Varian Associates, Inc.

Other

Litton Systems, Inc.

George K Farney

William A Gerard

Chris L Wheeland

Edward M Doyle

Kenneth F Ramacher

Michael S Worthington

Andrew S Wilczek

Roger A LaPlante

Fred A Feulner

A crossed-field amplifier (CFA) includes a cylindrical cathode having an emitting surface coaxially disposed within an annular anode structure. The cathode has at least one circumferential groove disposed in the emitting surface. The grooves are relatively deep in comparison with their width. The grooves provide a phase smoothing of the rotating electron cloud spokes operative during crossed-field interaction. CFA noise is reduced by removal of the out-of-phase electrons. Due to their deeply cycloiding paths, these out-of-phase electrons become trapped in the grooves within a region generally shielded from the electric field of the CFA.

Phase smoothing cathode for reduced noise crossed-field amplifier

A microwave tube similar in structure to a magnetron includes an output port and a separate input port. The tube includes a cathode, a reentrant anode circuit and means for producing crossed electric and magnetic fields in an interaction space between the cathode and the anode circuit. The microwave tube can be used as an injection-locked or injection-primed oscillator or as an amplifier. An input signal coupling network substantially blocks transfer of internally-generated RF energy at the operating frequency in a reverse direction through the input port toward the input signal source. The input coupling network includes an anode loop coupled between two points of equal phase and magnitude in the standing wave which exists on the anode circuit, and an input loop positioned for inductive coupling of the input signal to the anode loop. The input signal can be coupled to the input loop with a coaxial transmission line, a ridge waveguide or a twin-wire transmission line. The microwave tube can utilize conventional vane type or bar type anode circuits or can utilize mixed line anode circuits having both forward wave and backward wave sections.

Microwave tube with directional coupling of an input locking signal

The allowable gain of a crossed-field amplifier tube is increased by tapering the slow-wave interaction circuit to a smaller spatial period in the direction of circuit power flow. Concurrent variation of the electron beam drift velocity by tapering the dc electric or magnetic field further improves the gain and efficiency.

High gain crossed field amplifier

Noise in reentrant-stream crossed-field amplifiers is suspected of being generated by electrons re-entering the interaction region with large amplitude cycloidal motion near the slow-wave circuit. Means to increase the electric field in a portion of the drift region preceding the circuit lowers the noise, presumably by collecting these electrons. The field may be increased by decreasing the spacing between cathode and drift electrode or by applying a bias voltage on an insulated electrode.

Method and apparatus for reducing noise in crossed-field amplifiers

In a coaxial magnetron the resonant circuit interacting with the electrons is coupled to a stabilizing resonator operating in a mode with circular electric field. The coupling is thru a set of slots in the intervening wall. Undesirable resonances localized in the slots are damped by lossy material at the ends of the slots. Undesirable damping of the cavity mode is prevented by a conducting shield covering exposed area of the lossy material and spaced into the cavity away from the slots.

Magnetron slot mode absorber

An interdigital delay line for crossed field tubes has vanes extending from their interaction faces to a back wall. One end of each vane extends to the end of the face. The other end is cut out behind the interaction face leaving the face projecting. The interaction impedance is almost as high as that of a line with fingers supported by stubs at their centers, while the thermal dissipation is higher, approaching that of a line with vanes extending over the entire length of the fingers.

Growing community of inventors

Boxford, MA, United States of America

George K Farney