LARGE-SIGNAL CHARACTERISTICS OF A WIDE-BAND DIELECTRIC-LOADED GYRO-TWT AMPLIFIER

The bandwidth of a gyrotron traveling wave amplifier (gyro-TWT) has be en significantly increased by partially filling the interaction wavegu ide with dielectric to reduce the circuit's dispersion, The proof-of-p rinciple experiment was designed for X-band, and employs the fundament al mode of rectangular waveguide loaded with dielectric slabs along th e narrow sidewalls, The amplifier yields a peak output power of 55 kW with 11% efficiency, 27 db saturated gain, and an unprecedented untape red gyro-TWT constant-drive bandwidth of 11% and saturated bandwidth e xceeding 14%, The single-stage amplifier is completely zero-drive stab le, The 95-kV 5-A electron beam was produced by a single-anode magnetr on injection gun with upsilon(perpendicular to)/upsilon(z) = 0.6, as d etermined by the EGUN code, and Delta upsilon(z)/upsilon(z) = 4%, dete rmined as the best fit to the gyro-TWT large-signal simulation data, S imulation studies predict that by lowering the velocity spread to Delt a upsilon(z)/upsilon(z) = 2%, the amplifier performance will be furthe r enhanced to a constant-drive bandwidth of 20% with 15% efficiency.