JPH0927279A - Traveling wave tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid nonconformity that may be caused by the disturbance of helix pitches due to movement of a dielectric pole and to improve the characteristics of a waveguide by placing a cylindrical nonmagnetic metallic pipe at the end of the dielectric pole inside a metallic cylindrical envelope. SOLUTION: In a slow-wave circuit 2, a dielectric pole 10 and a helix 14 are provided inside a metallic cylindrical envelope 15, and stoppers 23, 24 respectively for the input and output sides of a nonmagnetic metallic pipe are placed at both ends of the dielectric pole 10. Each of the stoppers 23, 24 is in the form of a cylinder with a notch in part of it, the notch being shaped so that it does not make contact with the coaxial inner conductor 11 and the helix conductor 13 of input and output coaxial circuits 21, 22. Therefore, both ends of the dielectric pole 10 are held into place to prevent movement of the dielectric pole 10, thus preventing mismatching and degradation of oscillation and frequency characteristics that may result from the disturbance or deformation of helix pitches due to the movement of the pole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling wave tube, and more particularly to supporting a helix of a helix type slow wave circuit and a dielectric support in a helix type traveling wave tube.

[0002]

2. Description of the Related Art In recent years, traveling wave tubes used as power amplifier tubes for microwave communication relay stations and satellite communication earth stations have high efficiency, low power consumption, wide band, small size and light weight, and improved environmental resistance. High reliability is required. The diversification of information has progressed as the information transmission system has shifted to those for general customers, as symbolized by multimedia, rather than in some limited fields as in the past. This is because For example, if a general customer owns a power amplification device that uses a traveling wave tube, it is necessary to reduce the size and weight because it is installed on an outdoor antenna rack, and the environment resistance is sufficient to withstand even harsh environments. In addition, it should have excellent long-term stability, and at the same time, should have low power consumption. The present invention is one means for solving the above-mentioned problems.

Prior art is shown in FIGS. 5, 6 and 7. 5 and 6 are a cross-sectional view and a detailed view of the helix type traveling wave tube of the first conventional example. The electron gun (1) that emits an electron beam (9) is composed of a heater (5), a cathode (6), an anode (7) and a Wehnelt electrode (8). The slow wave circuit (2) has a helix (14) supported by a plurality of dielectric columns (10) in a metal cylindrical envelope (15), and is formed with an annular magnetic pole on the outer peripheral portion of the metal cylindrical envelope. A periodic magnetic field focusing device is installed to focus the electron beam (9) emitted from the electron gun (1) to the collector (4).

The collector (4) is a two-stage lower type of the first collector (16) and the second collector (17) in order to reduce the power consumption, and two cylindrical ceramics (20) are arranged. It is electrically insulated from the metal envelope (15).
The input coaxial circuit (21) and the output coaxial circuit (22), which are the entrances and exits of the microwave, are composed of a coaxial inner conductor (11) and a coaxial outer conductor (12), and each coaxial inner conductor (11). Is connected to the helix (14) via the helix conductor (13). In the dielectric strut (10), beryllia porcelain, boron nitride, etc. are used,
It improves energy conversion efficiency and heat dissipation of the helix (14).

The helix (14) and the dielectric support (1
0) is fastened and fixed in the metal cylindrical envelope (15) by a shrink fitting method in which the metal cylindrical envelope (15) is heated and expanded in advance and then inserted, or a mechanical press-fitting method. The electron beam (9) emitted from the electron gun (1) interacts with the microwave input from the input coaxial circuit (21) in the helix (14), and the amplified microwave is the output coaxial circuit. The electron beam (9) output from (22) and passing through the helix (14) is the collector (4).
Supplemented by.

FIG. 7 shows a conventional example 2 (JP-A-56-9135).
5) is a sectional view of a brazing helix type slow wave circuit of No. 5). Brazing helix type low speed circuit (28)
Is configured by dividing a part of the output side of the dielectric support column (10) and brazing and fixing the dielectric support column (10) at the output end to the helix (14) and the metal cylindrical envelope (15). There is. This is for efficiently dissipating the heat generated near the output terminal of the helix (14) having a high power density.

