allows simulation of laser pulse propagation through a plasma on the plasma time scale. We find that a laser pulse will propagate through a plasma for many vacuum diffraction lengths if either of two conditions are met: (1) an appropriately shaped plasma density channel can be obtained or (2) an ultrahigh power tailored laser pulse can be created.

  12. Characterization of electrons and x-rays produced using chirped laser pulses in a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Zhao, T. Z.; Behm, K.; He, Z.-H.; Maksimchuk, A.; Nees, J. A.; Yanovsky, V.; Thomas, A. G. R.; Krushelnick, K.

    2016-11-01

    The electron injection process into a plasma-based laser wakefield accelerator can be influenced by modifying the parameters of the driver pulse. We present an experimental study on the combined effect of the laser pulse duration, pulse shape, and frequency chirp on the electron injection and acceleration process and the associated radiation emission for two different gas types—a 97.5% He and 2.5% N2 mixture and pure He. In general, the shortest pulse duration with minimal frequency chirp produced the highest energy electrons and the most charge. Pulses on the positive chirp side sustained electron injection and produced higher charge, but lower peak energy electrons, compared with negatively chirped pulses. A similar trend was observed for the radiant energy. The relationship between the radiant energy and the electron charge remained linear over a threefold change in the electron density and was independent of the drive pulse characteristics. X-ray spectra showed that ionization injection of electrons into the wakefield generally produced more photons than self-injection for all pulse durations/frequency chirp and had less of a spread in the number of photons around the peak x-ray energy.

  13. Detailed numerical modeling of electron injection in the Laser Wakefield Accelerator: Particle Tracking Diagnostics in PIC codes

    NASA Astrophysics Data System (ADS)

    Fonseca, R. A.; Gargaté, L.; Martins, S. F.; Peano, F.; Vieira, J.; Silva, L. O.; Mori, W. B.

    2007-11-01

    The field of laser plasma acceleration has witnessed significant development over recent years, with experimental demonstrations of the production of quasi mono-energetic electron bunches, with charges of ˜ 50 pC and energies of up to 1 GeV [1]. Fully relativistic PIC codes, such as OSIRIS [2] are the best tools for modeling these problems, but sophisticated visualization and data analysis routines [3] are required to extract physical meaning from the large volumes of data produced. We report on the new particle tracking diagnostics being added into the OSIRIS framework and its application to this problem, specifically targeting self-injection. Details on the tracking algorithm implementation and post processing routines are given. Simulation results from laser wakefield accelerator scenarios will be presented, with detailed analysis of the self injection of the electron bunches. [1] W.P. Leemans et al, Nature Phys. 2 696 (2006) [2] R. A. Fonseca et al., LNCS 2331, 342, (2002) [3] R. A. Fonseca, Proceedings of ISSS-7, (2005)

  14. Using Betatron Emissions from Laser Wakefield Accelerated Electrons to Probe Ultra-fast Warm Dense Matter

    NASA Astrophysics Data System (ADS)

    Kotick, Jordan; Schumaker, Will; Condamine, Florian; Albert, Felicie; Barbrel, Benjamin; Galtier, Eric; Granados, Eduardo; Ravasio, Alessandra; Glenzer, Siegfried

    2015-11-01

    Laser wakefield acceleration (LWFA) has been shown to produce short X-ray pulses from betatron oscillations of electrons within the plasma wake. These betatron X-rays pulses have a broad, synchrotron-like energy spectrum and a duration on the order of the driving laser pulse, thereby enabling probing of ultrafast interactions. Using the 1 J, 40fs short-pulse laser at the Matter in Extreme Conditions experimental station at LCLS, we have implemented LWFA to generate and subsequently characterized betatron X-rays. Notch filtering and single photon counting techniques were used to measure the betatron X-ray spectrum while the spatial profile was measured using X-ray CCDs and image plates. We used an ellipsoidal mirror to focus the soft betatron X-rays for pump-probe studies on various targets in conjunction with LCLS X-ray and optical laser pulses. This experimental platform provides the conditions necessary to do a detailed study of warm-dense matter dynamics on the ultrafast time-scale.

  15. Controlled laser plasma wakefield acceleration of electrons via colliding pulse injection in non-collinear geometry

    NASA Astrophysics Data System (ADS)

    Toth, Csaba; Nakamura, Kei; Geddes, Cameron; Panasenko, Dmitriy; Plateau, Guillaume; Matlis, Nicholas; Schroeder, Carl; Esarey, Eric; Leemans, Wim

    2007-11-01

    Colliding laser pulses [1] have been proposed as a method for controlling injection of electrons into a laser wakefield accelerator (LWFA) and hence producing high quality electron beams with energy spread below 1% and normalized emittances < 1 micron. The. One pulse excites a plasma wake, and a collinear pulse following behind it collides with a counterpropagating pulse forming a beat pattern that boosts background electrons into accelerating phase. A variation of the original method uses only two laser pulses [2] which may be non-collinear. The first pulse drives the wake, and beating of the trailing edge of this pulse with the colliding pulse injects electrons. Non-collinear injection avoids optical elements on the electron beam path (avoiding emittance growth). We report on progress of non-collinear experiments at LBNL, using the Ti:Sapphire laser at the LOASIS facility of LBNL. New results indicate that the electron beam properties are affected by the presence of the second beam. [1] E. Esarey, et al, Phys. Rev. Lett 79, 2682 (1997) [2] G. Fubiani, Phys. Rev. E 70, 016402 (2004)

  16. Synergistic Direct/Wakefield Acceleration of Plasma Electrons In the Plasma Bubble Regime Using Tailored Laser Pulses

    NASA Astrophysics Data System (ADS)

    Shvets, Gennady

    2016-10-01

    The integration of direct laser acceleration (DLA) and laser wakefield acceleration (LWFA) is a new approach to plasma-based acceleration that confers several benefits over both schemes taken separately. Such integration requires a significant portion of the laser energy (e.g., a separate laser pulse) to trail the main bubble-producing laser pulse, and resonantly interact with the trapped accelerated electrons undergoing betatron motion inside the plasma bubble. I will demonstrate how electron dephasing from the accelerating wakefield, which is one of the key limitations of LWFA, is reduced by their growing undulating motion. Moreover, the distinct energy gains from wake and the laser pulse are compounding, thereby increasing the total energy gain. Even more significant increases of the overall acceleration can be obtained by moving away from single-frequency laser format toward combining mid-infrared laser pulses for plasma bubble generation with short-wavelength trailing pulses for DLA. Various injection mechanisms, such as ionization injection, external injection, self-injection, and their advantages will also be discussed. Translating these new concepts into specific experiments will take advantage of recent technological advances in synchronizing laser and electron beams, and using multiple beamlines for producing sophisticated laser pulse formats.

  17. Simulation of Laser Wake Field Acceleration using a 2.5D PIC Code

    SciTech Connect

    An, W. M.; Hua, J. F.; Huang, W. H.; Tang, Ch. X.; Lin, Y. Z.

    2006-11-27

    A 2.5D PIC simulation code is developed to study the LWFA( Laser WakeField Acceleration ). The electron self-injection and the generation of mono-energetic electron beam in LWFA is briefly discussed through the simulation. And the experiment of this year at SILEX-I laser facility is also introduced.

  18. High-Flux Femtosecond X-Ray Emission from Controlled Generation of Annular Electron Beams in a Laser Wakefield Accelerator.

    PubMed

    Zhao, T Z; Behm, K; Dong, C F; Davoine, X; Kalmykov, S Y; Petrov, V; Chvykov, V; Cummings, P; Hou, B; Maksimchuk, A; Nees, J A; Yanovsky, V; Thomas, A G R; Krushelnick, K

    2016-08-26

    Annular quasimonoenergetic electron beams with a mean energy in the range 200-400 MeV and charge on the order of several picocoulombs were generated in a laser wakefield accelerator and subsequently accelerated using a plasma afterburner in a two-stage gas cell. Generation of these beams is associated with injection occurring on the density down ramp between the stages. This well-localized injection produces a bunch of electrons performing coherent betatron oscillations in the wakefield, resulting in a significant increase in the x-ray yield. Annular electron distributions are detected in 40% of shots under optimal conditions. Simultaneous control of the pulse duration and frequency chirp enables optimization of both the energy and the energy spread of the annular beam and boosts the radiant energy per unit charge by almost an order of magnitude. These well-defined annular distributions of electrons are a promising source of high-brightness laser plasma-based x rays.

  19. Laser-wakefield accelerators as hard x-ray sources for 3D medical imaging of human bone.

    PubMed

    Cole, J M; Wood, J C; Lopes, N C; Poder, K; Abel, R L; Alatabi, S; Bryant, J S J; Jin, A; Kneip, S; Mecseki, K; Symes, D R; Mangles, S P D; Najmudin, Z

    2015-08-18

    A bright μm-sized source of hard synchrotron x-rays (critical energy Ecrit > 30 keV) based on the betatron oscillations of laser wakefield accelerated electrons has been developed. The potential of this source for medical imaging was demonstrated by performing micro-computed tomography of a human femoral trabecular bone sample, allowing full 3D reconstruction to a resolution below 50 μm. The use of a 1 cm long wakefield accelerator means that the length of the beamline (excluding the laser) is dominated by the x-ray imaging distances rather than the electron acceleration distances. The source possesses high peak brightness, which allows each image to be recorded with a single exposure and reduces the time required for a full tomographic scan. These properties make this an interesting laboratory source for many tomographic imaging applications.

  20. Analysis of radial and longitudinal field of plasma wakefield generated by a Laguerre-Gauss laser pulse

    SciTech Connect

    Firouzjaei, Ali Shekari; Shokri, Babak

    2016-06-15

    In the present paper, we study the wakes known as the donut wake which is generated by Laguerre-Gauss (LG) laser pulses. Effects of the special spatial profile of a LG pulse on the radial and longitudinal wakefields are presented via an analytical model in a weakly non-linear regime in two dimensions. Different aspects of the donut-shaped wakefields have been analyzed and compared with Gaussian-driven wakes. There is also some discussion about the accelerating-focusing phase of the donut wake. Variations of longitudinal and radial wakes with laser amplitude, pulse length, and pulse spot size have been presented and discussed. Finally, we present the optimum pulse duration for such wakes.

  1. Laser-wakefield accelerators as hard x-ray sources for 3D medical imaging of human bone

    PubMed Central

    Cole, J. M.; Wood, J. C.; Lopes, N. C.; Poder, K.; Abel, R. L.; Alatabi, S.; Bryant, J. S. J.; Jin, A.; Kneip, S.; Mecseki, K.; Symes, D. R.; Mangles, S. P. D.; Najmudin, Z.

    2015-01-01

    A bright μm-sized source of hard synchrotron x-rays (critical energy Ecrit > 30 keV) based on the betatron oscillations of laser wakefield accelerated electrons has been developed. The potential of this source for medical imaging was demonstrated by performing micro-computed tomography of a human femoral trabecular bone sample, allowing full 3D reconstruction to a resolution below 50 μm. The use of a 1 cm long wakefield accelerator means that the length of the beamline (excluding the laser) is dominated by the x-ray imaging distances rather than the electron acceleration distances. The source possesses high peak brightness, which allows each image to be recorded with a single exposure and reduces the time required for a full tomographic scan. These properties make this an interesting laboratory source for many tomographic imaging applications. PMID:26283308

  2. Effect of experimental laser imperfections on laser wakefield acceleration and betatron source

    PubMed Central

    Ferri, J.; Davoine, X.; Fourmaux, S.; Kieffer, J. C.; Corde, S.; Ta Phuoc, K.; Lifschitz, A.

    2016-01-01

    Laser pulses in current ultra-short TW systems are far from being ideal Gaussian beams. The influence of the presence of non-Gaussian features of the laser pulse is investigated here from experiments and 3D Particle-in-Cell simulations. Both the experimental intensity distribution and wavefront are used as input in the simulations. It is shown that a quantitative agreement between experimental data and simulations requires to use realistic pulse features. Moreover, some trends found in the experiments, such as the growing of the X-ray signal with the plasma length, can only be retrieved in simulations with realistic pulses. The performances on the electron acceleration and the synchrotron X-ray emission are strongly degraded by these non-Gaussian features, even keeping constant the total laser energy. A drop on the X-ray photon number by one order of magnitude was found. This clearly put forward the limitation of using a Gaussian beam in the simulations. PMID:27324915

  3. Effect of experimental laser imperfections on laser wakefield acceleration and betatron source.

    PubMed

    Ferri, J; Davoine, X; Fourmaux, S; Kieffer, J C; Corde, S; Ta Phuoc, K; Lifschitz, A

    2016-06-21

    Laser pulses in current ultra-short TW systems are far from being ideal Gaussian beams. The influence of the presence of non-Gaussian features of the laser pulse is investigated here from experiments and 3D Particle-in-Cell simulations. Both the experimental intensity distribution and wavefront are used as input in the simulations. It is shown that a quantitative agreement between experimental data and simulations requires to use realistic pulse features. Moreover, some trends found in the experiments, such as the growing of the X-ray signal with the plasma length, can only be retrieved in simulations with realistic pulses. The performances on the electron acceleration and the synchrotron X-ray emission are strongly degraded by these non-Gaussian features, even keeping constant the total laser energy. A drop on the X-ray photon number by one order of magnitude was found. This clearly put forward the limitation of using a Gaussian beam in the simulations.

  4. Proton driven plasma wakefield generation in a parabolic plasma channel

    NASA Astrophysics Data System (ADS)

    Golian, Y.; Dorranian, D.

    2016-11-01

    An analytical model for the interaction of charged particle beams and plasma for a wakefield generation in a parabolic plasma channel is presented. In the suggested model, the plasma density profile has a minimum value on the propagation axis. A Gaussian proton beam is employed to excite the plasma wakefield in the channel. While previous works investigated on the simulation results and on the perturbation techniques in case of laser wakefield accelerations for a parabolic channel, we have carried out an analytical model and solved the accelerating field equation for proton beam in a parabolic plasma channel. The solution is expressed by Whittaker (hypergeometric) functions. Effects of plasma channel radius, proton bunch parameters and plasma parameters on the accelerating processes of proton driven plasma wakefield acceleration are studied. Results show that the higher accelerating fields could be generated in the PWFA scheme with modest reductions in the bunch size. Also, the modest increment in plasma channel radius is needed to obtain maximum accelerating gradient. In addition, the simulations of longitudinal and total radial wakefield in parabolic plasma channel are presented using LCODE. It is observed that the longitudinal wakefield generated by the bunch decreases with the distance behind the bunch while total radial wakefield increases with the distance behind the bunch.

  5. Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch

    SciTech Connect

    Kuschel, S.; Hollatz, D.; Heinemann, T.; Karger, O.; Schwab, M. B.; Ullmann, D.; Knetsch, A.; Seidel, A.; Rodel, C.; Yeung, M.; Leier, M.; Blinne, A.; Ding, H.; Kurz, T.; Corvan, D. J.; Savert, A.; Karsch, S.; Kaluza, M. C.; Hidding, B.; Zepf, M.

    2016-07-20

    We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we introduce a robust and independently tunable plasma lens. We observe a density dependent reduction of the LWFA electron beam divergence from an initial value of 2.3 mrad, down to 1.4 mrad (rms), when the plasma lens is in operation. Such a plasma lens provides a simple and compact approach for divergence reduction well matched to the mm-scale length of the LWFA accelerator. The focusing forces are provided solely by the plasma and driven by the bunch itself only, making this a highly useful and conceptually new approach to electron beam focusing. Possible applications of this lens are not limited to laser plasma accelerators. Since no active driver is needed the passive plasma lens is also suited for high repetition rate focusing of electron bunches. As a result, its understanding is also required for modeling the evolution of the driving particle bunch in particle driven wake field acceleration.

  6. Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch

    DOE PAGES

    Kuschel, S.; Hollatz, D.; Heinemann, T.; ...

    2016-07-20

    We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we introduce a robust and independently tunable plasma lens. We observe a density dependent reduction of the LWFA electron beam divergence from an initial value of 2.3 mrad, down to 1.4 mrad (rms), when the plasma lens is in operation. Such a plasma lens provides a simple and compact approach for divergence reduction well matchedmore » to the mm-scale length of the LWFA accelerator. The focusing forces are provided solely by the plasma and driven by the bunch itself only, making this a highly useful and conceptually new approach to electron beam focusing. Possible applications of this lens are not limited to laser plasma accelerators. Since no active driver is needed the passive plasma lens is also suited for high repetition rate focusing of electron bunches. As a result, its understanding is also required for modeling the evolution of the driving particle bunch in particle driven wake field acceleration.« less

  7. Medical imaging using a laser-wakefield driven x-ray source

    NASA Astrophysics Data System (ADS)

    Cole, Jason; Wood, Jonathan; Lopes, Nelson; Poder, Kristjan; Kamperidis, Christos; Alatabi, Saleh; Bryant, Jonathan; Kneip, Stefan; Mecseki, Katalin; Norris, Dominic; Teboul, Lydia; Westerburg, Henrik; Abel, Richard; Jin, Andi; Symes, Dan; Mangles, Stuart; Najmudin, Zulfikar

    2016-10-01

    Laser-wakefield accelerators driven by high-intensity laser pulses are a proven centimetre-scale source of GeV electron beams. One of the proposed uses for these accelerators is the driving of compact hard x-ray synchrotron light sources. Such sources have been shown to be bright, have small source size and high photon energy, and are therefore interesting for imaging applications. By doubling the focal length at the Astra-Gemini laser facility of the Rutherford Appleton Laboratory, UK, we have significantly improved the average betatron x-ray flux compared to previous experiments. This fact, coupled to the stability of the radiation source, facilitated the acquisition of full 3D tomograms of hard bone tissue and soft mouse neonates, the latter requiring the recording of over 500 successive radiographs. Such multimodal performance is unprecedented in the betatron field and indicates the usefulness of these sources in clinical imaging applications, scalable to very high photon flux without compromising source size or photon energy.

  8. High-resolution and ultrafast imaging using betatron x-rays from laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Najmudin, Zulfikar

    2015-11-01

    Laser wakefield accelerators now routinely produce ~GeV energy gain in ~cm plasmas. and are simultaneously capable of producing high brightness and spatially coherent hard x-ray beams. This unique light-source has been used for medical applications, and also for ultrafast imaging in high energy density science. The experiments were performed with the Astra Gemini laser producing 10 J pulses with duration ~ 40 fs focussed to produce a spot of 25 μ m (fwhm) in a gas-cell of variable length to produce a low divergence beam of x-rays. The length of the gas cell was optimised to produce high contrast x-ray images of radiographed test objects. This source was used for full tomographic imaging of a human trabecular bone sample, with resolution exceeding the ~ 100 μ m level required for CT applications. Phase-contrast imaging of human prostate and mouse neonates at the micron level was also demonstrated. These studies indicate the usefulness of these sources in research and clinical applications. The ultrafast nature of the source was also demonstrated by performing time resolved imaging of a laser driven shock. The ultrashort duration of the x-ray source essentially freeze the motion of these fast moving transient phenomena.

  9. 3-D Simulations of Plasma Wakefield Acceleration with Non-Idealized Plasmas and Beams

    SciTech Connect

    Deng, S.; Katsouleas, T.; Lee, S.; Muggli, P.; Mori, W.B.; Hemker, R.; Ren, C.; Huang, C.; Dodd, E.; Blue, B.E.; Clayton, C.E.; Joshi, C.; Wang, S.; Decker, F.J.; Hogan, M.J.; Iverson, R.H.; O'Connell, C.; Raimondi, P.; Walz, D.; /SLAC

    2005-09-27

    3-D Particle-in-cell OSIRIS simulations of the current E-162 Plasma Wakefield Accelerator Experiment are presented in which a number of non-ideal conditions are modeled simultaneously. These include tilts on the beam in both planes, asymmetric beam emittance, beam energy spread and plasma inhomogeneities both longitudinally and transverse to the beam axis. The relative importance of the non-ideal conditions is discussed and a worst case estimate of the effect of these on energy gain is obtained. The simulation output is then propagated through the downstream optics, drift spaces and apertures leading to the experimental diagnostics to provide insight into the differences between actual beam conditions and what is measured. The work represents a milestone in the level of detail of simulation comparisons to plasma experiments.

  10. Short energetic electron bunches from laser wakefield accelerator with orthogonally polarized perpendicularly crossed laser pulses

    NASA Astrophysics Data System (ADS)

    Horný, Vojtěch; Petržílka, Václav; Klimo, Ondřej; Krůs, Miroslav

    2017-05-01

    Electron acceleration with optical injection by a perpendicularly propagating and orthogonally polarized low intensity laser pulse into a nonlinear plasma wave driven by a short intense laser pulse was explored by particle- in-cell simulations. The scheme presented here provides an energetic electron bunch in the first ion cavity with a low energy spread. The electron bunch short and compact, with the mean energy about 400 MeV and a low energy spread about 10 MeV in time of 6 ps of acceleration. The injected charge is several tens of pC for the low intensity of the injection pulse. Initial positions of electrons forming the energetic bunch are shown and then these electrons are followed during the simulation in order to understand the injection process and determine electron bunch properties.

  11. Tomographic characterisation of gas-jet targets for laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Couperus, J. P.; Köhler, A.; Wolterink, T. A. W.; Jochmann, A.; Zarini, O.; Bastiaens, H. M. J.; Boller, K. J.; Irman, A.; Schramm, U.

    2016-09-01

    Laser wakefield acceleration (LWFA) has emerged as a promising concept for the next generation of high energy electron accelerators. The acceleration medium is provided by a target that creates a local well-defined gas-density profile inside a vacuum vessel. Target development and analysis of the resulting gas-density profiles is an important aspect in the further development of LWFA. Gas-jet targets are widely used in regimes where relatively high electron densities over short interaction lengths are required (up to several millimetres interaction length, plasma densities down to 1018cm-3). In this paper we report a precise characterisation of such gas-jet targets by a laser interferometry technique. We show that phase shifts down to 4 mrad can be resolved. Tomographic phase reconstruction enables detection of non-axisymmetrical gas-density profiles which indicates defects in cylindrical nozzles, analysis of slit-nozzles and nozzles with an induced shock-wave density step. In a direct comparison between argon and helium jets we show that it cannot automatically be assumed, as is often done, that a nozzle measured with argon will provide the same gas density with helium.

  12. A Fast, Electromagnetically Driven Supersonic Gas Jet Target For Laser Wakefield Acceleration

    SciTech Connect

    Krishnan, Mahadevan; Wright, Jason; Ma, Timothy

    2009-01-22

    Laser-Wakefield acceleration (LWFA) promises electron accelerators with unprecedented electric field gradients. Gas jets and gas-filled capillary discharge waveguides are two primary targets of choice for LWFA. Present gas jets have lengths of only 2-4 mm at densities of 1-4x10{sup 19} /cm{sup 3}, sufficient for self-trapping and acceleration to energies up to {approx}150 MeV. While 3 cm capillary structures have been used to accelerate beams up to 1 GeV, gas jets require a well-collimated beam that is {>=}10 mm in length and <500 {mu}m in width, with a tunable gas density profile to optimize the LWFA process. This paper describes the design of an electromagnetically driven, fast supersonic gas valve that opens in <100 {mu}s, closes in <500 {mu}s and can operate at pressures beyond 1000 psia. The motion of the valve seat (flyer plate) is measured using a laser probe and compared with predictions of a model. The valve design is based on an optimization of many parameters: flyer plate mass and durability, driver bank speed and stored energy for high rep-rate (>10 Hz) operation, return spring non-linearity and materials selection for various components. Optimization of the valve dynamics and preliminary designs of the supersonic flow patterns are described.

  13. Developments in laser wakefield accelerators: From single-stage to two-stage

    NASA Astrophysics Data System (ADS)

    Li, Wen-Tao; Wang, Wen-Tao; Liu, Jian-Sheng; Wang, Cheng; Zhang, Zhi-Jun; Qi, Rong; Yu, Chang-Hai; Li, Ru-Xin; Xu, Zhi-Zhan

    2015-01-01

    Laser wakefield accelerators (LWFAs) are compact accelerators which can produce femtosecond high-energy electron beams on a much smaller scale than the conventional radiofrequency accelerators. It is attributed to their high acceleration gradient which is about 3 orders of magnitude larger than the traditional ones. The past decade has witnessed the major breakthroughs and progress in developing the laser wakfield accelerators. To achieve the LWFAs suitable for applications, more and more attention has been paid to optimize the LWFAs for high-quality electron beams. A single-staged LWFA does not favor generating controllable electron beams beyond 1 GeV since electron injection and acceleration are coupled and cannot be independently controlled. Staged LWFAs provide a promising route to overcome this disadvantage by decoupling injection from acceleration and thus the electron-beam quality as well as the stability can be greatly improved. This paper provides an overview of the physical conceptions of the LWFA, as well as the major breakthroughs and progress in developing LWFAs from single-stage to two-stage LWFAs. Project supported by the National Natural Science Foundation of China (Grant Nos. 11127901, 11425418, and 61221064), the National Basic Research Program of China (Grant No. 2011CB808100), and the Science and Technology Talent Project of Shanghai City, China (Grant Nos. 12XD1405200 and 12ZR1451700).

  14. Towards Attosecond High-Energy Electron Bunches: Controlling Self-Injection in Laser-Wakefield Accelerators Through Plasma-Density Modulation

    NASA Astrophysics Data System (ADS)

    Tooley, M. P.; Ersfeld, B.; Yoffe, S. R.; Noble, A.; Brunetti, E.; Sheng, Z. M.; Islam, M. R.; Jaroszynski, D. A.

    2017-07-01

    Self-injection in a laser-plasma wakefield accelerator is usually achieved by increasing the laser intensity until the threshold for injection is exceeded. Alternatively, the velocity of the bubble accelerating structure can be controlled using plasma density ramps, reducing the electron velocity required for injection. We present a model describing self-injection in the short-bunch regime for arbitrary changes in the plasma density. We derive the threshold condition for injection due to a plasma density gradient, which is confirmed using particle-in-cell simulations that demonstrate injection of subfemtosecond bunches. It is shown that the bunch charge, bunch length, and separation of bunches in a bunch train can be controlled by tailoring the plasma density profile.

  15. Simulation of ionization effects for high-density positron drivers in future plasma wakefield experiments

    SciTech Connect

    Bruhwiler, D.L.; Dimitrov, D.A.; Cary, J.R.; Esarey, E.; Leemans, W.P.

    2003-05-12

    The plasma wakefield accelerator (PWFA) concept has been proposed as a potential energy doubler for present or future electron-positron colliders. Recent particle-in-cell (PIC) simulations have shown that the self-fields of the required electron beam driver can tunnel ionize neutral Li, leading to plasma wake dynamics differing significantly from that of a preionized plasma. It has also been shown, for the case of a preionized plasma, that the plasma wake of a positron driver differs strongly from that of an electron driver. We will present new PIC simulations, using the OOPIC code, showing the effects of tunneling ionization on the plasma wake generated by high-density positron drivers. The results will be compared to previous work on electron drivers with tunneling ionization and positron drivers without ionization. Parameters relevant to the energy doubler and the upcoming E-164x experiment at the Stanford Linear Accelerator Center will be considered.

  16. A multi-beam, multi-terawatt Ti:sapphire laser system for laser wake-field acceleration studies

    NASA Astrophysics Data System (ADS)

    Tóth, Cs.; Geddes, C. G. R.; van Tilborg, J.; Leemans, W. P.

    2004-12-01

    The Lasers, Optical Accelerator Systems Integrated Studies (L'OASIS) Lab of LBNL operates a highly automated and remotely controlled Ti:sapphire chirped pulse amplification (CPA) laser system that provides synchronized beams of 2×1.0 TW, 12 TW, and 100 TW peak-power, in a unique, radiation shielded facility. The system has been specially designed for studying high field laser-plasma interactions and particularly aimed for the investigations of laser wake-field particle acceleration. It generates and recombines multiple beams having different pulse durations, wavelengths, and pulse energies for various stages of plasma preparation, excitation, and diagnostics. The amplifier system is characterized and continuously monitored via local area network (LAN) from a radiation shielded control room by an array of diagnostics, including beam profile monitoring cameras, remote controlled alignment options, self-correcting beam-pointing stabilization loops, pulse measurement tools, such as single-shot autocorrelator for pulse duration and third-order correlator for contrast measurements, FROG for pulse shape studies.

  17. A multi-beam, multi-terawatt Ti:sapphire laser system for laser wake-field acceleration studies

    SciTech Connect

    Toth, Cs.; Geddes, C.G.R.; Tilborg, J. van; Leemans, W.P.

    2004-12-07

    The Lasers, Optical Accelerator Systems Integrated Studies (L'OASIS) Lab of LBNL operates a highly automated and remotely controlled Ti:sapphire chirped pulse amplification (CPA) laser system that provides synchronized beams of 2x1.0 TW, 12 TW, and 100 TW peak-power, in a unique, radiation shielded facility. The system has been specially designed for studying high field laser-plasma interactions and particularly aimed for the investigations of laser wake-field particle acceleration. It generates and recombines multiple beams having different pulse durations, wavelengths, and pulse energies for various stages of plasma preparation, excitation, and diagnostics. The amplifier system is characterized and continuously monitored via local area network (LAN) from a radiation shielded control room by an array of diagnostics, including beam profile monitoring cameras, remote controlled alignment options, self-correcting beam-pointing stabilization loops, pulse measurement tools, such as single-shot autocorrelator for pulse duration and third-order correlator for contrast measurements, FROG for pulse shape studies.

  18. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    NASA Astrophysics Data System (ADS)

    He, Z.-H.; Thomas, A. G. R.; Beaurepaire, B.; Nees, J. A.; Hou, B.; Malka, V.; Krushelnick, K.; Faure, J.

    2013-02-01

    We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

  19. Laser beam coupling with capillary discharge plasma for laser wakefield acceleration applications

    NASA Astrophysics Data System (ADS)

    Bagdasarov, G. A.; Sasorov, P. V.; Gasilov, V. A.; Boldarev, A. S.; Olkhovskaya, O. G.; Benedetti, C.; Bulanov, S. S.; Gonsalves, A.; Mao, H.-S.; Schroeder, C. B.; van Tilborg, J.; Esarey, E.; Leemans, W. P.; Levato, T.; Margarone, D.; Korn, G.

    2017-08-01

    One of the most robust methods, demonstrated to date, of accelerating electron beams by laser-plasma sources is the utilization of plasma channels generated by the capillary discharges. Although the spatial structure of the installation is simple in principle, there may be some important effects caused by the open ends of the capillary, by the supplying channels etc., which require a detailed 3D modeling of the processes. In the present work, such simulations are performed using the code MARPLE. First, the process of capillary filling with cold hydrogen before the discharge is fired, through the side supply channels is simulated. Second, the simulation of the capillary discharge is performed with the goal to obtain a time-dependent spatial distribution of the electron density near the open ends of the capillary as well as inside the capillary. Finally, to evaluate the effectiveness of the beam coupling with the channeling plasma wave guide and of the electron acceleration, modeling of the laser-plasma interaction was performed with the code INF&RNO.

  20. Characterization of femtosecond electron bunches from a laser-wakefield accelerator using THz radiation

    NASA Astrophysics Data System (ADS)

    van Tilborg, Jeroen

    2005-10-01

    We report on the temporal characterization of laser-plasma-produced electron bunches, indicating ultra-short sub-50 fs charge structure. In the LOASIS laboratory at LBNL, the electron bunches are produced through the interaction of an intense (>10^19 Wcm-2) laser pulse with an underdense (˜10^19 cm-3) Helium plasma. The femtosecond multi-nanoCoulomb bunches have relativistic energies, with a 100% energy spread. As the bunch exits the plasma-vacuum interface, coherent transition radiation is emitted. Since the electron bunch is still dense and compact at the emission interface, the coherent spectrum of the intense radiation pulse covers the THz regime. Spectral and temporal measurements on the THz pulse are performed and correlated to the temporal properties of the electron bunch. Detection techniques such as Michelson interferometry, semiconductor switching, and electro-optic sampling are applied. The latter technique, where the THz electric field versus time is mapped out, provides detailed temporal structure of the radiation pulse, and by inference the electron bunch. The measurements indicate that THz radiation is emitted by a skewed bunch with a sub-50 fs rise time and a ˜600 fs tail (half-width-at-half-maximum), which is consistent with ballistic debunching of 100%-energy-spread beams during propagation. The electro-optic time resolution of the method was limited by the crystal properties. The Michelson interferometry and semiconductor switching experiments confirmed the femtosecond nature of the electron bunches. The electro-optic measurement also demonstrates shot-to-shot stability of the laser-wakefield accelerator (LWFA) as well as femtosecond synchronization between the electron bunch and the probe beam. This highlights the applicability of the LWFA in pump-probe experiments, where synchronized emission of x-rays, gamma rays, THz waves, NIR beams, and electron bunches is available. This work is supported by DoE under contract DE-AC02-05CH11231.

  1. Colliding pulse injection experiments in non-collinear geometry for controlled laser plasma wakefield acceleration of electrons

    NASA Astrophysics Data System (ADS)

    Toth, Csaba; Nakamura, K.; Geddes, C.; Michel, P.; Schroeder, C.; Esarey, E.; Leemans, W.

    2006-10-01

    A method for controlled injection of electrons into a plasma wakefield relying on colliding laser pulses [1] has been proposed a decade ago to produce high quality relativistic electron beams with energy spread below 1% and normalized emittances < 1 micron from a laser wakefield accelerator (LWFA). The original idea uses three pulses in which one pulse excites the plasma wake and a trailing laser pulse collides with a counterpropagating one to form a beat pattern that boosts background electrons to catch the plasma wave. Another, two-beam off-axis injection method [2] with crossing angles varying from 180 to 90 degrees avoids having optical elements on the path of the electron beam and has been studied at the LOASIS facility of LBNL as a viable method for laser triggered injection. It allows low dark current operation with controllable final beam energy and low energy spread. Here, we report on progress of electron optical injection via the two-beam non-collinear colliding pulse scheme using multi-terawatt Ti:Sapphire laser beams (45 fs, 100s of mJ) focused onto a Hydrogen gas plume. Experimental results indicate that electron beam properties are affected by the second beam. *This work is supported by DoE under contract DE-AC02-05CH11231. [1] E. Esarey, et al, Phys. Rev. Lett 79, 2682 (1997) [2] G. Fubiani, Phys. Rev. E 70, 016402 (2004)

  2. A 1 GeV Laser Wakefield Accelerator: Experimental Progress at the l'OASIS Facility of LBNL

    NASA Astrophysics Data System (ADS)

    Leemans, W. P.; Geddes, C. G. R.; Toth, C. S.; van Tilborg, J.; Nagler, B.; Michel, P.; Nakamura, K.; Esarey, E.; Schroeder, C. B.; Gonsalves, A.; Spence, D. J.; Hooker, S. M.; Filip, C.; Cowan, T.

