Abstract
A heavily loaded W-Band TE01 mode Gyro-TWT is currently being tested at UCD. The amplifier is predicted to generate 140 kW at 94 GHz with 50 dB saturated gain, 28% efficiency and 5% bandwidth. For stability and wide bandwidth, it is driven by a 100kV, 5A MIG electron beam with a velocity ratio of vl / vz= 1.0 . The characteristics of the amplifier are described in Table 1. As shown in Fig 1. dispersion diagram, TE11(1), and TE21(1) Gyro- BWO interactions must be suppressed for stable operation. To suppress these potential Gyro- BWO oscillations, the circuit has been heavily loaded with lossy carbon colloid, a technique recently employed to operate a high gain KaBand Gyro-TWT [1]. The large signal characteristics were evaluated with a large signal simulation code as shown in Fig. 2. A coaxial input coupler with -1dB insertion loss with 3% bandwidth is employed and a lower coupling coaxial coupler monitors the output power. The small Sgnal characteristics at a stable operating region yielded a gain of 34 dB and 2% bandwidth Fig 3. show the beam voltage and collector current wavefonns at a stable operating region with RF input on and off The linearity of the device under test is evident in Fig. 4. The experimental search for the large signal characteristics using a 100W, 5% bandwidth folded waveguide TWT has been hampered by the poor beam quality due to misalignment of the MIG. The MIG has recently been disassembled and carefully realigned. Results from the rebuilt device will be repolted.