OPERATION OF A LARGE-ORBIT HIGH-HARMONIC GYRO-TRAVELING-WAVE TUBE AMPLIFIER

The high-harmonic gyro-traveling wave tube (gyro-TWT) is a high-power (≥ 1 kW) millimeter wave amplifier based on the synchronous interaction of a beam of large-orbit axis-encircling electrons with a high-order cylindrical waveguide mode. Since the interaction occurs at a high harmonic of the cyclotron frequency, the intense magnetic fields required for the conventional fundamental-mode gyro-TWT are not required. A proof-of-principle experiment designed to demonstrate the interaction of a 150-mA 350-keV electron beam with the TE87, mode of a cylindrical waveguide is described. Principal results include a small signal gain of 10 dB, an interaction bandwidth of 4.3 percent, and a saturated power transfer from electron beam to wave of 0.5 kW. Additional measurements include the dependence of gain on electron beam current and the measurement of the beam's γ,β1; β11;and Δβ11;. Sufficient agreement between the experimental results, simulation codes, and an analytic description of the interaction is demonstrated to permit the design of high-performance millimeter wave amplifiers. © 1990 IEEE