Effect of Hydrostatic Pressure in an Electron Beam on the Operation of Traveling-Wave Devices

Abstract

Small velocity spreads in an electron beam appear to cause a decrease in gain and noise figure of a traveling‐wave tube. The actual decrease depends on a quantity μ, which can be interpreted physically as a measure of the ratio of the coupling of the electrons to each other via the hydrostatic pressure to the coupling of the electrons to the external wave guide circuit. Thus, physically, the effect of the velocity spread is to introduce further interactions among the electrons, in which the external circuit does not take part. This interaction may be thought of as a hydrostatic pressure similar to that in a liquid or gas.