NRL ubitron amplifier performance

Research is continuing on the NRL K/sub u/-band ubitron amplifier after several major component modifications. Specifically, the input coupler has been modified for broader bandwidth and lower transmission loss, and the wiggler has been redesigned to generate a much more uniform field in the interaction region and lengthened. Steps have also been taken to remove discontinuities that excited oscillations at high wiggler fields. With a 250 kV, 100 A, 4 mm radius beam and these modifications, we anticipate saturated gain of 25-30 db, output power of 1-5 MW, efficiency greater than 15%, and bandwidth exceeding 20% in the 12.4-18 GHz band. Measurements will be compared with the 3-D nonlinear code ARACHNE.<>