Effective bandwidth and the Kompfner dip for cyclotron autoresonance maser amplifiers

[[abstract]]This paper investigates the inadequacy of using the growth rate from the dispersion relation to represent the bandwidth of a cyclotron autoresonance maser (CARM) amplifier. It is shown that the dispersion relation can accurately predict the amplifier's bandwidth, but at least three waves that the electron beam couples to must be retained in the calculation. Interference between these waves must be included. The bandwidth of the coupling coefficient for the forward growing wave can be much narrower than the bandwidth of this wave's growth rate. In addition, the input signal has been observed to be almost totally absorbed by the electron beam at a specific frequency which is a function of the operating conditions. This phenomenon is caused by the beating between the forward constant amplitude wave and the forward growing wave. It is analogous to the Kompfner dip in a conventional linear beam traveling wave tube and can, therefore, become a useful diagnostic for determining the experimental parameters of a CARM amplifier.[[fileno]]2010126010072[[department]]物理