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The basic problem is to investigate the coupling processes between rotating electron beam modes and circuit modes. The problem is to determine analytically and experimentally these coupling processes, and to evaluate them for device application. An experimental device has been constructed and tested which exhibits backward-wave oscillations and forward-wave gain. Power output of 720 watts has been obtained in one experiment. Analytical results in the form of a general wave guide coupled-mode theory are available for guidance and understanding of the experimental results. (Author)

An analysis of 'force-free' mode coupling in the Cuccia coupler is carried out to supplement the transverse mode coupling analysis. The complete analytical and experimental results on the cyclotron-synchronous wave amplifier are available in AD-653 009. A computer analysis of the power converter was carried out which includes space-charge and finite beam size effects. These calculations give results not too different than the filamentary beam results. Using the same space-charge beam model as that used in the power converter analysis, a beam stability computer calculation was carried out for the amplifier. The results are somewhat different than the published curves of Sackinger and Buck, and Bass. (Author)

Experiments with the cyclotron-synchronous wave microwave amplifier (see AD-652 009) have encountered difficulties, in some cases, due to beam blow-up in the low pump voltage-low space charge regime. A computer-assisted theoretical investigation of the problem was undertaken and the results are reported.

The purpose of this project is to analytically and experimentally evaluate the interaction of waves in a wave guide with waves on a rotating electron beam. The methods of analysis include use of a general coupled-mode theory, a ballistic computer program, and an experimental evaluation. A new tube is being constructed in which the interaction current can be measured, and the reflection of power in the interaction will be reduced. Space-charge effects have been found to split the longitudinal modes so that they are no longer degenerate. Their effect on the coupling coefficients is small, and can be neglected in the first-order perturbation theory. The multiple-beam interaction has been analyzed, and it has been found that the single-beam analysis can be used if the d-c beam current of the multiple beam is replaced by an effective d-c beam current. Boundary conditions are imposed upon the five interacting modes, and it is found that only three waves are excited in the system. Two of these waves travel at beta sub e and are not excited. This allows the start-oscillations conditions to be found as a function of the device parameters for the backward-wave interactions. The problem of power saturation of the backward-wave oscillations has been initiated. Small-signal theory is used to determine an expression for the efficiency. The axial bunching in the O-type backward-wave oscillator is examined to determine how it is related to the a-c current for power saturation so that criteria for determining power saturation may be established for our device. (Author)

The purpose of this project is to evaluate analytically and experimentally the interaction of waves in a wave guide with waves on a rotating electron beam. The methods of analysis include use of a general coupled-mode theory, a ballistic computer program, and an experimental evaluation. It has been found that the previous power saturation criteria are invalid because they were based on a one- and two-dimensional model. A possible criterion is presented based on a three-dimensional model. The power output of the tube is still low, but it is expected that magnetic field shaping will increase it. Also, the tube has been observed to oscillate in two different modes separated in frequency by about 50 MHz. (Author)

The cyclotron-wave power converter is useful over the same frequency range as the Cuccia coupler. Its theoretical power-handling capability is very high, of the order of megawatts for a wide-gap Cuccia cavity and a few amperes beam current. Theoretical efficiency ranges from 0.60 to over 0.95, depending on power ratio, transistion length, the type of collector, and the final value of the B-field. These results are summarized. Measured efficiencies have been significantly lower, due mainly to difficulties associated with collector current reduction under r-f conditions with depressed collector voltage. (Author)