Patent ID: 7285915

Claim:
An electron gun comprising: an RF cavity having a first side with an electron emitting surface and a second side with an electron transmitting and emitting section; and a mechanism for producing an oscillating force which is applied to the emitting surface and the transmitting and emitting section so electrons are directed between the emitting surface and the transmitting and emitting section, wherein some of said electrons contact the emitting surface to generate additional electrons and said additional electrons contact the transmitting and emitting section to generate further additional electrons or escape the cavity through the transmitting and emitting section, with a resulting gain of electrons in a unidirectional flow after a time t is [δ 2 δ 1 (1−T)] ωt/2π) , where δ 1 is the number of secondary electrons emitted from the emitting surface, T is the ratio of transmitted to incident electrons for the transmitting and emitting section, δ 2 is the section electron secondary yield and ω is the radian RF frequency.