Non-adiabatic transition of beams in gyrotrons through various magnetic field profiles
Abstract
The achievement of efficiency enhancement in small-orbit gyrotrons by using
depressed collector techniques requires precisely configured magnetic field
profiles which present adiabatic as well as non-adiabatic transitions to the spent
beam. The effect of adiabatic changes can be evaluated analytically. That of
complex non-adiabatic transitions, however, must be studied by numerical
simulation of the particle trajectories. A single-particle code has been used to
study a variety of profiles such as steps, troughs, and peaks. Results are
presented showing the influence of the parameters of the field profile on the ratio
of perpendicular to parallel components of velocity. Beam heating effects are also
considered and examples are given of how they can be minimized.