KR19980058047U - Magnetron cathode structure - Google Patents

Abstract

The present invention relates to the structure of the cathode portion of the magnetron for removing the line noise leaking through the power line, the filament 17 for emitting hot electrons, and the first and second cathode support 23 for supporting the filament 17 And 25, external connection terminals 29 and 31 for supplying power to the filament 17 through the first and second cathode supports 23 and 25, and the external connection terminals 29 and 31, respectively. The cost is reduced and the manufacturing is easy because the choke coils 30 'and 32' which are connected and twisted to each other and the ferrite 40 having a pair of holes are formed to pass through the choke coils 30 'and 32'. Excellent effect.

Description

Magnetron cathode structure

The present invention relates to a magnetron, and more particularly, to a cathode portion structure of a magnetron for removing line noise leaking through a power line.

In the conventional magnetron, as illustrated in FIGS. 1 and 2, a plurality of (even) vanes are formed in the anode cylinder 13 formed in a cylindrical shape by a copper pipe or the like to form a plurality of resonant cavities to induce high frequency components. 15) are arranged at equal intervals toward the axial direction, and the anode body 13 and the vanes 15 constitute an anode.

In addition, near the tip side of the vane 15, the inner and outer equalizing rings 15a and 15b are connected to each other by the vanes 15 so as to obtain a constant resonance frequency by varying the capacitance at the upper and lower portions, respectively. In the vicinity of the central axis of the anode cylinder 13, a working space 12 is formed between the front end portions of the plurality of vanes 15 and the filaments 17.

In the working space 12, a filament heater 17 (hereinafter referred to as a filament) wound in a spiral shape by mixing and sintering tungsten (W) and thorium oxide (ThO ₂ ) to generate high heat is the anode body 13. ) Is arranged coaxially.

Upper and lower shield hats 20 and 21 are fixed to both ends of the filament 17 so as to prevent radiated hot electrons, which do not contribute to oscillation, in the central axis direction. The first cathode support 23, which is a central support made of molybdenum, is welded to the lower end of the upper shield hat 20 through a through hole formed in the center portion, and molybdenum is formed on the bottom surface of the lower shield hat 21 at the center portion. The second cathode support 25 is fixed by welding.

The first cathode support 23 supports the upper shield hat 20 while passing through the central axis of the filament 17, and the first and second cathode supports 23 and 25 support and fix the cathode of the magnetron. It is a filament electrode which is electrically connected to the external connection terminals 29 and 31 connected to the power supply terminals 30b and 32b through the through hole formed in the insulating ceramic 27 to supply current to the filament 17.

One end of the choke coils 30 and 32 is electrically connected to the external connection terminals 29 and 31, and a capacitor 34 disposed at the side wall of the box filter at the other end of the choke coils 30 and 32. And the ferrites 30a and 32a absorbing line noise of 1 GHz or less applied through the first and second cathode supports 23 and 25 in the process of generating microwaves in the choke coils 30 and 32. Is fixed along the longitudinal direction of the choke coils 30 and 32.

In addition, the upper and lower pole pieces having a funnel shape to form a magnetic flux on both side openings of the anode cylinder 13 so as to uniformly form magnetic flux in the working space 12 formed by the filaments 17 and the vanes 15. (33, 35) are welded together.

Upper and lower shield cups 37 and 39 are hermetically welded to upper and lower portions of the upper and lower pole pieces 33 and 35, respectively, and upper and lower portions of the upper and lower shield cups 37 and 39, respectively. The antenna ceramic 45 and the insulating ceramic 27 are hermetically welded to seal the inside of the anode cylinder 13 with a vacuum.

On the outer surfaces of the upper and lower shield cups 37 and 39, ring-shaped upper / lower magnets 41 and 43 are arranged in the anode cylinder 13 so as to maintain a constant magnetic field distribution. A cylindrical antenna ceramic 45 for insulating the antenna cap, which will be described later, is joined to the upper opening end of the upper shield cup 37 constituting the portion.

Further, in the drawing, an exhaust pipe 47 made of copper is joined to an upper side front end of the antenna ceramic 45, and the vane is output near the inner center of the exhaust pipe 47 so as to output the microwaves oscillated in the resonance cavity. The end of the antenna 49 is fixed in the exhaust pipe 47 while the antenna 49 derived from 15 extends axially through the through hole of the upper pole piece 33.

