FEL-OSCILLATOR SIMULATIONS WITH GENESIS 1.3

Modeling free-electron laser (FEL) oscillators requires calculation of both the light-beam interaction within the un-dulator and the propagation of the light outside the undula-tor. We present a paraxial Optical Propagation Code (OPC) based on the Spectral Method and Fresnel Diffraction Inte-gral, which in combination with Genesis 1.3 can be used to perform either steady-state or time-dependent FEL oscilla-tor simulations. A flexible scripting interface is used both to describe the optical resonator and to control the codes for propagation and amplification. OPC enables modeling of complex resonator designs that may include hard-edge elements (apertures) or hole-coupled mirrors with arbitrary shapes. Some capabilities of OPC are illustrated using the FELIX system as an example