Laser-driven radiation sources in the ALPHA-X project

The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laser-plasma accelerators for the production of ultra-short electron bunches with subsequent generation of high brilliance, short-wavelength radiation pulses. Ti:sapphire laser systems with peak power in the range 20-200 TW are coupled into mm-and cm-scale plasma channels in order to generate electron beams of energy 50-800 MeV. Ultra-short radiation pulses generated in these compact sources will be of tremendous benefit for time-resolved studies in a wide range of applications across many branches of science. Primary mechanisms of radiation production are (i) betatron radiation due to transverse oscillations of the highly relativistic electrons in the plasma wakefield, (ii) gamma ray bremsstrahlung radiation produced from the electron beams impacting on metal targets and (iii) undulator radiation arising from transport of the electron beam through a planar undulator. In the latter, free-electron laser action will be observed if the electron beam quality is sufficiently high leading to stimulated emission and a significant increase in the photon yield. All these varied source types are characterised by their high brilliance arising from the inherently short duration (similar to 1-10 fs) of the driving electron bunch.