JP2661517B2 - Traveling wave tube - Google Patents

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 using a periodic magnetic field as an electron beam focusing device, and more particularly to a cooling structure for a slow wave circuit.

[0002]

2. Description of the Related Art A traveling wave tube has an electron gun whose tube portion emits an electron beam, a slow wave circuit in which high frequency is amplified by an interaction between the electron beam and a high frequency, and an electron beam after the interaction. It comprises a collector for capturing, and a periodic magnetic field concentrator for generating a magnetic field for converging the electron beam to form a thin beam. These are arranged on a base plate which constitutes a part of the case of the traveling wave tube.

The slow wave circuit structure of the traveling wave tube and the periodic magnetic field focusing device will be described in detail with reference to FIG. FIG.
(A) and (b), 10 is a helix through which a microwave propagates, 11 is a helix support for supporting the helix, 2 is a pole piece, 12 is a spacer made of non-magnetic metal, and 1 is for focusing an electron beam. Is a cylindrical permanent magnet. The pole pieces 2 and the spacers 12 are alternately brazed to form a vacuum envelope.

In such a configuration, the electron beam emitted from the electron gun and accelerated is narrowed down to a narrow beam by the periodic magnetic field formed on the central axis and passes through the helix 10. At this time, the high frequency wave input from the input end of the helix 10 forms an electric field in the axial direction of the helix 10, and the high frequency electric field interacts with the electron beam to amplify the high frequency.

When the traveling wave tube is operating, the helix 10 is constantly accelerated by the heat generated by the collision of a part of the electron beam and the heat generated by the high frequency loss near the output end of the slow wave circuit. I have. The helix 10 is usually made of a material having a high melting point, such as molybdenum or tungsten. However, since a thin tape is wound in a spiral shape, the heat capacity is small. Helix temperatures can be hundreds of degrees or more.

In this case, gas is released from the helix 10 and the degree of vacuum in the traveling wave tube is degraded to make the operation of the traveling wave tube unstable. In addition, the rise in the temperature of the helix 10 raises the temperature of the cylindrical permanent magnet 1 disposed around, causing a change in the magnetic field strength due to the temperature characteristics of the permanent magnet,
Disturbs the focusing of the electron beam and deteriorates the transmittance of the electron beam.

[0007] Therefore, various devices have been conventionally devised as a structure for releasing the heat generated in the helix 10 to the base plate of the traveling wave tube. For example, FIG.
-25455, wherein the lower half peripheral surface of the periodic magnetic field focusing device is supported by a support 3b extending from the base plate 3a. FIG. 4 shows a structure described in Japanese Utility Model Application Laid-Open No. 2-8848 in which the magnet heat exchangers 25 and the pole piece heat exchangers 16 are alternately combined, and they are joined on the pace plate 3.

The conduction cooling system for dissipating heat generated in the helix to the pace plate by conduction as described above has a simple structure, so that the traveling wave tube can be reduced in size and weight.

[0009]

The structure of the prior art shown in FIG. 3, for example, has the advantage that the periodic magnetic field focusing device is supported over the entire axial direction so that the vibration resistance is excellent or the structure is simplified. However, the material of the support is the same as that of the base plate, and there is a drawback that heat transfer to the base plate is not sufficient compared to copper or the like because generally a lightweight and relatively high-strength aluminum alloy is used. .

In the structure of FIG. 4, the pole piece heat transfer plate 16 is made of a material such as copper.
Has a structure in which heat is released from the lower half circumferential surface, but has a disadvantage in that it is arranged on the base plate 3 alternately with the magnet heat conductors 25, so that vibration resistance is inferior and the structure becomes complicated. . Furthermore, since it is arranged on the plane of the base plate 3a, heat conduction inside the base plate 3a becomes a problem as described in the example of FIG.
There is a drawback that heat conduction to the radiator mounted outside the traveling wave tube is not sufficient.

[0011]

According to the present invention, a periodic magnetic field focusing device comprising a plurality of cylindrical permanent magnets and pole pieces alternately arranged on the outer periphery of a slow wave circuit structure is held on a support integral with a base plate. In the traveling wave tube, a copper plate is embedded in the support in the same arrangement as the arrangement of the pole pieces, the upper end surface of the copper plate contacts the lower half peripheral surface of the pole piece, and the lower end surface is flush with the bottom surface of the base plate. It is characterized by being.

