A Theoretical and Experimental Investigation of the Feasibility of Constructing High Power Two-Millimeter Backward-Wave Oscillators Using Ladder and Vane-Type Slow-Wave Structures.

摘要

The objective of the study was to investigate the use of magnetoelectrically focused electron beams in two-millimeter backward-wave oscillators at or near kilowatt power levels. An oscillator was constructed as a part of the investigation, designed from data obtained from previous work, resulting in a device that barely oscillated. This device demonstrated the practical solution to several significant problems: (1) the construction of ladder-line slow-wave structure; (2) a method of matching a ladder-type structure to a wave-guide transmission line; (3) demonstration in a microwave tube of a magnetoelectrically focused electron beam with an average radius of 6.8 mils and a current of 1.2 amps. Detailed field analyses of both a thick-ladder and a vane-type structure were carried out. Theoretical results obtained for dispersion, interaction impedance, and circuit loss are presented. Since known starting conditions for backward-wave oscillators as a function of loss and loss of space charge were too limited, start oscillation conditions were computed for values of QC from 0-25 and for values of loss from 0-225 db. Theoretical results computed for the dispersion and the loss of a thick-ladder circuit agreed with experimental data within 1-2 percent. The observed starting current in the oscillator was consistent with starting conditions calculated from the theoretical characteristics of the thick-ladder structure. (Author)