Microwave beam tube

Claim 1

In a microwave beam tube having an electron collector and a series of resonant cavities coaxially aligned for coupling an electron beam sequentially therethrough for obtaining velocity modulated output energy therefrom, the improvement of an input cavity electron emission system for providing periodic bunches of electrons emitted into the beam path and comprising: an input cavity resonator coaxially aligned with said resonant cavities and having an input loop for receiving alternating microwave input signals; a field effect electron emitter disposed for periodically releasing electrons into said input cavity toward said collector in response to said alternating microwave energy developed within said cavity, said emitter comprising a plurality of parallel, insulated, emitting fibers per unit area having a conductive backing plate in common with one wall of said input cavity, said plurality of insulated emitting fibers are several million parallel fibers per square centimeter forming a planar emitting surface for emitting electrons at prevailing ambient temperatures; an accelerating electrode, said accelerating electrode being coaxially aligned between said input cavity and a first cavity of said coaxial resonant cavities for developing an electric field between the emitter and electrode for directing electron beam flow from said emitter therethrough; and an electron drift space separating each of said coaxial resonant cavities from adjacent of said cavities.