Title: Generation of controllable plasma wakefield noise in particle-in-cell simulations,
Abstract: Numerical simulations of beam-plasma instabilities may produce quantitatively
incorrect results because of unrealistically high initial noise from which the
instabilities develop. Of particular importance is the wakefield noise, the
potential perturbations that have a phase velocity which is equal to the beam
velocity. Controlling the noise level in simulations may offer the possibility
of extrapolating simulation results to the more realistic low-noise case. We
propose a novel method for generating wakefield noise with a controllable
amplitude by randomly located charged rods propagating ahead of the beam. We
also illustrate the method with particle-in-cell simulations. The generation of
this noise is not accompanied by parasitic Cherenkov radiation waves.