[0012]

According to the present invention, since the lower half peripheral surface of the pole piece and the bottom surface of the base plate are directly connected by the copper plate embedded in the support, the heat generated in the slow wave circuit portion can be transmitted to the outside of the traveling wave tube with a small thermal resistance. Heat can be dissipated.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1A is a perspective view of a first embodiment of the present invention, and FIG. 1B is a sectional view in a radial direction. A plurality of cylindrical permanent magnets 1 and pole pieces 2 are alternately arranged on the outer periphery of a slow wave circuit structure composed of a helical helix 10 and three helical pillars 11 to form a periodic magnetic field focusing device. . The periodic magnetic field focusing device is held on a support 3b integral with the base plate 3a. The copper plate 4 is embedded in the support 3 b in the same arrangement as the arrangement of the pole pieces 2. The upper end surface of the copper plate 4 contacts the lower half peripheral surface of the pole piece 2, and the lower end surface is flush with the bottom surface of the base plate 3a.

According to this embodiment, the heat generated in the helix 10 is transmitted through the helix support 11, and is transmitted to the pole piece 2 and the cylindrical permanent magnet 1. Since the inner surface of the pole piece 2 is in direct contact with the helix support 11, heat is more easily transmitted than the cylindrical permanent magnet. Heat is radiated from the pole piece 2 to the outside through the copper plate 4 having high thermal conductivity, and the lower end surface of the copper plate 4 is flush with the bottom surface of the base plate 3a. Heat is dissipated directly to the tube mounting plate (not shown). Since the thermal conductivity of copper (3.9 W / cm / ° C) is more than three times that of aluminum alloy (1.2 W / cm / ° C), if copper is used for the heat conduction path, the temperature difference will be less than half that of conventional ones. It is possible to reduce.

FIGS. 2 (a), 2 (b) and 2 (c) show a second embodiment of the present invention, in which the constituent parts are divided into three parts for easy understanding. In the present embodiment, a copper plate is connected at the upper end surface and a comb-shaped (FIG. 2 (b)) is pressed into a support 3b (FIG. 2 (c)). Therefore, the upper half peripheral surface of the comb-shaped copper plate 5 contacts the lower half peripheral surface of the periodic magnetic field focusing device formed by the pole piece 2 and the cylindrical permanent magnet 1, and the lower end surface of each copper plate is the base plate 3.
It is the same plane as the bottom of a.

In the second embodiment, the cylindrical permanent magnet 1
Since heat is also conducted from the outer surface of the copper plate to the copper plate, heat dissipation is further improved. Although there is an idea that the entire body is formed by a single block instead of a comb-like shape, in this case, the weight becomes heavy and a method of embedding in the support 3b is problematic, which is not practical.

It is not necessary to provide the copper plate according to the present invention over the entire length of the periodic magnetic field focusing device of the traveling wave tube, and it is more effective to provide the copper plate only in the output side slow wave circuit portion that generates a lot of heat in the helix. is there.

[0018]

As described above, according to the present invention, since the lower half peripheral surface of the pole piece and the bottom surface of the base plate are directly connected by the copper plate, the thermal resistance is reduced, and the temperature rise of the slow wave circuit portion and the cylindrical permanent magnet is increased. Can be suppressed. Alternatively, for the same structural size, the allowable heat generation amount of the helix can be increased, so that a traveling wave tube having a larger output can be designed without increasing the structural size.

Further, since the copper plate has a structure to be embedded in the support and the base plate, the vibration resistance is improved and the production is easy. Furthermore, a support having good heat conductivity can be realized with a weight of a fraction of the weight of the case where the support is entirely made of copper.

[Brief description of the drawings]

FIGS. 1A and 1B are a perspective view and a radial sectional view of a first embodiment of the present invention.

FIGS. 2A, 2B, and 2C are exploded perspective views of a second embodiment of the present invention.

FIG. 3 is a perspective view of the inside of a case cover of a conventional traveling wave tube.

4 (a) and 4 (b) are views of a conventional periodic magnetic field focusing device and a supporting structure of a traveling wave tube.

5 (a) and 5 (b) are cross-sectional views of a slow wave circuit structure of a traveling wave tube and a periodic magnetic field focusing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical permanent magnet 2 Pole piece 3a Base plate 3b Support 4 Copper plate 5 Comb-shaped copper plate 10 Helix 11 Helix support

Claims (1)

(57) [Claims] 1. A traveling wave tube in which a periodic magnetic field focusing device in which a plurality of cylindrical permanent magnets and pole pieces are alternately arranged on an outer periphery of a slow wave circuit structure is held on a support integrated with a base plate. A copper plate is embedded in the support in the same arrangement as the arrangement of the pole pieces, and the upper end surface of the copper plate contacts the lower half peripheral surface of the pole piece, and the lower end surface is flush with the bottom surface of the base plate. Wave tube.