    2004-11-01

    Experimental progress towards a 1 GeV laser-driven plasma-based accelerator will be discussed. The design of the 1 GeV accelerator module consists of two components: (1) an all-optical electron injector and (2) a plasma channel for laser guiding and electron acceleration to high energy via the laser wakefield acceleration (LWFA) mechanism. Experimental results on the injector development include the demonstration of laser guiding at relativistic intensities in preformed plasmas and production of quasi-monochromatic electron beams with energy around 100 MeV. Progress on guiding 100 TW laser pulses in capillary-discharge-based plasma channels will be discussed and integration of these channels with the all-optical injector will be reported.

  3. High-quality electron beam generation and bright betatron radiation from a cascaded laser wakefield accelerator (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Jiansheng; Wang, Wentao; Li, Wentao; Qi, Rong; Zhang, Zhijun; Yu, Changhai; Wang, Cheng; Liu, Jiaqi; Qing, Zhiyong; Ming, Fang; Xu, Yi; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2017-05-01

    One of the major goals of developing laser wakefiled accelerators (LWFAs) is to produce compact high-energy electron beam (e-beam) sources, which are expected to be applied in developing compact x-ray free-electron lasers and monoenergetic gamma-ray sources. Although LWFAs have been demonstrated to generate multi-GeV e-beams, to date they are still failed to produce high quality e beams with several essential properties (narrow energy spread, small transverse emittance and high beam charge) achieved simultaneously. Here we report on the demonstration of a high-quality cascaded LWFA experimentally via manipulating electron injection, seeding in different periods of the wakefield, as well as controlling energy chirp for the compression of energy spread. The cascaded LWFA was powered by a 1-Hz 200-TW femtosecond laser facility at SIOM. High-brightness e beams with peak energies in the range of 200-600 MeV, 0.4-1.2% rms energy spread, 10-80 pC charge, and 0.2 mrad rms divergence are experimentally obtained. Unprecedentedly high 6-dimensional (6-D) brightness B6D,n in units of A/m2/0.1% was estimated at the level of 1015-16, which is very close to the typical brightness of e beams from state-of-the-art linac drivers and several-fold higher than those of previously reported LWFAs. Furthermore, we propose a scheme to minimize the energy spread of an e beam in a cascaded LWFA to the one-thousandth-level by inserting a stage to compress its longitudinal spatial distribution via velocity bunching. In this scheme, three-segment plasma stages are designed for electron injection, e-beam length compression, and e-beam acceleration, respectively. 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. Based on the high-quality e beams generated in the LWFA, we have experimentally realized a new scheme to enhance the

  4. Relativistic harmonics for turbulent wakefield diagnostics

    NASA Astrophysics Data System (ADS)

    Kuramitsu, Yasuhiro; Chen, Shih-Hung

    2017-06-01

    The propagation properties of relativistic harmonics excited in a plasma with an intense laser pulse is investigated theoretically and numerically. Focusing on the frequency separation, a cold electron fluid model in two spatial dimension is discussed to obtain the harmonic amplitude. The theoretical predictions are verified by performing particle-in-cell simulations in two spatial dimensions. When the laser amplitude is large, the strong ponderomotive force expels the electrons, creating a large amplitude density structures associated with the wakefield. The harmonics propagate obliquely with respect to the laser propagation direction, which is well represented by the structure of the high density layer resulting from the transverse poderomotive force. We also discuss a possible experimental setup to observe the density structures relevant to wakefield.

  5. Fluid simulation of relativistic electron beam driven wakefield in a cold plasma

    SciTech Connect

    Bera, Ratan Kumar; Sengupta, Sudip; Das, Amita

    2015-07-15

    Excitation of wakefield in a cold homogeneous plasma, driven by an ultra-relativistic electron beam is studied in one dimension using fluid simulation techniques. For a homogeneous rigid beam having density (n{sub b}) less than or equal to half the plasma density (n{sub 0}), simulation results are found to be in good agreement with the analytical work of Rosenzweig [Phys. Rev. Lett. 58, 555 (1987)]. Here, Rosenzweig's work has been analytically extended to regimes where the ratio of beam density to plasma density is greater than half and results have been verified using simulation. Further in contrast to Rosenzweig's work, if the beam is allowed to evolve in a self-consistent manner, several interesting features are observed in simulation viz. splitting of the beam into beam-lets (for l{sub b} > λ{sub p}) and compression of the beam (for l{sub b} < λ{sub p}), l{sub b} and λ{sub p}, respectively, being the initial beam length and plasma wavelength.

  6. Direct laser acceleration of electrons in plasma bubbles or ion channels with and without a longitudinal wakefield

    NASA Astrophysics Data System (ADS)

    Khudik, Vladimir; Zhang, Xi; Arefiev, Alexey; Shvets, Gennady

    2017-03-01

    We investigate the motion of electrons in a plasma bubble (or an ion channel) under combined action of an oscillating laser field, quasistatic transverse wakefield, and longitudinal electric field. The longitudinal field E∥ significantly influences the broadband resonance between betatron oscillations of electrons and oscillations of the laser wave, which results in the profoundly different electron dynamics at different signs and magnitudes of the longitudinal force -eE∥. Specifically, we make a contrast between three representative cases: when this force is absent (-eE∥ = 0), when it accelerates electrons (-eE∥ > 0), and when it decelerates them (-eE∥ < 0). We estimate the electron energy gain at given laser-plasma parameters.

  7. Analysis of radial and longitudinal force of plasma wakefield generated by a chirped pulse laser

    SciTech Connect

    Ghasemi, Leila; Afhami, Saeedeh; Eslami, Esmaeil

    2015-08-15

    In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefield generation is studied. Different types of chirps are employed in this study. Our results show that by the use of nonlinear chirped pulse the longitudinal wakefield and focusing force is stronger than that of linear chirped pulse. It is indicated that quadratic nonlinear chirped pulses are globally much efficient than periodic nonlinear chirped pulses. Our calculations also predict that in nonlinear chirped pulse case, the overlap of focusing and accelerating regions is broader than that achieved in linear chirped pulse.

  8. Parallel Higher-order Finite Element Method for Accurate Field Computations in Wakefield and PIC Simulations

    SciTech Connect

    Candel, A.; Kabel, A.; Lee, L.; Li, Z.; Limborg, C.; Ng, C.; Prudencio, E.; Schussman, G.; Uplenchwar, R.; Ko, K.; /SLAC

    2009-06-19

    Over the past years, SLAC's Advanced Computations Department (ACD), under SciDAC sponsorship, has developed a suite of 3D (2D) parallel higher-order finite element (FE) codes, T3P (T2P) and Pic3P (Pic2P), aimed at accurate, large-scale simulation of wakefields and particle-field interactions in radio-frequency (RF) cavities of complex shape. The codes are built on the FE infrastructure that supports SLAC's frequency domain codes, Omega3P and S3P, to utilize conformal tetrahedral (triangular)meshes, higher-order basis functions and quadratic geometry approximation. For time integration, they adopt an unconditionally stable implicit scheme. Pic3P (Pic2P) extends T3P (T2P) to treat charged-particle dynamics self-consistently using the PIC (particle-in-cell) approach, the first such implementation on a conformal, unstructured grid using Whitney basis functions. Examples from applications to the International Linear Collider (ILC), Positron Electron Project-II (PEP-II), Linac Coherent Light Source (LCLS) and other accelerators will be presented to compare the accuracy and computational efficiency of these codes versus their counterparts using structured grids.

  9. Pseudoresonant Laser Wakefield Acceleration Driven by lO.6-micrometer Laser Light

    DTIC Science & Technology

    2005-02-01

    This can bc an electro- magnctic wave. such as in inverse free electron lasers ( IFELs ) Manuscript re"ei’ed Juty 16. 2004: r<)vised Sepkmocr S. 2004...used IFELs . which were chosen primarily for experimental convenience. In fact, the overall STELLA approach can be applied to other acceleration...methods. This approach consists of first creating a microbunch or train of microbunches using the laser-driven mecharism. e.g. , IFEL . The microbunches

  10. Recent Progress at LBNL on Characterization of Laser WakefieldAccelerated Electron Bunches using Coherent Transition Radiation

    SciTech Connect

    Plateau, Guillaume R.; Esarey, Eric H.; Geddes, Cameron G.R.; Leemans, Wim P.; Matlis, Nicholas H.; Schroeder, Carl B.; van Tilborg,Jeroen; Toth, Csaba

    2007-06-25

    At LBNL, laser wakefield accelerators (LWFA) can now produce ultra-short electron bunches with energies up to 1 GeV [1]. As femtosecond electron bunches exit the plasma they radiate an intense burst in the terahertz range [2,3] via coherent transition radiation (CTR). Measuring the CTR properties allows non-invasive bunchlength diagnostics [4], a key to continuing rapid advance in LWFA technology. Experimental bunch length characterization for two different energy regimes through bolometric analysis and electro-optic (EO) sampling are presented. Measurements demonstrate both shot-to-shot stability of bunch parameters, and femtosecond synchronization between the bunch, the THz pulse, and the laser beam. In addition, this method of CTR generation provides THz pulses of very high peak power suitable for applications. Recent results reveal LWFA to be a promising intense ultrafast THz source.

  11. Dose properties of x-ray beams produced by laser-wakefield-accelerated electrons.

    PubMed

    Kainz, K K; Hogstrom, K R; Antolak, J A; Almond, P R; Bloch, C D

    2005-01-07

    Given that laser wakefield acceleration (LWFA) has been demonstrated experimentally to accelerate electron beams to energies beyond 25 MeV, it is reasonable to assess the ability of existing LWFA technology to compete with conventional radiofrequency linear accelerators in producing electron and x-ray beams for external-beam radiotherapy. We present calculations of the dose distributions (off-axis dose profiles and central-axis depth dose) and dose rates of x-ray beams that can be produced from electron beams that are generated using state-of-the-art LWFA. Subsets of an LWFA electron energy distribution were propagated through the treatment head elements (presuming an existing design for an x-ray production target and flattening filter) implemented within the EGSnrc Monte Carlo code. Three x-ray energy configurations (6 MV, 10 MV and 18 MV) were studied, and the energy width deltaE of the electron-beam subsets varied from 0.5 MeV to 12.5 MeV. As deltaE increased from 0.5 MeV to 4.5 MeV, we found that the off-axis and central-axis dose profiles for x-rays were minimally affected (to within about 3%), a result slightly different from prior calculations of electron beams broadened by scattering foils. For deltaE of the order of 12 MeV, the effect on the off-axis profile was of the order of 10%, but the central-axis depth dose was affected by less than 2% for depths in excess of about 5 cm beyond d(max). Although increasing deltaE beyond 6.5 MeV increased the dose rate at d(max) by more than 10 times, the absolute dose rates were about 3 orders of magnitude below those observed for LWFA-based electron beams at comparable energies. For a practical LWFA-based x-ray device, the beam current must be increased by about 4-5 orders of magnitude.

  12. Probing the K-edge of a laser heated aluminum plasma using X-rays from betatron oscillations in a laser wakefield accelerator with femtosecond resolution

    NASA Astrophysics Data System (ADS)

    Behm, Keegan; Hussein, Amina; Zhao, Tony; Hill, Edward; Maksimchuk, Anatoly; Nees, John; Yanovsky, Victor; Mangles, Stuart; Krushelnick, Karl; Thomas, Alexander; CenterUltrafast Optical Science Team; Plasmas Group Team

    2016-10-01

    Presented here are data from a two-beam pump-probe experiment. We used synchrotron-like X-rays created by betatron oscillations to probe a thin metal foil that is pumped by the secondary laser beam. The Hercules Ti:Sapphire laser facility was operated with a pulse duration of 34 fs and a power of 80 TW split. A 75-25 beam splitter was used to drive a laser wakefield accelerator and heat the secondary target. We observed opacity changes around the K-edge of thin aluminum foil as it was heated by an ultrafast pump laser. To understand how the opacity is changing with heating and expansion of the plasma, the delay between the two laser paths was adjusted on a femtosecond time scale from 50 to 400 fs. Experimental data for aluminum shows variation in opacity around the K-edge with changes in the probe delay. The transmitted synchrotron-like spectrum was measured using single photon counting on an X-ray CCD camera and was available on a shot-by-shot basis. The success of this work demonstrates a practical application for X-rays produced from betatron oscillations in a wakefield accelerator. U.S. Department of Energy and the National Nuclear Security Administration.

  13. Femtosecond probing around the K-edge of a laser heated plasma using X-rays from betatron oscillations in a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Behm, Keegan; Zhao, Tony; Maksimchuk, Anatoly; Yanovsky, Victor; Nees, John; Mangles, Stuart; Krushelnick, Karl; Thomas, Alexander; CenterUltrafast Optical Science Team; Plasmas Group Team

    2015-11-01

    Presented here are data from a two-beam pump-probe experiment. We used synchrotron-like X-rays created by betatron oscillations to probe a thin metal foil that is pumped by the secondary laser beam. The Hercules Ti:Sapph laser facility was operated with a pulse duration of 34 fs and a power of 65 TW split to drive a laser wakefield accelerator and heat the secondary target. We observed opacity changes around the K-edge of thin foils as they were heated by an ultrafast pump laser. To understand how the opacity is changing with heating and expansion of the plasma, the delay between the two laser paths was adjusted on a fs and ps time scale. Experimental data for polyvinylidene chloride (PVDC) and aluminum show variations in opacity around the Cl and Al K-edges with changes in the probe delay. The transmitted synchrotron-like spectrum was measured using single photon counting on an X-ray CCD camera and was available on a shot-by-shot basis. The success of this work demonstrates a practical application for X-rays produced from betatron oscillations in a wakefield accelerator. The compact size of these ``table-top'' accelerators and the ultrashort nature of the generated X-ray pulses allows pump-probe experiments that can probe events that occur on the femtosecond time scale.

  14. A New Type of Plasma Wakefield Accelerator Driven By Magnetowaves

    SciTech Connect

    Chen, Pisin; Chang, Feng-Yin; Lin, Guey-Lin; Noble, Robert J.; Sydora, Richard; /Alberta U.

    2011-09-12

    We present a new concept for a plasma wakefield accelerator driven by magnetowaves (MPWA). This concept was originally proposed as a viable mechanism for the 'cosmic accelerator' that would accelerate cosmic particles to ultra-high energies in the astrophysical setting. Unlike the more familiar plasma wakefield accelerator (PWFA) and the laser wakefield accelerator (LWFA) where the drivers, the charged-particle beam and the laser, are independently existing entities, MPWA invokes the high-frequency and high-speed whistler mode as the driver, which is a medium wave that cannot exist outside of the plasma. Aside from the difference in drivers, the underlying mechanism that excites the plasma wakefield via the ponderomotive potential is common. Our computer simulations show that under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over many plasma wavelengths. We suggest that in addition to its celestial application, the MPWA concept can also be of terrestrial utility. A proof-of-principle experiment on MPWA would benefit both terrestrial and celestial accelerator concepts.

  15. Improvements to laser wakefield accelerated electron beam stability, divergence, and energy spread using three-dimensional printed two-stage gas cell targets

    SciTech Connect

    Vargas, M.; Schumaker, W.; He, Z.-H.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Krushelnick, K.; Maksimchuk, A.; Yanovsky, V.; Thomas, A. G. R.

    2014-04-28

    High intensity, short pulse lasers can be used to accelerate electrons to ultra-relativistic energies via laser wakefield acceleration (LWFA) [T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979)]. Recently, it was shown that separating the injection and acceleration processes into two distinct stages could prove beneficial in obtaining stable, high energy electron beams [Gonsalves et al., Nat. Phys. 7, 862 (2011); Liu et al., Phys. Rev. Lett. 107, 035001 (2011); Pollock et al., Phys. Rev. Lett. 107, 045001 (2011)]. Here, we use a stereolithography based 3D printer to produce two-stage gas targets for LWFA experiments on the HERCULES laser system at the University of Michigan. We demonstrate substantial improvements to the divergence, pointing stability, and energy spread of a laser wakefield accelerated electron beam compared with a single-stage gas cell or gas jet target.

  16. Improvements to laser wakefield accelerated electron beam stability, divergence, and energy spread using three-dimensional printed two-stage gas cell targets

    NASA Astrophysics Data System (ADS)

    Vargas, M.; Schumaker, W.; He, Z.-H.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Krushelnick, K.; Maksimchuk, A.; Yanovsky, V.; Thomas, A. G. R.

    2014-04-01

    High intensity, short pulse lasers can be used to accelerate electrons to ultra-relativistic energies via laser wakefield acceleration (LWFA) [T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979)]. Recently, it was shown that separating the injection and acceleration processes into two distinct stages could prove beneficial in obtaining stable, high energy electron beams [Gonsalves et al., Nat. Phys. 7, 862 (2011); Liu et al., Phys. Rev. Lett. 107, 035001 (2011); Pollock et al., Phys. Rev. Lett. 107, 045001 (2011)]. Here, we use a stereolithography based 3D printer to produce two-stage gas targets for LWFA experiments on the HERCULES laser system at the University of Michigan. We demonstrate substantial improvements to the divergence, pointing stability, and energy spread of a laser wakefield accelerated electron beam compared with a single-stage gas cell or gas jet target.

  17. Mitigating Particle Integration Error in Relativistic Laser-Plasma Simulations

    NASA Astrophysics Data System (ADS)

    Higuera, Adam; Weichmann, Kathleen; Cowan, Benjamin; Cary, John

    2016-10-01

    In particle-in-cell simulations of laser wakefield accelerators with a0 greater than unity, errors in particle trajectories produce incorrect beam charges and energies, predicting performance not realized in experiments such as the Texas Petawatt Laser. In order to avoid these errors, the simulation time step must resolve a time scale smaller than the laser period by a factor of a0. If the Yee scheme advances the fields with this time step, the laser wavelength must be over-resolved by a factor of a0 to avoid dispersion errors. Here is presented and demonstrated with Vorpal simulations, a new electromagnetic algorithm, building on previous work, correcting Yee dispersion for arbitrary sub-CFL time steps, reducing simulation times by a0.

  18. Probing plasma wakefield using femtosecond relativistic electron bunches (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Hua, Jianfei

    2017-05-01

    Light-speed moving wakefield structure in a laser plasma accelerator is directly observed and quantitatively reconstructed using an ultrashort relativistic electron probe in a single shot. The stable electron probes utilized here are directly generated through laser wakefield acceleration via ionization injection. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. From the density image of the probe, the local plasma wavelength, the wake width and the electric field in linear wakes can be accurately calculated, leading to the first observation of plasma wakes at the density as low as 1017 cm-3. Furthermore, detailed features of multiple wakes excited by a laser with the aberrated profile are observed and confirmed by 3D PIC simulations. By varying the time delay between the driving laser and the probe, time-resolved observation of the wake evolution (excitation, propagation, and damping) can be readily obtained, and this suggests that ultrafast electron probe can be a powerful new tool for the study of wakefield acceleration. The method is particularly well suited for visualizing linear wakefields that can accelerate both electrons and positrons as well as collective fields associated with shocks and instabilities in plasmas and warm dense matter.

  19. High-Brightness High-Energy Electron Beams from a Laser Wakefield Accelerator via Energy Chirp Control

    NASA Astrophysics Data System (ADS)

    Wang, W. T.; Li, W. T.; Liu, J. S.; Zhang, Z. J.; Qi, R.; Yu, C. H.; Liu, J. Q.; Fang, M.; Qin, Z. Y.; Wang, C.; Xu, Y.; Wu, F. X.; Leng, Y. X.; Li, R. X.; Xu, Z. Z.

    2016-09-01

    By designing a structured gas density profile between the dual-stage gas jets to manipulate electron seeding and energy chirp reversal for compressing the energy spread, we have experimentally produced high-brightness high-energy electron beams from a cascaded laser wakefield accelerator with peak energies in the range of 200-600 MeV, 0.4%-1.2% rms energy spread, 10-80 pC charge, and ˜0.2 mrad rms divergence. The maximum six-dimensional brightness B6 D ,n is estimated as ˜6.5 ×1 015 A /m2/0.1 % , which is very close to the typical brightness of e beams from state-of-the-art linac drivers. These high-brightness high-energy e beams may lead to the realization of compact monoenergetic gamma-ray and intense coherent x-ray radiation sources.

  20. A high current, short pulse electron source for wakefield accelerators

    SciTech Connect

    Ho, Ching-Hung

    1992-12-31

    Design studies for the generation of a high current, short pulse electron source for the Argonne Wakefield Accelerator are presented. An L-band laser photocathode rf gun cavity is designed using the computer code URMEL to maximize the electric field on the cathode surface for fixed frequency and rf input power. A new technique using a curved incoming laser wavefront to minimize the space charge effect near the photocathode is studied. A preaccelerator with large iris to minimize wakefield effects is used to boost the drive beam to a useful energy of around 20 MeV for wakefield acceleration experiments. Focusing in the photocathode gun and the preaccelerator is accomplished with solenoids. Beam dynamics simulations throughout the preaccelerator are performed using particle simulation codes TBCI-SF and PARMELA. An example providing a useful set of operation parameters for the Argonne Wakefield Accelerator is given. The effects of the sagitta of the curved beam and laser amplitude and timing jitter effects are discussed. Measurement results of low rf power level bench tests and a high power test for the gun cavity are presented and discussed.

  1. A high current, short pulse electron source for wakefield accelerators

    SciTech Connect

    Ho, Ching-Hung.

    1992-01-01

    Design studies for the generation of a high current, short pulse electron source for the Argonne Wakefield Accelerator are presented. An L-band laser photocathode rf gun cavity is designed using the computer code URMEL to maximize the electric field on the cathode surface for fixed frequency and rf input power. A new technique using a curved incoming laser wavefront to minimize the space charge effect near the photocathode is studied. A preaccelerator with large iris to minimize wakefield effects is used to boost the drive beam to a useful energy of around 20 MeV for wakefield acceleration experiments. Focusing in the photocathode gun and the preaccelerator is accomplished with solenoids. Beam dynamics simulations throughout the preaccelerator are performed using particle simulation codes TBCI-SF and PARMELA. An example providing a useful set of operation parameters for the Argonne Wakefield Accelerator is given. The effects of the sagitta of the curved beam and laser amplitude and timing jitter effects are discussed. Measurement results of low rf power level bench tests and a high power test for the gun cavity are presented and discussed.

  2. Wakefields in a Dielectric Tube with Frequency Dependent Dielectric Constant

    SciTech Connect

    Siemann, R.H.; Chao, A.W.; /SLAC

    2005-05-27

    Laser driven dielectric accelerators could operate at a fundamental mode frequency where consideration must be given to the frequency dependence of the dielectric constant when calculating wakefields. Wakefields are calculated for a frequency dependence that arises from a single atomic resonance. Causality is considered, and the effects on the short range wakefields are calculated.

  3. Linear to non linear analysis for positron acceleration in plasma hollow channel wakefields

    NASA Astrophysics Data System (ADS)

    Amorim, Ligia Diana; An, Weiming; Mori, Warren B.; Vieira, Jorge

    2016-10-01

    Plasma wakefield accelerators are promising candidates for future generation compact accelerators. The standard regime of operation, non-linear or blowout regime, is reached when a particle bunch space charge or laser pulse ponderomotive force radially expels plasma electrons forming a bucket of ions that defocus positron bunches, thus preventing their acceleration. To avoid defocusing, hollow plasma channels have been considered. The corresponding wakefields have been examined in the linear and non-linear excitation regimes for electrons. It is therefore important to extend the theory for positron acceleration, particularly in the nonlinear regime where the wakefields strongly differ. In this work we explore the wakefield structure, examine the differences between the electron and positron beam cases, and explore positron acceleration in nonlinear regimes. We support our findings with multi-dimensional particle-in-cell simulations performed with OSIRIS and quasi-3D and QuickPIC.

  4. Wakefield accelerators

    SciTech Connect

    Simpson, J.D.

    1990-01-01

    The search for new methods to accelerate particle beams to high energy using high gradients has resulted in a number of candidate schemes. One of these, wakefield acceleration, has been the subject of considerable R D in recent years. This effort has resulted in successful proof of principle experiments and in increased understanding of many of the practical aspects of the technique. Some wakefield basics plus the status of existing and proposed experimental work is discussed, along with speculations on the future of wake field acceleration. 10 refs., 6 figs.

  5. Optical control of hard X-ray polarization by electron injection in a laser wakefield accelerator.

    PubMed

    Schnell, Michael; Sävert, Alexander; Uschmann, Ingo; Reuter, Maria; Nicolai, Maria; Kämpfer, Tino; Landgraf, Björn; Jäckel, Oliver; Jansen, Oliver; Pukhov, Alexander; Kaluza, Malte Christoph; Spielmann, Christian

    2013-01-01

    Laser-plasma particle accelerators could provide more compact sources of high-energy radiation than conventional accelerators. Moreover, because they deliver radiation in femtosecond pulses, they could improve the time resolution of X-ray absorption techniques. Here we show that we can measure and control the polarization of ultra-short, broad-band keV photon pulses emitted from a laser-plasma-based betatron source. The electron trajectories and hence the polarization of the emitted X-rays are experimentally controlled by the pulse-front tilt of the driving laser pulses. Particle-in-cell simulations show that an asymmetric plasma wave can be driven by a tilted pulse front and a non-symmetric intensity distribution of the focal spot. Both lead to a notable off-axis electron injection followed by collective electron-betatron oscillations. We expect that our method for an all-optical steering is not only useful for plasma-based X-ray sources but also has significance for future laser-based particle accelerators.

  6. Optical control of hard X-ray polarization by electron injection in a laser wakefield accelerator

    PubMed Central

    Schnell, Michael; Sävert, Alexander; Uschmann, Ingo; Reuter, Maria; Nicolai, Maria; Kämpfer, Tino; Landgraf, Björn; Jäckel, Oliver; Jansen, Oliver; Pukhov, Alexander; Kaluza, Malte Christoph; Spielmann, Christian

    2013-01-01

    Laser-plasma particle accelerators could provide more compact sources of high-energy radiation than conventional accelerators. Moreover, because they deliver radiation in femtosecond pulses, they could improve the time resolution of X-ray absorption techniques. Here we show that we can measure and control the polarization of ultra-short, broad-band keV photon pulses emitted from a laser-plasma-based betatron source. The electron trajectories and hence the polarization of the emitted X-rays are experimentally controlled by the pulse-front tilt of the driving laser pulses. Particle-in-cell simulations show that an asymmetric plasma wave can be driven by a tilted pulse front and a non-symmetric intensity distribution of the focal spot. Both lead to a notable off-axis electron injection followed by collective electron–betatron oscillations. We expect that our method for an all-optical steering is not only useful for plasma-based X-ray sources but also has significance for future laser-based particle accelerators. PMID:24026068

  7. Clean beams from laser wake-field accelerators via optical injection with a cleanup pulsea)

    NASA Astrophysics Data System (ADS)

    Cary, John R.; Giacone, R. E.; Nieter, C.; Bruhwiler, D. L.

    2005-05-01

    Multiple colliding-pulse injection schemes have been proposed as means for trapping electrons in the ultrashort acceleration buckets of laser-generated wake fields. The primary goal of this paper is to present a parameter study to determine the beams that can be obtained through collisions of collinear laser pulses in uniform plasma. The parameter study is through fully self-consistent, two-dimensional, particle-in-cell simulations, as previous work used only test-particle computations. To remove the multiple beams that can commonly be generated in colliding pulse injection, we use a cleanup pulse, a trailing laser pulse that absorbs the wake. The wake then no longer exists in the region where the trailing beamlets would be, and so the trailing beamlets no longer form. A series of simulations predicts that with such one can obtain single, short (⩽10fs) beams with a bunch charge of order 10pC, normalized emittance of order 2πμm, and energy spread of the order of 10%. The parameters of the beams are insensitive to the amplitude of the backward pulse above normalized amplitudes of abw≈0.4.

  8. High-brightness, high-energy radiation generation from non-linear Thomson scattering of laser wakefield accelerated electrons

    NASA Astrophysics Data System (ADS)

    Schumaker, W.; Zhao, Z.; Thomas, A. G. R.; Krushelnick, K.; Sarri, G.; Corvan, D.; Zepf, M.; Cole, J.; Mangles, S. P. D.; Najmudin, Z.

    2014-10-01

    To date, all-optical sources of high-energy (>MeV) photons have only been reported in the linear (a0 < 1) regime of Thomson scattering using laser wakefield acceleration (LWFA). We present novel results of high-brightness, high-energy photons generated via non-linear Thomson scattering using the two-beam Astra-Gemini laser facility. With one 300 TW beam, electrons were first accelerated to 500 MeV energies inside gas cells through the process of LWFA. A second 300 TW laser pulse focused to a0 = 2 was subsequently scattered off these electrons, resulting in a highly directional, small source size, and short pulse beam of photons with >10 MeV energies. The photon beam was propagated through a low- Z converter and produced Compton-scattered electrons that were spectrally measured by magnetic deflection and correlated with the incident photons. The measured photon yield at 15 MeV was 2 ×106 photons/MeV and, when coupled with the small source size, divergence, and pulse duration, results in a record peak brightness of 2 ×1019 photons/s/mm2/mrad2/0.1%bandwidth at 15 MeV photon energy. Current Affiliation: Stanford University/SLAC National Accelerator Laboratory.

  9. Laser Wakefield Acceleration: Structural and Dynamic Studies. Final Technical Report ER40954

    SciTech Connect

    Downer, Michael C.

    2014-04-30

    -15 seconds) in duration and 150 Joules in energy (equivalent to the muzzle energy of a small pistol bullet). This duration was well matched to the natural electron density oscillation period of plasma of 1/100 atmospheric density, enabling efficient excitation of a plasma wake, while this energy was sufficient to drive a high-amplitude wake of the right shape to produce an energetic, collimated electron beam. Continuing research is aimed at increasing electron energy even further, increasing the number of electrons captured and accelerated, and developing applications of the compact, multi-GeV accelerator as a coherent, hard x-ray source for materials science, biomedical imaging and homeland security applications. The second major advance under this project was to develop new methods of visualizing the laser-driven plasma wake structures that underlie laser-plasma accelerators. Visualizing these structures is essential to understanding, optimizing and scaling laser-plasma accelerators. Yet prior to work under this project, computer simulations based on estimated initial conditions were the sole source of detailed knowledge of the complex, evolving internal structure of laser-driven plasma wakes. In this project we developed and demonstrated a suite of optical visualization methods based on well-known methods such as holography, streak cameras, and coherence tomography, but adapted to the ultrafast, light-speed, microscopic world of laser-driven plasma wakes. Our methods output images of laser-driven plasma structures in a single laser shot. We first reported snapshots of low-amplitude laser wakes in Nature Physics in 2006. We subsequently reported images of high-amplitude laser-driven plasma “bubbles”, which are important for producing electron beams with low energy spread, in Physical Review Letters in 2010. More recently, we have figured out how to image laser-driven structures that change shape while propagating in a single laser shot. The latter techniques, which use

  10. High field terahertz emission from relativistic laser-driven plasma wakefields

    SciTech Connect

    Chen, Zi-Yu; Pukhov, Alexander

    2015-10-15

    We propose a method to generate high field terahertz (THz) radiation with peak strength of GV/cm level in the THz frequency gap range of 1–10 THz using a relativistic laser interaction with a gaseous plasma target. Due to the effect of local pump depletion, an initially Gaussian laser pulse undergoes leading edge erosion and eventually evolves to a state with leading edge being step function. Interacting with such a pulse, electrons gain transverse residual momentum and excite net transverse currents modulated by the relativistic plasma frequency. These currents give rise to the low frequency THz emission. We demonstrate this process with one and two dimensional particle-in-cell simulations.

  11. Dependence of electron trapping on bubble geometry in laser-plasma wakefield acceleration

    SciTech Connect

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

    2014-07-15

    The effect of bubble shape in laser-plasma electron acceleration was investigated. We showed the general existence of an ellipsoid bubble. The electromagnetic field in this bubble and its dependence on bubble shape were determined through theory. The electron-trapping cross-section for different bubble aspect ratios was studied in detail. When the shape of the bubble was close to spherical, the trapping cross-section reached to the maximum. When the bubble deviated from a spherical shape, the cross-section decreased until electron injection no longer occurred. These results were confirmed by particle-in-cell simulation.

  12. Note: Real-time monitoring via second-harmonic interferometry of a flow gas cell for laser wakefield acceleration.

    PubMed

    Brandi, F; Giammanco, F; Conti, F; Sylla, F; Lambert, G; Gizzi, L A

    2016-08-01

    The use of a gas cell as a target for laser wakefield acceleration (LWFA) offers the possibility to obtain stable and manageable laser-plasma interaction process, a mandatory condition for practical applications of this emerging technique, especially in multi-stage accelerators. In order to obtain full control of the gas particle number density in the interaction region, thus allowing for a long term stable and manageable LWFA, real-time monitoring is necessary. In fact, the ideal gas law cannot be used to estimate the particle density inside the flow cell based on the preset backing pressure and the room temperature because the gas flow depends on several factors like tubing, regulators, and valves in the gas supply system, as well as vacuum chamber volume and vacuum pump speed/throughput. Here, second-harmonic interferometry is applied to measure the particle number density inside a flow gas cell designed for LWFA. The results demonstrate that real-time monitoring is achieved and that using low backing pressure gas (<1 bar) and different cell orifice diameters (<2 mm) it is possible to finely tune the number density up to the 10(19) cm(-3) range well suited for LWFA.

  13. Note: Real-time monitoring via second-harmonic interferometry of a flow gas cell for laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Brandi, F.; Giammanco, F.; Conti, F.; Sylla, F.; Lambert, G.; Gizzi, L. A.

    2016-08-01

    The use of a gas cell as a target for laser wakefield acceleration (LWFA) offers the possibility to obtain stable and manageable laser-plasma interaction process, a mandatory condition for practical applications of this emerging technique, especially in multi-stage accelerators. In order to obtain full control of the gas particle number density in the interaction region, thus allowing for a long term stable and manageable LWFA, real-time monitoring is necessary. In fact, the ideal gas law cannot be used to estimate the particle density inside the flow cell based on the preset backing pressure and the room temperature because the gas flow depends on several factors like tubing, regulators, and valves in the gas supply system, as well as vacuum chamber volume and vacuum pump speed/throughput. Here, second-harmonic interferometry is applied to measure the particle number density inside a flow gas cell designed for LWFA. The results demonstrate that real-time monitoring is achieved and that using low backing pressure gas (<1 bar) and different cell orifice diameters (<2 mm) it is possible to finely tune the number density up to the 1019 cm-3 range well suited for LWFA.

