An overview of programs for calculation of undulator radiation spectra

When considering how to optimize undulator design, numerical tools are needed to provide precise calculations of radiation spectra and angular distributions under various conditions. Here a short description of some existing computer codes is given, which make use of different and somewhat complementary approaches. In particular, the authors consider: i) methods based on straightforward integration of general radiation formulae; ii) those based on the Fast Fourier Transform algorithm (FFT); iii) those based on a given analytical form of the trajectory in an ideal undulator; iv) those based on appropriate approximations of exact formulae for some special cases. In some cases, convolution of radiation spectra with the phase space distribution of both the electron beam and the detector is taken into account. Some illustrative results of each program are reported, and their respective fields of application are considered