In addition, the outer surface of the exhaust pipe 47 serves to protect the welding fastening portion of the exhaust pipe 47 as well as prevent sparks caused by electric field concentration and act as a high frequency antenna, and simultaneously emit microwave output to the outside. The antenna ceramic 45 and the antenna cap 51 is placed thereon.

In addition, upper and lower yokes 53 and 55 for determining the amount of magnetic flux in the anode cylinder 13 are provided outside the anode cylinder 13 to connect the returned magnetic flux. And a plurality of aluminum cooling fins 57 are disposed under reduced pressure by the clamp member 55a fixed to the anode cylinder 13 and the lower yoke 55 between the lower yoke and the lower yoke 55. 43) and covered by the upper and lower yoke 53, 55 for forming a porcelain.

The operation of the magnetron configured as described above, when power is applied through the external connection terminals 29 and 31, the external connection terminal 29, the first cathode support 23, the upper shield hat 20, the filament ( 17), a closed circuit is formed by the lower shield hat 21, the second cathode support 25, and the external connection terminal 31 so that an operating current is supplied to the filament 17, and the filament 17 is heated. At high temperatures it begins to emit hot electrons into the working space 12.

At this time, a strong electric field is formed in the working space 12 between the outer surface of the filament 17 and the vanes 15 by the driving voltage applied to the second cathode support 25 and the anode, and the strong electric field is a vane ( 15) to the filament 17.

On the other hand, the magnetic flux generated from the upper magnet 41 is the upper pole piece 33, the working space 12, the lower pole piece 35, the lower magnet 43, the lower yoke 55, the upper yoke 53 ), A magnetic circuit composed of the upper magnet 41 is formed to form a high magnetic field in the working space 12.

Therefore, hot electrons emitted from the surface of the hot filament 17 into the working space 12 travel toward the vane 15 or the anode body 13 by the strong electric field present in the working space 12 and at the same time. The strong magnetic field in (12) is applied to the direction perpendicular to the direction of travel and spirals as the electrons advance toward the anode.

The movement of the electrons is made in all the working spaces 12, and the electrons form a group of electrons in accordance with the structural resonance circuit between the vanes 15 and the resonator 10, and repeatedly the electrons form a group of electrons. The vane 15 generates 2450 MHz band (fundamental wave) microwaves, which are resonance frequencies corresponding to the speed at which the electron group rotates.

Meanwhile, the line noise flowing back through the first and second cathode supports 23 and 25 during the microwave generation is absorbed by the ferrites 30a and 32a, removed or attenuated, and discharged to the outside.

However, since the magnetron has a structure in which ferrites 30a and 32a are inserted into the choke coils 30 and 32, as shown in FIG. 3, the magnetron is expensive and difficult to manufacture.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to change the cathode structure of the magnetron to provide a cathoderon structure of the magnetron which is inexpensive and easy to manufacture.

In order to achieve the above object, the cathode structure of the magnetron according to the present invention includes a filament for emitting hot electrons, first and second cathode supports for supporting the filaments, and the first and second cathode supports to the filament. It is characterized by consisting of an external connection terminal for supplying power, a choke coil connected to each of the external connection terminals and twisted with each other, and a ferrite having a pair of holes through which the choke coils pass.

1 is a longitudinal cross-sectional view of a magnetron according to the prior art,

2 is a cross-sectional view taken along the line A-A of FIG.

3 is a structural diagram schematically showing a cathode part of a magnetron according to the prior art;

4 is a structural diagram schematically showing a cathode portion of a magnetron according to an embodiment of the present invention;

5 is an equivalent circuit diagram of an inductor applied to the present invention.

* Description of the symbols for the main parts of the drawings *

17: filament 20: upper shield hat

21: lower shield hat 23: the first cathode support

25: second cathode support 27: insulating ceramic

29, 31: External connection terminal 30 ', 32': Choke coil

34: Capacitor 39: Lower Shield Cup

40: ferrite

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a structural diagram schematically showing the structure of the cathode portion of the magnetron according to an embodiment of the present invention, Figure 5 is an equivalent circuit diagram of the inductor applied to the present invention, the same reference numerals are attached to the same parts as in the prior art.

