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Volume Mode Traveling Wave Tube Amplifier

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Technical Report,15 Apr 2015,14 Apr 2020

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Massachusetts Institute of Technology Cambridge United States

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This is the final report for the research program Volume Mode Traveling Wave Tube Amplifier. High power sources of coherent radiation, producing Watts to tens of Watts of average power, are needed for applications in the millimeter wave and THz regimes. Overmoded traveling wave tubes offer the possibility of meeting these requirements in rugged and simple to fabricate devices. Three novel designs of W-band and 250 GHz TWTs have been developed at the Plasma Science and Fusion Center at MIT. The novel designs incorporate high-order mode operation and photonic band gap lattices to provide large diameter beam tunnels, compared to traditional designs. These designs were based on a previous major success with an overmoded W-Band coupled cavity traveling wave tube. The research accomplished included a detailed design of the volume mode traveling wave tube, outlined in the work of Hummelt et al. and Rosenzweig et al. These are described in the report and in publications. In addition, this program funded efforts, initiated in an earlier AFOSR program, on the interaction of high power microwaves with gases, as described in the papers by Schaub et al. and Stephens et al. A dedicated laboratory was established for testing W-Band and 250GHz vacuum electron devices, such as TWTs, klystrons, etc. As a benchmark case for operation at 250 GHz, a backward wave oscillator BWO was built using a split block assembly method. The structure was assembled and found to have good low loss coupling at 250 GHz as measured with a vector network analyzer. The BWO was tested at full voltage and current in microsecond pulsed operation. As of the writing of this report, the BWO did not achieve measurable output power. The BWO will undergo further testing at a future date.

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  • Electrical and Electronic Equipment

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