Phase smoothing cathode for reduced noise crossed-field amplifier

A low noise crossed-field amplifier having a cylindrical cathode coaxially spaced from and surrounded by an annular anode structure, said cathode having an emitting surface which emits a cloud of electrons, said electron cloud rotating about said cathode in an interaction area disposed between said emitting surface and said anode structure in response to a magnetic field applied thereto, said crossed-field amplifier comprising:

• means disposed in said cathode for phase smoothing said rotating electron cloud during crossed-field interaction by removing out-of-phase electrons from said cloud, said phase smoothing means collecting said out-of-phase electrons;
• wherein an RF signal traveling on said anode structure is amplified by said crossed-field interaction with said rotating cloud of electrons.

An electron gun for a microwave generating device having crossed electric and magnetic fields, comprising:

• a cylindrical cathode having an electron emitting surface;
• and
• at least one circumferential groove disposed in said emitting surface, wherein out-of-phase electrons emitted by said emitting surface are collected within said at least one groove.