  14. Note: Real-time monitoring via second-harmonic interferometry of a flow gas cell for laser wakefield acceleration

    SciTech Connect

    Brandi, F.; Giammanco, F.; Conti, F.; Lambert, G.; Gizzi, L. A.

    2016-08-15

    The use of a gas cell as a target for laser wakefield acceleration (LWFA) offers the possibility to obtain stable and manageable laser-plasma interaction process, a mandatory condition for practical applications of this emerging technique, especially in multi-stage accelerators. In order to obtain full control of the gas particle number density in the interaction region, thus allowing for a long term stable and manageable LWFA, real-time monitoring is necessary. In fact, the ideal gas law cannot be used to estimate the particle density inside the flow cell based on the preset backing pressure and the room temperature because the gas flow depends on several factors like tubing, regulators, and valves in the gas supply system, as well as vacuum chamber volume and vacuum pump speed/throughput. Here, second-harmonic interferometry is applied to measure the particle number density inside a flow gas cell designed for LWFA. The results demonstrate that real-time monitoring is achieved and that using low backing pressure gas (<1 bar) and different cell orifice diameters (<2 mm) it is possible to finely tune the number density up to the 10{sup 19} cm{sup −3} range well suited for LWFA.

  15. Injection of electrons into a laser wakefield accelerator driven in a capillary discharge waveguide using an embedded gas jet

    NASA Astrophysics Data System (ADS)

    Gonsalves, Anthony; Panasenko, Dmitriy; Nakamura, Kei; Lin, Chen; Monaghan, Eamonn; Toth, Csaba; Geddes, Cameron; Schroeder, Carl; Esarey, Eric; Leemans, Wim

    2008-11-01

    A key issue in laser wakefield accelerators (LWFAs) is injection of electrons into the accelerating region of the wake. Typically electron beams have been self-injected into the wake, requiring a higher plasma density than that for an optimized accelerating structure. This in turn limits the electron beam energy and quality that can be achieved. In this talk it is shown that this coupling of injection and acceleration can be addressed for LWFA in a capillary discharge waveguide with the use of a gas jet embedded into the capillary. Previous experiments without a gas jet have shown self-trapping and acceleration of electrons with energy up to 1 GeV [Leemans et al., Nature Phys. Vol. 2, 696, 2006]. The addition of a gas jet in this work has shown that injection can be turned on or off by a local density perturbation. Hence high-energy electrons can be produced for densities in the capillary lower than otherwise possible without the jet. Results will also be presented on the improvement of electron beam properties, as well as laser spectral modulation and pump depletion.

  16. Simulations of laser undulators

    NASA Astrophysics Data System (ADS)

    Milton, S. V.; Biedron, S. B.; Einstein, J. E.

    2016-09-01

    We perform a series of single-pass, one-D free-electron laser simulations based on an electron beam from a standard linear accelerator coupled with a so-called laser undulator, a specialized device that is more compact than a standard undulator based on magnetic materials. The longitudinal field profiles of such lasers undulators are intriguing as one must and can tailor the profile for the needs of creating the virtual undulator. We present and discuss several results of recent simulations and our future steps.

  17. Observation of Betatron X-Ray Radiation in a Self-Modulated Laser Wakefield Accelerator Driven with Picosecond Laser Pulses

    DOE PAGES

    Albert, F.; Lemos, N.; Shaw, J. L.; ...

    2017-03-31

    We investigate a new regime for betatron x-ray emission that utilizes kilojoule-class picosecond lasers to drive wakes in plasmas. When such laser pulses with intensities of ~ 5 × 1 0 18 W / cm 2 are focused into plasmas with electron densities of ~ 1 × 1 0 19 cm - 3 , they undergo self-modulation and channeling, which accelerates electrons up to 200 MeV energies and causes those electrons to emit x rays. The measured x-ray spectra are fit with a synchrotron spectrum with a critical energy of 10–20 keV, and 2D particle-in-cell simulations were used to modelmore » the acceleration and radiation of the electrons in our experimental conditions« less

  18. Observation of Betatron X-Ray Radiation in a Self-Modulated Laser Wakefield Accelerator Driven with Picosecond Laser Pulses.

    PubMed

    Albert, F; Lemos, N; Shaw, J L; Pollock, B B; Goyon, C; Schumaker, W; Saunders, A M; Marsh, K A; Pak, A; Ralph, J E; Martins, J L; Amorim, L D; Falcone, R W; Glenzer, S H; Moody, J D; Joshi, C

    2017-03-31

    We investigate a new regime for betatron x-ray emission that utilizes kilojoule-class picosecond lasers to drive wakes in plasmas. When such laser pulses with intensities of ∼5×10^{18}  W/cm^{2} are focused into plasmas with electron densities of ∼1×10^{19}  cm^{-3}, they undergo self-modulation and channeling, which accelerates electrons up to 200 MeV energies and causes those electrons to emit x rays. The measured x-ray spectra are fit with a synchrotron spectrum with a critical energy of 10-20 keV, and 2D particle-in-cell simulations were used to model the acceleration and radiation of the electrons in our experimental conditions.

  19. Laser wakefield generated X-ray probe for femtosecond time-resolved measurements of ionization states of warm dense aluminum.

    PubMed

    Mo, M Z; Chen, Z; Fourmaux, S; Saraf, A; Otani, K; Kieffer, J C; Tsui, Y Y; Ng, A; Fedosejevs, R

    2013-12-01

    We have developed a laser wakefield generated X-ray probe to directly measure the temporal evolution of the ionization states in warm dense aluminum by means of absorption spectroscopy. As a promising alternative to the free electron excited X-ray sources, Betatron X-ray radiation, with femtosecond pulse duration, provides a new technique to diagnose femtosecond to picosecond transitions in the atomic structure. The X-ray probe system consists of an adjustable Kirkpatrick-Baez (KB) microscope for focusing the Betatron emission to a small probe spot on the sample being measured, and a flat Potassium Acid Phthalate Bragg crystal spectrometer to measure the transmitted X-ray spectrum in the region of the aluminum K-edge absorption lines. An X-ray focal spot size of around 50 μm was achieved after reflection from the platinum-coated 10-cm-long KB microscope mirrors. Shot to shot positioning stability of the Betatron radiation was measured resulting in an rms shot to shot variation in spatial pointing on the sample of 16 μm. The entire probe setup had a spectral resolution of ~1.5 eV, a detection bandwidth of ~24 eV, and an overall photon throughput efficiency of the order of 10(-5). Approximately 10 photons were detected by the X-ray CCD per laser shot within the spectrally resolved detection band. Thus, it is expected that hundreds of shots will be required per absorption spectrum to clearly observe the K-shell absorption features expected from the ionization states of the warm dense aluminum.

  20. Laser wakefield generated X-ray probe for femtosecond time-resolved measurements of ionization states of warm dense aluminum

    SciTech Connect

    Mo, M. Z.; Chen, Z.; Tsui, Y. Y.; Fedosejevs, R.; Fourmaux, S.; Saraf, A.; Otani, K.; Kieffer, J. C.; Ng, A.

    2013-12-15

    We have developed a laser wakefield generated X-ray probe to directly measure the temporal evolution of the ionization states in warm dense aluminum by means of absorption spectroscopy. As a promising alternative to the free electron excited X-ray sources, Betatron X-ray radiation, with femtosecond pulse duration, provides a new technique to diagnose femtosecond to picosecond transitions in the atomic structure. The X-ray probe system consists of an adjustable Kirkpatrick-Baez (KB) microscope for focusing the Betatron emission to a small probe spot on the sample being measured, and a flat Potassium Acid Phthalate Bragg crystal spectrometer to measure the transmitted X-ray spectrum in the region of the aluminum K-edge absorption lines. An X-ray focal spot size of around 50 μm was achieved after reflection from the platinum-coated 10-cm-long KB microscope mirrors. Shot to shot positioning stability of the Betatron radiation was measured resulting in an rms shot to shot variation in spatial pointing on the sample of 16 μm. The entire probe setup had a spectral resolution of ∼1.5 eV, a detection bandwidth of ∼24 eV, and an overall photon throughput efficiency of the order of 10{sup −5}. Approximately 10 photons were detected by the X-ray CCD per laser shot within the spectrally resolved detection band. Thus, it is expected that hundreds of shots will be required per absorption spectrum to clearly observe the K-shell absorption features expected from the ionization states of the warm dense aluminum.

  1. The Argonne Wakefield Accelerator (AWA) laser system and its associated optics

    SciTech Connect

    Gai, W.; Konecny, R.; Power, J.

    1992-07-01

    Generating a 100 nC, 15 ps pulse length electron beam at the AWA requires a stable laser system capable of producing 1--3 ps, 5 mJ at 248 nm with the ability to shape the wave front. We have installed a combined Coherent ultra fast 702 dye laser and Lambda Physik excimer pulsed amplification system which meets these requirements. A device has been built to produce shaped laser pulses. Detailed characterizations of the laser system, its associated optics development, and timing/amplitude stabilization are presented.

  2. Laser Ranging Simulation Program

    NASA Technical Reports Server (NTRS)

    Piazolla, Sabino; Hemmati, Hamid; Tratt, David

    2003-01-01

    Laser Ranging Simulation Program (LRSP) is a computer program that predicts selected aspects of the performances of a laser altimeter or other laser ranging or remote-sensing systems and is especially applicable to a laser-based system used to map terrain from a distance of several kilometers. Designed to run in a more recent version (5 or higher) of the MATLAB programming language, LRSP exploits the numerical and graphical capabilities of MATLAB. LRSP generates a graphical user interface that includes a pop-up menu that prompts the user for the input of data that determine the performance of a laser ranging system. Examples of input data include duration and energy of the laser pulse, the laser wavelength, the width of the laser beam, and several parameters that characterize the transmitting and receiving optics, the receiving electronic circuitry, and the optical properties of the atmosphere and the terrain. When the input data have been entered, LRSP computes the signal-to-noise ratio as a function of range, signal and noise currents, and ranging and pointing errors.

  3. Wakefield Generation in Plasma Channels

    NASA Astrophysics Data System (ADS)

    Volfbeyn, P.; Leemans, W. P.; Brussaard, G. J. H.; Esarey, E.; Wurtele, J. S.

    1999-11-01

    Laser wakefield generation in plasma channels is experimentally studied. Plasma channels, produced using the ignitor-heater method [1] in hydrogen and nitrogen, have been used to guide intense (> 5 x 10^17 W/cm^2), short (<70 fs) infrared (800 nm) laser pulses. Laser pulses injected into these channels produce a plasma wake with a phase velocity close to the speed of light. The transverse density profile of the channel determines the properties of the laser mode as well as of the plasma wave mode. The longitudinally integrated properties of the channel are measured with a Mach-Zehnder interferometer using 400 nm radiation. The probe and reference beam are combined directly on a CCD camera to provide two-dimensional interferograms and also through a spectrometer to allow Fourier domain interferometry. Progress on measuring the transverse channel profile and wakefield amplitudes will be presented. [1] P. Volfbeyn, E. Esarey and W.P. Leemans, Phys. Plasmas 6, 2269 (1999).

  4. LASER WAKEFIELD ACCELERATION BEYOND 1 GeV USING IONIZATION INDUCED INJECTION*

    SciTech Connect

    Marsh, K A; Clayton, C E; Joshi, C; Lu, W; Mori, W B; Pak, A; silva, L O; Lemos, N; Fonseca, R A; de Freitas, S; Albert, F; Doeppner, T; Filip, C; Froula, D; Glenzer, S H; Price, D; Ralph, J; Pollock, B B

    2011-03-22

    A series of laser wake field accelerator experiments leading to electron energy exceeding 1 GeV are described. Theoretical concepts and experimental methods developed while conducting experiments using the 10 TW Ti:Sapphire laser at UCLA were implemented and transferred successfully to the 100 TW Callisto Laser System at the Jupiter Laser Facility at LLNL. To reach electron energies greater than 1 GeV with current laser systems, it is necessary to inject and trap electrons into the wake and to guide the laser for more than 1 cm of plasma. Using the 10 TW laser, the physics of self-guiding and the limitations in regards to pump depletion over cm-scale plasmas were demonstrated. Furthermore, a novel injection mechanism was explored which allows injection by ionization at conditions necessary for generating electron energies greater than a GeV. The 10 TW results were followed by self-guiding at the 100 TW scale over cm plasma lengths. The energy of the self-injected electrons, at 3 x 10{sup 18} cm{sup -3} plasma density, was limited by dephasing to 720 MeV. Implementation of ionization injection allowed extending the acceleration well beyond a centimeter and 1.4 GeV electrons were measured.

  5. Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic

    SciTech Connect

    Bakeman, M.S.; Van Tilborg, J.; Nakamura, K.; Gonsalves, A.; Osterhoff, J.; Sokollik, T.; Lin, C.; Robinson, K.E.; Schroeder, C.B.; Toth, Cs.; Weingartner, R.; Gruner, F.; Esarey, E.; Leemans, W.P.

    2010-06-01

    The design and current status of experiments to couple the Tapered Hybrid Undulator (THUNDER) to the Lawrence Berkeley National Laboratory (LBNL) laser plasma accelerator (LPA) to measure electron beam energy spread and emittance are presented.

  6. Plasma based wakefield acceleration using a 46MeV multibunched electron beam

    NASA Astrophysics Data System (ADS)

    Kallos, Efthymios; Ben-Zvi, Ilan; Zhou, Feng; Kimura, Wayne

    2005-10-01

    In the multibunch plasma wakefield acceleration scheme a series of electron microbunches are fed into a high density plasma and resonantly excite a wakefield that can accelerate the beam electrons. Here we present some recent experimental results conducted at Brookhaven's Accelerator test Facility (ATF) where ˜90 microbunches at 46MeV created through the IFEL effect with a 10.6μm CO2 laser interact with a high density 10^19cm-3 12mm long plasma. Some further PIC simulations provide insight into the physics of the interaction.

  7. Demonstration of a narrow energy spread, ∼0.5  GeV electron beam from a two-stage laser wakefield accelerator.

    PubMed

    Pollock, B B; Clayton, C E; Ralph, J E; Albert, F; Davidson, A; Divol, L; Filip, C; Glenzer, S H; Herpoldt, K; Lu, W; Marsh, K A; Meinecke, J; Mori, W B; Pak, A; Rensink, T C; Ross, J S; Shaw, J; Tynan, G R; Joshi, C; Froula, D H

    2011-07-22

    Laser wakefield acceleration of electrons holds great promise for producing ultracompact stages of GeV scale, high-quality electron beams for applications such as x-ray free electron lasers and high-energy colliders. Ultrahigh intensity laser pulses can be self-guided by relativistic plasma waves (the wake) over tens of vacuum diffraction lengths, to give >1  GeV energy in centimeter-scale low density plasmas using ionization-induced injection to inject charge into the wake even at low densities. By restricting electron injection to a distinct short region, the injector stage, energetic electron beams (of the order of 100 MeV) with a relatively large energy spread are generated. Some of these electrons are then further accelerated by a second, longer accelerator stage, which increases their energy to ∼0.5  GeV while reducing the relative energy spread to <5% FWHM.

  8. Laser-Wakefield driven compact Compton scattering gamma-ray source

    SciTech Connect

    Albert, F.; Froula, D. H.; Hartemann, F. V.; Joshi, C.

    2010-04-13

    We propose to demonstrate a novel x-ray and gamma-ray light source based on laser-plasma electron acceleration and Compton scattering at the Jupiter Laser Facility at LLNL. This will provide a new versatile and compact light source capability at the laboratory with very broad scientific applications that are of interest to many disciplines. The source’s synchronization with the seed laser system at a femtosecond time scale (i-e, at which chemical reactions occur) will allow scientists to perform pump-probe experiments with x-ray and gamma-ray beams. Across the laboratory, this will be a new tool for nuclear science, high energy density physics, chemistry, biology, or weapons studies.

  9. MeV-energy x rays from inverse compton scattering with laser-wakefield accelerated electrons.

    PubMed

    Chen, S; Powers, N D; Ghebregziabher, I; Maharjan, C M; Liu, C; Golovin, G; Banerjee, S; Zhang, J; Cunningham, N; Moorti, A; Clarke, S; Pozzi, S; Umstadter, D P

    2013-04-12

    We report the generation of MeV x rays using an undulator and accelerator that are both driven by the same 100-terawatt laser system. The laser pulse driving the accelerator and the scattering laser pulse are independently optimized to generate a high energy electron beam (>200  MeV) and maximize the output x-ray brightness. The total x-ray photon number was measured to be ∼1×10(7), the source size was 5  μm, and the beam divergence angle was ∼10  mrad. The x-ray photon energy, peaked at 1 MeV (reaching up to 4 MeV), exceeds the thresholds of fundamental nuclear processes (e.g., pair production and photodisintegration).

  10. Controlled electron injection in laser wakefield accelerators using axially tailored plasmas

    NASA Astrophysics Data System (ADS)

    Gonsalves, Anthony

    2009-11-01

    Controlling injection of electrons in laser plasma accelerators (LPA's) is crucial for improving the beam quality and enabling applications such as free electron lasers (FEL's). In addition, techniques are needed to control the amount of charge, energy and energy spread. To date, LPA's have typically operated in a highly nonlinear regime in which electrons are self-injected into a laser-excited plasma density wave. Although percent level energy spread beams have been demonstrated experimentally [1-4], production of lower energy spread beams will require accurate control of the injection process. In order to avoid self-trapping, an LPA would have to operate with lower wake amplitude, whether linear or non-linear. This also necessitates the use of a laser guiding structure to overcome diffraction of the laser beam. Such guiding structures have been obtained by transversely shaping the plasma density profile and they have successfully been used in experiments using laser-produced [2] or capillary-based channels [4]. In this talk, experimental results are presented that demonstrate the use of a longitudinally tailored plasma density profile in a capillary discharge waveguide to control trapping, significantly improving LPA performance. A gas jet was embedded in the capillary to locally alter the plasma density. It was found that electrons can be trapped and accelerated to hundreds of MeV using plasma densities in the capillary lower than in previous experiments, where no stable self-trapped electron beams were obtained in previous experiments [5]. It is found that using a longitudinally tailored density profile improves and increases control over electron beam properties. [4pt] [1] Mangles et al., Nature 431, 535 (2004)[0pt] [2] Geddes et al., Nature 431, 538 (2004)[0pt] [3] Faure et al., Nature 431, 541 (2004)[0pt] [4] Leemans et al., Nat. Phys. 2, 696 (2006)[0pt] [5] Nakamura et al., Phys. Plasmas 14, 056708 (2007)

  11. Absorber for wakefield interference management at the entrance of the wiggler of a free electron laser

    DOEpatents

    Marchlik, Matthew; Biallas, George Herman

    2017-03-07

    A method for managing the broad band microwave and TeraHertz (THz) radiation in a free electron laser (FEL) having a wiggler producing power in the electromagnetic spectrum. The method includes placement of broadband microwave and TeraHertz (THz) radiation absorbers on the upstream end of the wiggler. The absorbers dampen the bounced back, broad band microwave and THz radiation returning from the surfaces outside the nose of the cookie-cutter and thus preventing broadening of the electron beam pulse's narrow longitudinal energy distribution. Broadening diminishes the ultimate laser power from the wiggler. The broadband microwave and THz radiation absorbers are placed on either side of the slot in the cookie-cutter that shapes the wake field wave of the electron pulse to the slot shape of the wiggler chamber aperture. The broad band microwave and THz radiation absorber is preferably a non-porous pyrolytic grade of graphite with small grain size.

  12. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    PubMed Central

    Gessner, Spencer; Adli, Erik; Allen, James M.; An, Weiming; Clarke, Christine I.; Clayton, Chris E.; Corde, Sebastien; Delahaye, J. P.; Frederico, Joel; Green, Selina Z.; Hast, Carsten; Hogan, Mark J.; Joshi, Chan; Lindstrøm, Carl A.; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-01-01

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m−1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations. PMID:27250570

  13. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator.

    PubMed

    Gessner, Spencer; Adli, Erik; Allen, James M; An, Weiming; Clarke, Christine I; Clayton, Chris E; Corde, Sebastien; Delahaye, J P; Frederico, Joel; Green, Selina Z; Hast, Carsten; Hogan, Mark J; Joshi, Chan; Lindstrøm, Carl A; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A; Mori, Warren B; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m(-1) is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

  14. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    DOE PAGES

    Gessner, Spencer; Adli, Erik; Allen, James M.; ...

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. In this study, we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel ismore » created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m-1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.« less

  15. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    SciTech Connect

    Gessner, Spencer; Adli, Erik; Allen, James M.; An, Weiming; Clarke, Christine I.; Clayton, Chris E.; Corde, Sebastien; Delahaye, J. P.; Frederico, Joel; Green, Selina Z.; Hast, Carsten; Hogan, Mark J.; Joshi, Chan; Lindstrøm, Carl A.; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; O’Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. In this study, we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m-1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

  16. High Flux Spatially Coherent X-ray Generation from Laser Wakefield Accelerators

    NASA Astrophysics Data System (ADS)

    McGuffey, Chris

    2011-10-01

    Nonlinear plasma waves driven by existing ultra-intense short-pulse lasers can trap large numbers of electrons from the plasma (as many as 5 ×109) and accelerate them to ~ GeV energy over ~ 1 cm . The details of the trapping process and plasma wave structure dictate that the trapped electrons undergo transverse oscillatory motion on the microscopic scale of the plasma structure, resulting in short wavelength betatron radiation. These x-ray beams are presumed to retain the short-pulse characteristic of the laser, resulting in high peak flux, making the source a candidate for ultrafast temporally resolved imaging applications. Presented here are experimental studies of the scalings of fluence upon laser power, gas jet length, and electron beam parameters. The spectrum was directly measured by single hit spectroscopy to be broad and smooth with peak photon energy exceeding 10 keV . Additional measurements indicate that the beam source size can be as small as 1 μm and that the radiation exhibits spatial coherence. These two key characteristics allow advanced imaging capabilities including phase contrast imaging and tomography, as demonstrated by radiography studies of biological specimens. Collaborators: S. Kneip (Imperial College London), T. Matsuoka (Present affiliation: Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science), W. Schumaker, V. Chvykov, F. Dollar, M. Vargas, G. Kalintchenko, V. Yanovsky, A. Maksimchuk, A. G. R. Thomas, and K. Krushelnick (University of Michigan). This work was supported by the NSF (award PHY-0114336), the NSF/DNDO (award F021166), and the NRC (award 38-09-953).

  17. Application of laser-wakefield-based x-ray source to global food security issues

    NASA Astrophysics Data System (ADS)

    Kieffer, J. C.; Fourmaux, S.; Hallin, E.; Arnison, P.; Brereton, N.; Pitre, F.; Dixon, M.; Tran, N.

    2017-05-01

    We present the development of a high throughput phase contrast screening system based on LWFA Xray sources for plant imaging. We upgraded the INRS laser-betatron beam line and we illustrate its imaging potential through the innovative development of new tools for addressing issues relevant to global food security. This initiative, led by the Global Institute of Food Security (GIFS) at the U of Saskatchewan, aims to elucidate that part of the function that maps environmental inputs onto specific plant phenotypes. The prospect of correlating phenotypic expression with adaptation to environmental stresses will provide researchers with a new tool to assess breeding programs for crops meant to thrive under the climate extremes.

  18. Transverse Electron Motion and Multiple Electron Injection in Blowout Bubble of Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    An analytical formula for electron motion in a spherical bubble was compared with data from electron acceleration experiments using the HERCULES laser system showing reasonable agreement. This also provides evidence for continuous injection of electrons into the bubble with multiple bunches in the bubble separated both transversely and longitudinally. The only free parameter in the analytical model was radius of the bubble (rb) which was found to be close to the matched spot size for self focusing. The RMS electron beam divergence is found to increase with bunch charge also suggesting tradeoff between beam divergence and photon number in applications for such beams as an x-ray source.

  19. Terahertz radiation as a bunch diagnostic for laser-wakefield-accelerated electron bunches

    SciTech Connect

    van Tilborg, Jeroen; Schroeder, Carl; Filip, Catalin; Toth, Csaba; Geddes, Cameron; Fubiani, Gwenael; Esarey, Eric; Leemans, Wim

    2011-06-17

    Experimental results are reported from two measurement techniques (semiconductor switching and electro-optic sampling) that allow temporal characterization of electron bunches produced by a laser-driven plasma-based accelerator. As femtosecond electron bunches exit the plasma-vacuum interface, coherent transition radiation (at THz frequencies) is emitted. Measuring the properties of this radiation allows characterization of the electron bunches. Theoretical work on the emission mechanism is presented, including a model that calculates the THz wave form from a given bunch profile. It is found that the spectrum of the THz pulse is coherent up to the 200 {micro}m thick crystal (ZnTe) detection limit of 4 THz, which corresponds to the production of sub-50 fs (rms) electron bunch structure. The measurements demonstrate both the shot-to-shot stability of bunch parameters that are critical to THz emission (such as total charge and bunch length), as well as femtosecond synchronization among bunch, THz pulse, and laser beam.

  20. Generation of 500 MeV-1 GeV energy electrons from laser wakefield acceleration via ionization induced injection using CO{sub 2} mixed in He

    SciTech Connect

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

    2013-04-01

    Laser wakefield acceleration of 500 MeV to 1 GeV electron bunches has been demonstrated using ionization injection in mixtures of 4% to 10% of CO{sub 2} in He. 80 TW laser pulses were propagated through 5 mm gas jet targets at electron densities of 0.4-1.5 Multiplication-Sign 10{sup 19}cm{sup -3}. Ionization injection led to lower density thresholds, a higher total electron charge, and an increased probability of producing electrons above 500 MeV in energy compared to self-injection in He gas alone. Electrons with GeV energies were also observed on a few shots and indicative of an additional energy enhancement mechanism.

  1. Acceleration of on-axis and ring-shaped electron beams in wakefields driven by Laguerre-Gaussian pulses

    SciTech Connect

    Zhang, Guo-Bo; Chen, Min E-mail: yanyunma@126.com; Luo, Ji; Zeng, Ming; Yuan, Tao; Yu, Ji-Ye; Yu, Lu-Le; Weng, Su-Ming; Ma, Yan-Yun E-mail: yanyunma@126.com; Yu, Tong-Pu; Sheng, Zheng-Ming

    2016-03-14

    The acceleration of electron beams with multiple transverse structures in wakefields driven by Laguerre-Gaussian pulses has been studied through three-dimensional (3D) particle-in-cell simulations. Under different laser-plasma conditions, the wakefield shows different transverse structures. In general cases, the wakefield shows a donut-like structure and it accelerates the ring-shaped hollow electron beam. When a lower plasma density or a smaller laser spot size is used, besides the donut-like wakefield, a central bell-like wakefield can also be excited. The wake sets in the center of the donut-like wake. In this case, both a central on-axis electron beam and a ring-shaped electron beam are simultaneously accelerated. Further, reducing the plasma density or laser spot size leads to an on-axis electron beam acceleration only. The research is beneficial for some potential applications requiring special pulse beam structures, such as positron acceleration and collimation.

  2. Analog Simulation of a Laser.

    ERIC Educational Resources Information Center

    Kessler, Gary

    1982-01-01

    Presents an analog simulation of laser properties (finding time evolution of the intensity of a ruby laser pulse) which serves as the basis of a three-four hour laboratory experiment. Includes programs for solution to rate equations of a three-level laser and production of a giant pulse in a ruby laser. (Author/SK)

  3. Analog Simulation of a Laser.

    ERIC Educational Resources Information Center

    Kessler, Gary

    1982-01-01

    Presents an analog simulation of laser properties (finding time evolution of the intensity of a ruby laser pulse) which serves as the basis of a three-four hour laboratory experiment. Includes programs for solution to rate equations of a three-level laser and production of a giant pulse in a ruby laser. (Author/SK)

  4. Spectroscopy of betatron radiation emitted from laser-produced wakefield accelerated electrons.

    PubMed

    Thorn, D B; Geddes, C G R; Matlis, N H; Plateau, G R; Esarey, E H; Battaglia, M; Schroeder, C B; Shiraishi, S; Stöhlker, Th; Tóth, C; Leemans, W P

    2010-10-01

    X-ray betatron radiation is produced by oscillations of electrons in the intense focusing field of a laser-plasma accelerator. These hard x-rays show promise for use in femtosecond-scale time-resolved radiography of ultrafast processes. However, the spectral characteristics of betatron radiation have only been inferred from filter pack measurements. In order to achieve higher resolution spectral information about the betatron emission, we used an x-ray charge-coupled device to record the spectrum of betatron radiation, with a full width at half maximum resolution of 225 eV. In addition, we have recorded simultaneous electron and x-ray spectra along with x-ray images that allow for a determination of the betatron emission source size, as well as differences in the x-ray spectra as a function of the energy spectrum of accelerated electrons.

  5. High-energy Coherent THz radiation From Laser Wakefield Accelerated Ultrashort Electron Bunches

    NASA Astrophysics Data System (ADS)

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

    2003-10-01

    We report on the observation of coherent THz radiation from femtosecond laser-accelerated electron bunches [1]. These multi-nC bunches, concentrated in a length of a few plasma periods (several tens of microns) will experience a strongly reduced space charge force due to shielding by the background ions. The radiation, scaling quadratically with bunch charge, is a combination of diffraction and transition radiation by the electrons passing the plasma-vacuum boundary. If both a large collection angle as well as a large transverse plasma size are realized, theory predicts energies on the other of 0.1 mJ per THz pulse for current electron beam properties. A first improvement of the collection angle has increased the detected energy from 5 nJ to 80 nJ. Recent results on the characterization of this source (such as the spectrum) will be discussed and electron beam properties at the boundary will be addressed. (This work is performed under DOE-contract DE-AC-03-76SF0098) [1] W. P. Leemans et al., Phys. Rev. Lett., in press (2003)

  6. Role of stochastic heating in wakefield acceleration when optical injection is used

    SciTech Connect

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

    2014-08-15

    The dynamics of an electron in two counterpropagating waves is investigated. Conditions for stochastic acceleration are derived. The possibility of stochastic heating is confirmed when two waves interact with low density plasma by performing PIC (Particle In Cell) code simulations. It is shown that stochastic heating can play an important role in laser wakefield acceleration. When considering low density plasma interacting with a high intensity wave perturbed by a low intensity counterpropagating wave, stochastic heating can provide electrons with the right momentum for trapping in the wakefield. The influence of stochastic acceleration on the trapping of electrons is compared to the one of the beatwave force which is responsible for cold injection. To do so, several polarizations for the colliding pulses are considered. For some value of the plasma density and pulse duration, a transition from an injection due to stochastic acceleration to a cold injection dominated regime—regarding the trapped charge—has been observed from 2D and 3D PIC code simulations. This transition is ruled by the ratio of the interaction length of the pulses to the longitudinal size of the bubble. When the interaction length of the laser pulses reaches the radius of the accelerating cavity stochastic heating becomes dominant, and might be necessary to get electrons trapped into the wakefield, when wakefield inhibition grows with plasma density.

  7. Beam dynamics simulations of the transverse-to-longitudinal emittance exchange proof-of-principle experiment at the Argonne Wakefield Accelerator.

    SciTech Connect

    Gao, F.; Gai, W.; Power, J. G.; Kim, K. J.; Sun, Y. E.; Piot, P.; Rihaoui, M.; High Energy Physics; Northern Illinois Univ.; FNAL

    2009-01-01

    Transverse-to-longitudinal emittance exchange has promising applications in various advanced acceleration and light source concepts. A proof-of-principle experiment to demonstrate this phase space manipulation method is currently being planned at the Argonne Wakefield Accelerator. The experiment focuses on exchanging a low longitudinal emittance with a high transverse horizontal emittance and also incorporates room for possible parametric studies e.g. using an incoming flat beam with tunable horizontal emittance. In this paper, we present realistic start-to-end beam dynamics simulation of the scheme, explore the limitations of this phase space exchange.

  8. Beam dynamics simulations of the transverse-to-longitudinal emittance exchange proof-of-principle experiment at the Argonne Wakefield Accelerator

    SciTech Connect

    Rihaoui, M.; Gai, W.; Kim, K.-J.; Power, J. G.; Piot, P.; Sun, Y.-E.

    2009-01-22

    Transverse-to-longitudinal emittance exchange has promising applications in various advanced acceleration and light source concepts. A proof-of-principle experiment to demonstrate this phase space manipulation method is currently being planned at the Argonne Wakefield Accelerator. The experiment focuses on exchanging a low longitudinal emittance with a high transverse horizontal emittance and also incorporates room for possible parametric studies e.g. using an incoming flat beam with tunable horizontal emittance. In this paper, we present realistic start-to-end beam dynamics simulation of the scheme, explore the limitations of this phase space exchange.

  9. Beam dynamics simulations of the transverse-to-longitudinal emittance exchange proof-of-principle experiment at the Argonne Wakefield Accelerator

    SciTech Connect

    Rihaoui, M.; Gai, W.; Kim, K.J.; Piot, Philippe; Power, John Gorham; Sun, Y.E.; /Fermilab

    2009-01-01

    Transverse-to-longitudinal emittance exchange has promising applications in various advanced acceleration and light source concepts. A proof-of-principle experiment to demonstrate this phase space manipulation method is currently being planned at the Argonne Wakefield Accelerator. The experiment focuses on exchanging a low longitudinal emittance with a high transverse horizontal emittance and also incorporates room for possible parametric studies e.g. using an incoming flat beam with tunable horizontal emittance. In this paper, we present realistic start-to-end beam dynamics simulation of the scheme, explore the limitations of this phase space exchange.

  10. X-ray phase contrast imaging of biological specimens with femtosecond pulses of betatron radiation from a compact laser plasma wakefield accelerator

    SciTech Connect

    Kneip, S.; McGuffey, C.; Dollar, F.; Chvykov, V.; Kalintchenko, G.; Krushelnick, K.; Maksimchuk, A.; Mangles, S. P. D.; Matsuoka, T.; Schumaker, W.; Thomas, A. G. R.; Yanovsky, V.; Bloom, M. S.; Najmudin, Z.; Palmer, C. A. J.; Schreiber, J.

    2011-08-29

    We show that x-rays from a recently demonstrated table top source of bright, ultrafast, coherent synchrotron radiation [Kneip et al., Nat. Phys. 6, 980 (2010)] can be applied to phase contrast imaging of biological specimens. Our scheme is based on focusing a high power short pulse laser in a tenuous gas jet, setting up a plasma wakefield accelerator that accelerates and wiggles electrons analogously to a conventional synchrotron, but on the centimeter rather than tens of meter scale. We use the scheme to record absorption and phase contrast images of a tetra fish, damselfly and yellow jacket, in particular highlighting the contrast enhancement achievable with the simple propagation technique of phase contrast imaging. Coherence and ultrafast pulse duration will allow for the study of various aspects of biomechanics.

