Crossed field amplifiers

Claim 1

A crossed field amplifier comprising two spaced electrodes means for applying a first electric potential field between said two electrodes, a radio frequency signal input for feeding input signals between said two electrodes at one end thereof, a radio frequency signal output for collecting the signal from between the electrodes, a cathode and anode disposed in spaced relation to one another adjacent one end of said two spaced electrodes, means for applying a second electric potential field between said cathode and anode to cause the cathode to emit electrons from a surface thereof, an evacuated envelope containing the two electrodes, the cathode, and the anode, a magnetic field system for producing a uniform magnetic field perpendicular to each of said first and second electric potential fields, whereby electrons emitted from the cathode are caused to travel between the two electrodes perpendicular to said magnetic field to interact with the radio frequency signals and provide amplification thereof, said magnetic field system including means for producing a non-uniform magnetic field component normal to said electron emitting surface of said cathode which component varies across said cathode surface whereby noise in the radio frequency signal output is reduced.