Calculations Pertaining to the Design of a Prebuncher for a 150-MeV Electron Linear Accelerator: II Radial Motion

In a previous paper, calculated results based on a one-dimensional ballistic model were presented to indicate the extent to which a current pulse of 150-keV electrons containing 1 μC of charge and having a duration of 15 nsec (FWHM) could be bunched by a combination of accelerating and decelerating voltage gaps followed by a drift space. In the present paper a very approximate perturbation model is used to determine the extent to which the prebuncher performance determined previously is modified by radial electron motion. It is found that if a longitudinal magnetic field of 1 kG is applied in the region containing the voltage gaps and if a sufficiently strong longitudinal magnetic field (~ 3 kG) is applied in the drift space the prebuncher performance determined here is essentially the same as that shown in the previous paper.