Large-signal theory of a two-stage wideband gyro-TWT

A self-consistent large-signal theory is used to obtain gain and efficiency of the two-stage tapered gyro-TWT in a nonuniform external magnetic field. Calculations show that it is possible to design a device having 45 percent bandwidth at 45-dB gain and 25 percent efficiency if the axial velocity spread of the beam electrons is zero. It is found that the gain and bandwidth are very sensitive to the degree of beam velocity spread, the external magnetic field profile, and the various beam and circuit parameters. An expression for the efficiency under quasi-linear approximation is also derived in order to get a physical understanding of the device performance.