RU2357318C1 - Magnetron with regulated power - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: present invention relates to electronic devices. The cathode of a magnetron is divided into electrical or thermal sections of arbitrary shape, size or location, connected to voltage proportional to the required power. According to this method, the filament-type cathode of the magnetron is made from a ring with a slit. Filament voltage is applied at the ends of the ring, depending on the power output from the electron-emitting layer deposited on the filament.

EFFECT: wider assortment of apparatus used for regulating power of the magnetron.

3 cl, 7 dwg

Description

The invention relates to electronic devices and can be used in household appliances and production processes.

Known magnetron [1, p. 282-289], which is a series of holes around the circumference in the anode block connected by narrow slots to the Central hole in which the cathode is located. Each hole in this series represents a resonator, that is, an oscillating system degenerated into a hole with a slot, where the hole is a coil of inductance, and its slot is a plane of the capacitor. Electrons are controlled in a magnetron by acting on the electron stream from the cathode of constant electric and magnetic fields. When voltage is applied to the cathode and anode, electrons fly out of the cathode and excite electric vibrations in the slots of the magnetron resonators with their moving electric field along a curved path. Electrical vibrations in the slots of the magnetron resonators form the so-called "spokes" of electrons - electron bunches stretched from the cathode to the anode. In this case, from the cathode to the anode, the thickness of the "spoke" decreases, and the electron density increases. In this case, the electron energy during their curvilinear motion and their grouping in the so-called "spokes" goes into the energy of electromagnetic oscillations of the magnetron.

In the present invention, to adjust the power of the magnetron, it is proposed to regulate the current of the cathode, for example, divided into electrical or thermal separate sections of any shape and size and any position on the cathode. The number of cathode sections to which voltage is applied is determined by the required output power.

This is shown in FIG. 1 and FIG. 2.

On the electric circuit of a magnetron with electrical sections (Fig. 1), anode 1, cathodes 2 and heater 3 are indicated.

On the electric circuit of a magnetron with a direct-heating cathode (individual thermal sections of one whole cathode) (Fig. 2), anode 1, heaters 3 and terminal 4 are shown — the combined output of the cathodes connected together — heaters and heaters proper. At the same time, the cathodes of various heaters are essentially one cathode, and one cathode voltage is supplied to it at terminal 4, and there are several heaters of sections of one cathode, and heat voltage is supplied to them at terminals 3 and 4, which creates a thermal section on the cathode that emits electrons. The number of heaters of a single cathode, to which the filament voltage is applied, is determined by the required magnetron power.

The difference between the first (electrical sections) and the second (thermal sections) methods is that the first method implements the maximum possible speed of power control, but it is required to switch very high voltages - units and tens of kilovolts. In the second method, the speed is determined by the heating time of the cathode, which is acceptable in most cases, but the voltage has to be switched, which is a maximum of several volts, which is much more practical.

Based on the proposed invention, a method for adjusting the power of a magnetron, inventions are provided regarding the design of such magnetron cathodes.

As is known [2, 3, 4], cathodes are of two types - indirect and direct heating. With indirect heating, the cathode consists of the cathode itself and a separate cathode heater - all this is called a cathode assembly. With direct glow, the cathode is directly heated by the glow current passing through it, and the cathode voltage is supplied to it. In this case, a voltage drop to fractions and units of volts occurs at the cathode from the flow of the cathode current, which, however, is not scary, since the anode voltage of the magnetron is several tens of kilovolts.

The magnetron cathode is usually a hollow cylinder - a tube, from the ends of which a filament voltage is supplied and from one end - the cathode voltage. Thus, the cathode filament and power circuits are galvanically connected. The convenience of such a cathode is that it quickly heats up. This increases the consumer appeal of the devices where the magnetron is located - in microwave ovens.

In the present invention (based on the proposed method for adjusting the magnetron power), the cathode is made of direct heat from several identical rings with a cut (Fig. 5) located one above the other with a small gap, and in sections the ends of the tapes 6 of the rings (Fig. 5) are brought out (bent at an angle of up to 90 ° - figure 4), and to them are attached voltage inputs 5.7, brought to the end of the resulting tube from the rings. Electron emitting layers are applied to the rings in proportion to the required power. Ribbon rings are heaters and are made, for example, of tungsten in the form of a flat ribbon (figa, b). The cuts of the rings are combined, and on the one side of the cut, a common input 5 is attached to the rings, and on the other hand, separate inputs 7 for each ring. These inputs can have bends in any plane and are removed from the end of the resulting cylinder from the rings. The common input 5 serves the total voltage of the filament and the cathode voltage. The remaining inputs 7 are supplied with a filament voltage in accordance with the necessary emission of electrons from this ring. Also inside the rings can be placed elements, for example, in the form of thin rods, fixing the shape of the rings and their location in space. In addition, the 5.7 inlets themselves are ring holders and also determine their location in space. In gaps and cuts, placement of electrically insulating gaskets is possible.

