Cathode constructive features influence on radiation characteristics in triodes with virtual cathode

Abstract

The increase in the efficiency and power of electromagnetic wave radiation in triodes with a virtual cathode is connected both with the level of interaction between the electron flow and the electromagnetic field of a resonant system and with the number of electrons in the interaction region. That is why, when constructing a generator, an essential point is choosing a cathode. The cathodes used in the experiments differ in their construction features (flat, needle, etc.), emissive ability and provide varied profiles and beam quality. These facts, in turn, influence generator efficiency. This work shows theoretical research of cathode construction features for electron movement, beam uniformity, frequency characteristics and radiation level. In a diode, power flow density of the electron beam depends on the effective area of cathode emission. It is shown that, unlike a diode, in a triode with a virtual cathode, the number of electrons in the interaction region may not depend on the emissive ability of a cathode. It occurs when the space-charge accumulation regime is realized. The accumulation time depends on the anode transparency and on the effective area of cathode emission.