  11. Kinetic simulations of laser parametric amplification in magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Jia, Qing; Shi, Yuan; Qin, Hong; Fisch, Nathaniel J.

    2017-09-01

    Laser pulse compression using magnetized resonance near the upper-hybrid frequency is promising for achieving higher output intensity in regimes previously thought impossible using unmagnetized plasmas. Using one dimensional particle-in-cell simulations, we verify that, by partially replacing plasma with an external transverse magnetic field of megagauss scale, the output pulse can be intensified by a factor of a few, due to the increased allowable amplification time despite a decreased growth rate. Further improvement is impeded by the generation of an electromagnetic wakefield, to which the amplified pulse loses more energy than it does in the unmagnetized case. This limitation can however be circumvented by the use of a stronger pump. In contrast to unmagnetized compression, the magnetized amplification remains efficient when the pump intensity is well above the wavebreaking threshold, until a higher phase-mixing threshold is exceeded. This surprising resilience to wavebreaking in magnetized plasma is of great benefit for magnetized compression.

  12. 2.5D Numerical Simulation of Excitation of Coherent Chain of Electron Wake-Field Bubbles by Optimal Non-Resonant Chain of Dense Relativistic Electron Bunches

    SciTech Connect

    Maslov, V. I.; Lotov, K. V.; Onishchenko, I. N.; Svistun, O. M.

    2010-06-16

    It is shown that optimal difference of frequencies of following of electron bunches and following of wake-field bubbles exists, so N-1 drive-bunches strengthen chain of wakefield bubbles and N-th bunch gets in maximal accelerating wakefield.

  13. Generating high-brightness electron beams via ionization injection by transverse colliding lasers in a plasma-wakefield accelerator.

    PubMed

    Li, F; Hua, J F; Xu, X L; Zhang, C J; Yan, L X; Du, Y C; Huang, W H; Chen, H B; Tang, C X; Lu, W; Joshi, C; Mori, W B; Gu, Y Q

    2013-07-05

    The production of ultrabright electron bunches using ionization injection triggered by two transversely colliding laser pulses inside a beam-driven plasma wake is examined via three-dimensional particle-in-cell simulations. The relatively low intensity lasers are polarized along the wake axis and overlap with the wake for a very short time. The result is that the residual momentum of the ionized electrons in the transverse plane of the wake is reduced, and the injection is localized along the propagation axis of the wake. This minimizes both the initial thermal emittance and the emittance growth due to transverse phase mixing. Simulations show that ultrashort (~8 fs) high-current (0.4 kA) electron bunches with a normalized emittance of 8.5 and 6 nm in the two planes, respectively, and a brightness of 1.7×10(19) A rad(-2) m(-2) can be obtained for realistic parameters.

  14. Laser Altimeter for Flight Simulator

    NASA Technical Reports Server (NTRS)

    Webster, L. D.

    1986-01-01

    Height of flight-simulator probe above model of terrain measured by automatic laser triangulation system. Airplane simulated by probe that moves over model of terrain. Altitude of airplane scaled from height of probe above model. Height measured by triangulation of laser beam aimed at intersection of model surface with plumb line of probe.

  15. Space simulators for laser optics

    NASA Technical Reports Server (NTRS)

    Gardner, Frank H.

    1988-01-01

    Different approaches that are being utilized to test laser optical systems are described. One of the most crucial areas in the testing phase is the stability of the laser optics mounted inside the space simulator. The thermal vacuum system, the refrigeration system, and the space simulator are discussed.

  16. Laser Altimeter for Flight Simulator

    NASA Technical Reports Server (NTRS)

    Webster, L. D.

    1986-01-01

    Height of flight-simulator probe above model of terrain measured by automatic laser triangulation system. Airplane simulated by probe that moves over model of terrain. Altitude of airplane scaled from height of probe above model. Height measured by triangulation of laser beam aimed at intersection of model surface with plumb line of probe.

  17. Particle-in-Cell Simulations of Gas Ionization by Short Intense Laser Pulses

    NASA Astrophysics Data System (ADS)

    Dimitrov, Dimitre; Bruhwiler, David; Leemans, Wim; Esarey, Eric; Catravas, Palma; Toth, Csaba; Shadwick, Brad; Cary, John; Giacone, Rodolfo; Verboncoeur, John; Mardahl, Peter

    2001-10-01

    Laser wakefield accelerators (LWFA) can generate accelerating gradients orders of magnitude larger than those obtained in conventional metal structures. In many LWFA experiments, the leading edge of the short, intense laser pulse completely ionizes a background neutral gas. An important question is the effect of laser ionization on the evolution of the laser pulse. Dispersive effects can modify the length and shape of the pulse as it propagates through the gas/plasma. Pulse steepening or break-up can affect the growth of the plasma wake. We will present particle-in-cell simulations using the ADK [M.V. Ammosov et al., Sov. Phys. JETP 64, p. 1191 (1986)] tunneling ionization model in the XOOPIC [J.P. Verboncoeur et al., J. Comp. Phys. 104, p. 321 (1993)] code. These simulations will be compared with experimental LWFA results from the l'OASIS laboratory of LBNL [W.P. Leemans et al., Phys. Plasmas 8, p. 2510 (2001)].

  18. Studies of a hybrid Trojan Horse wakefield accelerator with high transformer ratio

    NASA Astrophysics Data System (ADS)

    Cook, Nathan; Bruhwiler, David; Hidding, Bernhard; Vay, Jean-Luc; Webb, Stephen

    2015-11-01

    Plasma wakefield acceleration uses relativistic high-charge electron bunches to generate a plasma blowout supporting intense electric fields for trapping and acceleration. Dramatic improvements in emittance, peak current and brightness are achievable through laser-controlled ionization in the plasma blowout, which is the premise of the Trojan Horse approach. The hybrid Trojan Horse concept extends this approach to use the output beam from a laser plasma accelerator to drive a Trojan Horse, resulting in a compact system that can produce higher brightness bunches with order-of-magnitude lower energy spread. We are exploring the use of multiple, shaped laser pulses to resonantly inject a shaped electron drive bunch. The resulting output bunch could generate wakes in PWFA or beam-driven dielectric structures with transformer ratios of 5 to 10 or larger. Hence, a hybrid Trojan Horse accelerator with bunch shaping may provide a compact source of nC bunches that can drive a variety of systems for studying high-gradient wakefields and lepton acceleration. Initial work will use previously simulated electron bunches from a laser plasma accelerator to drive the plasma wakefield stage. We present preliminary results from simulations using the parallel, particle-in-cell framework Warp. Work supported by the U.S. Department of Energy, Office of High Energy Physics, under Award Number DE-SC0013855.

  19. Investigation of ionization-induced electron injection in a wakefield driven by laser inside a gas cell

    NASA Astrophysics Data System (ADS)

    Audet, T. L.; Hansson, M.; Lee, P.; Desforges, F. G.; Maynard, G.; Dobosz Dufrénoy, S.; Lehe, R.; Vay, J.-L.; Aurand, B.; Persson, A.; Gallardo González, I.; Maitrallain, A.; Monot, P.; Wahlström, C.-G.; Lundh, O.; Cros, B.

    2016-02-01

    Ionization-induced electron injection was investigated experimentally by focusing a driving laser pulse with a maximum normalized potential of 1.2 at different positions along the plasma density profile inside a gas cell, filled with a gas mixture composed of 99 %H2+1 %N2 . Changing the laser focus position relative to the gas cell entrance controls the accelerated electron bunch properties, such as the spectrum width, maximum energy, and accelerated charge. Simulations performed using the 3D particle-in-cell code WARP with a realistic density profile give results that are in good agreement with the experimental ones. The interest of this regime for optimizing the bunch charge in a selected energy window is discussed.

  20. Investigation of ionization-induced electron injection in a wakefield driven by laser inside a gas cell

    DOE PAGES

    Audet, T. L.; Hansson, M.; Lee, P.; ...

    2016-02-16

    Ionization-induced electron injection was investigated experimentally by focusing a driving laser pulse with a maximum normalized potential of 1.2 at different positions along the plasma density profile inside a gas cell, filled with a gas mixture composed of 99%H2+1%N2. Changing the laser focus position relative to the gas cell entrance controls the accelerated electron bunch properties, such as the spectrum width, maximum energy, and accelerated charge. Simulations performed using the 3D particle-in-cell code WARP with a realistic density profile give results that are in good agreement with the experimental ones. Lastly, we discuss the interest of this regime for optimizingmore » the bunch charge in a selected energy window.« less

  1. Investigation of ionization-induced electron injection in a wakefield driven by laser inside a gas cell

    SciTech Connect

    Audet, T. L.; Hansson, M.; Lee, P.; Desforges, F. G.; Maynard, G.; Dobosz Dufrénoy, S.; Lehe, R.; Vay, J. -L.; Aurand, B.; Persson, A.; Gallardo González, I.; Maitrallain, A.; Monot, P.; Wahlström, C. -G.; Lundh, O.; Cros, B.

    2016-02-16

    Ionization-induced electron injection was investigated experimentally by focusing a driving laser pulse with a maximum normalized potential of 1.2 at different positions along the plasma density profile inside a gas cell, filled with a gas mixture composed of 99%H2+1%N2. Changing the laser focus position relative to the gas cell entrance controls the accelerated electron bunch properties, such as the spectrum width, maximum energy, and accelerated charge. Simulations performed using the 3D particle-in-cell code WARP with a realistic density profile give results that are in good agreement with the experimental ones. Lastly, we discuss the interest of this regime for optimizing the bunch charge in a selected energy window.

  2. Suppressing Parasitic Effects in a Long Dielectric Wakefield Accelerator

    SciTech Connect

    Shchegolkov, Dmitry; Simakov, Evgenya Ivanovna; Jing, Chunguang; Li, Chen; Zholents, Alexander A.; Power, John G.

    2014-08-27

    Dielectric wakefield acceleration is a promising concept for increasing the accelerating gradient above the limits of conventional accelerators. Although superior gradients are reported in short dielectric wakefield accelerator tubes, problems arise when it comes to efficiency and multi-meter long interaction lengths. Here we discuss possible issues and provide some solutions backed by simulations.

  3. Terahertz radiation driven by two-color laser pulses at near-relativistic intensities: Competition between photoionization and wakefield effects

    PubMed Central

    González de Alaiza Martínez, P.; Davoine, X.; Debayle, A.; Gremillet, L.; Bergé, L.

    2016-01-01

    We numerically investigate terahertz (THz) pulse generation by linearly-polarized, two-color femtosecond laser pulses in highly-ionized argon. Major processes consist of tunneling photoionization and ponderomotive forces associated with transverse and longitudinal field excitations. By means of two-dimensional particle-in-cell (PIC) simulations, we reveal the importance of photocurrent mechanisms besides transverse and longitudinal plasma waves for laser intensities >1015 W/cm2. We demonstrate the following. (i) With two-color pulses, photoionization prevails in the generation of GV/m THz fields up to 1017 W/cm2 laser intensities and suddenly loses efficiency near the relativistic threshold, as the outermost electron shell of ionized Ar atoms has been fully depleted. (ii) PIC results can be explained by a one-dimensional Maxwell-fluid model and its semi-analytical solutions, offering the first unified description of the main THz sources created in plasmas. (iii) The THz power emitted outside the plasma channel mostly originates from the transverse currents. PMID:27255689

  4. Terahertz radiation driven by two-color laser pulses at near-relativistic intensities: Competition between photoionization and wakefield effects

    NASA Astrophysics Data System (ADS)

    González de Alaiza Martínez, P.; Davoine, X.; Debayle, A.; Gremillet, L.; Bergé, L.

    2016-06-01

    We numerically investigate terahertz (THz) pulse generation by linearly-polarized, two-color femtosecond laser pulses in highly-ionized argon. Major processes consist of tunneling photoionization and ponderomotive forces associated with transverse and longitudinal field excitations. By means of two-dimensional particle-in-cell (PIC) simulations, we reveal the importance of photocurrent mechanisms besides transverse and longitudinal plasma waves for laser intensities >1015 W/cm2. We demonstrate the following. (i) With two-color pulses, photoionization prevails in the generation of GV/m THz fields up to 1017 W/cm2 laser intensities and suddenly loses efficiency near the relativistic threshold, as the outermost electron shell of ionized Ar atoms has been fully depleted. (ii) PIC results can be explained by a one-dimensional Maxwell-fluid model and its semi-analytical solutions, offering the first unified description of the main THz sources created in plasmas. (iii) The THz power emitted outside the plasma channel mostly originates from the transverse currents.

  5. Phase-contrast imaging using radiation sources based on laser-plasma wakefield accelerators: state of the art and future development

    NASA Astrophysics Data System (ADS)

    Reboredo., D.; Cipiccia, S.; Grant, P. A.; Welsh, G. H.; Grant, D. W.; McKendrick, G.; Subiel, A.; Maneuski, D.; Wiggins, S. M.; Jaroszynski, D. A.

    2015-03-01

    Both the laser-plasma wakefield accelerator (LWFA) and X-ray phase-contrast imaging (XPCi) are promising technologies that are attracting the attention of the scientific community. Conventional X-ray absorption imaging cannot be used as a means of imaging biological material because of low contrast. XPCi overcomes this limitation by exploiting the variation of the refraction index of materials. The contrast obtained is higher than for conventional absorption imaging and requires a lower dose. The LWFA is a new concept of acceleration where electrons are accelerated to very high energy (~150 MeV) in very short distances (mm scale) by surfing plasma waves excited by the passage of an ultra-intense laser pulse (~1018 Wcm-2) through plasma. Electrons in the LWFA can undergo transverse oscillation and emit synchrotron-like (betatron) radiation in a narrow cone around the propagation axis. The properties of the betatron radiation produced by LWFA, such as source size and spectrum, make it an excellent candidate for XPCi. In this work we present the characterization of betatron radiation produced by the LWFA in the ALPHA-X laboratory (University of Strathclyde). We show how phase contrast images can be obtained using the betatron radiation in a free-space propagation configuration and we discuss the potential and limitation of the LWFA driven XPCi.

  6. X-ray phase contrast imaging of biological samples using a betatron x-ray source generated in a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Chaulagain, U.; Bohacek, K.; Kozlova, M.; Nejdl, J.; Krus, M.; Horny, V.; Mahieu, B.; Ta-Phuoc, K.

    2017-05-01

    In a plasma wakefield accelerator, an intense laser pulse propagates in an under-dense plasma that drives a relativistic plasma wave in which electrons can be injected and accelerated to relativistic energies within a short distance. These accelerated electrons undergo betatron oscillation and emit a collimated X-ray beam along the direction of electron velocity. This X-ray source is characterised with a source size of the order of a micrometer, a pulse duration of the order of femtosecond, and with a high spectral brightness. This novel X-ray source provides an excellent imaging tool to achieve unprecedented high-resolution image through phase contrast imaging. The phase contrast technique has the potential to reveal structures which are invisible with the conventional absorption imaging. In the X-ray phase contrast imaging, the image contrast is obtained thanks to phase shifts induced on the X-rays passing through the sample. It involves the real part of refractive index of the object. Here we present high-resolution phase contrast X-ray images of two biological samples using laser-driven Betatron X-ray source.

  7. Computational studies and optimization of wakefield accelerators

    SciTech Connect

    Tsung, Frank S.; Bruhwiler, David L.; Cary, John R.; Esarey, Eric H.; Mori, Warren B.; Vay, Jean-Luc; Martins, Samuel F.; Katsouleas, Tom; Cormier-Michel, Estelle; Fawley, William M.; Huang, Chengkun; Wang, Xiadong; Cowan, Ben; Decyk, Victor K.; Fonseca, Ricardo A.; Lu, Wei; Messmer, Peter; Mullowney, Paul; Nakamura, Kei; Paul, Kevin; Plateau, Guillaume R.; Schroeder, Carl B.; Silva, Luis O.; Toth, Csaba; Geddes, C.G.R.; Tzoufras, Michael; Antonsen, Tom; Vieira, Jorge; Leemans, Wim P.

    2008-06-16

    Laser- and particle beam-driven plasma wakefield accelerators produce accelerating fields thousands of times higher than radio-frequency accelerators, offering compactness and ultrafast bunches to extend the frontiers of high energy physics and to enable laboratory-scale radiation sources. Large-scale kinetic simulations provide essential understanding of accelerator physics to advance beam performance and stability and show and predict the physics behind recent demonstration of narrow energy spread bunches. Benchmarking between codes is establishing validity of the models used and, by testing new reduced models, is extending the reach of simulations to cover upcoming meter-scale multi-GeV experiments. This includes new models that exploit Lorentz boosted simulation frames to speed calculations. Simulations of experiments showed that recently demonstrated plasma gradient injection of electrons can be used as an injector to increase beam quality by orders of magnitude. Simulations are now also modeling accelerator stages of tens of GeV, staging of modules, and new positron sources to design next-generation experiments and to use in applications in high energy physics and light sources.

  8. Ultrahigh resolution and brilliance laser wakefield accelerator betatron x-ray source for rapid in vivo tomographic microvasculature imaging in small animal models

    NASA Astrophysics Data System (ADS)

    Fourmaux, Sylvain; Kieffer, Jean-Claude; Krol, Andrzej

    2017-03-01

    We are developing ultrahigh spatial resolution (FWHM < 2 μm) high-brilliance x-ray source for rapid in vivo tomographic microvasculature imaging micro-CT angiography (μCTA) in small animal models using optimized contrast agent. It exploits Laser Wakefield Accelerator (LWFA) betatron x-ray emission phenomenon. Ultrashort high-intensity laser pulse interacting with a supersonic gas jet produces an ion cavity ("bubble") in the plasma in the wake of the laser pulse. Electrons that are injected into this bubble gain energy, perform wiggler-like oscillations and generate burst of incoherent x-rays with characteristic duration time comparable to the laser pulse duration, continuous synchrotron-like spectral distribution that might extend to hundreds keV, very high brilliance, very small focal spot and highly directional emission in the cone-beam geometry. Such LWFA betatron x-ray source created in our lab produced 1021 -1023 photonsṡ shot-1ṡmrad-2ṡmm-2/0.1%bw with mean critical energy in the12-30 keV range. X-ray source size for a single laser shot was FWHM=1.7 μm x-ray beam divergence 20-30 mrad, and effective focal spot size for multiple shots FWHM= 2 μm. Projection images of simple phantoms and complex biological objects including insects and mice were obtained in single laser shots. We conclude that ultrahigh spatial resolution μCTA (FWHM 2 μm) requiring thousands of projection images could be accomplished using LWFA betatron x-ray radiation in approximately 40 s with our existing 220 TW laser and sub seconds with next generation of ultrafast lasers and x-ray detectors, as opposed to several hours required using conventional microfocal x-ray tubes. Thus, sub second ultrahigh resolution in vivo microtomographic microvasculature imaging (in both absorption and phase contrast mode) in small animal models of cancer and vascular diseases will be feasible with LWFA betatron x-ray source.

  9. Progress Toward E-157: A 1 GeV Plasma Wakefield Accelerator

    SciTech Connect

    Assmann, R

    1999-07-07

    A plasma based wakefield acceleration (PWFA) experiment, scheduled to run this summer, will accelerate parts of a 28.5 GeV bunch from the SLAC linac by up to 1 GeV over a length of 1 meter. A single 28.5 GeV bunch will both induce the wakefields in the one meter long plasma and witness the resulting acceleration fields. The experiment will explore and further develop the techniques that are needed to apply high-gradient PWFA to large scale accelerators. This paper summarizes the goals of the first round of experiments as well as the status of the individual components: construction and diagnosis of the homogeneous lithium oven plasma source and associated ionization laser, commissioning of the electron beam, simulated performance of the electron beam energy measurement, and first PIC simulations of the full meter long experiment.

  10. Wakefield Propagation in Plasma Channels

    NASA Astrophysics Data System (ADS)

    Geddes, Cameron; Leemans, Wim; Esarey, Eric; Shadwick, Brad; Wurtele, Johnathan

    2000-10-01

    Characteristics of laser wakefields propagating in plasma channels have been studied at the l'OASIS laser facility at LBNL. Plasma channels are formed in gas jets using the ignitor-heater method[1], allowing control of channel geometry and profile. The channels are characterized by longitudinal and transverse interferometry, giving both radial and longitudinal profiles of the channel. High intensity (>5E17 W/cm^2, 50fs) pulses at 800nm are guided in these channels and are used to create plasma wakes in the channel. Laser propagation in the channel is characterized by output mode images and energies, and the wakes are profiled by longitudinal spectral interferometry. Measurements of channel and wake profiles, and studies of wake dependence on channel parameters will be presented. [1]P.Volfbeyn, E.Esarey, W.P. Leemans, Phys Plasmas 6, 2269 (1999)

  11. Betatron x-ray radiation in the self-modulated wakefield acceleration regime (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Albert, Felicie

    2017-05-01

    Betatron x-ray radiation, driven by electrons from laser-wakefield acceleration, has unique properties to probe high energy density (HED) plasmas and warm dense matter. Betatron radiation is produced when relativistic electrons oscillate in the plasma wake of a laser pulse. Its properties are similar to those of synchrotron radiation, with a 1000 fold shorter pulse. This presentation will focus on the experimental challenges and results related to the development of betatron radiation in the self modulated regime of laser wakefield acceleration. 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.

  12. Longitudinal wakefield for an axisymmetric collimator

    SciTech Connect

    Blednykh A.; Krinsky, S.

    2012-05-25

    We consider the longitudinal point-charge wakefield, w(s), for an axisymmetric collimator having inner radius b, outer radius d, inner length g, and taper length L. The taper angle {alpha} is defined by tan {alpha} = (d-b)/L. Using the electromagnetic simulation code ECHO, we explore the dependence of the wakefield on a collimator's geometric parameters over a wide range of profiles: from small-angle tapers to step-function transitions. The point-charge wakefield is determined using an approximation introduced by Podobedov and Stupakov. We have found it useful to exhibit the wakefield as a function of the scaled variable s/d{alpha}. For small taper angles, our results illustrate the satisfaction of the longitudinal scaling found by Stupakov, Bane, and Zagorodnov; and for larger taper angles, the breaking of this longitudinal scaling is clearly depicted. The use of the scaled variable s/d{alpha} turns out to be especially well suited to describing the wakefield for a collimator with step-function profile ({alpha} = {pi}/2).

  13. Simulation of Laser Cutting

    NASA Astrophysics Data System (ADS)

    Schulz, Wolfgang; Nießen, Markus; Eppelt, Urs; Kowalick, Kerstin

    Laser cutting is a thermal separation process widely used in shaping and contour cutting applications. There are, however, gaps in understanding the dynamics of the process, especially issues related to cut quality. This work describes the advances in fundamental physical modelling and process monitoring of laser cutting, as well as time varying processes such as contour cutting. Diagnosis of ripple and dross formation is advanced to observe the melt flow and its separation simultaneously as well as the spatial shape of the cut kerf.

  14. Consistency analysis on laser signal in laser guided weapon simulation

    NASA Astrophysics Data System (ADS)

    Yin, Ruiguang; Zhang, Wenpan; Guo, Hao; Gan, Lin

    2015-10-01

    The hardware-in-the-loop simulation is widely used in laser semi-active guidance weapon experiments, the authenticity of the laser guidance signal is the key problem of reliability. In order to evaluate the consistency of the laser guidance signal, this paper analyzes the angle of sight, laser energy density, laser spot size, atmospheric back scattering, sun radiation and SNR by comparing the different working state between actual condition and hardware-in-the-loop simulation. Based on measured data, mathematical simulation and optical simulation result, laser guidance signal effects on laser seeker are determined. By using Monte Carlo method, the laser guided weapon trajectory and impact point distribution are obtained, the influence of the systematic error are analyzed. In conclusion it is pointed out that the difference between simulation system and actual system has little influence in normal guidance, has great effect on laser jamming. The research is helpful to design and evaluation of laser guided weapon simulation.

  15. High Gradient Wakefields in Dielectric Loaded Structures

    SciTech Connect

    Conde, M. E.; Franchini, F.; Gai, W.; Konecny, R.; Liu, W.; Power, J. G.; Yusof, Z.; Antipov, S.; Gao, F.; Wang, H.; Jing, C.

    2006-11-27

    Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches.

  16. High Gradient Wakefields in Dielectric Loaded Structures

    NASA Astrophysics Data System (ADS)

    Conde, M. E.; Antipov, S.; Franchini, F.; Gai, W.; Gao, F.; Jing, C.; Konecny, R.; Liu, W.; Power, J. G.; Wang, H.; Yusof, Z.

    2006-11-01

    Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches.

  17. High gradient wakefields in dielectric loaded structures.

    SciTech Connect

    Conde, M.E.; Franchini, F.; Gai, W.; Konecny, R.; Power, J.G.; Yusof, Z.; Liu, W.; Jing, C.; Antipov, S.; Wang, H.; High Energy Physics; Euclid Techlabs, LLC; IIT

    2006-01-01

    Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches.

  18. Argonne Wakefield Accelerator Update `92

    SciTech Connect

    Rosing, M.; Balka, L.; Chojnacki, E.; Gai, W.; Ho, C.; Konecny, R.; Power, J.; Schoessow, P.; Simpson, J.

    1992-09-01

    The Argonne Wakefield Accelerator (AWA) is an experiment designed to test various ideas related to wakefield technology. Construction is now underway for a 100 nC electron beam in December of 1992. This report updates this progress.

  19. Argonne Wakefield Accelerator Update '92

    SciTech Connect

    Rosing, M.; Balka, L.; Chojnacki, E.; Gai, W.; Ho, C.; Konecny, R.; Power, J.; Schoessow, P.; Simpson, J.

    1992-01-01

    The Argonne Wakefield Accelerator (AWA) is an experiment designed to test various ideas related to wakefield technology. Construction is now underway for a 100 nC electron beam in December of 1992. This report updates this progress.

  20. Modeling laser-plasma acceleration in the laboratory frame

    SciTech Connect

    2011-01-01

    A simulation of laser-plasma acceleration in the laboratory frame. Both the laser and the wakefield buckets must be resolved over the entire domain of the plasma, requiring many cells and many time steps. While researchers often use a simulation window that moves with the pulse, this reduces only the multitude of cells, not the multitude of time steps. For an artistic impression of how to solve the simulation by using the boosted-frame method, watch the video "Modeling laser-plasma acceleration in the wakefield frame."

  1. Generation of high-field narrowband terahertz radiation by counterpropagating plasma wakefields

    NASA Astrophysics Data System (ADS)

    Timofeev, I. V.; Annenkov, V. V.; Volchok, E. P.

    2017-10-01

    It is found that nonlinear interaction of plasma wakefields driven by counterpropagating laser or particle beams can efficiently generate high-power electromagnetic radiation at the second harmonic of the plasma frequency. Using a simple analytical theory and particle-in-cell simulations, we show that this phenomenon can be attractive for producing high-field ( ˜10 MV/cm) tunable terahertz radiation with a narrow line width. For laser drivers produced by existing petawatt-class systems, this nonlinear process opens the way to the generation of gigawatt, multi-millijoule terahertz pulses which are not presently available for any other generating schemes.

  2. Generation of annular, high-charge electron beams at the Argonne wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Wisniewski, E. E.; Li, C.; Gai, W.; Power, J.

    2012-12-01

    We present and discuss the results from the experimental generation of high-charge annular(ring-shaped)electron beams at the Argonne Wakefield Accelerator (AWA). These beams were produced by using laser masks to project annular laser profiles of various inner and outer diameters onto the photocathode of an RF gun. The ring beam is accelerated to 15 MeV, then it is imaged by means of solenoid lenses. Transverse profiles are compared for different solenoid settings. Discussion includes a comparison with Parmela simulations, some applications of high-charge ring beams,and an outline of a planned extension of this study.

  3. Generation of annular, high-charge electron beams at the Argonne wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Wisniewski, E. E.; Li, C.; Gai, W.; Power, J.

    2013-01-01

    We present and discuss the results from the experimental generation of high-charge annular(ring-shaped)electron beams at the Argonne Wakefield Accelerator (AWA). These beams were produced by using laser masks to project annular laser profiles of various inner and outer diameters onto the photocathode of an RF gun. The ring beam is accelerated to 15 MeV, then it is imaged by means of solenoid lenses. Transverse profiles are compared for different solenoid settings. Discussion includes a comparison with Parmela simulations, some applications of high-charge ring beams,and an outline of a planned extension of this study.

  4. Wakefield suppression using beatwave structures

    SciTech Connect

    Yu, D.; Kim, J.S.

    1991-12-31

    A proposed method of suppressing transverse wakefields in an accelerating structure makes use of the fact that superposition of long-range wakes excited by an electron bunch transversing a series of accelerating cells with different transverse frequencies can produce interference cancellation, thereby significantly reducing the magnitudes of the harmful wake potentials. Analytic calculations as well as time-domain and modal sum simulations are performed to the beatwave effects produced by detuned, disk-loaded cavities as function of their transverse frequency spread and the population density.

  5. Group velocity dispersion and relativistic effects on the wakefield induced by chirped laser pulse in parabolic plasma channel

    SciTech Connect

    Sohbatzadeh, F.; Akou, H.

    2013-04-15

    The excitation of wake field plasma waves by a short laser pulse propagating through a parabolic plasma channel is studied. The laser pulse is assumed to be initially chirped. In this regard, the effects of initial and induced chirp on the plasma wake field as well as the laser pulse parameters are investigated. The group velocity dispersion and nonlinear relativistic effects were taken into account to evaluate the excited wake field in two dimension using source dependent expansion method. Positive, negative, and un-chirped laser pulses were employed in numerical code to evaluate the effectiveness of the initial chirp on 2-D wake field excitation. Numerical results showed that for laser irradiances exceeding 10{sup 18}W/cm{sup 2}, an intense laser pulse with initial positive chirp generates larger wake field compared to negatively and un-chirped pulses.

  6. DOE-HEP Final Report for 2013-2016: Studies of plasma wakefields for high repetition-rate plasma collider, and Theoretical study of laser-plasma proton and ion acceleration

    SciTech Connect

    Katsouleas, Thomas C.; Sahai, Aakash A.

    2016-08-08

    There were two goals for this funded project: 1. Studies of plasma wakefields for high repetition-rate plasma collider, and 2. Theoretical study of laser-plasma proton and ion acceleration. For goal 1, an analytical model was developed to determine the ion-motion resulting from the interaction of non-linear “blow-out” wakefields excited by beam-plasma and laser-plasma interactions. This is key to understanding the state of the plasma at timescales of 1 picosecond to a few 10s of picoseconds behind the driver-energy pulse. More information can be found in the document. For goal 2, we analytically and computationally analyzed the longitudinal instabilities of the laser-plasma interactions at the critical layer. Specifically, the process of “Doppler-shifted Ponderomotive bunching” is significant to eliminate the very high-energy spread and understand the importance of chirping the laser pulse frequency. We intend to publish the results of the mixing process in 2-D. We intend to publish Chirp-induced transparency. More information can be found in the document.

  7. Optimization of the LCLS X-Ray FEL Output Performance in the Presence of Strong Undulator Wakefields

    SciTech Connect

    Reiche, S.; Bane, K.L.F.; Emma, P.; Huang, Z.; Nuhn, H.D.; Stupakov, G.V.; Fawley, W.M.; /LBL, Berkeley

    2006-03-17

    The Linac Coherent Light Source (LCLS) Free-Electron Laser will operate in the wavelength range of 1.5 to 15 Angstroms. Energy loss due to wakefields within the long undulator can degrade the FEL process by detuning the resonant FEL frequency. The wakefields arise from the vacuum chamber wall resistivity, its surface roughness, and abrupt changes in its aperture. For LCLS parameters, the resistive component is the most critical and depends upon the chamber material (e.g. Cu) and its radius. To study the expected performance in the presence of these wakefields, we make a series of start-to-end simulations with tracking codes PARMELA and ELEGANT and time-dependent FEL simulation codes Genesis 1.3 and Ginger. We discuss the impact of the wakefield on output energy, spectral bandwidth, and temporal envelope of the output FEL pulse, as well as the benefits of a partial compensation obtained with a slight z dependent taper in the undulator field. We compare these results to those obtained by decreasing the bunch charge or increasing the vacuum chamber radius. We also compare our results to those predicted in concurrent analytical work.

  8. Simulations of laser thrombolysis

    SciTech Connect

    Chapyak, E.J.; Godwin, R.P.

    1999-03-01

    The authors have shown that bubble expansion and collapse near the interface between two materials with modest property differences produces jet-like interpenetration of the two materials. The bubble dynamics at a water-viscous fluid interface is compared with that at the interface of water with a weak elastic-plastic material. The authors find that, despite rather similar behavior during bubble growth and the initial portion of bubble collapse, the terminal jetting behavior is quite different, even in direction. The elastic-plastic properties chosen realistically represent real and surrogate thrombus. Simulations using the elastic-plastic model quantitatively agree with laboratory thrombolysis mass removal experiments. In the earlier simulations of laboratory experiments, walls have been remote so as to not effect the dynamics. Here the authors present two-dimensional simulations of thrombolysis with water over elastic-plastic surrogate thrombus in a geometry representative of the clinical situation. The calculations include thin cylindrical elastic walls with properties and dimensions appropriate for arteries. The presence of these artery walls does not substantially change the interface jetting predicted in unconfined simulations.

  9. The Ion Wakefield Inside a Glass Box

    NASA Astrophysics Data System (ADS)

    Chen, Mudi; Matthews, Lorin; Hyde, Truell

    2016-10-01

    The formation of an ion wakefield downstream of dust particles in a complex plasma sheath has long been understood to have strong implications on their structure, stability and dynamics . The presence of the ion wake introduces interesting phenomena such as charge reduction on downstream particles and asymmetric interaction forces between upstream and downstream particles. Many of the self-ordered dust particle structures observed in complex plasma experiments are the result of the combination of the ion-wakefield and the external confinement; unfortunately, few experimental measurements isolating the effect of the wakefield have been conducted. In this experiment, 1-D dust particle structures (i.e., vertically aligned particle chains) are formed in a GEC RF reference cell within a glass box sitting on the powered lower electrode. A diode pumped, solid-state laser is used to perturb individual particles within the particle chain, allowing a map of the ion wakefield inside the glass box to be generated. The implications of these results will be discussed. NSF / DOE funding is gratefully acknowledged - PHY1414523 & PHY1262031.

