Abstract: Disclosed is a magnetron for a microwave oven which has a drain electrode (60) near a cathode (25) and in a position where an electron beam path is not interfered with. The cathode and the drain electrode are formed in spiral shapes. Turns of the cathode are alternately arranged with those of the drain electrode. When the magnetron is operated, the drain electrode is kept at the same potential as the cathode or is kept at a negative potential relative to that of the cathode. Therefore, positive ions in the vicinity of the cathode are collected at the drain electrode, thus decreasing high frequency noise.

Abstract: A magnetron unit is provided with anode cylinder with a number of vanes defining resonance cavities, and a cathode disposed along the axis of the anode cylinder. An axial interaction space into which a magnetic field is developed is disposed between the vanes and the cathode. Provided is a pair of main pole pieces with the interaction space located therebetween to supply the magnetic field into the interaction space. Permanent magnet members are magnetically coupled with the pair of the main pole pieces for supplying magnetic energy to the main pole pieces. The permanent magnet members are magnetically coupled with each other by a yoke. Auxiliary pole pieces are disposed at the top ends of the main pole pieces at a given interval. The auxiliary pole pieces are supported by bimetal members fixed to them. When the temperature of the permanent magnet member, the bimetallic members rises moves the auxiliary pole pieces toward the interaction space.

Abstract: A magnetron comprises an anode having an inner cylindrical wall and a plurality of copper vanes extending inwardly from the inner cylindrical wall, each vane having a notch in the top and bottom edges thereof. Each notch has an inner side edge, an outer side edge and a bottom edge. Inner and outer ring straps made of metal having a larger tensile strength than the vanes are placed in the notches. The inner ring strap is fixed to the inner side edge of alternative vanes. The inner side edge also has a slanting edge between the connection of the inner ring strap and the bottom edge to prevent cracking.

Abstract: In a magnetron device, a shield box is disposed covering a cathode stem and energizing power is supplied from the outside of the shield box to cathode lead terminals in the shield box.An energizing power supplying means comprises a transformer having a primary coil and a secondary coil which are both wound around a magnetic core and connect inductively the inner section of the shield box with the outer section. Thus high frequency noise which is a part of high frequency energy oscillated in anode resonant cavities and transmitted into the shield box through the cathode lead terminals is perfectly confined in the box. Therefore high frequency noise leaking out from the magnetron device toward a commercial power source is significantly reduced.

Abstract: The magnetron of this invention comprises permanent magnets, resonant cavity unit and microwave-oscillating member such as a filament all set in a cylindrical yoke made of soft magnetic material and used as an evacuated envelope. The magnetron is forced into an opening bored in a fitting board, or inserted into said opening, followed by tightening. This fitting board enables the magnetron to be easily mounted on a waveguide or microwave oven.

Abstract: A microwave heating apparatus comprises a heating oven chamber for receiving a substance to be heated and a magnetron with an anode cylinder for generating heat. The magnetron is positioned above the oven chamber, and, not only its output antenna to emit microwaves to the substance, but also its anode cylinder are exposed within the oven chamber. The heat generated by the anode cylinder is supplied into the oven chamber to elevate the temperature therein. As a result, the substance in the oven chamber is heated not only by the microwave but by the heat from the anode cylinder.

Abstract: In a magnetron of the permanent-magnet-externally disposed-type wherein a pair of permanent magnets are disposed outside an anode cylinder, a yoke magnetically coupling the pair of permanent magnets to each other is extended along the side wall of an anode cylinder of the magnetron, and this anode cylinder is securely fixed to the yoke. The permanent magnets are each supported between the yoke and a seal plate for sealing the opening of the anode cylinder of the magnetron.

Abstract: A magnetron for oscillating ultrashort waves by uniformly applying a magnetic field to electrons, which comprises a cylindrical electrode assembly consisting of concentrically arranged cathode and anode electrodes; a magnetizing device formed of a pair of mutually facing permanent magnets prepared from rare earth so as to apply a magnetic field at right angles to electrons emitted from the cathode electrode to the anode electrode; and wherein the mutually facing magnetic pole surfaces of the paired permanent magnets are so depressed as to present a surface shaped in the form of a revolving ellipsis in order to apply a uniform magnetic field to electrons for control of their orbit, thereby producing from an outlet circuit oscillated electric waves which have resonated in the resonance cavity section of the anode electrode.