- Helmholtz-Zentrum Dresden-Rossendorf e.V.
Bautzner Landstrasse 400
D-01328 Dresden
Germany - +493512602616
Michael Bussmann
Helmholtz-Zentrum Dresden Rossendorf, Institute of Radiation Physics, Department Member
- Computer Science, Physics, Theoretical Physics, Computational Physics, Plasma Physics, Applied Physics, and 9 moreAtomic, Molecular, And Optical Physics, Medical Physics, High Energy Physics, Radiation Physics, Atomic and Molecular Physics, Accelerator Physics, X-ray Physics, Interested in scientific research in the field of radiation protection and nuclear physics, and Engineeringedit
- I'm a physicist at the Forschungszentrum Dresden-Rossendorf. My research topics are laser acceleration, laser cooling of ion beams, plasma physics and computational physics.edit
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Lensless imaging has emerged to an indispensable imaging modality allowing to surpass the resolution limit of imaging optics. At the same time, attosecond science has uncovered ultrafast dynamics in atoms, molecules, and complex... more
Lensless imaging has emerged to an indispensable imaging modality allowing to surpass the resolution limit of imaging optics. At the same time, attosecond science has uncovered ultrafast dynamics in atoms, molecules, and complex materials. Clearly, combining attosecond temporal resolution with nanometer spatial resolution would allow unique studies of ultrafast dynamics on the smallest spatio-temporal scales. Unfortunately, the required bandwidth of attosecond pulses conflicts with the coherence requirements for lensless imaging. Here, we present a straightforward method to surpass the temporal coherence limit in Fourier-Transform-Holography by a factor of five. In a first experiment, a spatial resolution of 38 nm (2.8 {\lambda}) has been achieved with a bandwidth supporting a Fourier-limited pulse duration of only 320 as. This paves the way for an ultrafast view on nanoscale dynamics of energy, charges or spins, which are the basis of next-generation electronics, data storage, ener...
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The $^2S_{1/2} - ^2P_{1/2}$ and $^2S_{1/2} - ^2P_{3/2}$ transitions in Li-like carbon ions stored and cooled at a velocity of $\beta \approx 0.47$ in the Experimental Storage Ring (ESR) at the GSI Helmholtz Centre in Darmstadt have been... more
The $^2S_{1/2} - ^2P_{1/2}$ and $^2S_{1/2} - ^2P_{3/2}$ transitions in Li-like carbon ions stored and cooled at a velocity of $\beta \approx 0.47$ in the Experimental Storage Ring (ESR) at the GSI Helmholtz Centre in Darmstadt have been investigated in a laser spectroscopy experiment. Resonance wavelengths have been obtained using a new continuous-wave UV laser system and a novel extreme UV (XUV) detection system used to detect forward emitted fluorescence photons. The results obtained for the two transitions are compared to existing experimental and theoretical data. A discrepancy found in an earlier laser spectroscopy measurement at the ESR with results from plasma spectroscopy and interferometry could be resolved and agreement between experiment and theory is confirmed. Nonetheless, the experimental uncertainty is still smaller than that of state-of-the art theory.
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Plasma wakefield accelerators can be driven either by intense laser pulses (LWFA) or by intense particle beams (PWFA). A third approach that combines the complementary advantages of both types of plasma wakefield accelerator has been... more
Plasma wakefield accelerators can be driven either by intense laser pulses (LWFA) or by intense particle beams (PWFA). A third approach that combines the complementary advantages of both types of plasma wakefield accelerator has been established with increasing success over the last decade and is called hybrid LWFA→PWFA. Essentially, a compact LWFA is exploited to produce an energetic, high-current electron beam as a driver for a subsequent PWFA stage, which, in turn, is exploited for phase-constant, inherently laser-synchronized, quasi-static acceleration over extended acceleration lengths. The sum is greater than its parts: the approach not only provides a compact, cost-effective alternative to linac-driven PWFA for exploitation of PWFA and its advantages for acceleration and high-brightness beam generation, but extends the parameter range accessible for PWFA and, through the added benefit of co-location of inherently synchronized laser pulses, enables high-precision pump/probing,...
