We will be giving an overview on the development of the “ELI-beamline facility” being currently implemented and opened as a user facility within the Extreme Light Infrastructure (ELI) project based on the European ESFRI (European Strategy Forum on Research Infrastructures) process.
ELI-Beamlines is the high-energy, repetition-rate laser pillar of the ELI (Extreme Light Infrastructure) project. The main objective of the ELI-Beamlines facility is the delivery of ultra-intense high-energy pulses for high field experiments and the generation and applications of high-brightness X-ray sources and accelerated particles. The high power laser systems currently prepared and used for the generation of higher repetition rate sources of x-rays and particles are L1 (Allegra) a 1 kHz diode pumped laser produced sub-20fs OPCPA system and the L3 (HAPLS) a 10 Hz, 1 PW (30fs) laser using as the active medium Ti:sapphire with new gas cooled diode pumped Nd doped Glass pump laser. The lasers will be able to provide focused intensities attaining >1018-21 Wcm-2 suitable for generation of x-rays and particles (electrons and ions). We will discuss the infrastructure concerning the availability of experimental areas, including secondary sources of particles and x-rays in the wavelength range between 20 eV-100 keV and few Mev and their practical implementation at the ELI-Beamline user facility. The sources are either based on direct interaction of the laser beams with gaseous targets (high order harmonics) or will first accelerate electrons which then will interact with laser produced wigglers (Betatron radiation) or directly injected into undulators (laser driven LUX or later X-FEL). The direct interaction (collision) of laser accelerated electrons with the intense focused laser again will lead to short pulse high energy radiation via Compton or Thomson scattering for different applications opening also the route to fundamental physics investigations in high intensity interaction due to the 4 gamma 2 Lorentz boost of the intensity seen by high energy (GeV- > 106) electrons.
Nowadays by using the optical parametric chirped-pulse amplification (OPCPA) technique it is reasonable to expect the laser pulse energy up to 10 Joules with the repetition rate of 10-25 Hz. Development of such laser systems with the pulse compression down to 30 fs opens a way to build compact free-electron laser (FEL) based on the laser wakefield acceleration (LWFA). Combination of new laser development with constant improvement of the LWFA electron beam parameters has great potential in future development of the compact high repetition rate FEL, which is extremely demanded by the X-ray user community. The LWFA-driven FEL project called “LUIS" is currently under preparation at ELI-Beamlines in Czech Republic in collaboration with University of Hamburg. The LUIS project aims to experimentally demonstrate the stable and reliable generation of X-ray photons with a wavelength below 5 nm for user applications. An overview of the LUIS project including design features and a description of all the instrumentation used to characterize the laser, plasma, electron beam, photon generation and other subsystems will be presented in the frame of this report. The main challenges and future development of the laser-driven compact X-ray free electron laser with the radiation wavelength less than nm will also be discussed.
The laser-driven Undulator X-ray source (LUX) is designed to be a user beamline providing ultra-short EUV photon
pulses with a central wavelength tuneable in the range of 0.4 to 4.5 nm and a peak brilliance of up to 10<sup>21</sup>
photons/(s.mrad<sup>2</sup>.mm<sup>2</sup>.0.1% B.W.), which makes this source comparable with modern synchrotron sources. The source
shall provide a focal spot size well below 10 μm and a range of auxiliary beams for complex pump-and-probe
experiments and it is also an important experimental milestone towards a future laser driven Free Electron Laser.
Unique femtosecond nature of the laser-plasma electron acceleration in combination with extremely small transverse
emittance of the electron beam is the major advantage of the LWFA technique. Preservation of the electron beam quality
is a complicated task for a dedicated electron beam line, which has to be designed to transport the electron beam from the
LWFA source up to the undulator. In this report we discuss main requirements on the LWFA source and the electron
beam optics of the LUX source and solutions to produce required quality photon beam in the undulator and we also
discuss the effect of realistic setup parameters on the quality of the electron beam in the undulator within the range of