Transverse traveling wave tube amplifier studies

Summary form only given, as follows. We report results from a study into a transverse traveling wave tube amplifier (TTWT) configuration that produces a series of bunched beams propagating in one direction and extracts RF power perpendicular to this. The configuration described should (1) produce short bunch lengths for efficient interaction and (2) lower the losses due to accelerated electrons in the output waveguide. For an initial study six 50 kV beams are propagated in tubes laying side-by-side and separated by a distance equal to /spl lambda//2 of the input RF wave. The transverse, input waveguide produces a RF modulation on each beam that is phase shifted by /spl pi//2 relative to its neighbor. The beams then propagate through a bunching cavity followed by a second transverse waveguide that is positioned at a distance such that the beam bunching is a maximum in this output region. In early simulations efficiencies of /spl sim/20% have been achieved and we expect this to increase as the system configuration is optimized. Results will be presented from extensive MAGIC code simulations for 50 and 700 kV beams seeking to optimize the operation of this TTWT geometry. Results from a proof-of-principal experiment using 50 kV electron beams will also be discused.