Source size and angular divergence of wiggler radiation

The source size and angular divergence are very important properties which are necessary to design optical elements in the beamline. We report on the source distribution of wiggler radiation (WR), which is not expressed as simple expressions as the undulator radiation. Assuming that the WR is completely incoherent, angular and spatial profile functions are derived as the simple summation of those of photons emitted at every position of the wiggler. Then, the beam size and angular divergence are calculated using these functions. Simple mathematical functions to approximate these values are shown to help the synchrotron radiation users and beamline scientists estimate their own beamline performances