JPH05225917A - Collector structure for microwave tube - Google Patents

Abstract

PURPOSE:To provide a collector structure for a microwave tube, excellent in a heat radiating characteristic and a withstand voltage characteristic, where ceramic electrode struts or joining portions are difficult to be broken so as to enhance reliability. CONSTITUTION:In a collector structure of a microwave tube, a plurality of collector electrodes 1, 2, 3 are arranged in a file at predetermined intervals along an axis of the tube inside collector vacuum envelopes 14, 15, and circumferential edges 1a, 2a, 3a are electrically insulated from each other and held by ceramic electrode struts 4, 5, 6, 7. The collector vacuum envelope is made of a clad material consisting of a metal 16 having almost the same thermal expansion coefficient as that of ceramics and copper 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave tube collector structure suitable for use in traveling wave tubes, klystrons and the like.

[0002]

2. Description of the Related Art Generally, in a microwave tube, a high frequency acting section such as a slow wave circuit and a collector structure are arranged downstream of an electron beam in an electron gun section. For example, a traveling-wave tube mounted on an artificial satellite employs a potential-decreasing collector structure that operates by lowering the collector potential below the potential of the high-frequency action section in order to improve power utilization efficiency.

Conventionally, this type of collector structure is constructed as shown in FIG. 3, and reference numerals 1, 2, and 3 in FIG. 3 are first, second, and third collectors arranged in series along the tube axis. Electrodes, and their respective peripheral edge portions (flange portions) 1a, 2a, 3a are electrically insulated from each other and held by ceramic electrode columns 4, 5, 6, 7. Further, reference numeral 8 is a collector support substrate, 9 is a heat transfer support plate, 10 and 11 are collector vacuum envelopes, 12 is a connection end plate connected to a high-frequency acting unit (not shown), and 13 is a support cylinder.

By the way, in order to cool the collector electrodes 1, 2, 3 to transfer the heat generated in the collector electrodes 1, 2, 3 to the collector vacuum envelopes 10, 11, (1) mainly by radiation. And (2) mainly due to conduction. In the collector structure as described above, it is known that the following materials are used as materials for the collector vacuum envelopes 10 and 11. (1) Heat transfer mainly by radiation (a) Stainless steel, Kovar (trade name), etc. (2) Heat transfer mainly by conduction (a) Stainless steel, Kovar, etc. (b) Copper

[0005]

However, the collector structure as described above has the following disadvantages. (1) −
In the case of heat transfer due to radiation in (a), a sufficient amount of heat is not transferred unless the temperature on the radiating side is high, so the collector electrode becomes hot and the operation tends to become unstable.

In the case of heat transfer by conduction of (2) mainly, since there are only a limited number of heat conduction paths, if stainless steel, Kovar, etc. of (2)-(a) are used for the collector vacuum envelope, Due to the poor thermal conductivity of the material, the temperature gradient of the collector vacuum envelope itself is large. Therefore, the efficiency of heat conduction from the collector vacuum envelope to the outside further decreases, and the collector electrode becomes hot.

When copper of (2)-(b) is used for the collector vacuum envelope, the thermal conductivity of the material is good, so the temperature gradient of the collector vacuum envelope is small, but the mechanical strength is low. Since it is weak, it must be reinforced by thickening the material, and it tends to be heavy. Further, since copper has a thermal expansion coefficient approximately twice as large as that of ceramics, the ceramic electrode columns or the collector vacuum envelope itself is likely to be stressed by heat, resulting in lack of reliability. The present invention solves the above-mentioned inconveniences, and an object of the present invention is to provide a collector structure of a microwave tube having excellent heat dissipation characteristics and withstand voltage characteristics.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a plurality of collector electrodes are vertically arranged in a collector vacuum envelope along a tube axis at predetermined intervals, and their peripheral portions are electrically connected to each other by ceramic electrode columns. The collector vacuum envelope, which is insulated and held, is a microwave tube collector structure made of a clad material of copper and a metal having a coefficient of thermal expansion close to that of ceramics.

[0009]

According to the present invention, the heat dissipation characteristics and the withstand voltage characteristics are excellent, and the ceramic electrode columns or joints are less likely to be damaged, and the reliability is improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. The embodiment of FIG. 1 is an application of the present invention to a helix type traveling wave tube, and is constructed as follows.

That is, if the same parts as those in the conventional example (FIG. 3) are designated by the same reference numerals, the reference numeral 12 in the figure is a connecting end plate connected to a high frequency acting part (not shown). Through the support cylinder 13 to the collector support substrate 8
Is provided. Near the connection end plate 12, first, second, and third collector electrodes 1, 2, and 3 are vertically arranged along the tube axis from the upstream side to the downstream side of the beam at predetermined intervals, and each peripheral edge (flange (Parts) 1a, 2a, 3a are electrically insulated from each other and held by ceramic electrode columns 4, 5, 6, 7. The electrode columns 4 are fixed to the collector supporting substrate 8, and the electrode columns 7 are fixed to the heat transfer supporting plate 9. Further, collector vacuum envelopes 14 and 15 are provided so as to surround the collector electrodes 1, 2, 3 and the electrode columns 4, 5, 6, 7 and are fixed to the collector support substrate 8 and the heat transfer support plate 9. Has been done.

