Simulation of a concept for a compact ultrafast X-ray pulse source based on RF and THz technologies

We study through simulations a layout mixing RF and THz technologies for a compact ultrafast X-ray pulse source based on Inverse Compton Scattering (ICS), aiming to deliver few femtoseconds to sub-femtosecond pulses. The layout consists of an S-band gun as the electron source and a dielectric-loaded circular waveguide driven by a multicycle THz pulse to accelerate and longitudinally compress the bunch, before X-ray generation via ICS with a laser pulse. We detail several schemes allowing the optimization of the electron bunch properties. This optimization leads to a preliminary layout and various working points able to deliver 0.1–5 pC bunches, ranging from 15 to 18 MeV average kinetic energy, 0.4 to 5 fs rms length, 0.1% to 2.6% rms energy spread, and 5 to 13 μm rms transverse size. Simultaneously, the beamline is kept compact (≈1.3 m up to the ICS point), which has not yet been achieved using only conventional RF technologies. The properties of the X-ray pulse are investigated with simulations, showing ...