The rods and bushings are mounted in ceramics from the ends of the cylinder from the rings.

You can do without a common input 5 and replace it with an input of type 7 at each end of the ring, remove the inputs 7 outside the vacuum part of the magnetron, and there already carry out connections and switching.

It is possible to stamp a blank from high-resistance foil, where the bushings are replaced by the foil material, and then bend the foil sections that replace the rods as needed and cover them with current-conducting metal. It is possible to stamp from the sheet blank all tape rings immediately in the form of a comb (Fig.7). It is possible to stamp the common input 9, which is fastened, for example, by welding under pressure to the common input 5.

It is possible to place the common input 5 in the middle of the ring inside it with the tape covering the ring and the gap when the tape enters the circle (Fig. 6), while the input 5 is connected by the connection 8 to the tape 6. Moreover, the gap at the point of attachment of the general input 5 can be equal distances from the gap at the inputs 7, and at different distances from it.

To control the power, the required number of rings (tapes) is selected and the glow current is supplied only to them, respectively, the emission of electrons occurs only from them. At the same time, the place where all the tapes are connected by a common rod is the place of cathode voltage input through this rod. Since the tapes are the same, the glow current flows in them the same way, and they are equally heated and equally capable of emitting electrons, and the emission of electrons depends only on the size of the emitting layer deposited on the tapes or on its absence.

The emitting layer on the heater can be applied using a spray gun through a stencil. The durability of such a cathode is quite sufficient for the microwave oven to operate for at least 10 years. During this time, the natural process of obsolescence of the household appliance will occur, both physical and moral.

It is also possible to use as an emitter of electrons just heater tapes of different widths and thicknesses, up to the wire, without applying an electron-emitting layer to them. Compared with the oxide layer deposited on the heater tape emitting electrons at a temperature of about 1100 ° C, the emission from a simple heater is extremely small and significant only at temperatures around 2000 ° C. Therefore, the use of just a heater as a cathode makes it possible to increase the discreteness of the power setting to tenths or even hundredths of a percent of the total power of the magnetron.

The use of such a cathode is possible not only in magnetrons, but also in other microwave devices of type M, for example, in amplifiers. This allows you to adjust their gain or stabilize the gain when the emission of electrons changes with time. In addition, the cathode can also be used in type O devices, including those with a different emission surface.

It is known to make a cermet cathode from rings [3, p. 103], on the basis of such a cathode it is possible to place the rings in a similar manner on an insulating gasket and supply cathode voltage to each individual ring of the cathode inside the insulating gasket between the rings and the heater.

Information sources

1. A guide to the basics of radar technology. Edited by V.V. Druzhinin. Military Publishing House of the Ministry of Defense, Moscow, 1967

2. Volkova Z.P., Khotin V.M. “Materials of Electrovacuum Production”, L., Energy, Leningrad Branch, 1980.

3. Evstigneev S.I., Tkachenko A.A. “Cathodes and heaters of electric vacuum devices”, M., Higher School, 1975.

4. Antonov V.A. "Technology for the production of electrovacuum and semiconductor devices", M., Higher School, 1979.

Claims (3)

1. Magnetron with adjustable power, characterized in that its cathode is divided into electrical or thermal separate sections of arbitrary shape, size or location on the cathode, which are connected to the voltage depending on the required power. 2. A magnetron with adjustable power according to claim 1, characterized in that the cathode is made of direct heat from the same rings (possibly from a tape) with a cut and an emitting layer deposited on the rings and the rings are placed one above the other with a small gap, combining their cuts; in the place of the cut of the ring, contacts made of the material of the ring are bent inward and the electrical voltage inputs are connected to them, on the one hand the input is shared by all the rings and the cathode voltage and the voltage are applied to it, and on the other hand, the individual inputs for the voltage are made separately for each ring; filament voltage is applied to the rings through separate entries, depending on the need for the required emission of electrons from the ring, and all inputs are bent in any form and removed from the end of the tube, which the rings form. 3. A magnetron with adjustable power according to claim 2, characterized in that its cathode is made of rings, where the common input is located in the middle of the ring with a section equidistant from the section of the ring, a layer emitting electrons is not applied to some rings, and the rings themselves are made of different diameters and sizes in section.

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