Further, although not shown, in the traveling wave tube, a beam shaver is provided between the input coaxial circuit and the electron gun to prevent unnecessary electrons at the outer edge of the electron beam from entering the helix. Example 3 (for example, Japanese Patent Laid-Open No. 4-2
No. 80038 and Japanese Patent Laid-Open No. 3-173045) have been proposed.

[0008]

In the helix type traveling wave tube shown in FIGS. 5 and 6 of the above-mentioned conventional example 1, the dielectric support column (10) and the helix (14) are the metal cylindrical envelope (15). It is fastened with metal stress. Dielectric support (1
0) and helix (14) use beryllia porcelain and molybdenum, which have relatively small thermal expansion coefficients.
On the other hand, a non-magnetic stainless material having a large coefficient of thermal expansion is generally used for the metal cylindrical envelope (15).

Therefore, in baking in the evacuation process of the traveling wave tube, the dielectric support column (10) housed with the metal cylindrical envelope (15) is placed in order to keep the traveling wave tube bulb in an atmosphere of about 500 ° C. The fastening stress decreases due to the difference in the coefficient of thermal expansion of the helix (14). Depending on the finished size of each part, the metal cylindrical envelope (15) and the dielectric support (10),
The supporting force of the helix (14) is reduced, and the dielectric support (1
The position shift of 0) occurs. The displacement of the dielectric support column (10) may occur in the tube axial direction, the radial direction, or both directions at the same time, depending on the mounting direction of the tube during baking.

The positional deviation of the dielectric support column (10) causes pitch irregularity and deformation of the helix (14) when baking is completed and the temperature of the tube returns to room temperature, resulting in mismatch of input / output circuit and frequency. This may cause deterioration of characteristics and problems such as oscillation. Also, the helix (14) and the dielectric support (1
0) Contact failure occurs, the heat dissipation of the helix (14) deteriorates, and the temperature increase of the helix (14) increases the loss of the circuit and causes a problem such as output reduction. Since the fitting allowance of the helix (14) and the dielectric strut (10) to be housed with the metal cylindrical envelope (15) is about 10 microns, it is necessary to accurately make the dimensions of each part, which results in a high price. Therefore, it becomes difficult to provide inexpensive products.

In the slow wave circuit structure of the helix type traveling wave tube shown in FIG. 7 of the conventional example 2, the divided dielectric support column (10) on the output coaxial circuit side has the helix (14) and the metal cylindrical envelope (15). However, the above-mentioned problems are unlikely to occur, but there is a possibility that displacement of the dielectric support column (10) in the non-brazing portion may occur.
Especially, the dielectric support column (10) having the divided attenuator (26) is not fixed, and thus the dielectric support column (10) is not fixed.
If the position shift occurs, the helix (14) is disturbed or deformed, and since the area of high power density is high, problems such as oscillation and output reduction due to an increase in reflected waves are likely to occur. . Further, in Conventional Example 2, the other dielectric support pillar (10) must be disposed in a state in which the divided dielectric support pillars (10) are brazed, which may be caused by uneven metal stress due to brazing, thermal history, etc. There is a risk that the dielectric support (10) may be damaged, the pitch of the helix may be disturbed, or fitting failure may occur.

Further, the conventional example 1 (FIGS. 5 and 6) uses the two-stage potential-decreasing collector to reduce the power consumption, but in this structure, the potential of the second collector (17) is greatly increased. Since it is lowered, the low-velocity electrons in the electron beam (9) trapped by the collector (4) are likely to return to the helix (14), which causes oscillation and cross-modulation characteristics of the return electrons. When the space formed by the end of the cylindrical envelope (15) and the first collector (16) resonates with the operating frequency of the traveling wave tube, the microwave amplified by the helix (14) A part of it propagates to the collector (4) side and leaks from the cylindrical ceramic (20) that insulates and supports the slow wave circuit (2) and the first collector (16).

