JPH0228587Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a radiation-cooled multistage collector mainly used in high-power traveling wave tubes mounted on satellites.

In high-power traveling wave tubes mounted on satellites, the collector electrode is divided into multiple parts and different voltages are applied to each part in order to minimize power consumed as heat loss in the collector and improve efficiency. In this way, a multi-stage collector is generally used that separates the electron beams, which have a velocity distribution after mutual use with a high frequency, according to their respective velocities and captures them while minimizing heat loss. In addition, since a lot of heat is generated in the collector, in order to prevent the temperature of the satellite body from rising, a traveling wave tube is installed on the satellite with the collector protruding outside the outer wall of the satellite, and the heat generated in the collector is directly transmitted to space. A radiation-cooled collector that dissipates radiation by radiation is used. Radiation-cooled multi-stage collectors used in such traveling wave tubes for satellites include:
Small size, light weight, and reliability against environmental conditions such as vibration and temperature are particularly required.

Conventional multi-stage collectors have each collector electrode made of a thin metal plate into the desired shape;
Cylindrical porcelain insulators of the desired height arranged at several locations symmetrical about the central axis are stacked alternately, each collector electrode is placed at the desired position, and the porcelain insulators at both ends are stacked alternately. It is connected to a metal support member, and the metal support member is further connected to a metal vacuum envelope that covers the entire structure. In this structure, the heat generated at each collector electrode is transferred from the higher temperature collector electrode to the lower temperature electrode by radiation.
Also transmitted from each collector electrode to the vacuum envelope,
It is also transmitted by conduction from the high-temperature collector electrode to the vacuum envelope via the porcelain insulator and the low-temperature collector electrode, and is eventually dissipated from the vacuum envelope into space by radiation. . The connection between the collector electrode and the porcelain insulator, which is a path for transmitting heat from the collector electrode to the vacuum envelope by conduction, is difficult to fix by brazing because there is a risk of damage due to the difference in thermal expansion. Therefore, conventional devices have a structure in which the connection portions are mechanically tightened using screws and nuts to bring them into contact.
However, due to differences in thermal expansion of the constituent members, the structure was not such that the contact between the connecting parts could always be maintained in good condition. If the contact condition deteriorates, heat dissipation by conduction from the collector electrode to the vacuum envelope will not be sufficient, leading to an increase in the collector electrode temperature, and as a result, the vacuum inside the tube will decrease due to gas release from the high temperature part. There is a risk of deterioration and even malfunction due to this.

In order to prevent such problems, it is possible to increase the surface area of the vacuum envelope and lower the temperature of the vacuum envelope, but this increases the size and weight of the collector. The increased weight of the collector also requires that the support structure of the collector be made stronger to withstand vibrations, further increasing the weight.

This invention provides a multistage collector that eliminates these conventional drawbacks, and allows good contact between the collector electrode and the porcelain insulator that supports it to be maintained at all times. That is, by inserting a dish-shaped spring washer into one end of the screw and tightening it with a nut, the elastic force of the dish-shaped spring washer is utilized to avoid deterioration of the contact state.

Next, this invention will be explained with reference to embodiments shown in the drawings. FIG. 1 shows a multi-stage collector in cross-section along a plane passing through the central axis. A support plate 2 that supports the collector is brazed to the body 1 (only a portion is shown), and a stainless steel bellows 3 is attached to the support plate 2.
A cylindrical vacuum envelope 4 made of thin-walled metal is brazed to the vacuum envelope 4, and this vacuum envelope 4 and a dish-shaped vacuum envelope 5 made of thin-walled metal are arc welded at their respective brim portions to create a collector vacuum. An envelope is formed. Further, a support plate 7 is brazed to the support plate 2 via stainless steel columns 6. The outer edge of the support plate 7 is brazed to the connection between the bellows 3 and the vacuum envelope 4. Each of the first to fourth collector electrodes 8, 9, 10, and 11, each made of a thin metal plate into a desired shape, is connected to a cylindrical porcelain insulator 12 of a desired height at several locations symmetrical about the central axis. The porcelain insulator 12 is maintained at a required spacing in the central axis direction.
The first collector electrode side is connected to the support plate 7, and the fourth collector electrode side is connected to the support plate 13. A screw 14 and an insulating tube 15 pass through holes drilled in each of the first to fourth collector electrodes inside the porcelain insulator 12, and one end of the screw 14 is brazed to the support plate 7. , and the other end is tightened with a nut 18 via a flat washer 17 after 162 dish-shaped spring washers are arranged facing each other through a support plate 13. The dish-shaped spring washer has a shape as shown in FIG. 2, and is made of a high-temperature spring material such as Inconel. The support plate 13 supports the vacuum envelopes 4 and 5.
connected to the connection part. Fourth collector electrode 1
1 is connected to the bottom center of the vacuum envelope 5 via an insulating member 19 made of porcelain.

