A numerical model of electron beam shot noise

A numerical method of simulating electron beam shot noise in free electron lasers is presented. The method uses a quasi-uniform phase space distribution of appropriately charged weighted macroparticles. The statistical properties of the macroparticles are derived directly from the temporal Poisson statistical properties of the real electron distribution. Unlike previous methods, our method does not rely upon any averaging over a resonant radiation period timescale and so more correctly describes the underlying physics. The method also allows shot noise to be modeled self-consistently in un-averaged FEL models which are able to describe sub-wavelength phenomena such as Coherent Spontaneous Emission.