Sanyo Electric Co., Ltd.

Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Masayuki Aiga

Nagisa Kuwahara

Takeshi Ishii

Tetsuji Hashiguchi

Takanori Handa

Kazuki Miki

Toshiyuki Tsukada

Yoshitaka Shibata

Masafumi Kuroda

Katsunori Ueno

To provide a magnetron capable of reducing noises in a low frequency band of 30 MHz or less without deteriorating the stability of a load depending on phases, and also ensuring the precision of assembly dimensions without increasing the number of components, a coiled filamentis arranged between an input-side end hatand an output-side end hatwhich are supported by a cathode supporting rod. A larger-diameter bossin the end hatextends to the interior of an interaction space, a smaller-diameter bossand one endof the filamentare secured to each other, and the other endis secured to a bossof the end hat. Here, the dimension of an axial free length part F which forms an electron emission part which is not secured to the end hatsandof the filamentis set to 50% or more and 80% or less of the axial dimension H of plate-like vanes, and the electron emission part is arranged so as to be displaced to the output side.

Magnetron

The magnetron includes: a cylindrical-shaped anode barrel memberhaving two openings respectively formed in the two end portions thereof; a cathode structure memberdisposed on the center axis of the anode barrel member; more than one anode vanedisposed radially through an action spacein the periphery of the cathode structure memberand fixedly mounted on the inner wall surface of the anode barrel member; and, a pair of funnel-shaped pole piecesandrespectively disposed in their associated ones of the two openings formed in the two end portions of the anode barrel member, each pole piece including a small-diameter flat portion FLhaving a penetration hole formed in the central portion thereof, a large-diameter flat portion FLhaving a diameter larger than the diameter of the small-diameter flat portion FL, and a conical-shaped slanting portion SL for connecting the large-diameter flat portion FLand small-diameter flat portion FLto each other. Of the pair of pole piecesand, the input side pole pieceincludes, besides the penetration holeA formed in the central portion thereof, three or more, preferably, four penetration holesB respectively formed in the slanting portion SL thereof, each hole having an area of 16.6 mm.

In the magnetron, an upper end hatA is used as a composing element of a cathode structure memberA and includes a portionAa which is in contact with one end portionof a filament coil. The thickness of the portionAa is reduced, whereby the portionAa is held not in contact with a center lead. Owing to this, heat generated in the filament coilcan travel to the upper end hatA without traveling directly to the center lead. Therefore, even when the quantity of input power is reduced to such a degree as to be able to reduce noise, or even when the electron radiation area of the filament coilis reduced, the getter effect can be displayed fully. As a result of this, noise reduction and cost reduction can be realized at the same time.

For an anode assemblyof a magnetron, a plurality of plate shaped vanesradially arranged at an inner circumference of the roughly round shaped anode assemblyhas a end portion arranged at a central axis of the anode assemblywith a step shape Df having a reduced thickness in a range of predetermined length L from an end portion, so that increase of the facing area of the respective adjacent plate shaped vanesis suppressed while the separation distance of the end portions of the vanes is secured.

A cathode substrateis heated to 400 to 600&#xb0; C. in the atmosphere of hydrocarbon gas such as methane and the gas is allowed to react with the surface of the cathode substrateby a thermal CVD method. Thus, an electron emission source in which graphite nano-fibersare allowed to grow in a gaseous-phase on the surface of the cathode substrateby using nickel or iron existing on the surface of the cathode substrateas a nucleus is held between upper and lower end hatsto form a cathode part

Magnetron with graphite nano-fibers on cathode

A magnetron comprising an anode portion having an anode cylinder and vanes, a cathode portion having a coil-shaped filament, magnetic poles disposed at the upper and lower ends of the filament, ring-shaped permanent magnets made of a Sr ferrite magnet containing La&#x2014;Co, an input portion and an output portion. The diameter &#x3c6;a of the inscribed circle at the ends of the vanes constituting the anode portion is in the range of 7.5 to 8.5 mm, and the outside diameter &#x3c6;c of the coil-shaped filamentconstituting the cathode portion is in the range of 3.4 to 3.6 mm.

