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Dual-energy electron beams from a compact laser-driven accelerator


Ultrafast pump–probe experiments open the possibility to track fundamental material behaviour, such as changes in electronic configuration, in real time. To date, most of these experiments are performed using an electron or a high-energy photon beam that is synchronized to an infrared laser pulse. Entirely new opportunities can be explored if not only a single, but multiple synchronized, ultrashort, high-energy beams are used. However, this requires advanced radiation sources that are capable of producing dual-energy electron beams, for example. Here, we demonstrate simultaneous generation of twin-electron beams from a single compact laser wakefield accelerator. The energy of each beam can be individually adjusted over a wide range and our analysis shows that the bunch lengths and their delay inherently amount to femtoseconds. Our proof-of-concept results demonstrate an elegant way to perform multi-beam experiments in the future on a laboratory scale.

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Fig. 1: Dual-energy femtosecond electron and X-ray source.
Fig. 2: Experimental tuning of electron beam energy using shock-front and colliding-pulse injection schemes.
Fig. 3: Demonstration of dual-energy electron beams and PIC simulations.
Fig. 4: Proposed radiation source and timing control based on dual-energy electron beams.
Fig. 5: Radiation generation using an all-optical Compton source.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.


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This work was supported by DFG through the Cluster of Excellence Munich-Centre for Advanced Photonics (MAP EXC 158), DFG-Project Transregio TR-18 funding schemes, by EURATOM-IPP and the Max-Planck-Society. L.V. acknowledges the support by a grant from the Swedish Research Council (2016-05409). The authors thank F. Krausz for helpful comments. A.D. thanks I. Andriyash (WIS) for support with Chimera.

Author information




A.B., M.H., K.K., J.W., J.X., L.V. and S.K. performed the experiments with ATLAS-60 at the MPQ. A.D., H.D., M.F.G., J.G., S.S. and S.K. performed the experiments with the upgraded laser system at LEX Photonics. A.D., K.K., S.S. and J.W. analysed the experimental data. A.D. performed PIC simulations, radiation and beam transport calculations. A.D., W.H., K.K., J.W., L.V. and S.K. discussed the results. A.D., K.K. and J.W. wrote the paper. S.K. supervised the project.

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Correspondence to A. Döpp or S. Karsch.

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Supplementary information

Supplementary Information

Further experimental data as well as discussions about electron bunch delay, possible applications and beam transport.

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Wenz, J., Döpp, A., Khrennikov, K. et al. Dual-energy electron beams from a compact laser-driven accelerator. Nat. Photonics 13, 263–269 (2019).

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