Conceptual design for an hard X-ray Free Electron Laser based on CLIC X-band structure

In this paper, a conceptual design of a hard X-ray Free-Electron Laser (FEL) facility based on CLIC-like X-band accelerating structure has been presented. The injector, based on an X-band rf gun, the main accelerating sections, using high-gradient CLIC-like structures including rf power distribution, and the two bunch compressors have been discussed. Simulations of the rf gun, of the injector, and of the linac have been performed, successfully meeting the stringent requirements in terms of minimum projected emittance, sliced emittance, and minimum bunch length. Full 6-D start-to-end linac simulations have been performed taking into account wakefield effects, misalignment of accelerator components, Coherent Synchrotron Radiation (CSR), and small dynamic variations of phase, voltage, and injection time. The performance of FEL at λ=1 Angstrom (Å) has also been evaluated for self-amplified spontaneous emission (SASE) FEL mode. A radiation power of about 10 GW has been achieved with a photon pulse length of 30 fs. The main advantage of the proposed design is that it achieved the required beam parameters in very short length, rendering the facility quite compact.