As shown in FIG. 4, the magnetron structure of the magnetron according to the present invention is a filament for emitting hot electrons, and hot electrons, which are loss currents that do not contribute to oscillation, are not provided at both ends of the filament 17 in the direction of the center axis. The upper and lower shield hats 20 and 21 are fixed to prevent radiation, and the lower shield hat 21 has a through hole formed in the center with a first cathode support 23, which is a central support made of molybdenum, in the center. It is fused and fixed to the lower end portion of the upper shield hat 20 through, and the second cathode support 25 made of molybdenum is welded to the bottom surface of the lower shield hat 21.

The first cathode support 23 supports the upper shield hat 20 while passing through the central axis of the filament 17, and the first and second cathode supports 23 and 25 support and fix the cathode of the magnetron. It is a filament electrode which is electrically connected to the external connection terminals 29 and 31 through a through hole formed in the insulating ceramic 27 to supply current to the filament 17.

One end of the choke coils 30 'and 32' is electrically connected to the external connection terminals 29 and 31, and the choke coils 30 'and 32' are connected to the first and second cathode supports 23 and 25. After passing through a pair of holes formed in the ferrite 40, which is a rectangular parallelepiped absorbing line noise of 1GHz or less applied through), the ends of the choke coils 30 'and 32' are connected to the condenser 34. Each is electrically connected.

Referring to the operation of the negative electrode structure of the magnetron configured as described above are as follows.

First, when power is applied through the external connection terminals 29 and 31, the external connection terminal 29, the first cathode support 23, the upper shield hat 20, the filament 17, the lower shield hat 21 ), The second cathode support 25 and the external connection terminal 31 constitute a closed circuit so that the operating current is supplied to the filament 17. Accordingly, when the filament 17 is heated, the working space 12 is heated at a high temperature. It begins to emit hot electrons into it.

At this time, a strong electric field is formed in the working space 12 between the outer surface of the filament 17 and the vanes 15 by the driving voltage applied to the second cathode support 25 and the anode, and the strong electric field is a vane ( 15) to the filament 17.

On the other hand, the magnetic flux generated from the upper magnet 41 is the upper pole piece 33, the working space 12, the lower pole piece 35, the lower magnet 43, the lower yoke 55, the upper yoke 53 ), A magnetic circuit composed of the upper magnet 41 is formed to form a high magnetic field in the working space 12.

Subsequently, hot electrons emitted from the surface of the hot filament 17 into the working space 12 travel toward the vane 15 or the anode cylinder 13 by a strong electric field present in the working space 12 and at the same time. The strong magnetic field in (12) is applied to the direction perpendicular to the direction of travel and spirals as the electrons advance toward the anode.

The movement of the electrons is performed in all the working spaces 12, and the electrons form a group of electrons according to the structural resonant circuit between the vanes 15 and the resonator 10 to repeatedly perform the progress to the high potential vanes 15. The vane 15 generates microwaves in the 2450 MHz band (fundamental wave) which is a resonance frequency corresponding to the speed at which the electron group rotates.

At this time, line noise due to impedance matching defect or abnormal oscillation shape of the magnetron is generated, and the filament 17 acts as an antenna to receive the line noise and transmit the line noise through the first and second cathode supports 23 and 25. When the transmitted line noise is applied to the choke coils 30 'and 32' through the external connection terminals 29 and 31, the choke coils 30 'and 32', the ferrite 40 and the condenser 34 are L. The line noise is removed by constituting the / G resonant circuit and applied to the external connection terminals 29 and 31 by passing only AC power of 50 to 60 Hz.

As shown in FIG. 5, the inductance L of the resonant circuit has a self-inductance L of each choke coil 30 'and 32' and a mutual inductance M between the choke coils 30 'and 32'. Is determined by

As described above, according to the negative electrode structure of the magnetron according to the present invention, the choke coils passing through the holes of the single ferrite are twisted together, thereby reducing the cost and making the manufacturing easy.

Claims (1)

The filament 17 through a filament 17 for emitting hot electrons, first and second cathode supports 23 and 25 for supporting the filament 17 and the first and second cathode supports 23 and 25. External connection terminals 29 and 31 for supplying power to each other, choke coils 30 'and 32' connected to the external connection terminals 29 and 31 and twisted with each other, and the choke coils 30 'and 32 respectively. Magnet structure of the magnetron, characterized in that consisting of a ferrite (40) having a pair of holes to pass through.