In this case, each collector vacuum envelope 14, 1
As shown in FIG. 2A, the reference numeral 5 is composed of a clad material of a metal 16 having a coefficient of thermal expansion close to that of ceramics, such as Kovar, and copper 17. In this embodiment, two layers of copper 17 are used to form a metal 16 such as Kovar, as shown.
Has a sandwiched structure. still,
The collector vacuum envelopes 14 and 15, the collector support substrate 8 and the heat transfer support plate 9 are thermally joined by brazing or the like.

During operation, an electron beam is trapped by each collector electrode 1, 2, 3 and each electrode generates heat. The heat generated in the collector electrodes 1, 2, 3 is transferred to the collector vacuum envelopes 14, 15 mainly through the electrode columns 4, 5, 6, 7 and the collector support substrate 8 and the heat transfer support plate 9. To be done. Further, heat is dissipated from the collector vacuum envelopes 14 and 15 to the outside by conduction or radiation.

Generally, in a collector structure having a structure in which heat is mainly conducted from the collector electrode to the collector vacuum envelope by conduction, the number of heat conduction paths is finite, so that the collector vacuum envelope is made of a material having poor heat conduction. When using, the temperature difference between the location near the heat conduction path of the collector vacuum envelope and the location far from it is large. Therefore, the efficiency of heat transfer from the collector vacuum envelope to the outside is further deteriorated.

However, according to the present invention, since the heat conduction of the portion of the copper 17 of the clad material constituting the collector vacuum envelopes 14 and 15 is good, the above-mentioned temperature difference is unlikely to occur and the heat transfer to the outside. Therefore, the temperature of the collector electrodes 14 and 15 can be lowered.

Further, in the above-mentioned clad material (hereinafter, the clad material of Kovar and copper will be described as an example),
Due to the low yield point of copper, the coefficient of thermal expansion is dominated by that of Kovar. As a result, the coefficient of thermal expansion of Kovar is about 60.
Since it is larger than ceramics at 0 ° C or higher, it is approximately 600
When brazing is performed at a temperature of ℃ or more, the stress applied to the ceramic electrode columns 4 to 7 in the tube axis direction becomes a compressive force. Furthermore, even when the residual stress at room temperature due to brazing is eliminated by annealing, the normal operating temperature (approximately 400 ° C
In the following), since the coefficient of thermal expansion of Kovar is smaller than that of ceramics, a force is applied to the ceramics in the compression direction. Therefore, problems such as damage to the ceramics or the joint portion do not occur. (Modification)

FIG. 2B shows a modified example of the collector vacuum envelope, and the same effect as that of the above-mentioned embodiment can be obtained. That is, in this modified example, the collector vacuum envelope has a metal 16 and a copper 1 whose coefficient of thermal expansion is close to that of ceramics, as in the above embodiment.
7 is a clad material, but as shown in the figure, a metal 16 close to ceramics is located on the vacuum side and a copper 17 on the atmosphere side.
Is located. In short, the clad material copper 17 may be on the vacuum side, the atmosphere side, or both sides. The present invention can also be applied to the case where a paint containing a material having a large emissivity as a main component is applied to the atmosphere side surfaces of the collector vacuum envelopes 14 and 15. The clad material forming the collector vacuum envelopes 14 and 15 may have a coefficient of thermal expansion larger than that of ceramics at the brazing temperature.

The clad material forming the collector vacuum envelopes 14 and 15 may have a coefficient of thermal expansion smaller than that of ceramics at the maximum temperature reached by the collector electrode during operation.

[0019]

According to the present invention, since the collector vacuum envelope surrounding the collector electrode is made of a clad material of a metal having a coefficient of thermal expansion close to that of ceramics and copper, heat is mainly conducted in the copper portion. The heat dissipation characteristics are excellent, damage to the ceramic electrode columns or joints does not occur easily, and reliability is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a collector structure of a microwave tube according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing two examples in which a main part of FIG. 1 is enlarged.

FIG. 3 is a cross-sectional view showing a collector structure of a conventional microwave tube.

[Explanation of symbols]

1, 2, 3 ... Collector electrodes, 1a, 2a, 3a ... Peripheral portions, 4, 5, 6, 7 ... Ceramic electrode columns, 8 ... Collector support substrate, 9 ... Heat transfer support plate, 14, 15 ... Collector vacuum Envelope, 16 ... Metal whose thermal expansion coefficient is close to that of ceramics, 17 ... Copper.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Ide 1385-1 Shimoishigami, Otawara-shi, Tochigi Stock company Toshiba Nasu electron tube factory

Claims (4)

[Claims] 1. A collector structure of a microwave tube, wherein a plurality of collector electrodes are arranged at a predetermined interval in a collector vacuum envelope, and each peripheral portion is electrically insulated and held by ceramic electrode columns. The collector vacuum envelope is a collector structure of a microwave tube, which is made of a clad material of a metal having a coefficient of thermal expansion close to that of ceramics and copper. 2. The collector structure for a microwave tube according to claim 1, wherein a paint containing a material having a large emissivity as a main component is applied to the atmosphere side surface of the collector vacuum envelope. 3. The collector structure of the microwave tube according to claim 1, wherein the clad material forming the collector vacuum envelope has a coefficient of thermal expansion larger than that of ceramics at a brazing temperature. 4. The collector structure of the microwave tube according to claim 1, wherein the clad material forming the collector vacuum envelope has a coefficient of thermal expansion at a maximum temperature of the collector electrode during operation smaller than that of ceramics.