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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), See also AD-695 682.

A theory of transverse-wave interactions using a realistic model of the beam suitable for high-power amplifiers is presented. The energy exchange mechanism in transverse-wave interactions is reviewed, and the energy spread induced in a beam with non-zero size and space charge by high-power transverse- wave interactions is calculated. Various choices of design parameters are considered to show the basic design contraints in terms of the maximum efficiency attainable in high-power amplifiers. The power saturation characteristics of transverse-wave amplifiers are examined by analyzing the nonlinear behavior of transverse-wave interactions. Results of the analyses provide the theoretical basis for predicting capabilities and limitations of high-power, high-efficiency transverse-wave amplifiers. The purpose of the experimental study was to verify the validity and determine limitations of various theoretical design equations. Experimental results confirm the theoretical predictions, and thus provide added credence to the theoretical projection of the potential device capabilities., Reports Control Symbol OSD-1866. See also Interim rept. no. 4, AD0709611.

The objective of this study is to determine the feasibility of a microwave time-delay device employing an ion beam. The inherently low drift velocity of ion suggests the possibility of a broadband device with a long variable delay. The program is divided into three major problem areas: (1) ion sources, (2) beam transmission and (3) RF experiments. Thermionic emitters of alkali ions are used as the source of ions. A novel technique has been developed to fabricate 'impregnated' ion emitters. The ion current density (Li+ and K+) of several mA/sq cm has been obtained. At low frequencies the delay of the AC modulation on the ion beam was measured. Variable time delays greater than 1 microsec have been measured. The problem of RF signal coupling to the ion beam has been investigated at microwave frequencies. Novel methods of the RF coupling by transferring modulation from an electron beam to an ion beam are discussed. (Author)

Experimental studies of the ion-beam delay line at 500 MHz are described. The emphasis of the present study is on the technique of ion-beam modulation by the transfer of modulation from an electron beam to the ion beam. The theory of modulation transfer mechanism by a reflecting electron beam is presented, and the experiment to observe the effect is described. Based on results of these investigations, it was concluded that the most promising method of ion-beam modulation is the classical technique of gap modulation. An experimental device was designed and constructed to demonstrate the feasibility of the ion-beam delay line at 500 MHz. (Author)

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), See also Triannual rept. no. 2, AD-689 472.

Results of experimental work on annular plasma columns are presented. The plasma density was determined by measuring the dipole resonance using a section of a stripline. Results of the stripline measurement were used to locate the passband of the backward surface wave. The theoretically predicted forward and backward surface waves were measured. Agreement between the theory and the experiment is excellent. Theoretical consideration is given to a possible spurious oscillation resulting from electron beam interaction with the plasma body wave and a criterion for the existence of backward wave in a plasma column. Experimental results are presented of the measurement of the conductivity of pyrolytic graphiteBN layered material. The real part of the effective conductivity measured for one sample was 0.006 mho/meter. This value of the conductivity represents a possible improvement of 100000 in the loss characteristics of microwave slow-wave circuits built with this material over the pyrolytic graphite structures previouly discussed.

Contents: Plasma Synthesis with Opposing Electron and Ion Guns; Wedge-Supported Helix for High-Power TWT; Plasma Noise Generator; Ion Focusing in High-Power Beam Tubes.