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It is common in the HPC community that the achieved performance with just CPUs is limited for many computational cases. The EuroHPC pre-exascale and the coming exascale systems are mainly focused on accelerators, and some of the largest... more
It is common in the HPC community that the achieved performance with just CPUs is limited for many computational cases. The EuroHPC pre-exascale and the coming exascale systems are mainly focused on accelerators, and some of the largest upcoming supercomputers such as LUMI and Frontier will be powered by AMD Instinct™ accelerators. However, these new systems create many challenges for developers who are not familiar with the new ecosystem or with the required programming models that can be used to program for heterogeneous architectures. In this paper, we present some of the more well-known programming models to program for current and future GPU systems. We then measure the performance of each approach using a benchmark and a mini-app, test with various compilers, and tune the codes where necessary. Finally, we compare the performance, where possible, between the NVIDIA Volta (V100), Ampere (A100) GPUs, and the AMD MI100 GPU.
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Plasma wakefield accelerators can be driven by either an intense laser pulse (LWFA) or a high-current particle beam (PWFA). A plasma accelerator combining both schemes consists of a LWFA providing an electron beam which subsequently... more
Plasma wakefield accelerators can be driven by either an intense laser pulse (LWFA) or a high-current particle beam (PWFA). A plasma accelerator combining both schemes consists of a LWFA providing an electron beam which subsequently drives a PWFA in the highly nonlinear regime. This scenario explicitly makes use of the advantages unique to each method, particularly exploiting the capabilities of PWFA schemes to provide energy-boosted high-brightness beams, while the LWFA stage inherently fulfils the demand for compact high-current electron bunches required as PWFA drivers. Effectively, the subsequent PWFA stage operates as a beam brightness and energy booster of the initial LWFA output, aiming to match the demanding beam quality requirements of accelerator based light sources. We present a design study based on theoretical considerations and full-detailed particle-in-cell simulations, aiming to address the feasibility and the capabilities of this promising strategy. Besides, we repo...
Realistic simulations of experiments at large scale photon facilities, such as optical laser laboratories, synchrotrons, and free electron lasers, are of vital importance for the successful preparation, execution, and analysis of these... more
Realistic simulations of experiments at large scale photon facilities, such as optical laser laboratories, synchrotrons, and free electron lasers, are of vital importance 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 highly excited matter. Traditional photon science modelling takes into account only isolated aspects of an experiment, such as the beam propagation, the photon-matter interaction, or the scattering process, making idealized assumptions about the remaining parts, e.g.\ the source spectrum, temporal structure and coherence properties of the photon beam, or the detector response. In SIMEX, we have implemented a platform for complete start-to-end simulations, following the radiation from the source, through the beam transport optics to the sample or target under investigation, its interaction with and scattering from the samp...
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Research Interests: Computer Science, Simulation, GPU, Big Data, Interactive, and 4 moreParticle in Cell, HPC, LPA, and Laser Plasma
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Plasma wakefield accelerators are capable of sustaining gigavolt-per-centimeter accelerating fields, surpassing the electric breakdown threshold in state-of-the-art accelerator modules by 3-4 orders of magnitude. Beam-driven wakefields... more
Plasma wakefield accelerators are capable of sustaining gigavolt-per-centimeter accelerating fields, surpassing the electric breakdown threshold in state-of-the-art accelerator modules by 3-4 orders of magnitude. Beam-driven wakefields offer particularly attractive conditions for the generation and acceleration of high-quality beams. However, this scheme relies on kilometer-scale accelerators. Here, we report on the demonstration of a millimeter-scale plasma accelerator powered by laser-accelerated electron beams. We showcase the acceleration of electron beams to 128 MeV, consistent with simulations exhibiting accelerating gradients exceeding 100 GV m−1. This miniaturized accelerator is further explored by employing a controlled pair of drive and witness electron bunches, where a fraction of the driver energy is transferred to the accelerated witness through the plasma. Such a hybrid approach allows fundamental studies of beam-driven plasma accelerator concepts at widely accessible ...