  10. High resolution simulation of beam dynamics in electron linacs for x-ray free electron lasers

    NASA Astrophysics Data System (ADS)

    Qiang, J.; Ryne, R. D.; Venturini, M.; Zholents, A. A.; Pogorelov, I. V.

    2009-10-01

    In this paper we report on large-scale high resolution simulations of beam dynamics in electron linacs for the next-generation x-ray free electron lasers (FELs). We describe key features of a parallel macroparticle simulation code including three-dimensional (3D) space-charge effects, short-range structure wakefields, coherent synchrotron radiation (CSR) wakefields, and treatment of radio-frequency (rf) accelerating cavities using maps obtained from axial field profiles. We present a study of the microbunching instability causing severe electron beam fragmentation in the longitudinal phase space which is a critical issue for future FELs. Using parameters for a proposed FEL linac at Lawrence Berkeley National Laboratory (LBNL), we show that a large number of macroparticles (beyond 100 million) is generally needed to control the numerical macroparticle shot noise and avoid overestimating the microbunching instability. We explore the effect of the longitudinal grid on simulation results. We also study the effect of initial uncorrelated energy spread on the final uncorrelated energy spread of the beam for the FEL linac.

  11. Transverse Wakefields from Tapered Collimators: Measurements and Analysis

    SciTech Connect

    Tenenbaum, Peter G

    2001-07-27

    We report on a series of measurements of the transverse wakefield from tapered collimators. The collimators were designed to principally present a geometric impedance to the beam, and to minimize impedances from resistivity or surface features; in addition, the geometries of the collimators were selected to permit examination of the scaling behavior of the wakefield due to collimator taper angle and minimum gap size. We present the measured near-center wakefields of the collimators, as well as the effect of bunch-length variation. The measurements are compared to analytic models and MAFIA simulations.

  12. Radial equilibrium of relativistic particle bunches in plasma wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Lotov, K. V.

    2017-02-01

    Drive particle beams in linear or weakly nonlinear regimes of the plasma wakefield accelerator quickly reach a radial equilibrium with the wakefield, which is described in detail for the first time. The equilibrium beam state and self-consistent wakefields are obtained by combining analytical relationships, numerical integration, and first-principles simulations. In the equilibrium state, the beam density is strongly peaked near the axis, the beam radius is constant along most of the beam, and longitudinal variation of the focusing strength is balanced by varying beam emittance. The transverse momentum distribution of beam particles depends on the observation radius and is neither separable nor Gaussian.

  13. Synergy Between Experiments and Simulations in Laser and Beam-Driven Plasma Acceleration and Light Sources

    NASA Astrophysics Data System (ADS)

    Mori, Warren B.

    2015-11-01

    Computer simulations have been an integral part of plasma physics research since the early 1960s. Initially, they provided the ability to confirm and test linear and nonlinear theories in one-dimension. As simulation capabilities and computational power improved, then simulations were also used to test new ideas and applications of plasmas in multi-dimensions. As progress continued, simulations were also used to model experiments. Today computer simulations of plasmas are ubiquitously used to test new theories, understand complicated nonlinear phenomenon, model the full temporal and spatial scale of experiments, simulate parameters beyond the reach of current experiments, and test the performance of new devices before large capital expenditures are made to build them. In this talk I review the progress in simulations in a particular area of plasma physics: plasma based acceleration (PBA). In PBA a short laser pulse or particle beam propagates through long regions of plasma creating plasma wave wakefields on which electrons or positrons surf to high energies. In some cases the wakefields are highly nonlinear, involve three-dimensional effects, and the trajectories of plasma particles cross making it essential that fully kinetic and three-dimensional models are used. I will show how particle-in-cell (PIC) simulations were initially used to propose the basic idea of PBA in one dimension. I will review some of the dramatic progress in the experimental demonstration of PBA and show how this progress was dramatically helped by a synergy between experiments and full-scale multi-dimensional PIC simulations. This will include a review of how the capability of PIC simulation tools has improved. I will also touch on some recent progress on improvements to PIC simulations of PBA and discuss how these improvements may push the synergy further towards real time steering of experiments and start to end modeling of key components of a future linear collider or XFEL based on PBA

  14. Studies on high-quality electron beams and tunable x-ray sources produced by laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    The applications of laser wake field accelerators (LWFA) rely heavily on the quality of produced high energy electron beams and X-ray sources. We present our recent progress on this issue. Firstly we propose a bichromatic laser ionization injection scheme for obtaining high quality electron beams. With the laser pulse combinations of 800 nm and 267 nm, or 2400 nm and 800 nm in wavelengths, electron beams with energy spread of 1% or lower can be produced. Secondly we propose polarization tunable X-ray sources based on LWFA. By shooting a laser pulse into a preformed plasma channel with a skew angle referring to the channel axis, the plasma channel can act as a helical undulator for elliptically polarized X-rays.

  15. Radiation emission from braided electrons in interacting wakefields

    NASA Astrophysics Data System (ADS)

    Wallin, Erik; Gonoskov, Arkady; Marklund, Mattias

    2017-09-01

    The radiation emission from electrons wiggling in a laser wakefield acceleration (LWFA) process, being initially considered as a parasitic effect for the electron energy gain, can eventually serve as a novel X-ray source, which could be used for diagnostic purposes. Although several schemes for enhancing the X-ray emission in LWFA has been recently proposed and analyzed, finding an efficient way to use and control this radiation emission remains an important problem. Based on analytical estimates and 3D particle-in-cell simulations, we here propose and examine a new method utilizing two colliding LWFA patterns with an angle in between their propagation directions. Varying the angle of collision, the distance of acceleration before the collision and other parameters provide an unprecedented control over the emission parameters. Moreover, we reveal here that for a collision angle of 5°, the two wakefields merge into a single LWFA cavity, inducing strong and stable collective oscillations between the two trapped electron bunches. This results in an X-ray emission which is strongly peaked, both in the spatial and frequency domains. The basic concept of the proposed scheme may pave a way for using LWFA radiation sources in many important applications, such as phase-contrast radiography.

  16. Numerical simulations of LWFA for the next generation of laser systems

    SciTech Connect

    Martins, S. F.; Vieira, J.; Fiuza, F.; Silva, L. O.; Trines, R.; Norreys, P.

    2009-01-22

    The development of new laser systems based on OPCPA will push Laser Wakefield Accelerators (LWFA) to a qualitatively new energy range. As in the past, numerical simulations will play a critical role in testing, probing and optimizing the physical parameters and setup of these upscale experiments. Based on the prospective design parameters for the future Vulcan 10 PW OPCPA laser system, we have determined the optimal parameters for a single LWFA stage from theoretical scalings for such system, which predict accelerations to the energy frontier, with self-injected electrons in excess of 10 GeV for a self-guided configuration, and above 50 GeV bunches with externally-injected electrons in a laser-guided configuration. These parameters were then used as a baseline for 3D full scale simulations with OSIRIS and QuickPIC. A 12 GeV self-injected beam was obtained with both codes, in agreement with theoretical predictions for the maximum energy gain and the injected charge. Preliminary results on the laser-guided configuration already confirm the accelerating gradients and the stability of the laser guided propagation for long distances required to reach the higher energies predicted by the theoretical scalings for this scenario.

  17. High energy photon emission from wakefields

    SciTech Connect

    Farinella, D. M. Lau, C. K.; Taimourzadeh, S.; Hwang, Y.; Abazajian, K.; Canac, N.; Taborek, P.; Tajima, T.; Zhang, X. M.; Koga, J. K.; Ebisuzaki, T.

    2016-07-15

    Experimental evidence has accumulated to indicate that wakefield acceleration (WFA) accompanies intense and sometimes coherent emission of radiation such as from betatron radiation. The investigation of this issue has additional impetus nowadays because we are learning (1) there is an additional acceleration process of the ponderomotive acceleration; (2) WFA may become relevant in much higher density regimes; (3) WFA has been proposed as the mechanism for extreme high energy cosmic ray acceleration and gamma ray bursts for active galactic nuclei. These require us to closely examine the radiative mechanisms in WFA anew. We report studies of radiation from wakefield (self-injected betatron) and ponderomotive (laser field) mechanisms in scalings of the frequency and intensity of the driver, as well as the plasma density.

  18. Characterisation of electron beams from laser-driven particle accelerators

    SciTech Connect

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

    2012-12-21

    The development, understanding and application of laser-driven particle accelerators require accurate measurements of the beam properties, in particular emittance, energy spread and bunch length. Here we report measurements and simulations showing that laser wakefield accelerators can produce beams of quality comparable to conventional linear accelerators.

  19. Transverse wakefield of waveguide damped structures and beam dynamics

    SciTech Connect

    Lin, Xintian

    1995-08-01

    In the design of new high energy particle colliders with higher luminosity one is naturally led to consider multi-bunch operation. However, the passage of a leading bunch through an accelerator cavity Generates a wakefield that may have a deleterious effect on the motion of the subsequent bunches. Therefore, the suppression of the wakefield is an essential requirement for beam stability. One solution to this problem, which has been studied extensively is to drain the wakefield energy out of the cavity by means of waveguides coupled with the cavity and fed into matched terminations. Waveguide dimensions are chosen to yield a cutoff frequency well above the frequency of the accelerating mode so that the latter is undamped. This paper presents a thorough investigation of the wakefield for this configuration. The effectiveness of waveguide damping has typically been assessed by evaluating the resultant Qext of higher order cavity modes to determine their exponential damping rate. We have developed an efficient method to calculate Qext of the damped modes from popular computer simulation codes such as MAFIA. This method has been successively applied to the B-factory RF cavity We have also found another type of wakefield, associated with waveguide cut-off, which decays as t-3/2 rather than in the well-known exponentially damped manner. Accordingly, we called it the persistent Wakefield. A similar phenomenon with essentially the same physical origin but occurring in the decay of unstable quantum states, has received extensive study. Then we have developed various methods of calculating this persistent wakefield, including mode matching and computer simulation. Based on a circuit model we estimate the limit that waveguide damping can reach to reduce the wakefield.

  20. Laser-capillary interaction for the EXIN project

    NASA Astrophysics Data System (ADS)

    Bisesto, F. G.; Anania, M. P.; Bacci, A. L.; Bellaveglia, M.; Chiadroni, E.; Cianchi, A.; Curcio, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Galletti, M.; Gallo, A.; Ghigo, A.; Marocchino, A.; Mostacci, A.; Petrarca, M.; Pompili, R.; Rossi, A. R.; Serafini, L.; Vaccarezza, C.

    2016-09-01

    The EXIN project is under development within the SPARC_LAB facility of the National Laboratory of Frascati (LNF-INFN). This project aims to accelerate pre-existing electron bunches with high brightness by exploiting the wakefield plasma acceleration technique, while preserving the initial brightness. The wakefield is excited inside a dielectric capillary by high intensity laser pulses produced by the FLAME laser interacting with a gas. In this work, we present numerical simulations in order to optimize energy coupling between our laser with super-Gaussian transverse profile and a dielectric capillary. Moreover, an overview of the experimental layout will be given.

  1. The Effect of the Self-Magnetic Field on the Current Limit in a Laser Wakefield Accelerator (LWFA)

    NASA Astrophysics Data System (ADS)

    Tai, Ling-Chieh; Zhang, Peng; Koh, Wee-Shing; Ang, Lay-Kee; Chen, Shih-Hung

    2008-11-01

    The challenge for the development of LWFA is achieving a nC- and GeV-level electron beam. Previous experiments [1] produced a GeV electron beam with total charges 30 pC, which is much less than the theoretical prediction [2]. The discrepancy might be due to the space charge and self-magnetic fields in the electron beam. The electrostatic diode model [3] for the space-charge-limited current has been developed and verified by the simulation. In order to understand the effect of the self-magnetic field on a relativistic electron beam, particle-in-cell simulations with electrostatic and electromagnetic models are performed, respectively. The simulation results can help the development of a new theoretical model based on a parabolic potential profile, which can be applied on more precise predictions of the limited currents in LWFA. 1. W. Leemans et al., Nature Phys. 2, 696 (2006). 2. W. Lu et al., Phys. Rev. ST Accel. Beams 10, 061301 (2007). 3. L. K. Ang et al., Phys. Rev. Lett. 98, 164802 (2007).

  2. Particle-in-Cell Simulations of THz Coherent Transition Radiation from Laser-Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Bruhwiler, D.; Messmer, P.; Cary, J. R.; Leemans, W. P.; Esarey, E.; Schroeder, C.; Geddes, C.; van Tilborg, J.; Shadwick, B.

    2004-11-01

    Laser wakefield accelerator (LWFA) concepts are characterized by ultra-high gradients and ultra-short (tens of fs) bunch lengths. Non-invasive bunch-length diagnostics, at or very near the plasma exit, are key to continuing the rapid advances in LWFA technology. These short bunches can radiate strongly at THz frequencies via coherent transition radiation (CTR) as they exit the plasma [1]. Careful measurements of the THz spectrum will provide the necessary bunch-length diagnostic [2], once the effects of various secondary complications have been quantified. Particle-in-cell simulations, using the VORPAL code [3] are being used to characterize CTR emitted from a self-modulated LWFA. The status of this on-going work will be presented. [1] Wim Leemans et al., Phys. Rev. Lett. 91, 074802-1 (2003). [2] C. Schroeder et al., Phys. Rev. E 69, 016501 (2004). [3] C. Nieter and J. Cary, J. Comp. Phys. 196, 488 (2004).

  3. Plasma Wakefield Experiments at FACET

    SciTech Connect

    Hogan, M.J.; England, R.J.; Frederico, J.; Hast, C.; Li, S.Z.; Litos, M.; Walz, D.; An, W.; Clayton, C.E.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Tochitsky, S.; Muggli, P.; Pinkerton, S.; Shi, Y.; /Southern California U.

    2011-08-19

    FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23GeV, 3nC electron bunches compressed to {approx}20{micro}m long and focused to {approx}10{micro}m wide. The intense fields of the FACET bunches will be used to field ionize neutral lithium or cesium vapor produced in a heat pipe oven. Previous experiments at the SLAC FFTB facility demonstrated 50GeV/m gradients in an 85cm field ionized lithium plasma where the interaction distance was limited by head erosion. Simulations indicate the lower ionization potential of cesium will decrease the rate of head erosion and increase single stage performance. The initial experimental program will compare the performance of lithium and cesium plasma sources with single and double bunches. Later experiments will investigate improved performance with a pre-ionized cesium plasma. The status of the experiments and expected performance are reviewed. The FACET Facility is being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The facility will begin commissioning in summer 2011 and conduct an experimental program over the coming five years to study electron and positron beam driven plasma acceleration with strong wake loading in the non-linear regime. The FACET experiments aim to demonstrate high-gradient acceleration of electron and positron beams with high efficiency and negligible emittance growth.

  4. Simulation of laser radar imagery

    NASA Astrophysics Data System (ADS)

    Sheffer, Albert D., Jr.; Thompson, Fred L.

    1986-01-01

    Software has been developed for the simulation of laser radar range imagery. Two versions have been developed: the first is an idealized model which is noise-free and with zero dropout rate; the second includes both pointing and range noise effects and provides for calculation of probability of detection for each pixel, with dropout occurring for probabilities below threshold, and also allows for user control over a number of other parameters such as scanning convention (unidirectional vs bidirectional), scan efficiency, and trajectory update rates. Each version allows for motion of a LADAR sensor across a terrain database on which faceted objects (targets and clutter) have been placed. For each pixel the program calculates the laser exit beam direction, based upon the combined effects of the sensor sweep pattern and the motion and attitude of the sensor platform. The exit beam is traced for intersection with the terrain or an object. Program output consists of the x, y, z-coordinates of the intersection point and the (real-number) range to that point for each pixel. This output can then be converted to a displayable range image. The software is currently implemented on a VAX 11/750 computer operating under VMS.

  5. Particle-in-cell simulations of plasma accelerators and electron-neutral collisions

    SciTech Connect

    Bruhwiler, David L.; Giacone, Rodolfo E.; Cary, John R.; Verboncoeur, John P.; Mardahl, Peter; Esarey, Eric; Leemans, W.P.; Shadwick, B.A.

    2001-10-01

    We present 2-D simulations of both beam-driven and laser-driven plasma wakefield accelerators, using the object-oriented particle-in-cell code XOOPIC, which is time explicit, fully electromagnetic, and capable of running on massively parallel supercomputers. Simulations of laser-driven wakefields with low ({approx}10{sup 16} W/cm{sup 2}) and high ({approx}10{sup 18} W/cm{sup 2}) peak intensity laser pulses are conducted in slab geometry, showing agreement with theory and fluid simulations. 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 of XOOPIC required by this work, and summarize the issues relevant to modeling relativistic electron-neutral collisions in a particle-in-cell code.

  6. Numerical simulation of imaging laser radar system

    NASA Astrophysics Data System (ADS)

    Han, Shaokun; Lu, Bo; Jiang, Ming; Liu, Xunliang

    2008-03-01

    Rational and effective design of imaging laser radar systems is the key of imaging laser radar system research. Design must fully consider the interrelationship between various parameters. According to the parameters, choose suitable laser, detector and other components. To use of mathematical modeling and computer simulation is an effective imaging laser radar system design methods. This paper based on the distance equation, using the detection statistical methods, from the laser radar range coverage, detection probability, false-alarm rate, SNR to build the laser radar system mathematical models. In the process of setting up the mathematical models to fully consider the laser, atmosphere, detector and other factors on the performance that is to make the models be able to respond accurately the real situation. Based on this using C# and Matlab designed a simulation software.

  7. Laser pulse evolution and electron acceleration in plasmas

    NASA Astrophysics Data System (ADS)

    Esarey, Eric

    2000-04-01

    Laser-driven plasma-based accelerators(For a review see, E. Esarey et al., IEEE Trans. Plasma Sci. 24, 252 (1996).) require the propagation of intense laser pulses over long distances in plasmas, the generation of large amplitude wakefields, and the injection and acceleration of electrons. This talk will discuss the nonlinear propagation of short laser pulses in plasmas, with or without channels. Non-paraxial effects will be analyzed and simulated, including finite pulse duration, finite group velocity, and dispersion(E. Esarey et al., Phys. Rev. Lett., submitted.). These effects on the evolution of the forward Raman and self-modulation instabilities, that lead the generation of wakefields, will be examined. Also discussed are methods for self-trapping and injecting electrons into the wakefield. Application to ongoing experiments at LBNL(W.P. Leemans et al., Phys. Plasma 5, 1615 (1998); in preparation.) will be discussed.

  8. Wakefield potentials of corrugated structures

    DOE PAGES

    Novokhatski, A.

    2015-10-22

    A corrugated structure, which is used in “dechirper” devices, is usually a pipe or two plates with small corrugations (bumps) on the walls. There is a good single-mode description of the wake potentials excited by a relativistic bunch if the wave length of the mode is much longer than the distance between the bumps in the pipe. However, ultrashort bunches, which are now used in free electron lasers, excite much higher frequency fields and the corresponding wake potentials will be very different from the single-mode description. We have made analyses of these wake potentials based on a numerical solution ofmore » Maxwell’s equations. It was confirmed that the behavior of the wakefields of ultrashort bunches in corrugated structures is not much different from the fields excited usually in accelerating structures where the wake potentials are described by the exponential function. For a practical application we present results for the SLAC “dechirper.” We also carried out calculations for a similar device, that was installed and measured at the Pohang Accelerator Laboratory, Korea. As a result, we find very good agreement with the experimental results.« less

  9. Simulation based analysis of laser beam brazing

    NASA Astrophysics Data System (ADS)

    Dobler, Michael; Wiethop, Philipp; Schmid, Daniel; Schmidt, Michael

    2016-03-01

    Laser beam brazing is a well-established joining technology in car body manufacturing with main applications in the joining of divided tailgates and the joining of roof and side panels. A key advantage of laser brazed joints is the seam's visual quality which satisfies highest requirements. However, the laser beam brazing process is very complex and process dynamics are only partially understood. In order to gain deeper knowledge of the laser beam brazing process, to determine optimal process parameters and to test process variants, a transient three-dimensional simulation model of laser beam brazing is developed. This model takes into account energy input, heat transfer as well as fluid and wetting dynamics that lead to the formation of the brazing seam. A validation of the simulation model is performed by metallographic analysis and thermocouple measurements for different parameter sets of the brazing process. These results show that the multi-physical simulation model not only can be used to gain insight into the laser brazing process but also offers the possibility of process optimization in industrial applications. The model's capabilities in determining optimal process parameters are exemplarily shown for the laser power. Small deviations in the energy input can affect the brazing results significantly. Therefore, the simulation model is used to analyze the effect of the lateral laser beam position on the energy input and the resulting brazing seam.

  10. Generation of wakefields by whistlers in spin quantum magnetoplasmas

    SciTech Connect

    Misra, A. P.; Brodin, G.; Marklund, M.; Shukla, P. K.

    2010-12-15

    The excitation of electrostatic wakefields in a magnetized spin quantum plasma by the classical and the spin-induced ponderomotive force (CPF and SPF, respectively) due to whistler waves is reported. The nonlinear dynamics of the whistlers and the wakefields is shown to be governed by a coupled set of nonlinear Schroedinger and driven Boussinesq-like equations. It is found that the quantum force associated with the Bohm potential introduces two characteristic length scales, which lead to the excitation of multiple wakefields in a strongly magnetized dense plasma (with a typical magnetic field strength B{sub 0} or approx. 10{sup 9} T and particle density n{sub 0} > or approx. 10{sup 36} m{sup -3}), where the SPF strongly dominates over the CPF. In other regimes, namely, B{sub 0} < or approx. 10{sup 8} T and n{sub 0} < or approx. 10{sup 35} m{sup -3}, where the SPF is comparable to the CPF, a plasma wakefield can also be excited self-consistently with one characteristic length scale. Numerical results reveal that the wakefield amplitude is enhanced by the quantum tunneling effect; however, it is lowered by the external magnetic field. Under appropriate conditions, the wakefields can maintain high coherence over multiple plasma wavelengths and thereby accelerate electrons to extremely high energies. The results could be useful for particle acceleration at short scales, i.e., at nanometer and micrometer scales, in magnetized dense plasmas where the driver is the whistler wave instead of a laser or a particle beam.

  11. Theory, Modeling, and Simulation of Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

    1998-01-01

    Semiconductor lasers play very important roles in many areas of information technology. In this talk, I will first give an overview of semiconductor laser theory. This will be followed by a description of different models and their shortcomings in modeling and simulation. Our recent efforts in constructing a fully space and time resolved simulation model will then be described. Simulation results based on our model will be presented. Finally the effort towards a self-consistent and comprehensive simulation capability for the opto-electronics integrated circuits (OEICs) will be briefly reviewed.

  12. Theory, Modeling, and Simulation of Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

    1998-01-01

    Semiconductor lasers play very important roles in many areas of information technology. In this talk, I will first give an overview of semiconductor laser theory. This will be followed by a description of different models and their shortcomings in modeling and simulation. Our recent efforts in constructing a fully space and time resolved simulation model will then be described. Simulation results based on our model will be presented. Finally the effort towards a self-consistent and comprehensive simulation capability for the opto-electronics integrated circuits (OEICs) will be briefly reviewed.

  13. Cosmic Plasma Wakefield Acceleration

    SciTech Connect

    Chen, P

    2004-04-26

    Recently we proposed a new cosmic acceleration mechanism which was based on the wakefields excited by the Alfven shocks in a relativistically owing plasma. In this paper we include some omitted details, and show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f({epsilon}) {proportional_to} 1/{epsilon}{sup 2}. As an example, we discuss the possible production of super-GZK ultra high energy cosmic rays (UHECR) in the atmosphere of gamma ray bursts. The estimated event rate in our model agrees with that from UHECR observations.

  14. High-gradient generation in dielectric-loaded wakefield structures.

    SciTech Connect

    Conde, M. E.; Antipov, S.; Franchini, F.; Gai, W.; Gao, F.; Jing, C.; Konecny, R.; Liu, W.; Power, J. G.; Wang, H.; Yusof, Z.; High Energy Physics; Euclid Concepts LLC

    2006-01-01

    Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches.

  15. Inter-satellite laser link simulation analysis

    NASA Astrophysics Data System (ADS)

    Tong, Lanjuan; Guan, Hui; Wang, Zhilin

    2015-11-01

    The characteristic of satellite communication link was firstly described and four application modes were put forward. By comparison, it is suggested that microwave link is used in satellite-to-ground communication and laser link is used in inter-satellite communication. Secondly the condition and composition of laser link establishment was analyzed and laser link model was set up, and the principle and composition of APT system was described. Finally, based on STK and MATLAB platform, the process of inter-satellite laser link establishment was designed, and setting the scene of TDRS capturing and tracking user's satellite as an example, simulation was realized and demonstrated.

  16. Billion particle linac simulations for future light sources

    SciTech Connect

    Ryne, R. D.; Venturini, M.; Zholents, A. A.; Qiang, J.

    2008-09-25

    In this paper we report on multi-physics, multi-billion macroparticle simulation of beam transport in a free electron laser (FEL) linac for future light source applications. The simulation includes a self-consistent calculation of 3D space-charge effects, short-range geometry wakefields, longitudinal coherent synchrotron radiation (CSR) wakefields, and detailed modeling of RF acceleration and focusing. We discuss the need for and the challenges associated with such large-scale simulation. Applications to the study of the microbunching instability in an FEL linac are also presented.

  17. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe.

    PubMed

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

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

  18. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    SciTech Connect

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

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

  19. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    DOE PAGES

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; ...

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of themore » wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.« less

  20. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    PubMed Central

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

    2016-01-01

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method. PMID:27403561

  1. Argonne Wakefield Accelerator facility upgrade.

    SciTech Connect

    Conde, M.E.; Gai, W.; Konecny, R.; Power, J.G.; Schoessow, P.; Sun, X.

    2001-07-11

    The Argonne Wakefield Accelerator has been successfully used for conducting wakefield experiments in dielectric loaded structures and plasmas. Although the initial wakefield experiments were successful, higher drive beam quality would substantially improve the wakefield accelerating gradients. For this reason they have built a new 1-1/2 cell L-band photocathode RF gun. This gun is expected to produce 10-100 nC bunches with 2-5 ps rms pulse length and normalized emittance less than 100 mm mrad. The gun will initially have a copper photocathode, which will soon be replaced by a high quantum efficiency cesium telluride one, allowing the generation of a train of high charge bunches. the beam energy at the exit of the gun cavity will be in the range 7.5-10 MeV. A standing-wave linac structure operating at the same frequency (1.3 GHz) will increase the beam energy to about 15 MeV. This beam will be used in high-gradient wakefield acceleration experiments and other high intensity electron beam applications. Traveling-wave dielectric loaded structures, operating at 7.8 and 15.6 GHz, will be excited by the propagation of single bunches or by trains of up to 32 electron bunches, reaching gradients in excess of 100 MV/m over distances of the order of 1 meter.

  2. Maritime Laser Communications Trial 98152-19703

    DTIC Science & Technology

    2012-06-01

    held at Port Wakefield Proof & Experimental Establishment in September 2011. A novel analogue FM ship-to-shore communications system was used to...Laser Communications Trial 98152-19703 held at Port Wakefield Proof & Experimental Establishment in September 2011. The primary objective of the...27 APPENDIX A : PORT WAKEFIELD TIDE LEVELS

  3. The Simulation of Off-Axis Laser Propagation Using Heleeos

    DTIC Science & Technology

    2006-03-01

    56 Laser Pointer Test...55 6. Laser pointer simulation ....................................................................................... 57 7... lasers have many different uses and can be found in much of today’s new technology. They are used in DVD players, CD players, builder’s leveling

  4. Development of our laser fusion integration simulation

    NASA Astrophysics Data System (ADS)

    Li, Jinghong; Zhai, Chuanlei; Li, Shuanggui; Li, Xin; Zheng, Wudi; Yong, Heng; Zeng, Qinghong; Hang, Xudeng; Qi, Jin; Yang, Rong; Cheng, Juan; Song, Peng; Gu, Peijun; Zhang, Aiqing; An, Hengbin; Xu, Xiaowen; Guo, Hong; Cao, Xiaolin; Mo, Zeyao; Pei, Wenbing; Jiang, Song; Zhu, Shao-ping

    2013-11-01

    In the target design of the Inertial Confinement Fusion (ICF) program, it is common practice to apply radiation hydrodynamics code to study the key physical processes happening in ICF process, such as hohlraum physics, radiation drive symmetry, capsule implosion physics in the radiation-drive approach of ICF. Recently, many efforts have been done to develop our 2D integrated simulation capability of laser fusion with a variety of optional physical models and numerical methods. In order to effectively integrate the existing codes and to facilitate the development of new codes, we are developing an object-oriented structured-mesh parallel code-supporting infrastructure, called JASMIN. Based on two-dimensional three-temperature hohlraum physics code LARED-H and two-dimensional multi-group radiative transfer code LARED-R, we develop a new generation two-dimensional laser fusion code under the JASMIN infrastructure, which enable us to simulate the whole process of laser fusion from the laser beams' entrance into the hohlraum to the end of implosion. In this paper, we will give a brief description of our new-generation two-dimensional laser fusion code, named LARED-Integration, especially in its physical models, and present some simulation results of holhraum.

  5. Optical eye simulator for laser dazzle events.

    PubMed

    Coelho, João M P; Freitas, José; Williamson, Craig A

    2016-03-20

    An optical simulator of the human eye and its application to laser dazzle events are presented. The simulator combines optical design software (ZEMAX) with a scientific programming language (MATLAB) and allows the user to implement and analyze a dazzle scenario using practical, real-world parameters. Contrary to conventional analytical glare analysis, this work uses ray tracing and the scattering model and parameters for each optical element of the eye. The theoretical background of each such element is presented in relation to the model. The overall simulator's calibration, validation, and performance analysis are achieved by comparison with a simpler model based uponCIE disability glare data. Results demonstrate that this kind of advanced optical eye simulation can be used to represent laser dazzle and has the potential to extend the range of applicability of analytical models.

  6. Frequency Domain Tomography Of Evolving Laser-Plasma Accelerator Structures

    SciTech Connect

    Dong Peng; Reed, Stephen; Kalmykov, Serguei; Shvets, Gennady; Downer, Mike

    2009-01-22

    Frequency Domain Holography (FDH), a technique for visualizing quasistatic objects propagating near the speed of light, has produced 'snapshots' of laser wakefields, but they are averaged over structural variations that occur during propagation through the plasma medium. Here we explore via simulations a generalization of FDH--that we call Frequency Domain Tomography (FDT)--that can potentially record a time sequence of quasistatic snapshots, like the frames of a movie, of the wake structure as it propagates through the plasma. FDT utilizes a several probe-reference pulse pairs that propagate obliquely to the drive pulse and wakefield, along with tomographic reconstruction algorithms similar to those used in medical CAT scans.

  7. Laser hardening process simulation for mechanical parts

    NASA Astrophysics Data System (ADS)

    Tani, G.; Orazi, L.; Fortunato, A.; Campana, G.; Cuccolini, G.

    2007-02-01

    In this paper a numerical simulation of laser hardening process is presented. The Finite Difference Method (FDM) was used to solve the heat transfer and the carbon diffusion equations for a defined workpiece geometry. The model is able to predict the thermal cycle into the target material, the phase transformations and the resulting micro-structures according to the laser parameters, the workpiece dimensions and the physical properties of the workpiece. The effects of the overlapping tracks of the laser beam on the resulting micro-structures is also considered. The initial workpiece micro-structure is taken into account in the simulation by a digitized photomicrograph of the ferrite perlite distribution before the thermal cycle. Experimental tests were realized on a C43 plate and the good agreement between the theoretical and experimental results is shown.

  8. Wakefield: Community and Library Analysis.

    ERIC Educational Resources Information Center

    Trumpeter, Margo C.; Donahue, Mary Ellen

    This community analysis was conducted in order to characterize and identify the information needs of the Wakefield community, and library services and use were evaluated to determine how well the library meets these needs. The study included an examination of the history of the town and its physical characteristics, economic development, and…

  9. Laser method for simulating the transient radiation effects of semiconductor

    NASA Astrophysics Data System (ADS)

    Li, Mo; Sun, Peng; Tang, Ge; Wang, Xiaofeng; Wang, Jianwei; Zhang, Jian

    2017-05-01

    In this paper, we demonstrate the laser simulation adequacy both by theoretical analysis and experiments. We first explain the basic theory and physical mechanisms of laser simulation of transient radiation effect of semiconductor. Based on a simplified semiconductor structure, we describe the reflection, optical absorption and transmission of laser beam. Considering two cases of single-photon absorption when laser intensity is relatively low and two-photon absorption with higher laser intensity, we derive the laser simulation equivalent dose rate model. Then with 2 types of BJT transistors, laser simulation experiments and gamma ray radiation experiments are conducted. We found good linear relationship between laser simulation and gammy ray which depict the reliability of laser simulation.

  10. Dipole-mode wakefields in dielectric-loaded rectangular waveguide accelerating structures.

    PubMed

    Jing, Chunguang; Liu, Wanming; Xiao, Liling; Gai, Wei; Schoessow, P; Wong, Thomas

    2003-07-01

    By applying different symmetric boundary conditions, we found that the transverse wakefields generated by an electron bunch traveling through a partially loaded rectangular dielectric structure at an off center position can be decomposed into corresponding orthogonal longitudinal section electric (LSE) and longitudinal section magnetic (LSM) modes for guided waves as in the case of longitudinal wakefields treated previously. The wakefields are characterized using the normalized shunt impedance R/Q, a function of the geometry of the accelerating structure, for both LSE and LSM modes. A numerical example is given for an X-band waveguide structure and detailed results are given for the several leading transverse wakefield terms. The analytic results obtained are in agreement with the results from the time domain simulation tool MAFIA.

  11. Dipole-mode wakefields in dielectric-loaded rectangular waveguide accelerating structures

    NASA Astrophysics Data System (ADS)

    Jing, Chunguang; Liu, Wanming; Xiao, Liling; Gai, Wei; Schoessow, P.; Wong, Thomas

    2003-07-01

    By applying different symmetric boundary conditions, we found that the transverse wakefields generated by an electron bunch traveling through a partially loaded rectangular dielectric structure at an off center position can be decomposed into corresponding orthogonal longitudinal section electric (LSE) and longitudinal section magnetic (LSM) modes for guided waves as in the case of longitudinal wakefields treated previously. The wakefields are characterized using the normalized shunt impedance R/Q, a function of the geometry of the accelerating structure, for both LSE and LSM modes. A numerical example is given for an X-band waveguide structure and detailed results are given for the several leading transverse wakefield terms. The analytic results obtained are in agreement with the results from the time domain simulation tool MAFIA®.

