Overview of SASE free-electron laser simulation codes

The concept of Free Electron Lasers (FEL) based on the principal of Self-Amplified Spontaneous Emission (SASE) was established more than a decade ago. The pace of R&D efforts towards using the concept for 4th Generation Radiation Facilities has been picking up as SASE experiments at optical and infrared wavelengths are being conducted and SASE projects at x-ray wavelengths are under construction or are expecting funding in the foreseeable future. Computer simulation codes are essential tools for a meaningful design of an FEL project. During the 1980s a number of codes had been written, suitable for simulating the SASE process. These codes have been used for the designs of the Linac Coherent Light Source (LCLS) and TESLA Test Facility (TTF) projects as well as for a number of long-wavelengths experiments. Based on experience gained, existing codes are being improved and new codes are under development to study additional aspects of the FEL design. This paper compares SASE FEL codes that are presently available by focussing on aspects such as time dependence, separated function focussing, field errors, undulator module separations, wakefield treatment, computer platforms, code availability, post-processors and others.