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With the rapid development of short-pulse intense laser sources, studies of matter under extreme irradiation conditions enter further unexplored regimes. In addition, an application of X-ray Free-Electron Lasers (XFELs) delivering intense... more
With the rapid development of short-pulse intense laser sources, studies of matter under extreme irradiation conditions enter further unexplored regimes. In addition, an application of X-ray Free-Electron Lasers (XFELs) delivering intense femtosecond X-ray pulses, allows to investigate sample evolution in IR pump - X-ray probe experiments with an unprecedented time resolution. Here we present a detailed study of the periodic plasma created from the colloidal crystal. Both experimental data and theory modeling show that the periodicity in the sample survives to a large extent the extreme excitation and shock wave propagation inside the colloidal crystal. This feature enables probing the excited crystal, using the powerful Bragg peak analysis, in contrast to the conventional studies of dense plasma created from bulk samples for which probing with Bragg diffraction technique is not possible. X-ray diffraction measurements of excited colloidal crystals may then lead towards a better und...
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The Horizon 2020 project EuPRAXIA (European Plasma Research Accelerator with eXcellence In Applications) is producing a conceptual design report for a highly compact and cost-effective European facility with multi-GeV electron beams... more
The Horizon 2020 project EuPRAXIA (European Plasma Research Accelerator with eXcellence In Applications) is producing a conceptual design report for a highly compact and cost-effective European facility with multi-GeV electron beams accelerated using plasmas. EuPRAXIA will be set up as a distributed Open Innovation platform with two construction sites, one with a focus on beam-driven plasma acceleration (PWFA) and another site with a focus on laser-driven plasma acceleration (LWFA). User areas at both sites will provide access to free-electron laser pilot experiments, positron generation and acceleration, compact radiation sources, and test beams for high-energy physics detector development. Support centres in four different countries will complement the pan-European implementation of this infrastructure.
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This release fixes a broken laser profile (wavepacket), allows to use icc as the host compiler, fixes a bug when writing openPMD files in simulations without particle species ("vacuum") and a problem with GPU device selection on... more
This release fixes a broken laser profile (wavepacket), allows to use icc as the host compiler, fixes a bug when writing openPMD files in simulations without particle species ("vacuum") and a problem with GPU device selection on shared node usage via CUDA_VISIBLE_DEVICES. Please refer to our CHANGELOG.md for a full list of features, fixes and user interface changes. Thanks to René Widera and Richard Pausch for spotting the issues and providing fixes!
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This release fixes energy density output, minor openPMD issues, corrects a broken species manipulator to derive density weighted particle distributions, fixes a rounding issue in ionization routines that can cause simulation corruption... more
This release fixes energy density output, minor openPMD issues, corrects a broken species manipulator to derive density weighted particle distributions, fixes a rounding issue in ionization routines that can cause simulation corruption for very small particle weightings and allows the moving window to start immediately with timestep zero. For ionization input, we now verify that the number of arguments in the input table matches the ion species' proton number. All fixes are backported to work in C++98 (and C++11) mode. Please refer to our ChangeLog for a full list of features, fixes and user interface changes. Thanks to Axel Huebl, René Widera, Richard Pausch, Alexander Debus, Marco Garten, Heiko Burau and Thomas Kluge for spotting the issues and providing fixes!
