Electron trajectories in the PPM-focused coupled-cavity TWT

Trajectories of electrons in a coupled-cavity TWT with ppm focusing are plotted in both
r-z
and
x-y
views. Plots are given for magnetic fields from 1.0 to 1.9 times the Brillouin field, and for small signal and saturated RF conditions. It is shown that a suitably programmed field can control the beam entry problem and minimize the RF debunching, while significantly reducing the beam exit angle. The computer program is briefly described.