Parametric study of an X-ray FEL

An FEL utilizing a high energy, high current and low emittance beam to produce radiation shorter than 2إis investigated in this paper. This device is an extension of the previously proposed 40إLinac Coherent Light Source based on the Stanford linear accelerator. Here we investigate the performance characteristics and parameter sensitivities of this single pass, high gain FEL amplifier operating by self-amplified spontaneous emission (SASE). We begin by comparing various approaches to this short wavelength source and justify our choice of a helical undulator operating on the fundamental frequency. Numerical simulations as well as extensions of previous studies are used to show performance as a function of undulator parameters, startup noise, emittance, focusing, current and energy spread. Further studies and parameter modifications are proposed where needed.