STUDY OF TRANSVERSE WAVE INTERACTIONS.
Triannual rept. no. 3, 1 Jan-30 Apr 67,
UTAH UNIV SALT LAKE CITY MICROWAVE DEVICE AND PHYSICAL ELECTRONICS LAB
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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
- Electrical and Electronic Equipment
- Radiofrequency Wave Propagation