Studies of crossed-field amplifiers relating to stability, noise, and electron guns

Abstract

This paper is presented in two parts: A.) Considerations of Stability and Noise Improvement of Crossed Field Amplifiers, and B.) Beam Analyzer Measurements of a Wide Dynamic Range Crossed Field Gun. A.) The authors have confirmed that in the absence of drive signal, oscillation instabilities in high power crossed field amplifiers are a forward wave phenomenon. Analyses suggest that these instabilities are caused by cyclotron wave interaction. Predicted frequencies and/their tuning are in fair agreement with measurements. Practical designs are discussed in relation to stability, efficiency and electron gun design. B.) The authors have proposed a crossed field gun for optimum beam launching under a wide range of cathode current densities in a fixed magnetic field. Desirable frequency and amplitude modulation characteristics of the device output are expected, using this gun. A beam analyzer is being assembled comprising the Wide Dynamic Range Gun, a drift region and collector. Grid wires in the drift region will permit study of the nature of the electron beam. The design is being simulated on a digital computer, including space charge effects. The computer model will be briefly discussed.