[0013]

SUMMARY OF THE INVENTION The present invention is a helix type retarder in which a dielectric strut and a helix are arranged inside a metal cylindrical envelope, and the helix and the dielectric strut are fastened and supported by the metal cylindrical envelope. In a traveling wave tube having a wave circuit,
A cylindrical non-magnetic metal tube is disposed at the input side end and the output side end of the dielectric strut end in the metal cylindrical envelope, or at either the input side end or the output side end. Is a traveling wave tube. Further, the present invention is the traveling wave tube described above, wherein the inner diameter of the cylindrical non-magnetic metal tube is substantially equal to the inner diameter of the helix.

Further, according to the present invention, a cylindrical insulator is disposed on the outer periphery of the cylindrical nonmagnetic metal tube to electrically insulate the cylindrical metal envelope from the cylindrical nonmagnetic metal tube. The traveling wave tube described above. Further, the present invention is characterized in that each of the inner conductors forming the input part coaxial circuit and the output part coaxial circuit and a conductor connecting the end of the helix are extended and joined to a cylindrical non-magnetic metal. Is a traveling wave tube.

[0015]

According to the present invention, in the helix type traveling wave tube, the end portion of the dielectric support in the metal cylindrical envelope has an input side end and an output side end, or a cylindrical shape at either the input side end or the output side end. A non-magnetic metal tube is provided, and the non-magnetic metal tube provided in the metal cylinder envelope functions as a stopper to prevent the dielectric support column from being displaced. It serves to prevent misalignment, oscillation, and deterioration of frequency characteristics due to disturbance or deformation of the helix pitch. That is, in the helix type traveling wave tube in which the helix and the dielectric support are arranged in the metal cylindrical envelope, it is possible to eliminate the problem caused by the pitch disturbance due to the displacement of the dielectric support and improve the characteristics. It is a thing.

In the present invention, the dielectric column and the helix are fastened to the metal cylindrical envelope by the stress of the metal, and are arranged in the metal cylindrical envelope and have a cylindrical shape that functions as a stopper. The metal tube is made of the same material as that of the metal cylindrical envelope or a non-magnetic metal having a coefficient of expansion close to that of the metal cylindrical envelope, and the outer diameter of the metal tube fits the inner diameter of the metal cylindrical envelope. For example, beryllia porcelain and molybdenum, which have a relatively low coefficient of thermal expansion, are used for the dielectric columns and helices.
A non-magnetic stainless material is used for the metal cylinder envelope.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings.

[0018]

First Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. Figure 1 is a cross-sectional view of a helix type traveling wave tube.
2 is an enlarged sectional view of the input side, and FIG. 3 shows various stoppers. In FIG. 1, the electron gun (1) is composed of a heater (5), a cathode (6), an anode (7) and a Wehnelt electrode (8). The slow wave circuit (2) is provided with a plurality of dielectric columns (10) and helices (14) in a metal cylindrical envelope (15), and an annular magnetic pole (18) is provided on the outer periphery of the metal cylindrical envelope. A periodic magnetic field focusing device (3) formed by an annular magnet (19) is installed, and an electron gun (1) is installed.
The electron beam (9) emitted from the laser is focused to the collector (4).

The collector (4) is the first collector (16).
And a second collector (17) with two cylindrical ceramics (20) arranged. It is electrically insulated from the metal envelope (15). The input coaxial circuit (21) and the output coaxial circuit (22) are composed of a coaxial inner conductor (11),
It is composed of an outer coaxial conductor (12), and each inner coaxial conductor (11) is connected to the helix (14) through a helix conductor (13).

The electron beam (9) emitted from the electron gun (1) is supported and fixed by the metal cylindrical envelope (15) of the slow wave circuit (2) and the dielectric support (10), and the helix (14).
When passing through, the microwave is amplified by the interaction with the microwave, and after passing through the helix (14), it is trapped by the first collector (16) and the second collector (17).

