JP2745916B2 - The cavity resonator of a multi-cavity klystron. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cavity resonator of a multi-cavity klystron in which an inner conductor for adjusting a resonance frequency can move in a non-contact manner inside a cylindrical outer conductor.

[0002]

2. Description of the Related Art A multi-cavity klystron has advantages such as high efficiency and high gain as compared with other microwave tubes and relatively easy handling. Used in the field.

FIG. 3 is a schematic view showing a general multi-cavity klystron. When a predetermined voltage V ₀ is applied to the electron gun 10, an electron beam 14 is output from the electron gun 10 to the collector 12. An input cavity 16, intermediate cavities 18, 20 and an output cavity 22 are arranged along the flow direction of the electron beam 14. A general multi-cavity klystron has 4 to 6 cavity resonators.

In the multi-cavity klystron configured as described above, the electron beam 14 is velocity-modulated by an electromagnetic wave (input signal) applied to the input cavity 16 and tuned by the intermediate cavities 18 and 20. However, the modulation becomes stronger as going downstream, and as a result, the amplified electromagnetic wave (output signal) can be extracted from the output cavity 22. In this case, it is necessary to adjust the resonance frequency of the cavity resonator so that an electromagnetic wave having a predetermined frequency is obtained as an output signal. Since the tuner for adjusting the resonance frequency of the cavity resonator has a significant effect on the electrical characteristics and stability of the multi-cavity klystron, the quality of the multi-cavity klystron is determined by its performance. You. Therefore, great care must be taken in designing the tuner section of the cavity resonator.

FIG. 4 is a cross-sectional view showing a cavity resonator of a conventional multi-cavity klystron. The cavity wall member 4 is a box-shaped member whose one end is opened, and a pair of drift tubes 3 are arranged inside thereof with their tip portions facing each other. A cylindrical outer conductor 1 is arranged on the open end side of the cavity wall member 4. A rod-shaped inner conductor 2 is fitted inside the outer conductor 1 so as not to contact the outer conductor 1. The inner conductor 2 can move in the axial direction inside the outer conductor 1 while maintaining the interval with the outer conductor 1. A bellows 5 is provided between the outer conductor 1 and the inner conductor 2, so that the cavity wall member 4 and the inner space of the outer conductor 1 are airtightly shut off from the outside and maintained in a vacuum. .

A groove having an L-shaped cross section is provided on the peripheral surface of the tip of the inner conductor 2. The tip of the inner conductor 2 is a choke 6. The choke section 6 is set such that the distance between AB and BC is 1/4 of the operating wavelength. That is, the distance between A and C forms a choke that is の of the operating wavelength. Therefore, since the point C is short-circuited at a high frequency, the point A which is 離 れ wavelength away from the point C is also short-circuited at a high frequency.

In the thus configured cavity resonator, when the inner conductor 2 is moved in the axial direction, the resonance frequency of the cavity resonator changes. The inner conductor 2 is required to move smoothly without lowering Q _{0 of the} cavity resonator.

By the way, when the operating frequency of the cavity resonator is low, a so-called contact-type tuner in which the inner conductor moves while contacting the outer conductor can be employed, so that such a demand can be satisfied. Relatively easy. However, when the operating frequency is higher than the Ku band, the dimensions of the cavity resonator itself are reduced, and the dimensions of the contact type tuner are also reduced, so that extremely high processing accuracy is required. For this reason, when the operating frequency is high, machining is relatively easy,
The non-contact type tuner described above is employed.

[0009]

However, the cavity resonator of a conventional multi-cavity klystron provided with a non-contact type tuner has the following problems. That is,
Conventionally, molybdenum has been used as a material of the inner conductor 1 of a non-contact type tuner because of its high mechanical strength and small thermal expansion coefficient. However, since molybdenum has a relatively high electric resistance, the drift tube 3 of the inner conductor 1 is not operated during operation.
The inner conductor 1 is heated by the high-frequency current flowing on the side surface. As a result, the inner conductor 1 expands to change the resonance frequency and the electrical characteristics, or the portion of the inner conductor 1 that is outside the vacuum is oxidized, and air leaks from the joint with the bellows 5. There is.

The present invention has been made in view of the above problems, and has a multi-cavity type capable of suppressing heating of an inner conductor and avoiding inconveniences such as a change in resonance frequency and electric characteristics and occurrence of leakage. An object of the present invention is to provide a klystron cavity resonator.

[0011]

According to the present invention, a cavity resonator of a multi-cavity klystron has a cavity wall member in which a pair of drift tubes are disposed at an appropriate interval. A cylindrical outer conductor fixed to the cavity wall member and having an inner space communicating with the inner space of the cavity wall member; and a non-contact fit inside the outer conductor and movable in the axial direction of the outer conductor. In the cavity resonator of a multi-cavity klystron having an inner conductor, a conductor layer made of a conductor having an electric resistance of 2.5 μΩcm or less is provided on a surface of the inner conductor on the drift tube side at an operating frequency. It is characterized by being provided with a layer thickness greater than the depth of the skin.

[0012]

In the present invention, the inner conductor is formed of a conductor having an electric resistance of 2.5 μΩ · cm or less on the surface of the inner conductor on the drift tube side,
A conductor layer having a layer thickness equal to or greater than the skin depth (Skin Depth) at the operating frequency is provided. Therefore, the heat generated by the high-frequency current flowing on the surface of the inner conductor on the drift tube side during operation is reduced as compared with the conventional case, and the change in the resonance frequency due to the expansion of the inner conductor and the change in the electrical characteristics due to the temperature change can be avoided. Oxidation of the inner conductor is suppressed.

