Small signal bandwidth characteristics of a travelling-wave gyrotron amplifier

Abstract

Small signal gain calculations on a travelling-wave gyrotron amplifier (gyro-TWA) show that for a low density uni-velocity beam, for which space charge forces can be neglected, moderate band widths, between 5% and 20%, can be attained at the expense of basic electronic efficiency. Interaction between the beam and the first four TE_on modes of the circular cylindrical waveguide interaction region is considered and, for nil four cases, it is shown that at a given beam voltage mid current level an optimum bandwidth condition exists which is principally governed by the transverse-to-axial velocity ratio of the electrons in the uni-velocity gyrating beam.