In a magnetron apparatus in accordance with the present invention, a first notch , a second notch and a third notch are formed in each of anode segments disposed radially inside an anode cylinder , whereby the passage of high-frequency current flowing through the resonator comprising the two anode segments adjacent to each other, the anode cylinder and strap rings and is made narrow and long.

Magnetron apparatus

A magnetron includes an anode cylinder (1), a plurality of vanes (2) attached to the inside of the cylinder, a cylindrical metallic container (15), an output-side insulating tube (16), an antenna conductor (11), and a choke body (21). A hollow cylindrical metallic container (15) forms an airtight space at one end of the anode cylinder (1) and one end of a hollow output-side insulating tube (16) is airtightly connected to the container (15). An antenna conductor (11) electrically coupled with one of the vanes (2) extends through the cylindrical metallic container (15) and the output-side insulating tube (16). One end of a choke body (21) of a length of 1/4 wavelength of a harmonic to be suppressed is electrically coupled with the cylindrical metallic container (15), and its other end. The choke body is an annular groove type (21) or of a coaxial type (31).

Magnetron having coaxial choke means extending into the output side

In an interaction space (4) defined between a cathode (3) and forward end portions of vanes (2), a permanent magnet (12) applies a uniform direct-current magnetic field along an axial direction of the cathode (3). Direct-current or low-frequency high voltage is applied between the cathode (3) and the respective vanes (2). Spaces (14) enclosed by respective pairs of adjacent vanes (2) and the inner wall of an anode cylinder (1) define cavity resonators. High-frequency electric fields formed in the cavity resonators are concentrated to the forward end portions of the vanes (2), and partially leak into the interaction space (4). Under such conditions, an electron group emitted from the cathode (3) rotates about the cathode (3) in the interaction space (4), thereby interaction takes place between the electron group and the high-frequency electric fields, to oscillate microwaves. The inner surface of a flange part (6) of a top hat (7) supporting one end of a filament (5) of the cathode (3) is located in a position closer to the interaction spaces (4) by length within a range of 0.1 to 0.6 mm from first end surfaces of the vanes (2) along the axial direction, thereby to suppress undesired fifth harmonic generated with the microwaves of a basic frequency at this time.

Magnetron with harmonic suppression means

High voltage through type capacitor comprising includes a cylindrical dielectric having first and second electrodes formed on both end faces thereof, a through conductor connected to the first electrode, and a ground plate connected to the second electrode. In the high voltage through type capacitor, and insulating material selected from the group of self-adhesive silicone rubber and elastic silicone gel is used for insulating at least between the cylindrical dielectric and the through conductor.

High voltage through type capacitor and manufacturing method therefor

In an interaction space (7) defined between a cathode (2) and forward ends of vanes (3), an even direct-current magnetic field is applied by magnets (8) along the axial direction of the cathode (2). Direct-current or low-frequency high voltage is applied between the cathode (2) and the respective vanes (3). Spaces (6) surrounded by respective two adjacent vanes (3) and the inner wall of the anode cylinder (4) define cavity resonators, which generate high-frequency electric fields concentrated to the forward end portions of the respective vanes (3) and partially leaking in the interaction space (7). Under such conditions, an electron group emitted from the cathode (2) rotates about the cathode (2) in the interaction space, whereby interaction takes place between the electron group and the high-frequency electric fields to oscillate microwaves. At this time, undesired higher harmonics generated with the microwaves of basic frequency are suppressed by arranging inner strap rings (5a) in positions separated from the forward ends of the vanes (3) to exceed a prescribed interval.

The ratio b/a of the width a of the forward end surface 30a of each vane 30 to the interval b between the opposed forward end portions of the respective adjacent vanes 30 is set to be not more than 2.3, whereby distribution density of a high-frequency electric field concentrated in the vicinity of the forward end portions of the vane 30 can be equalized.

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Hyogo, Japan

Masayuki Aiga