AC space charge effects in gyrotrons†

This paper presents a fully self-consistent small signal theory of TEom and TEom gyrotrons. In particular, a reduced plasma frequency ϖp, and a plasma reduction factor It as applicable to those devices are derived, thus describing fully the beam behaviour in gyro-klystrons. The lasing mechanism taking place in fast-wave devices is shown to lead to a resonance in the plasma reduction factor R under typical gyrotron operation, resulting in a space charge related gain parameter Cs which modifies significantly the gain parameter C derived previously neglecting AC space charge effects. This result may modify the traditional approach of simulating gyrotron operation under large signal conditions