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Phase Space Momentum, ADIOS One-Particle Dumps & Field Names This release fixes a bug in the phase space plugin which derived a too-low momentum bin for particles below the typical weighting (and too-high for above it). ADIOS dumps... more
Phase Space Momentum, ADIOS One-Particle Dumps & Field Names This release fixes a bug in the phase space plugin which derived a too-low momentum bin for particles below the typical weighting (and too-high for above it). ADIOS dumps crashed on one-particle dumps and in the name of on-the-fly particle-derived fields species name and field name were in the wrong order. The plugins libSplash (1.6.0) and PNGwriter (0.6.0) need exact versions, later releases will require a newer version of PIConGPU. Please refer to our ChangeLog for a full list of features, fixes and user interface changes before getting started. Thanks to Axel Huebl, René Widera, Sergei Bastrakov and Sebastian Hahn for contributing to this release!
In the effort of achieving high-energetic ion beams from the interaction of ultrashort laser pulses with a plasma, volumetric acceleration mechanisms beyond Target Normal Sheath Acceleration have gained attention. A relativisticly intense... more
In the effort of achieving high-energetic ion beams from the interaction of ultrashort laser pulses with a plasma, volumetric acceleration mechanisms beyond Target Normal Sheath Acceleration have gained attention. A relativisticly intense laser can turn a near critical density plasma slowly transparent, facilitating a synchronized acceleration of ions at the moving relativistic critical density front. While simulations promise extremely high ion energies in in this regime, the challenge resides in the realization of a synchronized movement of the ultra- relativistic laser pulse (a0>∼30) driven reflective relativistic electron front and the fastest ions, which imposes a narrow parameter range on the laser and plasma parameters. We present an analytic model for the relevant processes, confirmed by a broad parameter simulation study in 1D- and 3D-geometry. By tayloring the pulse length and plasma density profile at the front side, we can optimize the proton acceleration performance ...
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This is the first release of PIConGPU requiring C++11. We added a newly developed current solver (EmZ), support for the generation of Bremsstrahlung, Thomas-Fermi Ionization, Laguerre-modes in the Gaussian-Beam laser, in-simulation plane... more
This is the first release of PIConGPU requiring C++11. We added a newly developed current solver (EmZ), support for the generation of Bremsstrahlung, Thomas-Fermi Ionization, Laguerre-modes in the Gaussian-Beam laser, in-simulation plane for laser initialization, new plugins for in situ visualization (ISAAC), a generalized particle calorimeter and a GPU resource monitor. Initial support for clang (host and device) has been added and our documentation has been streamlined to use Sphinx from now on. Please refer to our ChangeLog for a full list of features, fixes and user interface changes before getting started. We also started continuous documentation ("a manual") with Sphinx: https://picongpu.readthedocs.io This page will in the mid time frame replace our wiki and will allow you to select a specific version of PIConGPU. Such a "release-aware documentation" is important to us since our tools, workflows and models naturally change over time (for the better). Also,...
Milestone M4.1 for work package 4 (SIMEX) of EUCALL
Dataset and scripts for the paper with title Evaluating Programming Models for the HPC GPU Ecosystem
In the frame of the EUCALL WP, Pulse Characterisation and Control (PUCCA) project, the ESRF is designing a wavefront sensor prototype for the hard X-ray energy regime based on the principle of X-ray speckle tracking. Alongside this... more
In the frame of the EUCALL WP, Pulse Characterisation and Control (PUCCA) project, the ESRF is designing a wavefront sensor prototype for the hard X-ray energy regime based on the principle of X-ray speckle tracking. Alongside this instrument, we also developed a dedicated and versatile software package for wavefront retrieval and reconstruction from speckle experimental data.<br> The present report is structured as follows: Chapter 2 presents the working principle behind our instrument, gives details regarding the experimental workflow and detector calibration, and describes our software implementation for wavefront computation, including a study on software optimization possibilities as a contribution of our colleagues from EUCALL WP5, Ultrafast Data Acquisition (UFDAC); Ch. 3 describes the instrument and its main components; Ch. 4 gives an overview of the experimental campaigns through which the instrument was tested at three different large-scale X-ray facilities; finally,...
