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Hybrid Wakefield Acceleration

Electron acceleration activities at the Center for Advance Laser Applications aim to produce ultrashort and low emittance electron bunches for subsequent x-ray generation. Technologies based on plasma electron accelerators can bridge the regime between conventional x-ray tubes and large-scale synchrotrons/free electron lasers. High brightness medium to hard x-ray radiation has many applications in medicine, industry and science. Notably medical phase contrast imaging of human tissues requires high brilliance x-ray sources in order to achieve the best trade-off between high quality images, acceptable radiation dose, compactness and affordable coasts.

Wakefields in plasmas can either be driven by high intensity laser pulses (LWFA), or by high current particle bunches (PWFA). Both mechanisms have their distinct advantages.

The ATLAS-3000 laser system allows to operate a powerful source of LWFA electrons. This technology has been studied and refined in the working group over the last decade and relativistic electrons (few hundred MeV) at high bunch charge (nC level) are routinely produced. These LWFA electrons exhibit few μm source size and on the order of 10 fs bunch length. However, they have a comparably large divergence on the order of a few mrad because of the intrinsically “hot injection” in the presence of the relativistic laser driver. Charge and energy of the electron bunches sensitively depend on the driving laser parameters and fluctuations.
On the other hand, plasma wakefield acceleration is a viable tool to generate low emittance electrons – a number of advanced injection schemes for PWFA experiments has been suggested over the last years. However, PWFA typically requires large scale particle accelerators like linacs or synchrotron machines to generate the particle driver.

The hybrid approach aims to combine advantages of both types of plasma-based accelerators. The underlying idea is to use the available nanocoulomb class electron bunches from the LWFA stage as a driver for a subsequent PWFA stage. In our experiments a new electron bunch is injected and accelerated in the PWFA stage. The emittance of this electrons from the second stage is potentially much lower and more controllable than in pure LWFA.

Further reading:

  • Demonstration of a compact plasma accelerator powered by laser-accelerated electron beams
    T Kurz, T Heinemann, MF Gilljohann, YY Chang, JP Cabada─č, A Debus, ...
    Nature Communications 12, 2895 (2021)
  • Physics of High-Charge Electron Beams in Laser-Plasma Wakefields
    J Götzfried, A Döpp, MF Gilljohann, FM Foerster, H Ding, S Schindler, ...
    Physical Review X 10 (4), 041015 (2020)
  • Dual-energy electron beams from a compact laser-driven accelerator
    J Wenz, A Döpp, K Khrennikov, S Schindler, MF Gilljohann, H Ding, ...
    Nature Photonics 13 (4), 263-269 (2019)
  • Direct observation of plasma waves and dynamics induced by laser-accelerated electron beams
    MF Gilljohann, H Ding, A Döpp, J Götzfried, S Schindler, G Schilling, ...
    Physical Review X 9 (1), 011046 (2019)

Research coordinator:

PhD student:

In collaboration with: HZDR (Dresden, Germany), LOA (Palaiseau, France), University of Strathclyde (Glasgow, Scotland), DESY (Hamburg, Germany)