The purpose of the program is the study and evaluation of the tetrahedron beam geometry for application in microwave tubes. The electron beam which is alternately flat in the two cross-dimensions allows a closer and better defined coupling to klystron gaps than is possible with round electron beams. Velocity modulation with good uniformity for the second and third harmonic frequency becomes possible at the beam perveance of 0.00000115. Theoretical studies show that the electron beam has at a small degree of modulation sufficient second harmonic content to generate the optimum saw tooth potential in the center cavity of a three cavity klystron. The relative phase and amplitudes are adjusted by tuning the cavity in the fundamental frequency lower and in the second harmonic equal or higher than resonant. It is also shown that a two cavity klystron can be improved in efficiency for the fundamental frequency by tuning the output cavity to the second or third harmonic and not loading it at this frequency. The kinematically computed 58 is increased to 67 in this case. A flat beam gun with perveance 0.00000115 for the experimental three cavity klystron was constructed and the demountable klystron construction was completed. Author
Triannual rept. no. 8, 4 Jun-3 Oct 68,
See also Triannual rept. no. 7 dated Jan 69, AD-847 760.