High Frequency MEMS-based TWTS using Novel Interaction Circuits and Beam Sources

From consultations with the Army program manager, it was determined that the Army has a strong need for improved amplifiers in the W band. Accordingly, the proposed Phase II overall technical objective is to develop a 10 W, W-band prototype planar helix TWT. In Phase I, we addressed improving the repeatability, cost and yields of conventional Ka-band TWTs by introducing novel circuits, beam sources and collectors taking advantage of MEMS fabrication techniques. The results are promising, and further investigation is expected to lead to revolutionary advances in TWT technology. In particular, we found that the planar helix is a promising circuit for batch fabrication at Ka-band through THz frequencies. The circuit holds several other advantages including large impedance for high RF efficiency; thermal stability; and a geometry allowing the use of a sheet beam. Sheet beam operation results in reduced current density and lighter magnet weight for the same voltage and current as compared to a round beam. Alternatively, a sheet beam can provide increased current, lower voltage, and shorter TWT length for the same current density as a round beam.