Measurements of traveling-wave tube noise figure

The general structure of the tube is shown and a brief description of the electrode disposition given. Variation of noise figure is described as a function of the first anode voltage with beam current as a parameter. The independence of current is pointed out. A plot is shown of noise figure as a function of the perveance of the cathode to first-anode region and the possible significance of the beam shape in this region is described. The variation of noise figure with frequency is described and some results are given on the effect of helix size.