JPH05174717A - Cavity resonator for multi-cavity type klystron - Google Patents

Abstract

PURPOSE:To avoid deterioration in the high frequency characteristics and variation in the tuning frequency due to thermal expansion of a metal plate by providing a conductive material layer consisting of a conductor, whose electric resistance is below 2.5muOMEGA.cm, on that side of the metal plate which is facing a drift tube. CONSTITUTION:A copper plating layer 4b is provided on the surface of a metal plate 4 which faces a drift tube 2. The impedance for a high frequency current flowing at the surface of the metal plate 4, therefore, reduces in association with the operation of a cavity resonator, which permits reducing power loss and allows avoiding deterioration of the Q-value. It may also work well that a plating of any other metal having an electric resistance of 2.5muOMEGA.cm or less is formed over the surface of the metal plate 4, or a layer of such metal attached thereto. Exceeding 2.5muOMEGA.cm gives insufficient reduction of the impedance for the high frequency current flowing at the surface of the metal plate, and it is not possible to exert satisfactory effect. One example of conductor having electric resistance below 2.5muOMEGA.cm, besides copper, is gold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cavity for a multi-cavity klystron in which a part of a frequency-adjustable movable tuner moves while elastically contacting an inner wall surface of a cavity envelope during resonance frequency adjustment. Resonator.

[0002]

2. Description of the Related Art A microwave tube using a cavity resonator such as a klystron is currently used in various fields such as communication and broadcasting. The tuning frequency of each cavity resonator of a microwave tube of this type can be adjusted so as to obtain a predetermined frequency during operation.

As a tuning frequency adjusting method for the cavity resonator, the tuning frequency is changed by changing the inductance of the cavity resonator, the tuning frequency is changed by changing the capacitance, and these methods. There is a method of changing the tuning frequency by combining both.

3 (a) and 3 (b) are a schematic vertical sectional view and a horizontal sectional view, respectively, showing a conventional cavity resonator for a multicavity klystron. This cavity resonator is a so-called L tuning type cavity resonator in which the tuning frequency is changed by changing the inductance.

The cavity resonator is introduced into the cavity envelope 1 from the box-shaped cavity envelope 1 and the wall surface of the cavity envelope 1 and the tips thereof are arranged to face each other. It is composed of a pair of drift tubes 2. Further, a thin metal plate 4 called a diaphragm is arranged in the cavity envelope 1.
The center of the metal plate 4 is connected to the connecting rod 5, and the volume of the resonant cavity 3 can be changed by moving the connecting rod 5 in the axial direction. A bellows 10 is provided between the connecting rod 5 and the cavity envelope 1 so that the interior space of the cavity envelope 1 is airtightly shut off from the outside to maintain a vacuum. It has become.

A variable tuner 6 is provided at the upper and lower ends of the metal plate 4. This variable tuning element 6 has a metal wire support 7 having a substantially elliptical cross section and spiral grooves provided on its peripheral surface, and a metal wound around the metal wire support 7 along the groove. And the line 8. This metal wire 8
Is made of an elastic metal wire such as a tungsten wire, and is slightly separated from the metal wire support 7 in the plane portion of the metal wire support 7. The metal wire 8 is in contact with the inner wall surface 9 of the cavity envelope 1 at a portion slightly separated from the metal wire support 7.

In the conventional cavity resonator thus constructed, the metal rod 4 is moved while the connecting rod 5 is moved in the axial direction to bring the movable tuner 6 into contact with the inner wall surface of the cavity envelope 1. Move the volume of the resonant cavity 3 (that is, the amount of inductance)
Is changed to change the resonance frequency of the cavity resonator.

[0008]

However, the above-mentioned conventional cavity resonator has the following problems. That is, in the cavity resonator, when the connecting rod 5 is moved in its axial direction, it is strong against the fixed portion of the movable tuner 6 and the metal plate 4 which are in contact with the inner wall surface 9 of the cavity envelope 1. Stress is applied. Therefore, it is necessary to use a metal having high strength such as cupro-nickel as the material of the metal plate 4. However, since a metal having a high strength is generally not sufficiently conductive, the conventional cavity resonator has a drawback that a power loss due to a high-frequency current flowing on the surface of the metal plate 4 is large during operation. Further, since the power loss in the resonance circuit is large, the Q value showing the high frequency characteristics of the resonator becomes low. Further, there is a problem that the metal plate 4 is thermally expanded by the heat generated in the metal plate 4 and the resonance frequency is changed.

The present invention has been made in view of the above problems, and provides a cavity resonator for a multi-cavity klystron that can reduce power loss and have excellent high frequency characteristics, and can avoid fluctuations in resonance frequency. The purpose is to provide.

[0010]

A cavity resonator for a multi-cavity klystron according to the present invention comprises a box-shaped cavity envelope, and a cavity from a wall surface of the cavity envelope. A pair of drift tubes which are introduced into the envelope and whose tips are arranged to face each other, and a metal wire which is spirally arranged and a part of which contacts the inner wall surface of the cavity envelope. And a movable tuner with
In a multi-cavity klystron cavity resonator provided with a metal plate supporting the movable tuner and capable of adjusting the volume of the resonance cavity, the electric resistance is 2.5 on the surface of the metal plate on the drift tube side. It is characterized in that a conductor layer made of a conductor of μΩ · cm or less is provided.