Laser cooling, applied as a stand-alone cooling technique, or in combination with electron cooling, has high potential to generate relativistic ion beams with high phas espace densities. Even the generation of crystalline ion beams might... more
Laser cooling, applied as a stand-alone cooling technique, or in combination with electron cooling, has high potential to generate relativistic ion beams with high phas espace densities. Even the generation of crystalline ion beams might be accessible. A neccessary prerequisite to reach this goal is the implementation of powerful diagnostics for the characterization of the resulting ion beam parameters. Schottky pick-up techniques [1] will lead a long way in this direction, but might be running short for the highest phase-space densities targeted. Optical diagnost ics, making use of the collection of scattered optical photons during resonant excitation of relativistic ions, will open a second window for characterizing the ion beam with improved momentum resolution. Therefore, we have developed two different detector systems for the UV-range ( λ ∼150 nm): one system uses a photomultiplier tube (PMT) and is mounted in air (on a CaF2 viewport), the other system is based on a photochann...
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In recent years nanoscale coherent imaging has emerged as an indispensable imaging modality allowing to surpass the resolution limit given by classical imaging optics. At the same time, attosecond science has experienced enormous progress... more
In recent years nanoscale coherent imaging has emerged as an indispensable imaging modality allowing to surpass the resolution limit given by classical imaging optics. At the same time, attosecond science has experienced enormous progress and has revealed the ultrafast dynamics in atoms, molecules, and complex materials. Combining attosecond temporal resolution of pump-probe experiments with nanometer spatial resolution would allow studying ultrafast dynamics on the smallest spatio-temporal scales but has not been demonstrated yet. Unfortunately, the large bandwidth of attosecond pulses usually hinders high-resolution coherent imaging. Here we present a robust holography-enhanced coherent imaging method, which allows combining high quality and high spatial resolution coherent imaging with a large spectral bandwidth. By implementing our method at a high harmonic source we demonstrate, for the first time, a spatial resolution of 34 nm (2.5 {\lambda}) in combination with a spectral ban...
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Please read our ChangeLog about the new features and syntax changes to your parameter files. With this release we started to write a comprehensive documentation in our wiki. Feel free to contribute and update articles!
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Please read our ChangeLog about the new features and syntax changes to your parameter files. With this release we added flexible species attributes, a generalized ZigZag current scheme (40-50% speedup) and Jetson-TK1 dev kit support... more
Please read our ChangeLog about the new features and syntax changes to your parameter files. With this release we added flexible species attributes, a generalized ZigZag current scheme (40-50% speedup) and Jetson-TK1 dev kit support (32bit).
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simex_platform: A software framework for simulations of photon experiments at advanced laser light sources.
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We demonstrate that optical free-electron lasers (OFELs) realized with Traveling-Wave Thomson-Scattering (TWTS) are by orders of magnitude more efficient and brilliant than corresponding OFELs utilizing head-on Thomson scattering... more
We demonstrate that optical free-electron lasers (OFELs) realized with Traveling-Wave Thomson-Scattering (TWTS) are by orders of magnitude more efficient and brilliant than corresponding OFELs utilizing head-on Thomson scattering geometries. In addition, we emphasize that TWTS OFELs as opposed to standard head-on Thomson scattering geometries scale favorably with regard to space-charge effects degrading emittance, energy losses through photon recoil and transverse coherence of the resulting FEL beam. The presented TWTS OFELs scenarios are assumed to be driven either by conventional, rf-accelerated electrons or by currently available laser wakefield-accelerated electrons featuring energy spreads at the one percent level.
