Modeling of a twystrode gun using FEAs

An inductive output amplifier twystrode has previously been considered. This device requires a miniaturized electron gun and FEAs are being employed. The advantages of using FEAs include the ability to premodulate the electron beam. Beam modulation occurs in the microscopic FEAs inside the electron gun area. The authors present results of macroscopic beam trajectories by using the Herrmannsfeldt trajectory code. In these simulations electrons are emitted from the cathode surface with energies in the range of 10 to 40 eV. The first gun design assumes a miniaturized Pierce type cathode employing FEAs. The emission of an annular beam is made at 0.03" of the cathode radius along the magnetic flux line of the pole piece field. Different electron gun geometries are also considered to protect the FEA cathode from back ion-bombardment.