| High power millimeter-wave radar is of great interest for various applications including imaging, precision tracking, remote sensing, and jet engine modulation (JEM) classification. The gyrotron traveling-wave tube (gyro-TWT) amplifiers, because they can provide order-of-magnitude improvement in peak power over the state-of-the-art linear-beam amplifiers while retaining the broadband operation, are attractive candidates for the next generation advanced radar system. Particularly, the interest in the 92--96 GHz atmospheric windows at W-band that offers superior performance through cloud, fog and smoke in radar applications, has led to the development of the W-band gyro-TWT.; The gyro-TWTs, however, as evidenced in previous experiments are susceptible to spontaneous oscillations which has been the limiting factor of their performance. In this dissertation work, a W-band TE01 gyro-TWT employing a novel distributed wall loss scheme has been developed. The circuit of the amplifier has been heavily loaded to suppress numerous oscillations.; The stability of the of the amplifier against spurious oscillation has been checked with linear codes. The performance of the W-band TE01 gyro-TWT has been evaluated using a self-consistent nonlinear particle-tracing code to meet the power, bandwidth, gain, and efficiency requirements.; The W-band TE01 gyro-TWT has underwent numerous modifications with each version extensively hot tested. Through the course of this dissertation research, six separate versions were tested in the quest to improve electron beam quality and to eliminate sources of instability. The best performance obtained in the W-band TE01 gyro-TWT was 75 kW saturated output power, 45 dB saturated gain, 22.5% efficiency with a 3 dB bandwidth of 3.5 GHz (3.7%) in the zero-drive stable condition.; The experimental demonstration of the W-band TE01 gyro-TWT conducted in this work has successfully realized its objectives and has made major contributions in the extension of the state-of-the-art millimeter-wave amplifier technology. Further improvements to the current W-band TE01 gyro-TWT are suggested to increase the performance of the device such as employing well-matched output section, utilizing depressed collectors, and increase of system compactness. For future research avenue, high average power operation and W-band TE01 gyro-BWO research efforts are discussed. |
