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Fifth Generation of Ultra Bright X Ray Beam

Final Report Summary - X-FIVE (Fifth Generation of Ultra Bright X Ray Beam)

In many domains of science, scientific discoveries rely on sophisticated and robust technologies that are the fruits of years of basic fundamental research. Fundamental research on laser plasma interaction in the relativistic regime is now contributing in modern accelerator technics with the demonstrated concept of Laser Plasma Accelerators (LPA).

LPA requires first powerful laser systems able to deliver stable laser pulses in the few tens of TW (1TW = 1012 Watt) to a few PW (1PW = 1015 Watt) and, second, the mastering of the giant electric field components in the plasma medium produced with the well-characterized laser pulse.

The “secret” of this new area of science relies on our ability to manipulate relativistic electrons with intense laser pulses. In LPA, the electric field with extreme value in the hundreds of GV/m results from the collective motion of electrons produced by the intense laser pulse. The aims of the ERC X-five project is by playing with the two components of the electric field to improve the properties of the electron beam delivered by the LPA and to explore the different approaches to wiggle the relativistic electrons for producing compact ultra-bright X ray beams.

We discovered during the X Five ERC project concepts of plasma booster and of laser plasma lens that allow a better stability and an improvement of the relativistic electrons beam quality. New concepts of wigglers using either a plasma medium that results of the ionization and the heating of nanowires irradiated by the laser pulse or by using an optical lattice that results from the beating of two laser pulses have been also explored theoretically and experimentally. By producing in this compact and elegant way high quality electron beams, Laser Plasma Accelerators offer now the possibility to generate intense and ultra short energetic radiation beams with a few fs duration (1 fs= 10-15s).

The performance and quality of laser-plasma generated electron beams have been fairly improved during the course of the project, and new beam optics concepts and equipment have been successfully commissioned. The design, installation, and experiments show that electron beams delivered by LPA can be manipulated along an FEL transport and undulator radiating line, showing the great potential for producing a bright and compact Free Electron Laser by coupling the electron beam with an undulator. Although laser-plasma based FEL gain could not yet be demonstrated, these experiments are making encouraging progress. The new and growing community is more active than ever and positive to successfully demonstrate FEL gain with a proof-of-principle experiment in the near future.

These developments of LPA and of compact FEL machines have played a crucial role in the roadmap of large-scale research centre in Europe for example with the three ELI’s pillars and with the EuPRAXIA project. They have also contributed to create a unique synergy between Laser and Accelerator community for the benefice of science and with in the very near future societal applications.