An input side stopper (23) and an output side stopper (24) are arranged at both ends of the dielectric support column (10). This dielectric support column (10) can prevent misalignment by pressing and fixing the dielectric support column (10) at both ends like the above-mentioned conventional dielectric support column with an attenuator. Becomes Further, the input side stopper (23) and the output side stopper (24) have a cylindrical shape and have a notch in a part, and their outer diameters are appropriate to the inner diameter of the metal cylindrical envelope (15). The dimensions are such that they fit together, and the inner diameter is approximately twice the outer diameter of the helix (14) because it does not affect the trajectory of the electron beam or the like. A non-magnetic metal is used as the material.

The input side stopper (23) and the output side stopper (24) are provided with a notch on the side end portion where the notch is formed.
0) contact both ends and connect the notch to the input coaxial circuit (2
1) After positioning in the direction of the output portion coaxial circuit (22), the fitting portion with the metal cylindrical envelope (15) is joined and fixed by laser welding or the like. The notch of the stopper (23) is formed in a shape that does not contact the coaxial inner conductor (11) and the helix conductor (13) of the input / output coaxial circuit (21). Further, it is preferable that the stopper (24) is also formed in the same shape.

FIG. 2A is an enlarged cross-sectional view on the input side of the cross-sectional view of the helix type traveling wave tube shown in FIG. 1, and FIG.
-A arrow view (view seen from the electron gun side) is shown. FIG. 2 (A)
As shown in (B), a plurality of dielectric columns (10) and helices (14) are provided in the metal cylindrical envelope (15), and the input side stopper (2) is provided at the end of the dielectric columns (10).
3) is provided. The tip of the stopper (23) on the side where the cutout is provided is in contact with the input end of the dielectric support (10). The notch of the stopper (23) is located on the outer periphery of the coaxial outer conductor (12) of the input coaxial circuit (21), and the coaxial inner conductor (11) and the helix conductor (1).
3) Avoid contact with.

The input-side stopper (23) and the output-side stopper (24) have side ends that come into contact with the dielectric support column (10), and also have an input coaxial circuit (21) and an output coaxial circuit (22). Although it is positioned, various shapes are conceivable, and FIGS. 3A to 3C show examples of various stoppers of the present invention. FIG. 3A is the same as the stopper shown in FIG. 2 and shows a basic shape.

FIG. 3 (B) has three grooves (b), which incorporates the ends of three dielectric struts (10) in the axial direction of the dielectric struts (10). This not only prevents the positional deviation but also prevents the radial deviation of the pipe. In the stopper shown in FIGS. 3A and 3B, the inner diameter is about twice the helix inner diameter, but the stopper shown in FIG. The fitting groove (b) is provided, and the inner diameter on the side not having the notch is smaller than the inner diameter at the notch (a) side, that is, the inner diameter on the side not having the notch is D It is a stopper that has almost the same inner diameter as the helix. Although not shown, the inner diameter of all the stoppers may be D and may be substantially equal to the helix inner diameter.

By using these, the return electrons from the collector are trapped by the stopper, and the electrons diverging temporarily when the operating voltage is applied are trapped on the input side so as not to adversely affect the helix. It is possible to combine the functions of a beam shaver. Also, if the distance between the helix (14) and the helix (14) is reduced by reducing the stopper inner diameter dimension d and changing the height of the cutout portion, the electromagnetic field of the slow wave circuit propagation mode in this portion is affected. It is also possible to improve impedance matching with the input / output coaxial circuit by selecting the shape.

[0027]

Second Embodiment FIG. 4 shows another embodiment of the present invention. FIG. 4 is a sectional view of the output side of the helix type traveling wave tube. As shown in FIG. 4, the slow wave circuit (2) includes a metal cylindrical envelope (15).
An electron beam emitted from an electron gun is provided with a dielectric pillar (10) and a helix (14) inside, and a periodic magnetic field concentrator formed by an annular magnetic pole on the outer periphery of the metal cylindrical envelope. To the collector (4). The collector (4) has a first collector (16) and a second collector (17) and two cylindrical ceramics (20).
Is arranged. The output coaxial circuit (22), which is the entrance and exit of microwaves, includes a coaxial inner conductor (11) and a coaxial outer conductor (1).
2) and the coaxial inner conductor (11) is connected to the helix (14) through the helix conductor (13).

