Hitachi, Ltd.

Hitachi Electronic Devices Co., Ltd.

Hitachi Device Engineering Co., Ltd.

Hitachi Device Eng. Co., Ltd.

Seiji Kitakaze

Toshio Ogura

Tomokatsu Oguro

Mamoru Tsuzurahara

Akikazu Harada

Masumi Kuga

Mamoru Tsuzurabara

Hidetsuyo Baba

Yuichi Ito

Iwao Umeki

Jiro Kusano

A magnetron having eight anode vanes (2) arranged radially inside an anode cylinder (3) and a helically coiled, directly heated filament positioned along the anode cylinder. The magnetron oscillates at a basic frequency of 2450 MHz. The external diameter of the helically coiled, directly heated filament is in the range of 2.6 to 3.2 mm, and the diameter between the internal ends of the anode vanes is in the range of 7.0 to 8.0 mm.

Magnetron with improved mode separation

A magnetron preventing increases of dark current by making an axial static magnetic field on a plane containing an inner surface of an end shield on the microwave output port side in the interaction space different from the static magnetic field on a plane containing an inner surface of the end shield on the cathode stem side. The interaction-space-side axial end of a peripheral portion of the end shield associated with the weaker static magnetic field is displaced a predetermined distance axially toward the interaction space from the axial ends of the magnetron vanes. In one embodiment, the axial static magnetic field on a plane containing an inner surface of the end shield on the microwave output port side in the interaction space is made stronger than the static magnetic field on a plane containing an inner surface of the end shield on the cathode stem side. This compensates for eccentricity of the axis of the cathode with respect to the axis of the anode vanes. Such eccentricity is greater on the microwave output port side remote from the cathode stem.

Magnetron with reduced dark current

A magnetron includes inner and outer strap rings for providing a linkage among vanes which are disposed inside of an anode cylinder. The inner and outer strap rings have their diameters determined such that their algebraic mean is 1.75-1.95 times the diameter of an interaction space defined by the inner tips of the vanes. The magnetron structure achieves a significant leakage supression effect against spurious microwaves, particularly the fifth harmonic.

Magnetron

In a magnetron cathode assembly having a filament for emitting thermoelectrons, upper and lower end shields fixed at upper and lower ends of the filament, a center lead fixed at and connected to the upper end shield, a side lead fixed at and connected to the lower end shield, and an insulating spacer having through holes with which the center and side leads are respectively engaged, the insulating spacer comprises a groove which has a width substantially the same as a diameter of one of the through holes and which clamps a bent portion of at least one of the center and side leads.

Magnetron cathode assembly with grooved insulating spacer

A magnetron has a filter circuit inserted in a feeder line to a cathode electrode included in a high frequency generator and comprised of choke coils and a capacitor connected in series, in order to suppress leakage of unwanted high frequency components from the cathode electrode. At least one of the choke coils has an air-core coarse coil winding close to the cathode electrode which has at least two turns and a remainder of fine coil winding wound about a ferrite core, so that burning of the choke coil and overheating of the ferrite core can readily be prevented without imparing the function to suppress unwanted high frequency component leakage.

Growing community of inventors

Mobara, Japan

Seiji Kitakaze