When the electric resistance of the conductor exceeds 2.5 μΩ · cm and when the thickness of the conductor layer is smaller than the depth of the skin at the operating frequency, the above effects cannot be sufficiently obtained. Therefore, the conductor layer has an electric resistance of
It is necessary to be made of a conductor of 2.5 μΩ · cm or less and have a layer thickness not less than the skin depth at the operating frequency. In addition, as a conductor having an electric resistance of 2.5 μΩ · cm or less,
For example, copper (1.72μΩ ・ cm) and gold (2.4μΩ ・ cm)
Etc.

[0014]

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

FIG. 1 is a sectional view showing a cavity resonator of a multi-cavity klystron according to a first embodiment of the present invention.

The present embodiment is different from the prior art in that a copper plating layer 7 is provided on the surface of the inner conductor 2 on the side of the drift tube 3, and the other configuration is basically the same as the conventional one. 1, the same components as those in FIG. 4 are denoted by the same reference numerals, and the detailed description thereof will be omitted.

The inner conductor 2 has at least the drift tube 3
The tip on the side is made of molybdenum. A copper plating layer 7 is provided on a surface of the inner conductor 2 on the side of the drift tube 3. The thickness of the copper plating layer 7 is set to be equal to or greater than the skin depth at the operating frequency. Further, a groove having an L-shaped cross section is provided on the peripheral surface of the distal end portion of the inner conductor 2, and a choke portion 6 is formed as in the conventional case.

In this embodiment, since at least the tip of the inner conductor 2 on the drift tube 3 side is formed of molybdenum, the inner conductor 2 has a small thermal expansion coefficient and has sufficient strength. Further, since the copper plating layer 7 is provided on the surface of the inner conductor 2 on the side of the drift tube 3, the impedance to the high-frequency current flowing on the surface of the inner conductor 2 during operation is low, and the power loss can be reduced. 2 can be suppressed. Therefore, it is possible to avoid the fluctuation of the resonance frequency and the fluctuation of the electric characteristics due to the thermal expansion of the inner conductor 2. Further, since the oxidation of the inner conductor 2 can be suppressed, the occurrence of a leak can be avoided. Further, in the present embodiment, at least the tip portion of the inner conductor 2 is made of molybdenum, so that the mechanical strength is high.

In consideration of the fact that copper is diffused into molybdenum due to brazing or the like in a manufacturing process, the thickness of the copper plating layer 7 is finally greater than the skin depth at the operating frequency. It is necessary to perform copper plating with a certain thickness. Further, in the above-described embodiment, the case where copper is plated on the surface of the inner conductor 2 on the side of the drift tube 3 has been described. However, instead of copper, another metal (for example, gold) having an electric resistance of 2.5 μΩ · cm or less is used. Etc.) may be plated. Furthermore, instead of plating, a metal plate with an electric resistance of 2.5 μΩ
It may be joined to the surface of the inner conductor by cladding or brazing.

FIG. 2 is a sectional view showing a cavity resonator of a multi-cavity klystron according to a second embodiment of the present invention.

This embodiment is different from the first embodiment in that the choke portion is also plated with copper, and the other structure is basically the same as that of the first embodiment. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and the detailed description thereof will be omitted.

In this embodiment, the copper plating layer 7a is formed not only on the surface of the inner conductor 2 on the side of the drift tube 3 but also on the choke portion 6.
It is also provided on the surface. The thickness of the copper plating layer 7a is set to be equal to or greater than the skin depth of the operating frequency.

In this embodiment, the same effect as that of the first embodiment can be obtained, and in addition, the effect of reducing the leakage of the high-frequency current to the choke portion can be obtained.

[0024]

As described above, according to the present invention, the conductor layer made of a conductor having an electric resistance of a predetermined value or less is provided on the surface of the inner conductor, which is fitted into the outer conductor in a non-contact manner, on the drift tube side. Is provided with a thickness equal to or greater than the depth of the skin at the operating frequency, so that power loss due to high-frequency current can be suppressed and heating of the inner conductor can be suppressed. Accordingly, it is possible to avoid the fluctuation of the resonance frequency and the fluctuation of the electric characteristics due to the thermal expansion, and it is possible to suppress the oxidation of the inner conductor, thereby preventing the occurrence of the leak.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a cavity resonator of a multi-cavity klystron according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a cavity resonator of a multi-cavity klystron according to a second embodiment of the present invention.

FIG. 3 is a schematic view showing a general multi-cavity klystron.

FIG. 4 is a cross-sectional view showing a cavity resonator of a conventional multi-cavity klystron.

[Explanation of symbols]

 1; outer conductor 2; inner conductor 3; drift tube 4; cavity wall member 5; bellows 6; choke portion 7, 7a; copper plating layer 10; electron gun 12; 20; intermediate cavity 22; output cavity

Claims (1)

(57) [Claims] 1. A cavity wall member in which a pair of drift tubes is disposed at an appropriate distance therebetween, and an interior space fixed to the cavity wall member and an interior space of the cavity wall member. In a cavity resonator of a multi-cavity klystron having a communicating cylindrical outer conductor and an inner conductor which is fitted into the outer conductor in a non-contact manner and is movable in the axial direction of the outer conductor, The surface of the conductor on the drift tube side has an electric resistance of 2.5 μΩ · c
A cavity resonator of a multi-cavity klystron, wherein a conductor layer made of a conductor having a thickness of not more than m is provided with a layer thickness greater than a skin depth at an operating frequency.