  12. Modeling of 10 GeV-1 TeV laser-plasma accelerators using Lorentz boosted simulations

    SciTech Connect

    Vay, J. -L.; Geddes, C. G. R.; Esarey, E.; Schroeder, C. B.; Leemans, W. P.; Cormier-Michel, E.; Grote, D. P.

    2011-12-13

    We study modeling of laser-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98, 130405 (2007)] that allows direct and efficient full-scale modeling of deeply depleted and beam loaded laser-plasma stages of 10 GeV-1 TeV (parameters not computationally accessible otherwise). This verifies the scaling of plasmaaccelerators to very high energies and accurately models the laser evolution and the accelerated electron beam transverse dynamics and energy spread. 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. Agreement at the percentage level is demonstrated between simulations using different frames of reference for a 0.1 GeV class stage. In addition, obtaining these speedups and levels of accuracy was permitted by solutions for handling data input (in particular, particle and laser beams injection) and output in a relativistically boosted frame of reference, as well as mitigation of a high-frequency instability that otherwise limits effectiveness.

  13. High Transformer ratios in collinear wakefield accelerators.

    SciTech Connect

    Power, J. G.; Conde, M.; Yusof, Z.; Gai, W.; Jing, C.; Kanreykin, A.; Schoessow, P.; High Energy Physics; Euclid Techlabs, LLC

    2008-01-01

    Based on our previous experiment that successfully demonstrated wakefield transformer ratio enhancement in a 13.625 GHz dielectric-loaded collinear wakefield accelerator using the ramped bunch train technique, we present here a redesigned experimental scheme for even higher enhancement of the efficiency of this accelerator. Design of a collinear wakefield device with a transformer ratio R2, is presented. Using a ramped bunch train (RBT) rather than a single drive bunch, the enhanced transformer ratio (ETR) technique is able to increase the transformer ratio R above the ordinary limit of 2. To match the wavelength of the fundamental mode of the wakefield with the bunch length (sigmaz=2 mm) of the new Argonne wakefield accelerator (AWA) drive gun (where the experiment will be performed), a 26.625 GHz dielectric based accelerating structure is required. This transformer ratio enhancement technique based on our dielectric-loaded waveguide design will result in a compact, high efficiency accelerating structures for future wakefield accelerators.

  14. Recent Experiment on Wakefield Transformer Ratio Enhancement at AWA

    SciTech Connect

    Jing, C.; Kanareykin, A.; Power, J. G.; Conde, M.; Liu, W.; Yusof, Z.; Gai, W.

    2010-11-04

    One technique to enhance the transformer ratio beyond the ordinary limit of 2 in a collinear wakefield acceleration scheme is to use a ramped bunched train (RBT). The first experimental demonstration has been reported in [1]. However, due to the mismatch between the beam bunch length and frequency of the accelerating structure, the observed transformer ratio was only marginally above 2 in the earlier experiment. We recently revisited this experiment with an optimized bunch length using the laser stacking technique at Argonne Wakefield Accelerator (AWA) facility. A transformer ratio of 3.4 has been measured using two drive bunches. Attempting to use four drive bunches met with major challenges. In this article, measurement results and data analysis from these experiments are presented in detail.

  15. Two-color beam generation based on wakefield excitation

    NASA Astrophysics Data System (ADS)

    Bettoni, S.; Prat, E.; Reiche, S.

    2016-05-01

    Several beam manipulation methods have been studied and experimentally tested to generate two-color photon beams in free electron laser facilities to accommodate the user requests. We propose to use the interaction of the beam with an oscillating longitudinal wakefield source to obtain a suitable electron beam structure. The bunch generates two subpulses with different energies and delayed in time passing through a magnetic chicane after its longitudinal phase space has been modulated by the wakefield source. According to this approach the power of the emitted radiation is not degraded compared to the monochromatic beam, and the setup in the machine is quite simple because the bunch is manipulated only in the high energy section, where it is more rigid. We present the design applied to SwissFEL. We identified the parameters and the corresponding range of tunability of the time and energy separation among the two subbunches.

  16. Simulation of reflected and scattered laser radiation for designing laser shields.

    PubMed

    Konieczny, Piotr; Wolska, Agnieszka; Swiderski, Jacek; Zajac, Andrzej

    2008-01-01

    This paper presents a computer simulation of reflected and scattered laser radiation for calculating the angle of laser shields performed with the Laser Shield Solver computer program. The authors describe a method of calculating the shield angle for laser shields which protect workers against reflected and scattered laser radiation and which are made from different materials. The main assumptions of the program, which calculates and simulates reflected laser radiation from any material and which can be used for designing shield angles, are presented. Calculations are compared with measurements of reflected laser radiation. The results for one type of laser and different materials which interacted with a laser beam showed that the Laser Shield Solver was an appropriate tool for designing laser shields and its simulations of reflected laser radiation distribution have practical use.

  17. Argonne's new Wakefield Test Facility

    SciTech Connect

    Simpson, J.D.

    1992-07-20

    The first phase of a high current, short bunch length electron beam research facility, the AWA, is near completion at Argonne. At the heart of the facility is a photocathode based electron gun and accelerating sections designed to deliver 20 MeV pulses with up to 100 nC per pulse and with pulse lengths of approximately 15 ps (fw). Using a technique similar to that originated at Argonne's AATF facility, a separate weak probe pulse can be generated and used to diagnose wake effects produced by the intense pulses. Initial planned experiments include studies of plasma wakefields and dielectric wakefield devices, and expect to demonstrate large, useful accelerating gradients (> 100 MeV/m). Later phases of the facility will increase the drive bunch energy to more than 100 MeV to enable acceleration experiments up to the GeV range. Specifications, design details, and commissioning progress are presented.

  18. Dielectric Wakefield Accelerator to drive the future FEL Light Source.

    SciTech Connect

    Jing, C.; Power, J.; Zholents, A. )

    2011-04-20

    X-ray free-electron lasers (FELs) are expensive instruments and a large part of the cost of the entire facility is driven by the accelerator. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may provide a significant cost saving and reduction of the facility size. In this article, we investigate using a collinear dielectric wakefield accelerator to provide a high repetition rate, high current, high energy beam to drive a future FEL x-ray light source. As an initial case study, a {approx}100 MV/m loaded gradient, 850 GHz quartz dielectric based 2-stage, wakefield accelerator is proposed to generate a main electron beam of 8 GeV, 50 pC/bunch, {approx}1.2 kA of peak current, 10 x 10 kHz (10 beamlines) in just 100 meters with the fill factor and beam loading considered. This scheme provides 10 parallel main beams with one 100 kHz drive beam. A drive-to-main beam efficiency {approx}38.5% can be achieved with an advanced transformer ratio enhancement technique. rf power dissipation in the structure is only 5 W/cm{sup 2} in the high repetition rate, high gradient operation mode, which is in the range of advanced water cooling capability. Details of study presented in the article include the overall layout, the transform ratio enhancement scheme used to increase the drive to main beam efficiency, main wakefield linac design, cooling of the structure, etc.

  19. Radiation in 1.5 GeV and 12 GeV Laser Wakefield Acceleration Stages from PIC Simulations

    SciTech Connect

    Martins, J. L.; Martins, S. F.; Silva, L. O.

    2010-11-04

    A massivelly parallel post-processing radiation diagnostic for PIC codes is presented, which is then used to study the main features of the radiation from single LWFA stages (1.5 GeV and 12 GeV). This diagnostic also allows to examine radiation signatures associated with the physics of self-injection.

  20. Collisionless Plasma Astrophysics Simulation Experiments using Lasers

    SciTech Connect

    Woolsey, N. C.; Ash, A. D.; Courtois, C.; Gregory, C. D.; Hall, I. M.; Howe, J.; Dendy, R. O.

    2006-04-07

    Laboratory experiment is an attractive method of exploring the plasma physics that may occur in solar and astrophysical shocks. An experiment enables repeated and detailed measurements of a plasma as the input conditions are adjusted. To form a scaled experiment of an astrophysical shock a plasma physics model of the shock is required, and the important dimensionless parameters identified and reproduced in the laboratory. A laboratory simulation of a young supernova remnant is described. The experiment uses the interaction of two millimetre-sized counter-streaming laser-produced plasmas placed in a strong transverse magnetic field to achieve this scaling. The collision-free dynamics of the two plasmas and their interaction are studied with and without the magnetic field through spatially and temporally resolved optical measurements. Laboratory astroplasma physics experiments using high-energy, high-power laser technology enables us to reproduce in the laboratory the conditions of temperature and pressure that are met in extreme stellar environments.

  1. A preliminary design of the collinear dielectric wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Zholents, A.; Gai, W.; Doran, S.; Lindberg, R.; Power, J. G.; Strelnikov, N.; Sun, Y.; Trakhtenberg, E.; Vasserman, I.; Jing, C.; Kanareykin, A.; Li, Y.; Gao, Q.; Shchegolkov, D. Y.; Simakov, E. I.

    2016-09-01

    A preliminary design of the multi-meter long collinear dielectric wakefield accelerator that achieves a highly efficient transfer of the drive bunch energy to the wakefields and to the witness bunch is considered. It is made from 0.5 m long accelerator modules containing a vacuum chamber with dielectric-lined walls, a quadrupole wiggler, an rf coupler, and BPM assembly. The single bunch breakup instability is a major limiting factor for accelerator efficiency, and the BNS damping is applied to obtain the stable multi-meter long propagation of a drive bunch. Numerical simulations using a 6D particle tracking computer code are performed and tolerances to various errors are defined.

  2. Laser simulation at the Air Force Research Laboratory

    NASA Astrophysics Data System (ADS)

    Grosek, Jacob; Naderi, Shadi; Oliker, Benjamin; Lane, Ryan; Dajani, Iyad; Madden, Timothy

    2017-01-01

    The physics of high brightness, high-power lasers present a variety of challenges with respect to simulation. The Air Force Research Laboratory is developing high-fidelity models for Yb-doped, Tm-doped, and Raman fiber amplifiers, hollow-core optical fiber gas lasers, and diode pumped alkali lasers. The approach to simulation and the physics specific to each laser technology are described, along with highlights of results, and relevant modeling considerations and limitations.

  3. Simulation and calculation of particle trapping using a quasistatic 2D simulation code

    NASA Astrophysics Data System (ADS)

    Morshed, Sepehr; Antonsen, Thomas; Huang, Chengkun; Mori, Warren

    2008-11-01

    In LWFA schemes the laser pulse must propagate several centimeters and maintain its coherence over this distance, which corresponds to many Rayleigh lengths. These Wakefields and their effect on the laser can be simulated in quasistatic approximation [1, 2]. In this approximation the assumption is that the driver (laser) does not change shape during the time it takes for it to pass by a plasma particle. As a result the particles that are trapped and moving with near-luminal velocity can not be treated with this approximation. Here we have modified the 2D code WAKE with an alternate algorithm so that when a plasma particle gains sufficient energy from wakefields it is promoted to beam particle status which later on may become trapped in the wakefields of laser. Similar implementations have been made in the 3D code QUICKPIC [2]. We also have done comparison between WAKE and results from 200 TW laser simulations using OSIRIS [3]. These changes in WAKE will give users a tool that can be used on a desk top machine to simulate GeV acceleration.[0pt] [1] P. Mora and T. M. Antonsen Jr., Phys Plasma 4, 217 (1997)[0pt] [2] C. Huang et al. Comp Phys. 217 (2006)[0pt] [3] W. Lu et al. PRST, Accelerators and Beams 10, 061301 (2007)

  4. Observation of Wakefields and Resonances in Coherent Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Billinghurst, B. E.; Bergstrom, J. C.; Baribeau, C.; Batten, T.; Dallin, L.; May, T. E.; Vogt, J. M.; Wurtz, W. A.; Warnock, R.; Bizzozero, D. A.; Kramer, S.

    2015-05-01

    We report on high resolution measurements of resonances in the spectrum of coherent synchrotron radiation (CSR) at the Canadian Light Source (CLS). The resonances permeate the spectrum at wave number intervals of 0.074 cm-1 , and are highly stable under changes in the machine setup (energy, bucket filling pattern, CSR in bursting or continuous mode). Analogous resonances were predicted long ago in an idealized theory as eigenmodes of a smooth toroidal vacuum chamber driven by a bunched beam moving on a circular orbit. A corollary of peaks in the spectrum is the presence of pulses in the wakefield of the bunch at well-defined spatial intervals. Through experiments and further calculations we elucidate the resonance and wakefield mechanisms in the CLS vacuum chamber, which has a fluted form much different from a smooth torus. The wakefield is observed directly in the 30-110 GHz range by rf diodes, and indirectly by an interferometer in the THz range. The wake pulse sequence found by diodes is less regular than in the toroidal model, and depends on the point of observation, but is accounted for in a simulation of fields in the fluted chamber. Attention is paid to polarization of the observed fields, and possible coherence of fields produced in adjacent bending magnets. Low frequency wakefield production appears to be mainly local in a single bend, but multibend effects cannot be excluded entirely, and could play a role in high frequency resonances. New simulation techniques have been developed, which should be invaluable in further work.

  5. Dynamics of electron bunches at the laser-plasma interaction in the bubble regime

    NASA Astrophysics Data System (ADS)

    Maslov, V. I.; Svystun, O. M.; Onishchenko, I. N.; Tkachenko, V. I.

    2016-09-01

    The multi-bunches self-injection, observed in laser-plasma accelerators in the bubble regime, affects the energy gain of electrons accelerated by laser wakefield. However, understanding of dynamics of the electron bunches formed at laser-plasma interaction may be challenging. We present here the results of fully relativistic electromagnetic particle-in-cell (PIC) simulation of laser wakefield acceleration driven by a short laser pulse in an underdense plasma. The trapping and acceleration of three witness electron bunches by the bubble-like structures were observed. It has been shown that with time the first two witness bunches turn into drivers and contribute to acceleration of the last witness bunch.

  6. Application of Regression Designs for Simulation of Laser Cladding

    NASA Astrophysics Data System (ADS)

    Zhang, Qunli; Anyakin, Mykola; Zhuk, Ruslan; Pan, Yi; Kovalenko, Volodymyr; Yao, Jianhua

    Laser cladding is a complicated process controlled by most parameters such as laser beam, properties of matrix and powder, treatment status of base material, laser cladding parameters etc. The best way to choose the working conditions cheaply and fast is to use the processing simulation. The statistical modeling was used in this paper, which was developed after regression design based on the experimental results of 2Cr13 steel cladding with diode laser robotized system. The influence degrees of technological factors (laser power, laser scanning speed, defocusing amount and powder feeding rate) on the dimensions and hardness of laser clad layers were investigated.

  7. EXPERIMENTS ON LASER AND E-BEAM TRANSPORT AND INTERACTION IN A PLASMA CHANNEL.

    SciTech Connect

    POGORELSKY,I.V.; PAVLISHIN,I.V.; BEN-ZVI,I.; ET AL.

    2004-09-15

    An ablative capillary discharge is installed into a linac beamline and serves as a plasma source for generating and characterizing wakefields. Simultaneously, the electron beam is used as a tool for plasma diagnostics. A high-energy picosecond CO{sub 2} laser channeled within the same capillary strongly affects a counterpropagating electron beam. These observations, supported with simulations, suggest the possibility of manipulating relativistic electron beams by steep plasma channels ponderomotively produced by a laser.

  8. Beam-based measurements of long-range transverse wakefields in the Compact Linear Collider main-linac accelerating structure

    DOE PAGES

    Zha, Hao; Latina, Andrea; Grudiev, Alexej; ...

    2016-01-20

    The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures for its main linacs. In order to maintain beam stability in multibunch operation, long-range transverse wakefields must be suppressed by 2 orders of magnitude between successive bunches, which are separated in time by 0.5 ns. Such strong wakefield suppression is achieved by equipping every accelerating structure cell with four damping waveguides terminated with individual rf loads. A beam-based experiment to directly measure the effectiveness of this long-range transverse wakefield and benchmark simulations was made in the FACET test facility at SLAC using a prototype CLIC accelerating structure. Furthermore,more » the experiment showed good agreement with the simulations and a strong suppression of the wakefields with an unprecedented minimum resolution of 0.1 V/(pC mm m).« less

  9. Resistive wall wakefields of short bunches at cryogenic temperatures

    DOE PAGES

    Stupakov, G.; Bane, K. L. F.; Emma, P.; ...

    2015-03-19

    In this study, we present calculations of the longitudinal wakefields at cryogenic temperatures for extremely short bunches, characteristic for modern x-ray free electron lasers. The calculations are based on the equations for the surface impedance in the regime of the anomalous skin effect in metals. This paper extends and complements an earlier analysis of B. Podobedov, Phys. Rev. ST Accel. Beams 12, 044401 (2009). into the region of very high frequencies associated with bunch lengths in the micron range. We study in detail the case of a rectangular bunch distribution for parameters of interest of LCLS-II with a superconducting undulator.

  10. Accordion effect in a laser wakefield accelerator: Generating comb-like electron beams for a tunable pulsed source of polychromatic gamma-rays

    NASA Astrophysics Data System (ADS)

    Kalmykov, Serge; Davoine, Xavier; Ghebregziabher, Isaac; Shadwick, Bradley

    2016-10-01

    Trains of synchronized, fs-length GeV-scale electron bunches with a sub-micron normalized transverse emittance, brightness up to 1017 A/m2, and controlled energy spacing may be purposely produced in both plasma channels and uniform plasmas. A cavity of electron density, driven by an optimally designed multi-color stack of 10-TW-scale laser pulses, experiences expansions and contractions, periodically injecting electrons from the ambient dense plasma, accelerating them without compromising the beam quality. This periodic injection is naturally achieved in a plasma channel. The channel, however, is not a prerequisite to this effect. The number of comb components, as well as their charge and energy spacing, can be controlled in a uniform plasma by independently varying focal spots of the laser stack components. Inverse Thomson scattering from these comb-like beams produces synchronized sequences of quasi-monochromatic, fs-length gamma-ray flashes, which may become an asset to pump-probe experiments in dense plasmas. NSF Grant PHY-1535678.

  11. Simulations for Plasma and Laser Acceleration

    NASA Astrophysics Data System (ADS)

    Vay, Jean-Luc; Lehe, RéMi

    Computer simulations have had a profound impact on the design and understanding of past and present plasma acceleration experiments, and will be a key component for turning plasma accelerators from a promising technology into a mainstream scientific tool. In this article, we present an overview of the numerical techniques used with the most popular approaches to model plasma-based accelerators: electromagnetic particle-in-cell, quasistatic and ponderomotive guiding center. The material that is presented is intended to serve as an introduction to the basics of those approaches, and to advances (some of them very recent) that have pushed the state of the art, such as the optimal Lorentz-boosted frame, advanced laser envelope solvers and the elimination of numerical Cherenkov instability. The particle-in-cell method, which has broader interest and is more standardized, is presented in more depth. Additional topics that are cross-cutting, such as azimuthal Fourier decomposition or filtering, are also discussed, as well as potential challenges and remedies in the initialization of simulations and output of data. Examples of simulations using the techniques that are presented have been l out of this article for conciseness, and because simulation results are best understood when presented together, and contrasted with theoretical and/or experimental results, as in other articles of this volume.

  12. Simulations for Plasma and Laser Acceleration

    NASA Astrophysics Data System (ADS)

    Vay, Jean-Luc; Lehe, Rémi

    Computer simulations have had a profound impact on the design and understanding of past and present plasma acceleration experiments, and will be a key component for turning plasma accelerators from a promising technology into a mainstream scientific tool. In this article, we present an overview of the numerical techniques used with the most popular approaches to model plasma-based accelerators: electromagnetic particle-in-cell, quasistatic and ponderomotive guiding center. The material that is presented is intended to serve as an introduction to the basics of those approaches, and to advances (some of them very recent) that have pushed the state of the art, such as the optimal Lorentz-boosted frame, advanced laser envelope solvers and the elimination of numerical Cherenkov instability. The particle-in-cell method, which has broader interest and is more standardized, is presented in more depth. Additional topics that are cross-cutting, such as azimuthal Fourier decomposition or filtering, are also discussed, as well as potential challenges and remedies in the initialization of simulations and output of data. Examples of simulations using the techniques that are presented have been left out of this article for conciseness, and because simulation results are best understood when presented together, and contrasted with theoretical and/or experimental results, as in other articles of this volume.

  13. Magnetowave Induced Plasma Wakefield Acceleration for Ultra High Energy Cosmic Rays

    SciTech Connect

    Chang, Feng-Yin; Chen, Pisin; Lin, Guey-Lin; Noble, Robert; Sydora, Richard; /Alberta U.

    2009-10-17

    Magnetowave induced plasma wakefield acceleration (MPWA) in a relativistic astrophysical outflow has been proposed as a viable mechanism for the acceleration of cosmic particles to ultrahigh energies. Here we present simulation results that clearly demonstrate the viability of this mechanism for the first time. We invoke the high frequency and high speed whistler mode for the driving pulse. The plasma wakefield obtained in the simulations compares favorably with our newly developed relativistic theory of the MPWA. We show that, under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over hundreds of plasma skin depths. Invoking active galactic nuclei as the site, we show that MPWA production of ultrahigh energy cosmic rays beyond ZeV (10{sup 21} eV) is possible.

  14. Wakefields in Coherent Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Billinghurst, Brant E.; Bergstrom, J. C.; Baribeau, C.; Batten, T.; Dallin, L.; May, Tim E.; Vogt, J. M.; Wurtz, Ward A.; Warnock, Robert L.; Bizzozero, D. A.; Kramer, S.; Michaelian, K. H.

    2016-06-01

    When the electron bunches in a storage ring are sufficiently short the electrons act coherently producing radiation several orders of magnitude more intense than normal synchrotron radiation. This is referred to as Coherent Syncrotron Radiation (CSR). Due to the potential of CSR to provide a good source of Terahertz radiation for our users, the Canadian Light Source (CLS) has been researching the production and application of CSR. CSR has been produced at the CLS for many years, and has been used for a number of applications. However, resonances that permeate the spectrum at wavenumber intervals of 0.074 cm-1, and are highly stable under changes in the machine setup, have hampered some experiments. Analogous resonances were predicted long ago in an idealized theory. Through experiments and further calculations we elucidate the resonance and wakefield mechanisms in the CLS vacuum chamber. The wakefield is observed directly in the 30-110 GHz range by rf diodes. These results are consistent with observations made by the interferometer in the THz range. Also discussed will be some practical examples of the application of CSR for the study of condensed phase samples using both transmission and Photoacoustic techniques.

  15. Laser altimetry simulator. Version 3.0: User's guide

    NASA Technical Reports Server (NTRS)

    Abshire, James B.; Mcgarry, Jan F.; Pacini, Linda K.; Blair, J. Bryan; Elman, Gregory C.

    1994-01-01

    A numerical simulator of a pulsed, direct detection laser altimeter has been developed to investigate the performance of space-based laser altimeters operating over surfaces with various height profiles. The simulator calculates the laser's optical intensity waveform as it propagates to and is reflected from the terrain surface and is collected by the receiver telescope. It also calculates the signal and noise waveforms output from the receiver's optical detector and waveform digitizer. Both avalanche photodiode and photomultiplier detectors may be selected. Parameters of the detected signal, including energy, the 50 percent rise-time point, the mean timing point, and the centroid, can be collected into histograms and statistics calculated after a number of laser firings. The laser altimeter can be selected to be fixed over the terrain at any altitude. Alternatively, it can move between laser shots to simulate the terrain profile measured with the laser altimeter.

  16. Energy doubling of 42 GeV electrons in a metre-scale plasma wakefield accelerator.

    PubMed

    Blumenfeld, Ian; Clayton, Christopher E; Decker, Franz-Josef; Hogan, Mark J; Huang, Chengkun; Ischebeck, Rasmus; Iverson, Richard; Joshi, Chandrashekhar; Katsouleas, Thomas; Kirby, Neil; Lu, Wei; Marsh, Kenneth A; Mori, Warren B; Muggli, Patric; Oz, Erdem; Siemann, Robert H; Walz, Dieter; Zhou, Miaomiao

    2007-02-15

    The energy frontier of particle physics is several trillion electron volts, but colliders capable of reaching this regime (such as the Large Hadron Collider and the International Linear Collider) are costly and time-consuming to build; it is therefore important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators, a drive beam (either laser or particle) produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultrahigh accelerating fields over a substantial length to achieve a significant energy gain. Here we show that an energy gain of more than 42 GeV is achieved in a plasma wakefield accelerator of 85 cm length, driven by a 42 GeV electron beam at the Stanford Linear Accelerator Center (SLAC). The results are in excellent agreement with the predictions of three-dimensional particle-in-cell simulations. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of approximately 52 GV m(-1). This effectively doubles their energy, producing the energy gain of the 3-km-long SLAC accelerator in less than a metre for a small fraction of the electrons in the injected bunch. This is an important step towards demonstrating the viability of plasma accelerators for high-energy physics applications.

  17. Simulations of Relativistic Laser-Plasma Interactions

    SciTech Connect

    Nikolic, Lj.; Skoric, M.M.; Ishiguro, S.

    2004-12-01

    To investigate the growth of instabilities in an underdense plasma, a number of simulations was carried out using the one-dimensional electromagnetic (EM) relativistic particle-in-cell code. A new type of Raman-like scattering was identified in a subcritical regime, which is overdense for standard SRS. This novel instability is a parametric decay of the relativistic EM wave into a scattered light and an electron-acoustic ({omega} < {omega}p) electrostatic wave. In the linear stage, resonant matchings are well satisfied, while the scattered Stokes wave is always driven near critical. During nonlinear saturation, due to rapid growth and strong localization of the Stokes wave, narrow intense EM soliton-like structures with down-shifted laser light trapped inside are formed; eventually, to be irradiated through the plasma-vacuum interface in the form of intense low-frequency EM bursts. This behavior alters the distribution of laser energy between transmission, scattering losses and generation of energetic electrons.

  18. Photoinjector optimization using a derivative-free, model-based trust-region algorithm for the Argonne Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Neveu, N.; Larson, J.; Power, J. G.; Spentzouris, L.

    2017-07-01

    Model-based, derivative-free, trust-region algorithms are increasingly popular for optimizing computationally expensive numerical simulations. A strength of such methods is their efficient use of function evaluations. In this paper, we use one such algorithm to optimize the beam dynamics in two cases of interest at the Argonne Wakefield Accelerator (AWA) facility. First, we minimize the emittance of a 1 nC electron bunch produced by the AWA rf photocathode gun by adjusting three parameters: rf gun phase, solenoid strength, and laser radius. The algorithm converges to a set of parameters that yield an emittance of 1.08 μm. Second, we expand the number of optimization parameters to model the complete AWA rf photoinjector (the gun and six accelerating cavities) at 40 nC. The optimization algorithm is used in a Pareto study that compares the trade-off between emittance and bunch length for the AWA 70MeV photoinjector.

  19. Clutter discrimination algorithm simulation in pulse laser radar imaging

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-mei; Li, Huan; Guo, Hai-chao; Su, Xuan; Zhu, Fule

    2015-10-01

    Pulse laser radar imaging performance is greatly influenced by different kinds of clutter. Various algorithms are developed to mitigate clutter. However, estimating performance of a new algorithm is difficult. Here, a simulation model for estimating clutter discrimination algorithms is presented. This model consists of laser pulse emission, clutter jamming, laser pulse reception and target image producing. Additionally, a hardware platform is set up gathering clutter data reflected by ground and trees. The data logging is as clutter jamming input in the simulation model. The hardware platform includes a laser diode, a laser detector and a high sample rate data logging circuit. The laser diode transmits short laser pulses (40ns FWHM) at 12.5 kilohertz pulse rate and at 905nm wavelength. An analog-to-digital converter chip integrated in the sample circuit works at 250 mega samples per second. The simulation model and the hardware platform contribute to a clutter discrimination algorithm simulation system. Using this system, after analyzing clutter data logging, a new compound pulse detection algorithm is developed. This new algorithm combines matched filter algorithm and constant fraction discrimination (CFD) algorithm. Firstly, laser echo pulse signal is processed by matched filter algorithm. After the first step, CFD algorithm comes next. Finally, clutter jamming from ground and trees is discriminated and target image is produced. Laser radar images are simulated using CFD algorithm, matched filter algorithm and the new algorithm respectively. Simulation result demonstrates that the new algorithm achieves the best target imaging effect of mitigating clutter reflected by ground and trees.

  20. Experimental plasma wake-field acceleration project*

    NASA Astrophysics Data System (ADS)

    Militsyn, B. L.; Bechtenev, A. A.; Breizman, B. N.; Chebotaev, P. Z.; Koop, I. A.; Kudryavtsev, A. M.; Panasyuk, V. M.; Shatunov, Yu. M.; Skrinsky, A. N.

    1993-07-01

    A new experiment on plasma wake-field acceleration has been designed at the Budker Institute of Nuclear Physics in Novosibirsk. An intense modulated driving beam from the electron-positron booster (BEP), a storage ring, will be used to excite a nonlinear plasma wave in a dense plasma (n=1015 cm-3). Important advantages of this beam are its very low emittance (10-8 cmṡrad in the vertical direction), high energy (850 MeV), and high intensity (1012 particles). A new technique for modulating this beam at a submillimeter wavelength is proposed. A simple numerical code has been developed to simulate the plasma wave excitation with plasma nonlinearity and with three-dimensional effects taken into account. The code allows the calculation of the radial structure of the nonlinear wake field including the focusing force which was mostly neglected in previous studies but which is especially important for experiment. The present numerical simulations show that, in the proposed experiment, a 1 GeV/m accelerating gradient over a macroscopic distance is attainable.

  1. Exciton-polariton wakefields in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Terças, H.; Mendonça, J. T.

    2016-02-01

    We consider the excitation of polariton wakefields due to a propagating light pulse in a semiconductor microcavity. We show that two kinds of wakes are possible, depending on the constituents fraction (either exciton or photon) of the polariton wavefunction. The nature of the wakefields (pure excitonic or polaritonic) can be controlled by changing the speed of propagation of the external pump. This process could be used as a diagnostic for the internal parameters of the microcavity.

  2. Wakefield Computations for the Injector (Part I)

    SciTech Connect

    Limborg-Deprey, C.

    2010-12-13

    In this document, we report on basic wakefield computations used to establish the impedance budget for the LCLS injector. Systematic comparisons between analytic formulae and results from ABCI are done. Finally, a comparison between 2D and 3D wakefield calculations are given for a cross. The three parts of the document are presented as follows: (1) ABCI computations for a few structures (Flange, Bellows...); (2) Comparison analytic with ABCI runs; and (3) Comparison Cross and Cavity using MAFIA.

  3. Particle dynamics and its consequences in wakefield acceleration in a high energy collider

    SciTech Connect

    Cheshkov, S.; Tajima, T.; Horton, W.; Yokoya, K.

    1998-09-01

    The performance of a wakefield accelerator in a high energy collider application is analyzed by use of a nonlinear dynamics map built on a simple theoretical model of the wakefield generated by the laser pulse (or whatever other method) and a code based on this map. The crucial figures of merit for such a system other than the final energy include the emittance (that determines the luminosity). The more complex the system is, the more opportunities the system has to degrade the emittance (or entropy of the beam). This the map guides one to identify where the crucial elements lie that affect the emittance. If the focusing force of the wakefield is strong when there is a jitter in the position (or laser aiming) of each stage coupled with the spread in the individual particle betatron frequencies, particles experience a phase space mixing. This effect sensitively controls the emittance degradation. They investigate these effects both in a uniform plasma and in a plasma channel. They also study the effect of beam loading. Further, they briefly consider collision point physics issues for a collider expected or characteristic of such a construction based on a scenario for the multi-staged wakefield accelerators.

  4. Beyond injection: Trojan horse underdense photocathode plasma wakefield acceleration

    SciTech Connect

    Hidding, B.; Rosenzweig, J. B.; Xi, Y.; O'Shea, B.; Andonian, G.; Schiller, D.; Barber, S.; Williams, O.; Pretzler, G.; Koenigstein, T.; Kleeschulte, F.; Hogan, M. J.; Litos, M.; Corde, S.; White, W. W.; Muggli, P.; Bruhwiler, D. L.; Lotov, K.

    2012-12-21

    An overview on the underlying principles of the hybrid plasma wakefield acceleration scheme dubbed 'Trojan Horse' acceleration is given. The concept is based on laser-controlled release of electrons directly into a particle-beam-driven plasma blowout, paving the way for controlled, shapeable electron bunches with ultralow emittance and ultrahigh brightness. Combining the virtues of a low-ionization-threshold underdense photocathode with the GV/m-scale electric fields of a practically dephasing-free beam-driven plasma blowout, this constitutes a 4th generation electron acceleration scheme. It is applicable as a beam brightness transformer for electron bunches from LWFA and PWFA systems alike. At FACET, the proof-of-concept experiment 'E-210: Trojan Horse Plasma Wakefield Acceleration' has recently been approved and is in preparation. At the same time, various LWFA facilities are currently considered to host experiments aiming at stabilizing and boosting the electron bunch output quality via a trojan horse afterburner stage. Since normalized emittance and brightness can be improved by many orders of magnitude, the scheme is an ideal candidate for light sources such as free-electron-lasers and those based on Thomson scattering and betatron radiation alike.

  5. Performance calculation and simulation system of high energy laser weapon

    NASA Astrophysics Data System (ADS)

    Wang, Pei; Liu, Min; Su, Yu; Zhang, Ke

    2014-12-01

    High energy laser weapons are ready for some of today's most challenging military applications. Based on the analysis of the main tactical/technical index and combating process of high energy laser weapon, a performance calculation and simulation system of high energy laser weapon was established. Firstly, the index decomposition and workflow of high energy laser weapon was proposed. The entire system was composed of six parts, including classical target, platform of laser weapon, detect sensor, tracking and pointing control, laser atmosphere propagation and damage assessment module. Then, the index calculation modules were designed. Finally, anti-missile interception simulation was performed. The system can provide reference and basis for the analysis and evaluation of high energy laser weapon efficiency.

  6. Simulation study on laser cladding on preplaced powder layer with a tailored laser heat source

    NASA Astrophysics Data System (ADS)

    Tseng, W. C.; Aoh, J. N.

    2013-06-01

    This study proposes a tailored laser heat source model for the finite element analysis of the laser cladding process. The beam characteristics, including wavelength, beam radius, TEM mode and focusing conditions, were comprehensively considered in the heat source model. The model was integrated in a SYSWELD package to predict the temperature distribution and clad bead profile during laser cladding of preplaced cobalt powder layer on a steel substrate. Cladding process parameters were evaluated by varying the TEM mode, focusing conditions, wavelength and scanning speed. Single mode and tailored multi-mode TEMmixed laser beams were established for simulation. The numerical results were verified by performing a laser cladding experiment under the same conditions as the numerical model. The clad bead geometries predicted from the numerical simulation agreed well with those obtained from experiment. Thanks to the comprehensive feature of the proposed tailored laser heat source model, it also could be well applied to the numerical simulation of other laser material processes.

