Effects of beam and channel parameters on energy spread in periodically focused electron beams

Periodic focusing was previously shown to produce a longitudinal kinetic energy spread in a low energy (2.5keV, 40mA), space-charge dominated electron beam. New experimental results show how this energy spread develops in a 4.5keV, 220mA beam in a two-lens channel, and how the resulting shape and size of the distribution depend on the beam and channel parameters, including energy, current, lens focusing strengths, and on the evolution of the density profile. Individual particle motion is analyzed with a simulation, which includes nonlinearities in focusing and space-charge. It is shown how the particle motion leads to non-periodic growth in energy spread in a periodically focused beam. Comparison is made between the simulation and experimental results on the shape and size of the resulting distribution in longitudinal kinetic energy.