In FIG. 4, the dielectric support column (10) is the collector (4) of the outer conductor (12) of the output coaxial circuit (22).
Side to the position of the output side stopper (2
4) is provided. The output side stopper (24) is made of a cylindrical metal having no notch portion, and a cylindrical insulating ceramic (25) is arranged on the outer periphery of the metallic stopper.
It is electrically insulated from 5). Further, the helix conductor (13) extends from the coaxial inner conductor (11) connection portion and is connected to the output side stopper (24). The total length of the output stopper (24) is about 1 of the guide wavelength λ of the working frequency.
By setting / 4, a choke effect is given to the stopper (24). Therefore, by blocking the microwave propagating to the collector (4), it is possible to reduce the leakage electric wave from the cylindrical ceramic (20) adjacent to the first collector (16).

[0029]

As described above, according to the present invention, by disposing the cylindrical metal stopper in the slow wave circuit of the helix type traveling wave tube, it is possible to suppress the displacement of the dielectric support column in the exhaust process and to displace it. This has the effect of preventing misalignment, oscillation, and deterioration of frequency characteristics due to disturbance or deformation of the helix pitch caused by the above. Also, by making the inner diameter of the stopper almost the same as the inner diameter of the helix,
Not only can the effect of the beam shaver be exerted and the return electrons from the collector be suppressed, but the matching characteristics can be improved by adjusting the shape of the stopper.
By using a choke structure for the stopper, it is possible to reduce the amount of radio waves leaking to the collector side.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an input side according to the first embodiment of the present invention.

FIG. 3 is a view showing various stoppers of the present invention.

FIG. 4 is a partial cross-sectional view showing a second embodiment of the present invention.

FIG. 5 is a view showing a helix type traveling wave tube of Conventional Example 1.

FIG. 6 is a detailed view of part of FIG. 5 of Conventional Example 1.

FIG. 7 is a diagram showing a second conventional example.

[Explanation of symbols]

 1 Electron Gun 2 Slow Wave Circuit 3 Periodic Magnetic Field Focusing Device 4 Collector 5 Heater 6 Cathode 7 Anode 8 Wehnelt 9 Electron Beam 10 Dielectric Column 11 Coaxial Inner Conductor 12 Coaxial Outer Conductor 13 Helix Conductor 14 Helix 15 Metal Cylindrical Enclosure 16 First collector 17 Second collector 18 Disc-shaped magnetic pole 19 Circular magnet 20 Cylindrical ceramic 21 Input coaxial circuit 22 Output coaxial circuit 23 Input stopper 24 Output stopper 25 Insulation ceramic 26 Attenuator 27 Brazing surface 28 Brazing Helix type low speed circuit

Claims (4)

[Claims] 1. A traveling wave tube having a helix type slow-wave circuit in which a dielectric strut and a helix are arranged inside a metal cylindrical envelope, and the helix and the dielectric strut are fastened and supported by the metal cylindrical envelope. A cylindrical non-magnetic metal tube is arranged at the input side end and the output side end of the dielectric strut end in the metal cylindrical envelope, or at either the input side end or the output side end. A traveling wave tube characterized in that 2. The traveling wave tube according to claim 1, wherein the inner diameter of the cylindrical non-magnetic metal tube is substantially equal to the inner diameter of the helix. 3. A cylindrical insulator is provided on the outer peripheral portion of the cylindrical non-magnetic metal tube to electrically insulate the cylindrical metal envelope from the cylindrical non-magnetic metal tube. The traveling wave tube according to claim 1 or 2, characterized in that 4. An electric conductor connecting an inner conductor forming each of an input coaxial circuit and an output coaxial circuit and a helix end is extended and joined to a cylindrical non-magnetic metal. A traveling wave tube according to any one of 3 to 3.