  7. Phase unwrapping algorithms in laser propagation simulation

    NASA Astrophysics Data System (ADS)

    Du, Rui; Yang, Lijia

    2013-08-01

    Currently simulating on laser propagation in atmosphere usually need to deal with beam in strong turbulence, which may lose a part of information via Fourier Transform to simulate the transmission, makes the phase of beam as a 2-D array wrap by 2π . An effective unwrapping algorithm is needed for continuing result and faster calculation. The unwrapping algorithms in atmospheric propagation are similar to the unwrapping algorithm in radar or 3-D surface rebuilding, but not the same. In this article, three classic unwrapping algorithms: the block least squares (BLS), mask-cut (MCUT), and the Flynn's minimal discontinuity algorithm (FMD) are tried in wave-front reconstruction simulation. Each of those algorithms are tested 100 times in 6 same conditions, including low(64x64), medium(128x128), and high(256x256) resolution phase array, with and without noises. Compared the results, the conclusions are delivered as follows. The BLS-based algorithm is the fastest, and the result is acceptable in low resolution environment without noise. The MCUT are higher in accuracy, though they are slower with the array resolution increased, and it is sensitive to noise, resulted in large area errors. Flynn's algorithm has the better accuracy, and it occupies large memory in calculation. After all, the article delivered a new algorithm that based on Active on Vertex (AOV) Network, to build a logical graph to cut the search space then find minimal discontinuity solution. The AOV is faster than MCUT in dealing with high resolution phase arrays, and better accuracy as FMD that has been tested.

  8. Simulation of laser interaction with ablative plasma and hydrodynamic behavior of laser supported plasma

    NASA Astrophysics Data System (ADS)

    Tong, Huifeng; Yuan, Hong; Tang, Zhiping

    2013-01-01

    When an intense laser beam irradiates on a solid target, ambient air ionizes and becomes plasma, while part of the target rises in temperature, melts, vaporizes, ionizes, and yet becomes plasma. A general Godunov finite difference scheme WENO (Weighted Essentially Non-Oscillatory Scheme) with fifth-order accuracy is used to simulate 2-dimensional axis symmetrical laser-supported plasma flow field in the process of laser ablation. The model of the calculation of ionization degree of plasma and the interaction between laser beam and plasma are considered in the simulation. The numerical simulations obtain the profiles of temperature, density, and velocity at different times which show the evolvement of the ablative plasma. The simulated results show that the laser energy is strongly absorbed by plasma on target surface and that the velocity of laser supported detonation (LSD) wave is half of the ideal LSD value derived from Chapman-Jouguet detonation theory.

  9. Simulation of laser interaction with ablative plasma and hydrodynamic behavior of laser supported plasma

    SciTech Connect

    Tong Huifeng; Yuan Hong; Tang Zhiping

    2013-01-28

    When an intense laser beam irradiates on a solid target, ambient air ionizes and becomes plasma, while part of the target rises in temperature, melts, vaporizes, ionizes, and yet becomes plasma. A general Godunov finite difference scheme WENO (Weighted Essentially Non-Oscillatory Scheme) with fifth-order accuracy is used to simulate 2-dimensional axis symmetrical laser-supported plasma flow field in the process of laser ablation. The model of the calculation of ionization degree of plasma and the interaction between laser beam and plasma are considered in the simulation. The numerical simulations obtain the profiles of temperature, density, and velocity at different times which show the evolvement of the ablative plasma. The simulated results show that the laser energy is strongly absorbed by plasma on target surface and that the velocity of laser supported detonation (LSD) wave is half of the ideal LSD value derived from Chapman-Jouguet detonation theory.

  10. Molecular Dynamics Simulations of Laser Powered Carbon Nanotube Gears

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Globus, Al; Han, Jie; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    Dynamics of laser powered carbon nanotube gears is investigated by molecular dynamics simulations with Brenner's hydrocarbon potential. We find that when the frequency of the laser electric field is much less than the intrinsic frequency of the carbon nanotube, the tube exhibits an oscillatory pendulam behavior. However, a unidirectional rotation of the gear with oscillating frequency is observed under conditions of resonance between the laser field and intrinsic gear frequencies. The operating conditions for stable rotations of the nanotube gears, powered by laser electric fields are explored, in these simulations.

  11. Molecular Dynamics Simulations of Laser Powered Carbon Nanotube Gears

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Globus, Al; Han, Jie; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    Dynamics of laser powered carbon nanotube gears is investigated by molecular dynamics simulations with Brenner's hydrocarbon potential. We find that when the frequency of the laser electric field is much less than the intrinsic frequency of the carbon nanotube, the tube exhibits an oscillatory pendulam behavior. However, a unidirectional rotation of the gear with oscillating frequency is observed under conditions of resonance between the laser field and intrinsic gear frequencies. The operating conditions for stable rotations of the nanotube gears, powered by laser electric fields are explored, in these simulations.

  12. Simulations of laser locking to a LISA arm

    SciTech Connect

    Sylvestre, Julien

    2004-11-15

    We present detailed numerical simulations of a laser phase stabilization scheme for Laser Interferometer Space Antenna (LISA), where both lasers emitting along one arm are locked to each other. Including the standard secondary noises and spacecraft motions that approximately mimic LISA's orbit (excluding the rotation of the constellation), we verify that very stable laser phases can be obtained and that time delay interferometry can be used to remove the laser phase noise from measurements of gravitational wave strains. Most importantly, we show that this locking scheme can provide significant simplifications over LISA's baseline design in the implementation of time delay interferometry.

  13. Laser Guiding for GeV Laser-Plasma Accelerators

    SciTech Connect

    Leemans, Wim; Esarey, Eric; Geddes, Cameron; Schroeder, C.B.; Toth, Csaba

    2005-06-06

    Guiding of relativistically intense laser beams in preformed plasma channels is discussed for development of GeV-class laser accelerators. Experiments using a channel guided laser wakefield accelerator (LWFA) at LBNL have demonstrated that near mono-energetic 100 MeV-class electron beams can be produced with a 10 TW laser system. Analysis, aided by particle-in-cell simulations, as well as experiments with various plasma lengths and densities, indicate that tailoring the length of the accelerator, together with loading of the accelerating structure with beam, is the key to production of mono-energetic electron beams. Increasing the energy towards a GeV and beyond will require reducing the plasma density and design criteria are discussed for an optimized accelerator module. The current progress and future directions are summarized through comparison with conventional accelerators, highlighting the unique short term prospects for intense radiation sources based on laser-driven plasma accelerators.

  14. Transformer ratio saturation in a beam-driven wakefield accelerator

    SciTech Connect

    Farmer, J. P.; Martorelli, R.; Pukhov, A.

    2015-12-15

    We show that for beam-driven wakefield acceleration, the linearly ramped, equally spaced train of bunches typically considered to optimise the transformer ratio only works for flat-top bunches. Through theory and simulation, we explain that this behaviour is due to the unique properties of the plasma response to a flat-top density profile. Calculations of the optimal scaling for a train of Gaussian bunches show diminishing returns with increasing bunch number, tending towards saturation. For a periodic bunch train, a transformer ratio of 23 was achieved for 50 bunches, rising to 40 for a fully optimised beam.

  15. Summary Report of Working Group 4: Plasma Wakefield Acceleration

    SciTech Connect

    Rosenzweig, J.B.; Seryi, A.; /SLAC

    2012-06-11

    This report gives a guide to the discussions of Working Group 4 of the 2010 Advanced Accelerator Concepts Workshop, which was devoted to theory, simulation and experimental issues associated with plasma wakefield acceleration (PWFA). Sessions were organized thematically in this group, concentrating on broad issues of: exploitation of future facilities such as FACET; pushing the accelerating gradient beyond the current frontier, to over a TeV/m; use of positively charged beams to drive plasma wakes; resonant excitation of the PWFA with pulse trains; beam-plasma instabilities; and injection and capture of electron beams into PWFA systems.

  16. Quasi-stable injection channels in a wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Wiltshire-Turkay, Mara; Farmer, John P.; Pukhov, Alexander

    2016-05-01

    The influence of initial position on the acceleration of externally injected electrons in a plasma wakefield is investigated. Test-particle simulations show previously unobserved complex structure in the parameter space, with quasi-stable injection channels forming for particles injected in narrow regions away from the wake centre. Particles injected into these channels remain in the wake for a considerable time after dephasing and as a result achieve significantly higher energy than their neighbours. The result is relevant to both the planning and optimisation of experiments making use of external injection.

  17. Quasi-stable injection channels in a wakefield accelerator

    SciTech Connect

    Wiltshire-Turkay, Mara; Farmer, John P.; Pukhov, Alexander

    2016-05-15

    The influence of initial position on the acceleration of externally injected electrons in a plasma wakefield is investigated. Test-particle simulations show previously unobserved complex structure in the parameter space, with quasi-stable injection channels forming for particles injected in narrow regions away from the wake centre. Particles injected into these channels remain in the wake for a considerable time after dephasing and as a result achieve significantly higher energy than their neighbours. The result is relevant to both the planning and optimisation of experiments making use of external injection.

  18. Absorptivity Measurements and Heat Source Modeling to Simulate Laser Cladding

    NASA Astrophysics Data System (ADS)

    Wirth, Florian; Eisenbarth, Daniel; Wegener, Konrad

    The laser cladding process gains importance, as it does not only allow the application of surface coatings, but also additive manufacturing of three-dimensional parts. In both cases, process simulation can contribute to process optimization. Heat source modeling is one of the main issues for an accurate model and simulation of the laser cladding process. While the laser beam intensity distribution is readily known, the other two main effects on the process' heat input are non-trivial. Namely the measurement of the absorptivity of the applied materials as well as the powder attenuation. Therefore, calorimetry measurements were carried out. The measurement method and the measurement results for laser cladding of Stellite 6 on structural steel S 235 and for the processing of Inconel 625 are presented both using a CO2 laser as well as a high power diode laser (HPDL). Additionally, a heat source model is deduced.

  19. Automated detection and analysis of particle beams in laser-plasma accelerator simulations

    SciTech Connect

    Ushizima, Daniela Mayumi; Geddes, C.G.; Cormier-Michel, E.; Bethel, E. Wes; Jacobsen, J.; Prabhat, ,; R.ubel, O.; Weber, G,; Hamann, B.

    2010-05-21

    Numerical simulations of laser-plasma wakefield (particle) accelerators model the acceleration of electrons trapped in plasma oscillations (wakes) left behind when an intense laser pulse propagates through the plasma. The goal of these simulations is to better understand the process involved in plasma wake generation and how electrons are trapped and accelerated by the wake. Understanding of such accelerators, and their development, offer high accelerating gradients, potentially reducing size and cost of new accelerators. One operating regime of interest is where a trapped subset of electrons loads the wake and forms an isolated group of accelerated particles with low spread in momentum and position, desirable characteristics for many applications. The electrons trapped in the wake may be accelerated to high energies, the plasma gradient in the wake reaching up to a gigaelectronvolt per centimeter. High-energy electron accelerators power intense X-ray radiation to terahertz sources, and are used in many applications including medical radiotherapy and imaging. To extract information from the simulation about the quality of the beam, a typical approach is to examine plots of the entire dataset, visually determining the adequate parameters necessary to select a subset of particles, which is then further analyzed. This procedure requires laborious examination of massive data sets over many time steps using several plots, a routine that is unfeasible for large data collections. Demand for automated analysis is growing along with the volume and size of simulations. Current 2D LWFA simulation datasets are typically between 1GB and 100GB in size, but simulations in 3D are of the order of TBs. The increase in the number of datasets and dataset sizes leads to a need for automatic routines to recognize particle patterns as particle bunches (beam of electrons) for subsequent analysis. Because of the growth in dataset size, the application of machine learning techniques for

  20. High power CW iodine laser pumped by solar simulator

    NASA Technical Reports Server (NTRS)

    Lee, Ja H.; Lee, Min H.; Weaver, Willard R.

    1987-01-01

    An iodine photodissociation laser was pumped by a long Ar arc as the solar simulator to produce a 10-W CW output. Continuous lasing for 1 h was achieved with a flow of the laser material n-C3F7I. The 10-W CW output is the highest produced to date and establishes the feasibility of developing a solar-pumped laser for space power transmission.

  1. Space charge effect simulation at electrons channeling in laser fields

    NASA Astrophysics Data System (ADS)

    Frolov, E. N.; Dik, A. V.; Dabagov, S. B.

    2017-07-01

    In this work we present simulation results for electron beam channeling in ponderomotive potential of laser fields, calculated with a newly created code for electron beam dynamics taking into account space charge effect. It is shown that the use of laser field allows the electron beam to be shaped including focusing and collimation.

  2. LISP: a laser imaging simulation package for developing and testing laser vision systems

    NASA Astrophysics Data System (ADS)

    Wu, Kung C.

    1993-01-01

    The difficulties commonly encountered in developing laser imaging technologies are: (1) high cost of the laser system, and (2) time and cost involved in modeling and maneuvering a physical environment for the desired scenes. In contrast to the real imaging systems, computer generated laser images provide researchers with fast, accurate, cost-effective data for testing and developing algorithms. The laser imaging simulation package (LISP) described in this paper provides an interactive solid modeler that allows users to construct the artificial environment by various solid modelling techniques. Two fast ray tracing algorithms were developed and discussed in this paper for generating the near realistic laser data of any desired scene. These computer generated laser data facilitates the researchers in developing laser imaging algorithms. Thus, LISP not only provides an ideal testbed for developing and testing algorithms, but also an opportunity to explore the limitation of laser imaging applications.

  3. Enhancement of proton acceleration field in laser double-layer target interaction

    NASA Astrophysics Data System (ADS)

    Gu, Y. J.; Kong, Q.; Kawata, S.; Izumiyama, T.; Li, X. F.; Yu, Q.; Wang, P. X.; Ma, Y. Y.

    2013-07-01

    A mechanism is proposed to enhance a proton acceleration field in laser plasma interaction. A double-layer plasma with different densities is illuminated by an intense short pulse. Electrons are accelerated to a high energy in the first layer by the wakefield. The electrons accelerated by the laser wakefield induce the enhanced target normal sheath (TNSA) and breakout afterburner (BOA) accelerations through the second layer. The maximum proton energy reaches about 1 GeV, and the total charge with an energy higher than 100 MeV is about several tens of μC/μm. Both the acceleration gradient and laser energy transfer efficiency are higher than those in single-target-based TNSA or BOA. The model has been verified by 2.5D-PIC simulations.

  4. Enhancement of proton acceleration field in laser double-layer target interaction

    SciTech Connect

    Gu, Y. J.; Kong, Q.; Li, X. F.; Yu, Q.; Wang, P. X.; Kawata, S.; Izumiyama, T.; Ma, Y. Y.

    2013-07-15

    A mechanism is proposed to enhance a proton acceleration field in laser plasma interaction. A double-layer plasma with different densities is illuminated by an intense short pulse. Electrons are accelerated to a high energy in the first layer by the wakefield. The electrons accelerated by the laser wakefield induce the enhanced target normal sheath (TNSA) and breakout afterburner (BOA) accelerations through the second layer. The maximum proton energy reaches about 1 GeV, and the total charge with an energy higher than 100 MeV is about several tens of μC/μm. Both the acceleration gradient and laser energy transfer efficiency are higher than those in single-target-based TNSA or BOA. The model has been verified by 2.5D-PIC simulations.

  5. Increasing the transformer ratio at the Argonne wakefield accelerator.

    SciTech Connect

    Power, J.G.; Conde, M.; Liu, W.; Yusof, Z.; Gai, W.; Jing, C.; Kanareykin, A.

    2011-01-01

    The transformer ratio is defined as the ratio of the maximum energy gain of the witness bunch to the maximum energy loss experienced by the drive bunch (or a bunch within a multidrive bunch train). This plays an important role in the collinear wakefield acceleration scheme. A high transformer ratio is desirable since it leads to a higher overall efficiency under similar conditions (e.g. the same beam loading, the same structure, etc.). One technique to enhance the transformer ratio beyond the ordinary limit of 2 is to use a ramped bunch train. The first experimental demonstration observed a transformer ratio only marginally above 2 due to the mismatch between the drive microbunch length and the frequency of the accelerating structure [C. Jing, A. Kanareykin, J. Power, M. Conde, Z. Yusof, P. Schoessow, and W. Gai, Phys. Rev. Lett. 98, 144801 (2007)]. Recently, we revisited this experiment with an optimized microbunch length using a UV laser stacking technique at the Argonne Wakefield Accelerator facility and measured a transformer ratio of 3.4. Measurements and data analysis from these experiments are presented in detail.

  6. Dielectric-Based Wakefield Power Extractor

    SciTech Connect

    Jing, C.; Antipov, S.; Gao, F.; Kanareykin, A.; Schoessow, P.; Gai, W.; Conde, M.; Liu, W.; Power, J. G.; Konecny, R.; Yusof, Z.

    2010-11-04

    In the Two Beam Accelerator (TBA), wakefield power extractors which extract high power RF from a high current beam are used to power high gradient accelerating structures. A dielectric-based Wakefield Power Extractor (DWPE) is one option in addition to the metallic structures considered previously, like the CLIC PETS (Power Extraction and Transfer Structure). 7.8 GHz and 26 GHz DWPE prototypes have been successfully built and tested at the Argonne Wakefield Accelerator (AWA) facility. We are currently designing an X-band version for a potential application with the CLIC beam. In this article, we report on test results of the 26 GHz DWPE and the preliminary design of the X-band structure. Future plan and possible difficulties in the development of DWPEs are also discussed.

  7. Laser-driven hypersonic air-breathing propulsion simulator

    NASA Technical Reports Server (NTRS)

    Joshi, Prakash B.; Lo, Edmond Y.; Pugh, Evan R.

    1992-01-01

    A feasibility study is presented of simulating airbreathing propulsion on small scale hypersonic models using laser energy. The laser heat addition scheme allows simultaneous inlet and exhaust flows during wind tunnel testing of models with scramjet models. The proposed propulsion simulation concept has extended the Kantrowitz (1974) idea to propulsive wind tunnel models of hypersonic aircraft. Critical issues in aeropropulsive testing of models based on a ramjet power plant are addressed which include transfer of the correct amount of energy to the flowing gas, efficient absorption of laser energy into the gas, and test performance under tunnel reservoir conditions and at reasonable Reynolds numbers.

  8. Theoretical model simulating CO2 laser welding of tissues

    NASA Astrophysics Data System (ADS)

    Ravid, Avi; Katzir, Abraham

    1996-12-01

    3D finite difference computerized model was developed to simulate the thermal behavior of biological tissue irradiated with a CO2 laser beam. The model uses standard thermal processes and in addition takes into consideration water evaporation and the corresponding changes in the thermal properties of the tissue. The results contain a temperature and biological damage map of the irradiated tissue. Experimental results of test made on Lucite irradiated with CO2 laser fit very well the theoretical predictions. The model was then used for simulations of tissue welding and the results indicate that an improved method could be used for CO2 laser welding.

  9. Potential of solar-simulator-pumped alexandrite lasers

    NASA Technical Reports Server (NTRS)

    Deyoung, Russell J.

    1990-01-01

    An attempt was made to pump an alexandrite laser rod using a Tamarak solar simulator and also a tungsten-halogen lamp. A very low optical laser cavity was used to achieve the threshold minimum pumping-power requirement. Lasing was not achieved. The laser threshold optical-power requirement was calculated to be approximately 626 W/sq cm for a gain length of 7.6 cm, whereas the Tamarak simulator produces 1150 W/sq cm over a gain length of 3.3 cm, which is less than the 1442 W/sq cm required to reach laser threshold. The rod was optically pulsed with 200 msec pulses, which allowed the alexandrite rod to operate at near room temperature. The optical intensity-gain-length product to achieve laser threshold should be approximately 35,244 solar constants-cm. In the present setup, this product was 28,111 solar constants-cm.

  10. Simulation of Laser Interaction with Ablative Plasma and ydrodynamic of Laser Supported Plasma(LSP)

    NASA Astrophysics Data System (ADS)

    Huifeng, Tong; Zhiping, Tang

    2011-06-01

    A general Godunov finite difference schemes-WENO(Weighted Essentially Non-Oscillatory) Schemes which have fifth-order accuracy was used to make a numerical calculation for 2-dimensional axis symmetrical laser-supported plasma flow field under laser ablated solid target. The models of the calculation of ionization degree of plasma and the interaction between laser beam and plasma and the simplified eos(equation of state) of plasma were considered in the simulation. The plasma field parameters during and after laser duration variation with time are also obtained. The simulation results show that the laser beam power was strong absorbed by plasma of target surface, and the velocity of LSD(Laser Supported Detonation) wave is half of ideal LSD value which derived from C-J detonation theory.

  11. PIC Simulations of direct laser accelerated electron from underdense plasmas using the OMEGA EP Laser

    NASA Astrophysics Data System (ADS)

    Hussein, Amina; Batson, Thomas; Krushelnick, Karl; Willingale, Louise; Arefiev, Alex; Wang, Tao; Nilson, Phil; Froula, Dustin; Haberberger, Dan; Davies, Andrew; Theobald, Wolfgang; Williams, Jackson; Chen, Hui

    2016-10-01

    The OMEGA EP laser system is used to study channeling phenomena and direct laser acceleration (DLA) through an underdense plasma. The interaction of a ps laser pulse with a subcritical density CH plasma plume results in the expulsion of electron along the laser axis, forming a positively charged channel. Electrons confined within this channel are subject to the action of the laser field as well as the transverse electric field of the channel, resulting the DLA of these electrons and the formation of a high energy electron beam. We have performed 2D simulations of ultra-intense laser radiation with underdense plasma using the PIC code EPOCH to investigate electron densities and self-consistently generated electric fields, as well as electron trajectories. This work was supported by the National Laser Users' Facility (NLUF), DOE.

  12. Wakefields in SLAC linac collimators

    DOE PAGES

    Novokhatski, A.; Decker, F. -J.; Smith, H.; ...

    2014-12-02

    When a beam travels near collimator jaws, it gets an energy loss and a transverse kick due to the backreaction of the beam field diffracted from the jaws. The effect becomes very important for an intense short bunch when a tight collimation of the background beam halo is required. In the Linac Coherent Light Source at SLAC a collimation system is used to protect the undulators from radiation due to particles in the beam halo. The halo is most likely formed from gun dark current or dark current in some of the accelerating sections. However, collimators are also responsible formore » the generation of wake fields. The wake field effect from the collimators not only brings an additional energy jitter and change in the trajectory of the beam, but it also rotates the beam on the phase plane, which consequently leads to a degradation of the performance of the Free Electron Laser at the Linac Coherent Light Source. In this paper, we describe a model of the wake field radiation in the SLAC linac collimators. We use the results of a numerical simulation to illustrate the model. Based on the model, we derive simple formulas for the bunch energy loss and the average kick. We also present results from experimental measurements that confirm our model.« less

  13. Examining laser triangulation system performance using a software simulation

    NASA Astrophysics Data System (ADS)

    Collier, Jeffery S.; Nurre, Joseph H.

    1999-03-01

    The invention of the laser diode, the microcomputer and the CCD camera have made possible the new technology of triangulation measurement systems. Current applications range from scanning the insides of old pipes, to a vision tool for the blind. As such, it is important that techniques be developed to minimize the error in laser triangulation measurement systems. Due to the nonlinear nature of the problem and the fact that error is dependent on an ever changing and vast number of subjects, a computer simulation was written to examine the trade-off between occlusion and data quality. A computer simulation allows for a large amount of flexibility. The software gives the user the ability to calculate the error for a given triangulation configuration without having to build and test the actual hardware. This paper describes and demonstrates the use of the simulator. Limitless laser triangulation systems can be modeled and most subjects represented in CAD files can be used in the computer simulation.

  14. Target model and simulation for laser imaging fuze

    NASA Astrophysics Data System (ADS)

    Li, Weiheng; Song, Chengtian

    2013-09-01

    Image detection is an important direction of fuze development nowadays, and laser imaging fuze is one of the main technologies. This paper carries out the research in simulation technology of the process with detection, scan and imaging, which is used in laser imaging fuze for tank target, and get the simulation images information of different intersection conditions, including tank spot information,distance information and power information. The target coordinate system is established with the movement characteristics,physical characteristics and existing coordinate system of tank target. And through transferring missile coordinates to the target coordinate system as well as the relative movement between the different time intervals, the model of missile-target in time and space is build up. The model is build up according to the tank target and diffusion properties of different background, including desert, soil, vegetation, and buildings. The relations of scattering power and bidirectional reflectance distribution function deduced the laser echo power calculation formula, which can calculate the echoes incidence to each surface of the laser.The design of laser imaging fuze simulation system is complicated ,which contains the technology of the process with detection, scan and imaging used in laser imaging fuze for tank target. The simulation system products the tank spot picture, the distance gradation picture, and the power gradation picture. The latter two contains two-dimensional information, the scanning distance as well as the value of echo power to meet the expected design effects.

  15. Optical Frequency Domain Visualization of Electron Beam Driven Plasma Wakefields

    NASA Astrophysics Data System (ADS)

    Zgadzaj, Rafal; Downer, M. C.; Muggli, Patric; Yakimenko, Vitaly; Babzien, Marcus; Kusche, Karl; Fedurin, Mikhail

    2010-11-01

    Beam-driven plasma wakefield accelerators (PWFA), such as the ``plasma afterburner,'' are a promising approach for significantly increasing the particle energies of conventional accelerators. The study and optimization of PWFA would benefit from an experimental correlation between the parameters of the drive bunch, the accelerated bunch and the corresponding, accelerating plasma wave structure. However, the plasma wave structure has not yet been observed directly in PWFA. We will report our current work on noninvasive optical Frequency Domain Interferometric (FDI) and Holographic (FDH) visualization of beam-driven plasma waves. Both techniques employ two laser pulses (probe and reference) co-propagating with the particle drive-beam and its plasma wake. The reference pulse precedes the drive bunch, while the probe overlaps the plasma wave and maps its longitudinal and transverse structure. The experiment is being developed at the BNL/ATF Linac to visualize wakes generated by two and multi-bunch drive beams.

  16. Novel concepts for laser-plasma-based acceleration of electrons using ultrahigh power laser pulses

    NASA Astrophysics Data System (ADS)

    Kim, Joon-Koo

    Analytical and numerical studies of plasma physics in ultra-intense plasma wave generation, electron injection, and wavebreaking are performed, which are relevant to the subject of plasma wake-field accelerators. A method for generating large-amplitude nonlinear plasma waves, which utilizes an optimized train of independently adjustable, intense laser pulses, is analyzed in one dimension both theoretically and numerically (using both Maxwell-fluid and particle-in-cell codes). Optimal pulse widths and interpulse spacings are computed for pulses with either square or finite-rise-time sine shapes. A resonant region of the plasma-wave phase space is found where the plasma wave is driven most efficiently by the laser pulses. Resonant excitation is found to be superior for electron acceleration to either beatwave or single- pulse excitation because comparable plasma wave amplitudes may be generated at lower plasma densities, reducing electron-phase detuning, or at lower laser intensities, reducing laser-plasma instabilities. The idea of all-optical acceleration of electrons in the wakefield is also discussed. It is shown that the injection of background plasma electrons can be accomplished using the large ponderomotive force of an injection laser pulse in either collinear or transverse geometry with respect to the direction of pump propagation, thus removing the necessity of an expensive first-stage linac system for injection of electrons. Detailed nonlinear analysis of the trapping and acceleration of electrons inside the separatrix of the wakefield is formulated and compared with PIC (Particle- In-Cell) and fluid simulations. The three-dimensional wave-breaking of relativistic plasma waves driven by a ultrashort high-power lasers, is described within a framework of cold 2-D fluid theory. It is shown that the transverse nonlinearity of the plasma wave results in temporally increasing transverse plasma oscillation in the wake of the laser pulse, inevitably inducing wave

  17. Energy Measurement in a Plasma Wakefield Accelerator

    SciTech Connect

    Ischebeck, R

    2007-07-06

    In the E-167 plasma wakefield acceleration experiment, electrons with an initial energy of 42GeV are accelerated in a meter-scale lithium plasma. Particles are leaving plasma with a large energy spread. To determine the spectrum of the accelerated particles, a two-plane spectrometer has been set up.

  18. Electron cloud wakefields in bunch trains

    NASA Astrophysics Data System (ADS)

    Petrov, F. B.; Boine-Frankenheim, Oliver

    2016-02-01

    Electron cloud is a concern for many modern and future accelerator facilities. There are a number of undesired effects attributed to the presence of electron clouds. Among them are coherent instabilities, emittance growth, cryogenic heat load, synchronous phase shift and pressure rise. In long bunch trains one can observe the emittance growth getting faster along the bunch train. The interaction between the beam and the electron cloud is a two-stream interaction. The prameters of the electron cloud wakefields depend on the beam intensity, beam centroid perturbations, and on the electron density and perturbations. If the electron cloud forgets the bunch centroid perturbation very fast, the buildup itself, via growing density, becomes a way of coupling between the bunches. In the present paper we address how the bunch perturbation shape affects the multi-bunch wakefields under the conditions similar to the CERN LHC and SPS. We study the interplay between the single-bunch and multi-bunch electron cloud wakefields. The effect of the dipole magnetic field on the multi-bunch wakefields is studied.

  19. Collective effects on the wakefield and stopping power of an ion beam pulse in plasmas

    SciTech Connect

    Zhang, Ling-yu; Zhao, Xiao-ying; Qi, Xin E-mail: duanws@nwnu.edu.cn Duan, Wen-shan E-mail: duanws@nwnu.edu.cn Xiao, Guo-qing; Yang, Lei E-mail: duanws@nwnu.edu.cn

    2015-05-15

    A two-dimensional (2D) particle-in-cell simulation is carried out to study the collective effects on the wakefield and stopping power for a hydrogen ion beam pulse propagation in hydrogen plasmas. The dependence of collective effects on the beam velocity and density is obtained and discussed. For the beam velocity, it is found that the collective effects have the strongest impact on the wakefield as well as the stopping power in the case of the intermediate beam velocities, in which the stopping power is also the largest. For the beam density, it is found that at low beam densities, the collective contribution to the stopping power increase linearly with the increase of the beam density, which corresponds well to the results calculated using the dielectric theory. However, at high beam densities, our results show that after reaching a maximum value, the collective contribution to the stopping power starts to decrease significantly with the increase of the beam density. Besides, at high beam densities, the wakefield loses typical V-shaped cone structures, and the wavelength of the oscillation wakefield increases as the beam density increases.

  20. Dielectric Wakefield Accelerator Experiments at the SABER Facility

    SciTech Connect

    Kanareykin, A.; Thompson, M.C.; Berry, M.K.; Blumenfeld, I.; Decker, F.J.; Hogan, M.J.; Ischebeck, R.; Iverson, R.H.; Kirby, N.A.; Siemann, Robert H.; Walz, D.R.; Badakov, H.; Cook, A.M.; Rosenzweig, J.B.; Tikhoplav, R.; Travish, G.; Muggli, P.; /Southern California U.

    2008-01-28

    Electron bunches with the unparalleled combination of high charge, low emittances, and short time duration, as first produced at the SLAC Final Focus Test Beam (FFTB), are foreseen to be produced at the SABER facility. These types of bunches have enabled wakefield driven accelerating schemes of multi-GV/m in plasmas. In the context of the Dielectric Wakefield Accelerators (DWA) such beams, having rms bunch length as short as 20 um, have been used to drive 100 um and 200 um ID hollow tubes above 20 GV/m surface fields. These FFTB tests enabled the measurement of a breakdown threshold in fused silica (with full data analysis still ongoing) [1]. With the construction and commissioning of the SABER facility at SLAC, new experiments would be made possible to test further aspects of DWAs including materials, tube geometrical variations, direct measurements of the Cerenkov fields, and proof of acceleration in tubes >10 cm in length. This collaboration will investigate breakdown thresholds and accelerating fields in new materials including CVD diamond. Here we describe the experimental plans, beam parameters, simulations, and progress to date as well as future prospects for machines based of DWA structures.

  1. Appearance of Density Cavitations in the Laser Wake in Simulations of High Intensity Laser-Plasma Interactions

    SciTech Connect

    Wang, T.-L.

    2009-01-22

    Nonlinear interactions of high intensity, ultrashort laser pulses with underdense plasmas produce many interesting features that may appear in computer simulations. One of these features commonly observed in Particle-In-Cell (PIC) simulations is the spontaneous appearance of long-lived density cavitations in the plasma wake region behind the laser pulse. To study these cavitations, several small 2D PIC simulations are run in which plasma density, density ramps, total simulation time, laser pulsewidth, laser intensity, and laser polarization parameters have been varied. Based on the simulation results, some possible aspects of an experiment designed to directly detect these structures are discussed.

  2. Efficient method for transport simulations in quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Maczka, Mariusz; Pawlowski, Stanislaw

    2016-12-01

    An efficient method for simulating quantum transport in quantum cascade lasers is presented. The calculations are performed within a simple approximation inspired by Büttiker probes and based on a finite model for semiconductor superlattices. The formalism of non-equilibrium Green's functions is applied to determine the selected transport parameters in a typical structure of a terahertz laser. Results were compared with those obtained for a infinite model as well as other methods described in literature.

  3. Simulation of femtosecond pulsed laser ablation of metals

    NASA Astrophysics Data System (ADS)

    Davydov, R. V.; Antonov, V. I.

    2016-11-01

    In this paper a mathematical model for femtosecond laser ablation of metals is proposed, based on standard two-temperature model connected with 1D hydrodynamic equations. Wide-range equation of state has been developed. The simulation results are compared with experimental data for aluminium and copper. A good agreement for both metals with numerical results and experiment shows that this model can be employed for choosing laser parameters to better accuracy in nanoparticles production by ablation of metals.

  4. Simulated [111] Si-SiGe terahertz quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Lever, L.; Valavanis, A.; Ikonić, Z.; Kelsall, R. W.

    2008-01-01

    The prospect of developing a silicon laser has long been an elusive goal, mainly due to the indirect band gap and large effective carrier masses. We present a design for a terahertz intersubband laser grown on the [111] crystal plane and simulate performance using a rate equation method including scattering due to alloy disorder, interface roughness, carrier-phonon, and Coulombic interactions. We predict gain greater than 40cm-1 and a threshold current density of 70A/cm2.