[0011]

In the present invention, a conductor layer made of a conductor having an electric resistance of 2.5 μΩ · cm or less is provided on the surface of the metal plate on the drift tube side. As a result, the impedance with respect to the high-frequency current flowing on the surface of the metal plate during the operation of the cavity resonator can be reduced, the power loss can be reduced, the heat generation can be suppressed, and the fluctuation of the tuning frequency can be avoided.

When the electric resistance of the conductor exceeds 2.5 μΩ · cm, the impedance for high-frequency current flowing on the surface of the metal plate is not sufficiently reduced, and the above-mentioned effects cannot be sufficiently obtained. Therefore, the electrical resistance of the conductor must be 2.5 μΩ · cm or less. As a conductor with an electrical resistance of 2.5 μΩ · cm or less,
For example, copper (1.72 μΩ · cm) and gold (2.4 μΩ · cm)
Etc.

[0013]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

1 (a) and 1 (b) are a schematic cross sectional view and a vertical cross sectional view, respectively, showing a cavity resonator for a multicavity klystron according to an embodiment of the present invention. In addition, as shown in FIG.
(B) is a horizontal cross-sectional view and a vertical cross-sectional view showing a variable tuner and a metal plate, respectively.

The present embodiment is different from the conventional one in that the copper plating layer 4b is provided on the surface of the metal plate 4 on the drift tube 2 side, and the other constitutions are basically the same as the conventional one. 3A and 3B in FIGS. 1A and 1B.
The same reference numerals are given to the same components, and detailed description thereof will be omitted.

In this embodiment, a copper plating layer 4b is provided on the surface of the metal plate 4 on the drift tube 2 side. Also,
At the upper end and the lower end of the metal plate 4, as in the conventional case,
A movable tuner 6 is provided for each. This movable entrainer 6
Is a metal wire support 7 having a substantially oval cross section, and a metal wire storage groove 7 spirally provided on the peripheral surface of the metal wire support 7.
It is composed of an elastic metal wire 8 such as tungsten wound around a. This metal wire 8
A portion apart from the metal wire support 7 contacts the inner wall surface 9 of the cavity envelope 1. The metal plate 4 is formed of a metal having high strength such as cupro nickel.

In the present embodiment, since the copper plating layer 4b is provided on the surface of the metal plate 4 on the drift tube 2 side,
With the operation of the cavity resonator, the impedance with respect to the high frequency current flowing on the surface of the metal plate 4 is reduced as compared with the conventional case. Therefore, it is possible to reduce power loss and avoid deterioration of Q value. Further, the amount of heat generated on the surface of the metal plate 4 is small, and it is possible to avoid the fluctuation of the resonance frequency due to the thermal expansion of the metal plate 4.

In the present embodiment, the case where the surface of the metal plate 4 is plated with copper has been described. However, another metal having an electric resistance of 2.5 μΩ · cm or less on the surface of the metal plate 4 (eg gold). May be plated. Further, instead of plating, a metal plate having an electric resistance of 2.5 μΩ · cm or less may be joined to the surface of the metal plate 4 by clad or brazing.

[0019]

As described above, according to the present invention, there is provided a metal plate capable of adjusting the volume of the resonance cavity by supporting the movable tuner having the metal wire that contacts the inner wall surface of the cavity envelope. Since a conductor layer made of a conductor whose electric resistance is equal to or lower than a predetermined value is provided on the surface of the drift tube side, it is possible to reduce power loss as compared with the conventional one, and also due to deterioration of high frequency characteristics and thermal expansion of the metal plate. Fluctuations in tuning frequency can be avoided.

[Brief description of drawings]

1A and 1B are schematic cross-sectional views and vertical cross-sectional views, respectively, showing a cavity resonator for a multi-cavity klystron according to an embodiment of the present invention.

2A and 2B are a horizontal cross-sectional view and a vertical cross-sectional view showing a variable tuner and a metal plate, respectively.

3 (a) and 3 (b) are a schematic longitudinal sectional view and a transverse sectional view, respectively, showing a conventional cavity resonator for a multicavity klystron.

[Explanation of symbols]

 1; Cavity envelope 2; Drift tube 3; Resonance cavity 4; Metal plate 4b; Copper plating layer 5; Connecting rod 6; Movable tuner 7; Metal wire support 8; Metal wire 10; Bellows

Claims (1)

[Claims] 1. A box-shaped cavity envelope, and a cavity envelope which is introduced from the wall surface of the cavity envelope into the cavity envelope and whose tips are arranged to face each other. A pair of drift tubes,
A movable tuner provided with a metal wire arranged in a spiral shape, a part of which is in contact with the inner wall surface of the cavity envelope, and a metal plate capable of supporting the movable tuner and adjusting the volume of the resonance cavity. In the multi-cavity klystron cavity resonator with, the electric resistance is 2.5 μΩ on the surface of the metal plate on the drift tube side.
A cavity resonator for a multi-cavity klystron, characterized in that a conductor layer made of a conductor having a size of 1 cm or less is provided.