In such a configuration, voltages having a large potential drop from the body potential are applied to the first to fourth electrodes in that order through a power supply line (not shown). Therefore, among the electron beams that have generated a velocity distribution due to interaction with the high frequency, the slowest electrons are the first
Electrons with higher speeds enter the second to fourth collector electrodes in order, and heat loss occurs depending on the speed of the electrons at the time of incidence. The heat generated at each collector electrode is partially transferred by radiation from the hotter collector electrode to the cooler collector electrode, and from each collector electrode to the vacuum envelope. The remainder of the heat is transferred by conduction through the porcelain insulator 12 to the support plates 7 and 13 and then to the vacuum envelope by conduction. Further, a portion of the heat is transferred from the fourth collector electrode 11 to the vacuum envelope 5 by conduction through the porcelain insulating member 19. Since the support plate 7 and the vacuum envelope 4 are insulated from the support plate 2 by the stainless steel posts 6 and bellows 3, which have poor thermal conductivity, almost no heat generated in the collector is transferred to the body side. It is dissipated by radiation from the surface of the collector vacuum envelope into space.

In such a configuration, in order to improve heat transfer by conduction from the collector electrode to the vacuum envelope, the connection portions of each member in the conduction path must have good contact. However, if the first to fourth collector electrodes are respectively 8, 9, 10, 1
1. If the connection parts between the support plates 7 and 13 and the porcelain insulator 12 are brazed, contact thermal resistance is eliminated and heat can be transferred with a low temperature difference, but the amount of heat generated at each collector electrode is A shear force is generated at each connection due to the temperature difference between each collector electrode caused by the difference, and the difference in radial expansion between the collector electrode and the support plate due to the temperature difference.
There is a risk that the porcelain insulator will crack and the contact thermal resistance will increase. Therefore, in the conventional method, and also in this invention, the above-mentioned dangers associated with brazing joints are eliminated by tightening and contacting this connection part with the screw 14 and nut 18. It is.

However, in the conventional one, the screw 14
and the porcelain insulator tightened by the nuts 16, due to the difference between the total longitudinal thermal expansion of the screws of the collector electrodes 8, 9, 10, 11 and the support plate 13, and the thermal expansion of the screws. However, it is difficult to maintain good contact at all times. In other words, if alumina ceramic is used as the material for the porcelain insulator 12, and stainless steel is used as the material for the screw 14, for example, stainless steel has a larger coefficient of thermal expansion than alumina ceramic, so the screw and nut will become tighter when not in operation. Even when tightened, the screws reach high temperatures during operation, so the screws stretch and loosen more than the porcelain insulators. Furthermore, if molybdenum, which has a smaller thermal expansion coefficient than alumina ceramic, is used as the material for the screw 14, for example, if the screw and nut are tightly tightened when not in operation, the screw will be stretched and plastically deformed during high-temperature operation. It will end up being cut. In this invention, the disc-shaped spring washer absorbs the dimensional difference due to thermal expansion between the screw and the porcelain insulator etc. tightened by the screw and nut, so good contact is maintained over a wide temperature range from non-operation to operation. is obtained.

As explained in detail above, the multi-stage collector of this invention can obtain good contact conditions over a wide temperature range, thus avoiding the increase in collector temperature due to contact deterioration and the occurrence of problems caused by this, unlike conventional ones. It will be done. Furthermore, it is not necessary to increase the size of the collector to prevent this problem from occurring, and the collector can be made smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the radiation-cooled multi-stage collector of this invention, and FIG. 2 is a sketch of a dish-shaped spring washer according to the invention. 1... Body, 2, 7, 13... Support plate, 4,
5... Vacuum envelope, 8, 9, 10, 11... 1st, 2, 3, 4 collector electrodes, 12, 19... Porcelain insulator, 14... Screw, 15... Insulating tube, 1
6... dish-shaped spring washer, 17... flat washer,
18...Natsuto.

Claims (1)

[Scope of utility model registration request] A plurality of collector electrodes are arranged on a support member using porcelain insulators at required intervals at several locations symmetrical to the center axis, and are held between screws and nuts whose one end is fixed to the support member. A radiation-cooled multi-stage collector covered with a metal vacuum envelope, characterized in that a disc-shaped spring washer is inserted into one end of the screw and tightened with the nut.