A theoretical analysis of the beam energy spread induced by transverse-wave interactions is presented. The theory includes effects of finite beam size, space charges and rotation of the beam. A nonlinear theory is also developed to show a power saturation effect in synchronous-wave traveling-wave tubes due to velocity slipping caused by extended traveling-wave interactions. Results of these two theoretical studies point out important practical limitations on the output power and the efficiency of transverse-wave devices. An experimental vehicle designed as a diagnostic tool to investigate various effects theoretically predicted is described. (Author).

The theory of transverse-wave interactions is reviewed, and theoretical expressions for the gain, optimum efficiency and power output are presented to show design constraints for high-power, high-efficiency tubes. Numerical results of a calculation of the nonlinear behavior of synchronous-wave TWT are presented to show its saturation characteristics. An experimental low-power tube operating in the 500-1000 MHz band was constructed to test various theoretical predictions. The measured axial energy spread induced by the RF interaction and the power saturation characteristics are both in good agreement with the theory. (Author).

The reassembled cyclotron-synchronous wave amplifier was tested with little improvement. The experimental results indicate that further tests should be conducted with an optimum rho/rho sub br ratio at higher power levels. The cyclotron-wave power converter was operated to the three-watt level, and saturation results were observed which agree closely with theoretical predictions. The a-c characteristics of the device were examined. Present conversion efficiencies are somewhat lower than first reported. (Author).

The S-band amplifier was tested. Good coupling to the beam was obtained by the use of double-stub tuners. The smallsignal gain was low and appears to be sensitive to the d-c focusing conditions. The coupled-mode analysis, modified to account for space-charge and beam rotation, has shown that the coupling is quite complex, involving several cyclotron and synchronous idlers and longitudinal velocity and displacement modes. (Author).