  5. Simulation of High Power Lasers (Preprint)

    DTIC Science & Technology

    2010-06-01

    product of laser power. 5. References 1 Wilcox, D. C, Turbulence Modeling for CFD, DCW Industries, Inc. pp. 185-193, July 1998. 2 Menter, F. L...Modeling for CFD, DCW Industries, Inc. pp. 294-296, July 1998. 4 Perram, G. P, .Int. J. Chem. Kinet. 27, 817-28 (1995). 5 Madden, T. J. and Solomon

  6. Single event effects and laser simulation studies

    NASA Technical Reports Server (NTRS)

    Kim, Q.; Schwartz, H.; Mccarty, K.; Coss, J.; Barnes, C.

    1993-01-01

    The single event upset (SEU) linear energy transfer threshold (LETTH) of radiation hardened 64K Static Random Access Memories (SRAM's) was measured with a picosecond pulsed dye laser system. These results were compared with standard heavy ion accelerator (Brookhaven National Laboratory (BNL)) measurements of the same SRAM's. With heavy ions, the LETTH of the Honeywell HC6364 was 27 MeV-sq cm/mg at 125 C compared with a value of 24 MeV-sq cm/mg obtained with the laser. In the case of the second type of 64K SRAM, the IBM640lCRH no upsets were observed at 125 C with the highest LET ions used at BNL. In contrast, the pulsed dye laser tests indicated a value of 90 MeV-sq cm/mg at room temperature for the SEU-hardened IBM SRAM. No latchups or multiple SEU's were observed on any of the SRAM's even under worst case conditions. The results of this study suggest that the laser can be used as an inexpensive laboratory SEU prescreen tool in certain cases.

  7. Detailed numerical simulations of laser cooling processes

    NASA Technical Reports Server (NTRS)

    Ramirez-Serrano, J.; Kohel, J.; Thompson, R.; Yu, N.

    2001-01-01

    We developed a detailed semiclassical numerical code of the forces applied on atoms in optical and magnetic fields to increase the understanding of the different roles that light, atomic collisions, background pressure, and number of particles play in experiments with laser cooled and trapped atoms.

  8. Bio-heat transfer simulation of retinal laser irradiation.

    PubMed

    Narasimhan, Arunn; Jha, Kaushal Kumar

    2012-05-01

    Retinopathy is a surgical process in which maladies of the human eye are treated by laser irradiation. A two-dimensional numerical model of the human eye geometry has been developed to investigate transient thermal effects due to laser radiation. In particular, the influence of choroidal pigmentation and that of choroidal blood convection-parameterized as a function of choroidal blood perfusion-are investigated in detail. The Pennes bio-heat transfer equation is invoked as the governing equation, and finite volume formulation is employed in the numerical method. For a 500-μm diameter spot size, laser power of 0.2 W, and 100% absorption of laser radiation in the retinal pigmented epithelium (RPE) region, the peak RPE temperature is observed to be 103 °C at 100 ms of the transient simulation of the laser surgical period. Because of the participation of pigmented layer of choroid in laser absorption, peak temperature is reduced to 94 °C after 100 ms of the laser surgery period. The effect of choroidal blood perfusion on retinal cooling is found to be negligible during transient simulation of retinopathy. A truncated three-dimensional model incorporating multiple laser irradiation of spots is also developed to observe the spatial effect of choroidal blood perfusion and choroidal pigmentation. For a circular array of seven uniformly distributed spots of identical diameter and laser power of 0.2 W, transient temperature evolution using simultaneous and sequential mode of laser surgical process is presented with analysis.

  9. Computer simulations of laser-induced melting of aluminum

    NASA Astrophysics Data System (ADS)

    Tang, Hong; Bai, Mingze; Dou, Yusheng; Ran, Qi; Lo, Glenn V.

    2013-04-01

    Laser-induced solid-to-liquid phase transitions in 100 nm aluminum film were simulated using a hybrid model that combines molecular dynamics (MD) with a continuum description of the laser excitation and a two-temperature method (TTM) to model the relaxation of conduction band electrons. When the laser fluence provides more energy than needed for a complete melting of the film, the phase transition is characterized by an ultrafast collapse of the crystal structure within 2-3 ps. Otherwise, the transition involves a homogeneous nucleation and growth of liquid zones inside the crystal and a heterogeneous propagation of transition fronts from the external surfaces or nucleated liquid zones.

  10. Simulation of free-electron lasers seeded with broadband radiation

    SciTech Connect

    Bajlekov, Svetoslav; Fawley, William; Schroeder, Carl; Bartolini, Riccardo; Hooker, Simon

    2011-03-10

    The longitudinal coherence of free-electron laser (FEL) radiation can be enhanced by seeding the FEL with high harmonics of an optical laser pulse. The radiation produced by high-harmonic generation (HHG), however, has a fast-varying temporal profile that can violate the slowly varying envelope approximation and limited frequency window that is employed in conventional free-electron laser simulation codes. Here we investigate the implications of violating this approximation on the accuracy of simulations. On the basis of both analytical considerations and 1D numerical studies, it is concluded that, for most realistic scenarios, conventional FEL codes are capable of accurately simulating the FEL process even when the seed radiation violates the slowly varying envelope approximation. We additionally discuss the significance of filtering the harmonic content of broadband HHG seeds.

  11. Laser Doppler velocimeter system simulation for sensing aircraft wake vortices

    NASA Technical Reports Server (NTRS)

    Thomson, J. A. L.; Meng, J. C. S.

    1974-01-01

    A hydrodynamic model of aircraft vortex wakes in an irregular wind shear field near the ground is developed and used as a basis for modeling the characteristics of a laser Doppler detection and vortex location system. The trailing vortex sheet and the wind shear are represented by discrete free vortices distributed over a two-dimensional grid. The time dependent hydrodynamic equations are solved by direct numerical integration in the Boussinesq approximation. The ground boundary is simulated by images, and fast Fourier Transform techniques are used to evaluate the vorticity stream function. The atmospheric turbulence was simulated by constructing specific realizations at time equal to zero, assuming that Kolmogoroff's law applies, and that the dissipation rate is constant throughout the flow field. The response of a simulated laser Doppler velocimeter is analyzed by simulating the signal return from the flow field as sensed by a simulation of the optical/electronic system.

  12. Numerical Verification of the Power Transfer and Wakefield Coupling in the Clic Two-Beam Accelerator

    SciTech Connect

    Candel, Arno; Li, Z.; Ng, C.; Rawat, V.; Schussman, G.; Ko, K.; Syratchev, I.; Grudiev, A.; Wuensch, W.; /CERN

    2011-08-19

    The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its two-beam accelerator (TBA) concept envisions complex 3D structures, which must be modeled to high accuracy so that simulation results can be directly used to prepare CAD drawings for machining. The required simulations include not only the fundamental mode properties of the accelerating structures but also the Power Extraction and Transfer Structure (PETS), as well as the coupling between the two systems. Time-domain simulations will be performed to understand pulse formation, wakefield damping, fundamental power transfer and wakefield coupling in these structures. Applying SLAC's parallel finite element code suite, these large-scale problems will be solved on some of the largest supercomputers available. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel two-beam accelerator scheme.

  13. Simulations of ultrafast x-ray laser experiments

    NASA Astrophysics Data System (ADS)

    Fortmann-Grote, C.; Andreev, A. A.; Appel, K.; Branco, J.; Briggs, R.; Bussmann, M.; Buzmakov, A.; Garten, M.; Grund, A.; Huebl, A.; Jurek, Z.; Loh, N. D.; Nakatsutsumi, M.; Samoylova, L.; Santra, R.; Schneidmiller, E. A.; Sharma, A.; Steiniger, K.; Yakubov, S.; Yoon, C. H.; Yurkov, M. V.; Zastrau, U.; Ziaja-Motyka, B.; Mancuso, A. P.

    2017-06-01

    Simulations of experiments at modern light sources, such as optical laser laboratories, synchrotrons, and free electron lasers, become increasingly important for the successful preparation, execution, and analysis of these experiments investigating ever more complex physical systems, e.g. biomolecules, complex materials, and ultra-short lived states of matter at extreme conditions. We have implemented a platform for complete start-to-end simulations of various types of photon science experiments, tracking the radiation from the source through the beam transport optics to the sample or target under investigation, its interaction with and scattering from the sample, and registration in a photon detector. This tool allows researchers and facility operators to simulate their experiments and instruments under real life conditions, identify promising and unattainable regions of the parameter space and ultimately make better use of valuable beamtime. In this paper, we present an overview about status and future development of the simulation platform and discuss three applications: 1.) Single-particle imaging of biomolecules using x-ray free electron lasers and optimization of x-ray pulse properties, 2.) x-ray scattering diagnostics of hot dense plasmas in high power laser-matter interaction and identification of plasma instabilities, and 3.) x-ray absorption spectroscopy in warm dense matter created by high energy laser-matter interaction and pulse shape optimization for low-isentrope dynamic compression.

  14. A nonlinear particle dynamics map of wakefield acceleration in a linear collider

    SciTech Connect

    Tajima, T.; Cheshkov, S.; Horton, W.; Yokoya, K.

    1998-08-01

    The performance of a wakefield accelerator in a high energy collider application is analyzed. In order to carry out this task, it is necessary to construct a strawman design system (no matter how preliminary) and build a code of the systems approach. A nonlinear dynamics map built on a simple theoretical model of the wakefield generated by the laser pulse (or whatever other method) is obtained and they employ this as a base for building a system with multi-stages (and components) as a high energy collider. The crucial figures of merit for such a system other than the final energy include the emittance (that determines the luminosity). The more complex the system is, the more opportunities the system has to degrade the emittance (or entropy of the beam). Thus the map gu ides one to identify where the crucial elements lie that affect the emittance. They find that a strong focusing force of the wakefield coupled with a possible jitter of the axis (or laser aiming) of each stage and a spread in the betatron frequencies arising from different phase space positions for individual particles leads to a phase space mixing. This sensitively controls the emittance degradation. They show that in the case of a uniform plasma the effect of emittance growth is large and may cause serious problems. They discuss possibilities to avoid it and control the situation.

  15. Simulations of laser-initiated stress waves

    SciTech Connect

    Maitland, D.J.; Celliers, P.; Amendt, P.; Da Silva, L.; London, R.A.; Matthews, D.; Strauss, M.; Visuri, S.R.

    1997-03-07

    We present a study of the short-time scale (< 250 ns) fluid dynamic response of water to a fiber-delivered laser pulse of variable energy and spatial profile. The laser pulse was deposited on a stress confinement time scale. The spatial profile was determined by the fiber core radius r (110 and 500 microns) and the water absorption coefficient {mu}{sub 2} (200 and 50 l/cm). Considering 2D cylindrical symmetry, the combination of fiber radius and absorption coefficient parameters can be characterized as near planar (1{mu}{sub 2} greater than r), symmetric (1/{mu}{sub 2}=r), and side-directed (1/{mu}{sub 2} less than r). The spatial profile study shows how the stress wave various as a function of geometry. For example, relatively small absorption coefficients can result in side-propagating shear and tensile fields.

  16. Relativistically strong CO{sub 2} laser driver for plasma-channeled particle acceleration

    SciTech Connect

    Pogorelsky, I.V.

    1995-12-31

    Long-wavelength, short-duration laser pulses are desirable for plasma wakefield particle acceleration and plasma waveguiding. The first picosecond terawatt CO{sub 2} laser is under development to test laser-driven electron acceleration schemes.

  17. EDITORIAL: Laser and plasma accelerators Laser and plasma accelerators

    NASA Astrophysics Data System (ADS)

    Bingham, Robert

    2009-02-01

    This special issue on laser and plasma accelerators illustrates the rapid advancement and diverse applications of laser and plasma accelerators. Plasma is an attractive medium for particle acceleration because of the high electric field it can sustain, with studies of acceleration processes remaining one of the most important areas of research in both laboratory and astrophysical plasmas. The rapid advance in laser and accelerator technology has led to the development of terawatt and petawatt laser systems with ultra-high intensities and short sub-picosecond pulses, which are used to generate wakefields in plasma. Recent successes include the demonstration by several groups in 2004 of quasi-monoenergetic electron beams by wakefields in the bubble regime with the GeV energy barrier being reached in 2006, and the energy doubling of the SLAC high-energy electron beam from 42 to 85 GeV. The electron beams generated by the laser plasma driven wakefields have good spatial quality with energies ranging from MeV to GeV. A unique feature is that they are ultra-short bunches with simulations showing that they can be as short as a few femtoseconds with low-energy spread, making these beams ideal for a variety of applications ranging from novel high-brightness radiation sources for medicine, material science and ultrafast time-resolved radiobiology or chemistry. Laser driven ion acceleration experiments have also made significant advances over the last few years with applications in laser fusion, nuclear physics and medicine. Attention is focused on the possibility of producing quasi-mono-energetic ions with energies ranging from hundreds of MeV to GeV per nucleon. New acceleration mechanisms are being studied, including ion acceleration from ultra-thin foils and direct laser acceleration. The application of wakefields or beat waves in other areas of science such as astrophysics and particle physics is beginning to take off, such as the study of cosmic accelerators considered

  18. Baseline monitoring using aircraft laser ranging. [spaceborne laser simulation and aircraft laser tracking

    NASA Technical Reports Server (NTRS)

    Krabill, W. B.; Hoge, F. E.; Martin, C. F.

    1982-01-01

    The use of aircraft laser ranging for the determination of baselines between ground based retroreflectors was investigated via simulations and with tests at Wallops Flight Center using the Airborne Oceanographic Lidar (AOL) on the Wallops C-54 aircraft ranging to a reflector array deployed around one of the Wallops runways. The aircraft altitude and reflector spacing were chosen on the basis of scaled down modeling of spacecraft tracking from 1000 km of reflectors separated by some 52 km, or of high altitude (10 km) aircraft tracking of reflectors separated by some 500 m. Aircraft altitudes flown for different passes across the runway reflector array varied from 800 m to 1350 m, with 32 reflectors deployed over an approximtely 300 m x 500 m ground pattern. The AOL transmitted 400 pulses/sec with a scan rate of 5/sec in a near circular pattern, so that the majority of the pulses were reflected by the runway surface or its environs rather than by retroreflectors. The return pulse characteristics clearly showed the high reflectivity of portions of the runway, with several returns indistinguishable in amplitude from reflector returns. For each pass across the reflector field, typically six to ten reflector hits were identified, consistent with that predicted by simulations and the observed transmitted elliptical pulse size.

  19. Modeling and Simulation of Semiconductor Quantum Well Structures and Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

    1998-01-01

    In this talk I will cover two aspects of modeling and simulation efforts at NASA Ames Research Center. In the quantum well structure simulation, we typically start from the quantum mechanical calculation of the quantum well structures for the confined/and unconfined eigen states and functions. A bandstructure calculation of the k*p type is then performed for the confined valence states. This information is then used to computer the optical gain and refractive index of the quantum well structures by solving the linearized multiband semiconductor Bloch equations with the many-body interactions included. In our laser simulation, we typically solve the envelope equations for the laser field in space-time domain, coupled with a reduced set of material equations using the microscopic calculation of the first step. Finally I will show some examples of both aspects of simulation and modeling.

  20. Simulation of the main physical processes in remote laser penetration with large laser spot size

    DOE PAGES

    Khairallah, S. A.; Anderson, A.; Rubenchik, A. M.; ...

    2015-04-10

    A 3D model is developed to simulate remote laser penetration of a 1mm Aluminum metal sheet with large laser spot size (~3x3cm²), using the ALE3D multi-physics code. The model deals with the laser-induced melting of the plate and the mechanical interaction between the solid and the melted part through plate elastic-plastic response. The effect of plate oscillations and other forces on plate rupture, the droplet formation mechanism and the influence of gravity and high laser power in further breaking the single melt droplet into many more fragments are analyzed. In the limit of low laser power, the numerical results matchmore » the available experiments. The numerical approach couples mechanical and thermal diffusion to hydrodynamics melt flow and accounts for temperature dependent material properties, surface tension, gravity and vapor recoil pressure.« less

  1. A numerical simulation of photothermal response in laser medicine

    NASA Astrophysics Data System (ADS)

    Li, Xiaoxia; Fan, Shifu; Zhao, Youquan; Xiao, Songshan

    2004-03-01

    In this paper, we reported a numerical solution of laser induced thermal effect in the bio-tissue. The model of photothermal effect and classical Pennes bio-heat transfer equation were introduced. Finite element method (FEM), which was realized by Matlab software, was used to calculate the temperature distribution. He-Ne laser (633 nm) was used to simulate the physical therapy in in vivo skin tissue. Under the cylinder coordinates, the three-dimension (3-D) geometry of tissue was reduced to two-dimension (2-D) computation. The results contained the radial, axial and temperature 3-D color plot. Combining the time animation display was possible. By changing the laser and tissue parameters we can get different results. This will be the initial and indispensable work of the non-destructive evaluation of the laser induced injury.

  2. Measurements of radiation near an atomic spectral line in a 30 GeV plasma wakefield experiment, E157.

    NASA Astrophysics Data System (ADS)

    Catravas, P.; Chattopadhyay, S.; Esarey, E. H.; Leemans, W. P.; Assmann, R.; Decker, F.-J.; Iverson, R.; Hogan, M. J.; Siemann, R. H.; Walz, D.; Whittum, D.; Blue, B.; Clayton, C.; Joshi, C.; Marsh, K. A.; Mori, W. B.; Wang, S.; Katsouleas, T.; Lee, S.; Muggli, P.

    2000-10-01

    Cerenkov radiation from a 30 GeV electron beam propagating through a Li plasma column ( ~ 10^15 cm-3, >1 meter) has been utilized to extract the column neutral and UV-laser photoionized plasma density in a plasma wakefield experiment. Narrow bandwidth cones near the 670.8 nm atomic spectral line of Lithium neutrals were studied as a function of oven temperature, observation wavelength, and timing between laser and electron beam. Neutral and plasma densities obtained with the technique are roughly in agreement with accompanying betatron oscillations and UV absorption measurements. Large increases in the number of intercepted photons were observed near strong spectral lines of Lithium neutrals and ions and were found to depend on the relative timing of the electron beam and ionizing laser. We speculate that these emissions are due to increased recombination radiation from wakefield energy dissipation through excitation and ionization of the component species.

  3. Free-electron laser simulations on the MPP

    NASA Technical Reports Server (NTRS)

    Vonlaven, Scott A.; Liebrock, Lorie M.

    1987-01-01

    Free electron lasers (FELs) are of interest because they provide high power, high efficiency, and broad tunability. FEL simulations can make efficient use of computers of the Massively Parallel Processor (MPP) class because most of the processing consists of applying a simple equation to a set of identical particles. A test version of the KMS Fusion FEL simulation, which resides mainly in the MPPs host computer and only partially in the MPP, has run successfully.

  4. Numerical simulations of a diode laser BPH treatment system

    SciTech Connect

    Esch, V; London, R A; Papademetriou, S

    1999-02-23

    Numerical simulations are presented of the laser-tissue interaction of a diode laser system for treating benign prostate hyperplasia. The numerical model includes laser light transport, heat transport, cooling due to blood perfusion, thermal tissue damage, and enthalpy of tissue damage. Comparisons of the simulation results to clinical data are given. We report that a reasonable variation from a standard set of input data produces heating times which match those measured in the clinical trials. A general trend of decreasing damage volume with increasing heating time is described. We suggest that the patient-to- patient variability seen in the data can be explained by differences in fundamental biophysical properties such as the optical coefficients. Further work is identified, including the measurement and input to the model of several specific data parameters such as optical coefficients, blood perfusion cooling rate, and coagulation rates.

  5. Study the encountering simulation system for laser fuze based on intensity attenuation and fiber delay

    NASA Astrophysics Data System (ADS)

    Chen, Huimin; Li, Ping; Guo, Weirong

    2010-10-01

    Laser fuze is a kind of proximity fuze developed with laser technology. A encountering simulation system for laser fuze based on environment simulator and fiber retarder is introduced in this paper. The system can simulate the process for the laser fuze to approach the target quickly, with consideration of changing light path and intensity caused by factors like environment and distance. It can be a reference for the future design of laser fuze.

  6. Earth Model with Laser Beam Simulating Seismic Ray Paths.

    ERIC Educational Resources Information Center

    Ryan, John Arthur; Handzus, Thomas Jay, Jr.

    1988-01-01

    Described is a simple device, that uses a laser beam to simulate P waves. It allows students to follow ray paths, reflections and refractions within the earth. Included is a set of exercises that lead students through the steps by which the presence of the outer and inner cores can be recognized. (Author/CW)

  7. Simulation of laser beam propagation through the troposphere

    NASA Astrophysics Data System (ADS)

    Wang, Bao-feng; Luo, Xiu-juan; Zhang, Yu; Zeng, Zhi-hong; Wang, Feng

    2013-09-01

    Understanding and predicting laser beam propagation effects in the atmosphere is important for laser applications. Turbulence effects cause beam wander, beam broadening, intensity scintillations, which reducing the power in bucket and the tracking accuracy, etc. In this work, the phase screens are used to model atmosphere turbulence in the model of the laser propagation through troposphere. And according to the characteristics of the troposphere,a layered model is used. Laser propagation follows the Huygens-Fresnel principle between phase screens. Simulations with different grid point numbers were constructed, and numerical experiments were conducted. According to the simulated results including Strehl ratio, sharpness, and amplitude distribution, preceding phase screens have effect on the total energy of the receiving surface, but have little impact on amplitude distribution. And the phase screens, which are close to the receiving surface, have a significant impact on both amplitude distribution and the total receiving energy. The results suggests that in simulation one should increase grid point numbers as many as possible and needs to pay particular attention to parameters of the phase screens near the receiving surface in simulation.

  8. Simulation studies for a nuclear photon pumped excimer laser

    NASA Technical Reports Server (NTRS)

    Miller, T. G.; Hagefstration, J. E.

    1979-01-01

    Simulation studies were undertaken to determine the feasibility of a nuclear photon pumped excimer laser using a system where high pressure Xe is bombarded with electrons and protons to form 1720 A. Primary measurements included conversion efficiency and gain vs time measurements.

  9. Earth Model with Laser Beam Simulating Seismic Ray Paths.

    ERIC Educational Resources Information Center

    Ryan, John Arthur; Handzus, Thomas Jay, Jr.

    1988-01-01

    Described is a simple device, that uses a laser beam to simulate P waves. It allows students to follow ray paths, reflections and refractions within the earth. Included is a set of exercises that lead students through the steps by which the presence of the outer and inner cores can be recognized. (Author/CW)

  10. Plasma Wakefield Acceleration of an Intense Positron Beam

    SciTech Connect

    Blue, B

    2004-04-21

    The Plasma Wakefield Accelerator (PWFA) is an advanced accelerator concept which possess a high acceleration gradient and a long interaction length for accelerating both electrons and positrons. Although electron beam-plasma interactions have been extensively studied in connection with the PWFA, very little work has been done with respect to positron beam-plasma interactions. This dissertation addresses three issues relating to a positron beam driven plasma wakefield accelerator. These issues are (a) the suitability of employing a positron drive bunch to excite a wake; (b) the transverse stability of the drive bunch; and (c) the acceleration of positrons by the plasma wake that is driven by a positron bunch. These three issues are explored first through computer simulations and then through experiments. First, a theory is developed on the impulse response of plasma to a short drive beam which is valid for small perturbations to the plasma density. This is followed up with several particle-in-cell (PIC) simulations which study the experimental parameter (bunch length, charge, radius, and plasma density) range. Next, the experimental setup is described with an emphasis on the equipment used to measure the longitudinal energy variations of the positron beam. Then, the transverse dynamics of a positron beam in a plasma are described. Special attention is given to the way focusing, defocusing, and a tilted beam would appear to be energy variations as viewed on our diagnostics. Finally, the energy dynamics imparted on a 730 {micro}m long, 40 {micro}m radius, 28.5 GeV positron beam with 1.2 x 10{sup 10} particles in a 1.4 meter long 0-2 x 10{sup 14} e{sup -}/cm{sup 3} plasma is described. First the energy loss was measured as a function of plasma density and the measurements are compared to theory. Then, an energy gain of 79 {+-} 15 MeV is shown. This is the first demonstration of energy gain of a positron beam in a plasma and it is in good agreement with the predictions

  11. Understanding Femtosecond-Pulse Laser Damage through Fundamental Physics Simulations

    NASA Astrophysics Data System (ADS)

    Mitchell, Robert A., III

    It did not take long after the invention of the laser for the field of laser damage to appear. For several decades researchers have been studying how lasers damage materials, both for the basic scientific understanding of highly nonequilibrium processes as well as for industrial applications. Femtosecond pulse lasers create little collateral damage and a readily reproducible damage pattern. They are easily tailored to desired specifications and are particularly powerful and versatile tools, contributing even more industrial interest in the field. As with most long-standing fields of research, many theoretical tools have been developed to model the laser damage process, covering a wide range of complexities and regimes of applicability. However, most of the modeling methods developed are either too limited in spatial extent to model the full morphology of the damage crater, or incorporate only a small subset of the important physics and require numerous fitting parameters and assumptions in order to match values interpolated from experimental data. Demonstrated in this work is the first simulation method capable of fundamentally modeling the full laser damage process, from the laser interaction all the way through to the resolidification of the target, on a large enough scale that can capture the full morphology of the laser damage crater so as to be compared directly to experimental measurements instead of extrapolated values, and all without any fitting parameters. The design, implementation, and testing of this simulation technique, based on a modified version of the particle-in-cell (PIC) method, is presented. For a 60 fs, 1 mum wavelength laser pulse with fluences of 0.5 J/cm 2, 1.0 J/cm2, and 2.0 J/cm2 the resulting laser damage craters in copper are shown and, using the same technique applied to experimental crater morphologies, a laser damage fluence threshold is calculated of 0.15 J/cm2, consistent with current experiments performed under conditions similar

  12. Argonne`s new Wakefield Test Facility

    SciTech Connect

    Simpson, J.D.

    1992-07-20

    The first phase of a high current, short bunch length electron beam research facility, the AWA, is near completion at Argonne. At the heart of the facility is a photocathode based electron gun and accelerating sections designed to deliver 20 MeV pulses with up to 100 nC per pulse and with pulse lengths of approximately 15 ps (fw). Using a technique similar to that originated at Argonne`s AATF facility, a separate weak probe pulse can be generated and used to diagnose wake effects produced by the intense pulses. Initial planned experiments include studies of plasma wakefields and dielectric wakefield devices, and expect to demonstrate large, useful accelerating gradients (> 100 MeV/m). Later phases of the facility will increase the drive bunch energy to more than 100 MeV to enable acceleration experiments up to the GeV range. Specifications, design details, and commissioning progress are presented.

  13. Axionic suppression of plasma wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Burton, D. A.; Noble, A.; Walton, T. J.

    2016-09-01

    Contemporary attempts to explain the existence of ultra-high energy cosmic rays using plasma-based wakefield acceleration deliberately avoid non-standard model particle physics. However, such proposals exploit some of the most extreme environments in the Universe and it is conceivable that hypothetical particles outside the standard model have significant implications for the effectiveness of the acceleration process. Axions solve the strong CP problem and provide one of the most important candidates for cold dark matter, and their potential significance in the present context should not be overlooked. Our analysis of the field equations describing a plasma augmented with axions uncovers a dramatic axion-induced suppression of the energy gained by a test particle in the wakefield driven by a particle bunch, or an intense pulse of electromagnetic radiation, propagating at ultra-relativistic speeds within the strongest magnetic fields in the Universe.

  14. Airborne laser pressure recovery system - Numerical simulations

    NASA Astrophysics Data System (ADS)

    Horkovich, J. A.

    1993-07-01

    A numerical method capable of accurately predicting flowfields in a radial cylindrical supersonic diffusion laser (SDL) is developed by incorporating a modified two-layer Cebeci-Smith (Cebeci et al., 1970) algebraic eddy viscosity turbulence model into the compressible Navier-Stokes equations. The required modifications to the model are extremely sensitive to the von Karman universal mixing length constant, the sublayer thickness parameter, the Clausser outer region constant, and the downstream location in the diffuser duct at which these modifications are implemented. The experimental tests were conducted at a diffuser entrance unit Reynolds number 1.6 million per foot. It is shown that the diffuser performance is contrained by the source nozzle mixing losses, the duct length, and the requirement for wall boundary layer energization if the design requires a relatively short duct. The numerical solutions confirm the Neumann and Lustwerk (1949) experimental conclusions regarding minimum diffuser duct length if no wall boundary layer energization is employed.

  15. Simulation of Double-Pulse Laser Ablation

    NASA Astrophysics Data System (ADS)

    Povarnitsyn, Mikhail E.; Itina, Tatian E.; Khishchenko, Konstantin V.; Levashov, Pavel R.

    2010-10-01

    We investigate the physical reasons of a strange decrease in the ablation depth observed in femtosecond double-pulse experiments with increasing delay between the pulses. Two ultrashort pulses of the same energy produce the crater which is less than that created by a single pulse. Hydrodynamicsimulation shows that the ablation mechanism is suppressed when the delay between the pulses exceeds the electron-ion relaxation time. In this case, the interaction of the second laser pulse with the expanding target material leads to the formation of the second shock wave suppressing the rarefaction wave created by the first pulse. The modeling of the double-pulse ablation for different delays between pulses confirms this explanation.

  16. High power microwave source for a plasma wakefield experiment

    NASA Astrophysics Data System (ADS)

    Shafir, G.; Shlapakovski, A.; Siman-Tov, M.; Bliokh, Yu.; Leopold, J. G.; Gleizer, S.; Gad, R.; Rostov, V. V.; Krasik, Ya. E.

    2017-01-01

    The results of the generation of a high-power microwave (˜550 MW, 0.5 ns, ˜9.6 GHz) beam and feasibility of wakefield-excitation with this beam in under-dense plasma are presented. The microwave beam is generated by a backward wave oscillator (BWO) operating in the superradiance regime. The BWO is driven by a high-current electron beam (˜250 keV, ˜1.5 kA, ˜5 ns) propagating through a slow-wave structure in a guiding magnetic field of 2.5 T. The microwave beam is focused at the desired location by a dielectric lens. Experimentally obtained parameters of the microwave beam at its waist are used for numerical simulations, the results of which demonstrate the formation of a bubble in the plasma that has almost 100% electron density modulation and longitudinal and transverse electric fields of several kV/cm.

  17. Wake-field generation by the ponderomotive memory effect

    NASA Astrophysics Data System (ADS)

    Wolf, U.; Schamel, H.

    1997-10-01

    An analytical and numerical investigation of the plasma response to an imposed high frequency wave packet with a slow explicit time-dependent envelope is presented. An underlying picture of ponderomotive effects is developed, which shows that the explicit time dependence forces us to treat the problem kinetically, and furthermore, that a wake field is generated by the ponderomotive memory effect. The latter supplements the well-known ponderomotive force and fake heating effect. Several perturbation schemes are compared showing that the influence of resonant particles, treated by the method of characteristics, has to be taken into account for Langmuir wave packets with kλd>=0.2, where k is the wave number and λd the Debye length. A self-consistent Vlasov simulation shows the disappearance of the density depression in the case of immobile ions, whereas the wake-field pattern survives self-consistency.

  18. SHORT RANGE WAKEFIELD IN A FLAT PILLBOX CAVITY GENERATED BY A SUB-RELATIVISTIC BEAM BUNCH.

    SciTech Connect

    WANG,H.; PALMER,R.B.; GALLARDO,J.

    2001-06-18

    The short-range wakefield between two parallel conducting plates generated by a sub-relativistic beam bunch has been solved analytically by image charge method in time domain. Comparing with traditional modal analysis in frequency domain this algorithm simplifies mathematics and reveals great details of physics in electromagnetic field generation, propagation, reflection and causality. The calculated results have an excellent agreement with MAFIA and ABCI simulations in all range of beam velocities.

  19. Transverse Wakefields and Means to Suppress Wakefields in High Gradient Linear Colliders

    NASA Astrophysics Data System (ADS)

    Jones, Roger M.

    2015-10-01

    The symposium held at Tsinghua University, in honor of Dr. Juwen Wang, is a testament to his engagement with diverse areas of linear accelerators. My work has overlapped with his during the period of the Next Linear Collider/Japanese linear Collider (NLC/JLC) programe in particular. Here I report on the beam-exited long-range wakefield in these linacs, and also on subsequent developments in the context of the Compact Linear Collider programme (CLIC). This self-excited wakefield, if l unchecked, can at the very least cause a marked dilution in the beam emittance, and in the worst case can cause a catastrophic beam break up (BBU) instability rendering the particle beam unusable. To ameliorate this affect, there are two main strategies: one can either aim at heavily damping the wakefield (in practise requiring a Q value as low as ~10) or one can detune each of the accelerator's cells to ensure that each mode is excited at slightly different frequency, in a precise manner. The former approach entails placing damping waveguides and damping materials in relatively close proximity to the beam, and this is the approach adopted by the CLIC collaboration. For the NLC/JLC we collectively followed the latter approach, in which the dipole mode of each cell is detuned with an erf function profile along each accelerator structure. Eventually the modes, which form the wakefield, recohere and, to ensure the wakefield remains below a specified level a portion is coupled out through slots cut into each cell to an attached waveguide-like manifold. Typically medium Q values are aimed at, between 500 and 1000. This scheme entails suppressing the modes which comprise the wakefield-using damped and detuned structures (DDS). Sampling an attenuated portion of this manifold radiation also provides both a beam and structure diagnostic. A similar DDS design, but with more stringent wakefield suppression requirements, has been followed as an alternative to the CLIC damping scheme. Wakefield

  20. The computer simulation of laser proton acceleration for hadron therapy

    NASA Astrophysics Data System (ADS)

    Lykov, Vladimir; Baydin, Grigory

    2008-11-01

    The ions acceleration by intensive ultra-short laser pulses has interest in views of them possible applications for proton radiography, production of medical isotopes and hadron therapy. The 3D relativistic PIC-code LegoLPI is developed at RFNC-VNIITF for modeling of intensive laser interaction with plasma. The LegoLPI-code simulations were carried out to find the optimal conditions for generation of proton beams with parameters necessary for hadrons therapy. The performed simulations show that optimal for it may be two-layer foil of aluminum and polyethylene with thickness 100 nm and 50 nm accordingly. The maximum efficiency of laser energy transformation into 200 MeV protons is achieved on irradiating these foils by 30 fs laser pulse with intensity about 2.10^22 W/cm^2. The conclusion is made that lasers with peak power about 0.5-1PW and average power 0.5-1 kW are needed for generation of proton beams with parameters necessary for proton therapy.