HGHG schemes for short wavelengths

In this paper, we discuss a method to design a single-stage high Gain Harmonic Generation (HGHG) scheme with the aid of GENESIS 1.3 numerical code. To properly design an HGHG scheme, shot-noise effects in both undulators as well as the effect of the energy spread induced by the FEL process in the modulator have to be taken into account. We design the device evaluating these undesired effects separately in each stage and simulating the joint effects on the final configuration. The method will be illustrated following the example of an HGHG scheme for the SPARX project.