Final Report Project Name: Research on Novel High-power Microwave/millimeter Wave Sources and Report Documentation Page Research on Novel High-power Microwave/millimeter Wave Sources and Applications

Performance characteristics of a fundamental cyclotron harmonic, distributed-loss, TE01-mode gyrotron traveling-wave amplifier are studied theoretically. Absolute instabilities on both lower and higher order modes at the fundamental and second cyclotron harmonic frequencies present a severe limitation to the stable operating current and hence the device capability. General methods for stabilizing these unwanted oscillations are outlined, on the basis of which the gain, power, bandwidth, and efficiency are examined in a multi-dimensional parameter space under the marginal stability criterion. The results provide a basis for tradeoff considerations among power, bandwidth, and efficiency to reach a stable design optimized for the desired features. General trends are discussed and specific design examples, all with an ultra high gain, are presented as illustrative examples. PACS numbers: 84.40.Ik, 84.40.Fe