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ABSTRACT In the course of a high-intensity short laser pulse interacting with a solid target mediated by laser-generated plasma, back scattered light from Raman backscattering (RBS) can substantially affect the evolution of the laser... more
ABSTRACT In the course of a high-intensity short laser pulse interacting with a solid target mediated by laser-generated plasma, back scattered light from Raman backscattering (RBS) can substantially affect the evolution of the laser pulse in the plasma. Therefore, the RBS measurement is important in diagnosing processes occurring in the interaction. We will present time-integrated spectrum and power measurements of back scattered light centered at 1φ, 2φ and 3φ from coupling high-contrast ultra intense lasers (at ˜ 10^20 W/cm^2) to a solid. The backscattered spectra show distributed peaks between 300nm -1750nm with broadened width. From analysis we determine plasma conditions including scale length, density profile and temperature. Collisional particle-in-cell simulations (LSP) reveal the effect of this inhomogeneous plasma on heating and acceleration of electrons through stochastic heating and ponderomotive acceleration, as well as the succeeding ion acceleration through the target normal sheath acceleration (TNSA) mechanism.
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This releases fixes a potential deadlock encountered during checkpoints and initialization. Furthermore, we forgot to highlight that the 0.2.0 release also included a QED synchrotron emission scheme (based on the review in A. Gonoskov et... more
This releases fixes a potential deadlock encountered during checkpoints and initialization. Furthermore, we forgot to highlight that the 0.2.0 release also included a QED synchrotron emission scheme (based on the review in A. Gonoskov et al., PRE 92, 2015). Please refer to our CHANGELOG.md for a full list of features, fixes and user interface changes. Thank you to René Widera for spotting & fixing and Heiko Burau for the QED synchrotron photon emission implementation!
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Invited presentation given by Axel Huebl (HZDR, Germany) at the EPS 2019 conference in Milano (Italy) on July 11th, 2019.
Research Interests: Engineering and milestone
High-quality, stored ion beams can be obtained by means of electron cooling and/or stochastic cooling. At intermed iate kinetic energies ( γ≈1), these methods work very well. But at very high kinetic energies ( γ>5), they become less... more
High-quality, stored ion beams can be obtained by means of electron cooling and/or stochastic cooling. At intermed iate kinetic energies ( γ≈1), these methods work very well. But at very high kinetic energies ( γ>5), they become less effective. For instance, to reach electron cooling at γ=12, a very sophisticated (voltage up to 6 MV) and thus expensive electron cooling system is required. Therefore, another method was considered for the FAIR heavy-ion synchrotron SIS100: Laser cooling of bunched ion beams. Based on successful experiments with stored, relativistic heavy-ion beams at the ESR [1], it was (2013) decided to set up a laser cooling facility at the SIS100. Within the 3rd term of the Programme Oriented Funding (POFIII) of the Helmholtz Society, we wrote a proposal for this facility as part of accelerator research and development (ARD) within ”Matter and Technologies” [2]. Early 2014, the proposal was approved and received the highest marks (‘highlight’). Within FAIR@GSI p...
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Solving partial differential equations (PDE) is an indispensable part of many branches of science as many processes can be modelled in terms of PDEs. However, recent numerical solvers require manual discretization of the underlying... more
Solving partial differential equations (PDE) is an indispensable part of many branches of science as many processes can be modelled in terms of PDEs. However, recent numerical solvers require manual discretization of the underlying equation as well as sophisticated, tailored code for distributed computing. Scanning the parameters of the underlying model significantly increases the runtime as the simulations have to be cold-started for each parameter configuration. Machine Learning based surrogate models denote promising ways for learning complex relationship among input, parameter and solution. However, recent generative neural networks require lots of training data, i.e. full simulation runs making them costly. In contrast, we examine the applicability of continuous, mesh-free neural solvers for partial differential equations, physics-informed neural networks (PINNs) solely requiring initial/boundary values and validation points for training but no simulation data. The induced curs...
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A Reply to the Comment by C. Thaury et al.
Measured Thomson-backscattering X-ray spectra recorded as a function of the observation angle and quantitatively reproduced in simulations are presented. A traveling wave scheme is proposed to increase the yield and may allow for... more
Measured Thomson-backscattering X-ray spectra recorded as a function of the observation angle and quantitatively reproduced in simulations are presented. A traveling wave scheme is proposed to increase the yield and may allow for all-optical free-electron laser operation.