Characteristics of the hot cathode electron microscope gun

Abstract

Experiments have been carried out on hot cathode, high-voltage three-electrode electron guns. The brightness has been measured and found under optimum operating conditions to approach closely the value expected from the theoretical considerations developed by Langmuir. The effect of varying geometry over a fairly wide range is shown to be of secondary importance, except in as far as it influences the bias conditions and current efficiency. The mechanism of electron beam formation is discussed briefly.