JPS6217969Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a collector that has high efficiency in dissipating heat generated by collecting electron beams that have finished participating in the high frequency amplification function of a traveling wave tube.

In a traveling wave tube, part of the kinetic energy of an electron beam generated from an electron gun is converted into high frequency energy in a slow wave circuit, but most of it is converted into thermal energy in a collector.

Therefore, the collector becomes a heat generation source, and the heat generated in the collector increases the temperature of the tube during operation. However, for stable operation of the tube, it is necessary to lower the tube temperature as much as possible, so heat dissipation components are attached to the collector, and the heat generated in the collector is dissipated to the outside by means such as conduction cooling or forced air cooling. are doing.

Figure 1a shows a conventional traveling wave tube with a metal vacuum envelope, which uses a spiral slow wave circuit, has a periodic magnetic field device as an electron beam focusing device, and uses a conduction cooling method. FIG. 2 is a cross-sectional view, with some parts missing, showing a traveling wave tube housed in a metal case. Further, FIG. 1b shows a cross section taken along the line A-A' in FIG. 1a. 1st
In Figures a and b, an electron beam generated in an electron gun (not shown) is focused by a periodic magnetic field device 3 and guided to a substantially cylindrical collector 5 via a slow wave circuit 1. The ceramic ring 4 electrically insulates the collector 5 and the metal vacuum envelope 6 which are at the same potential as the slow wave circuit 1. A high frequency wave to be amplified is guided from an input section (not shown) to a slow wave circuit 1, amplified by interaction with an electron beam, and taken out from an output section 2. The heat generated in the collector 5 is conducted to the metal case substrate 12 via the heat radiator 7 that surrounds the outer circumferential surface of the collector 5, and is radiated to the outside. The case cover 11 and the case substrate 12 constitute the case 10, and are made of non-magnetic metal in consideration of heat dissipation and influence on the magnetic field generated by the periodic magnetic field device 3. In addition, case 10 is
In the case of a traveling wave tube having a metal vacuum envelope, this potential is the same as the DC potential of the slow wave circuit 1, and at the same time serves as a grounding point. Therefore, in order to operate the collector 5 at a lower potential than the DC potential of the slow wave circuit 1, the collector 5 and the case 10 need to be electrically insulated. A flat insulating plate 8 performs this function, and insulates between the metal heat sink 7 and the metal heat sink 9. As the insulating plate 8, an insulating material with good thermal conductivity, such as beryllia porcelain, is usually selected. A metal coating is formed on the surface of the insulating plate 8 that comes into contact with the heat sink 7 and the heat sink 9, and soldering is performed on each of these contact surfaces to improve heat conduction between the heat sink 7, the insulating plate 8, and the heat sink 9. It is fixed to the case board 12 in good condition.

However, in such a conventional structure, the collector 5 has a cylindrical shape, and the inner diameter of the cylindrical hole that accommodates the collector 5 of the heat sink 7 is equal to the collector 5.
Since it is machined to be slightly larger than the outer diameter of the collector 5, the effective contact area between the fitting part of the collector 5 and the heat sink 7, that is, the effective contact area necessary for heat conduction, decreases and the heat dissipation efficiency deteriorates. .

In order to improve this drawback, as shown in FIG. 1b, the heat sink 7 is tightened with screws 13 to firmly hold the collector 5 and to increase the contact area between the collector 5 and the heat sink 7. , Collector 5, etc. Since there are restrictions on the tightening torque for reasons such as preventing deformation of each component that makes up the tube, in the case of an actual tube, the effective contact area is about several tens of percent of the total area of the fitting part. The heat generated in the collector 5 was not well conducted to the heat sink 7, and the temperature of the collector 5 sometimes rose abnormally.

Furthermore, since there is a difference in the coefficient of thermal expansion between the metal heat sink 7 and heat sink 9 and the insulating plate 8 made of an insulator such as beryllia or alumina ceramic,
It is difficult to control the design and manufacturing conditions, and there is a high risk that minute cracks will occur in the insulating plate 8 due to soldering, reducing the withstand voltage, which may lead to a decrease in manufacturing yield. Also, case 10
On the other hand, since the tube components such as the output line 2 and the collector 5 must be held accurately at their respective predetermined positions, they must contact the case substrate 12 of the heat sink 9 from the central axis of the hole in the heat sink 7. It is necessary to keep the dimensional tolerance of the distance l to the surface as small as possible.
However, since the heat conduction path from the collector 5 to the case board 12 is formed by the heat sink 7, the insulating plate 8, and the heat sink 9, the dimensional accuracy of each component and the dimensional accuracy of the assembly by soldering are extremely high. Alternatively, after assembling the heat sink 7, insulating plate 8, and heat sink 9 by soldering, further processing is required to improve the accuracy of the dimension l, which also has the disadvantage that the heat sink of the collector is extremely expensive. Ta.

In addition, in order to eliminate the above-mentioned drawbacks, the second
As shown in the figure, a thin insulating sheet 22 made of Teflon or other material with high insulation resistance is wrapped around the collector 5.
A method was devised to dissipate heat to a heat sink through this sheet. However, conventional insulating sheets such as Teflon have high insulating properties but do not have high thermal conductivity and also lack elasticity. Generally, in this method, thermal conductivity is sacrificed because insulation is emphasized, and since elasticity is poor, it is difficult to increase the contact area between the collector 5 and the heat dissipating body 21, which is effective for heat conduction. Therefore, the application of this method was limited to traveling wave tubes, etc., where the amount of heat generated in the collector is small. Furthermore, in order to increase the contact area between the collector 5 and the heat sink 21, a metal cylinder 23 with good heat conduction is provided on the outer circumferential surface of the collector 5, so that the surface area of the collector 5 is substantially increased. Then, an insulating sheet 2 is placed on the outer circumferential surface of the metal cylinder.
Another disadvantage was that it required a complicated and large structure in which the heat dissipating body 21 was wound around the heat dissipating body 21 and brought into contact with the heat dissipating body 21.

The purpose of the present invention is to improve the drawbacks of the conventional structure described above, and to provide a traveling wave tube having a highly reliable collector heat dissipation structure that is small, inexpensive, and has a high heat conduction effect. be.

According to the present invention, there is provided an electron gun that generates an electron beam, a slow wave circuit that performs high frequency amplification through interaction between the electron beam and the high frequency, and an electron beam that has finished participating in the high frequency amplification effect in the slow wave circuit. In the traveling wave tube having a collector for collecting . More specifically, a traveling wave tube is obtained in which a heat radiator having a collector fitting groove with a substantially semicircular cross section and a substantially cylindrical collector are coupled via an insulating sheet.

FIG. 3 is a cross-sectional view showing an embodiment of the present invention. In FIG. 3, the heat sink 41 has a collector fitting groove with a substantially semicircular cross section, and the metal fixing member 4
3 has a collector fitting portion having a substantially semicircular cross section. The cylindrical collector 5 is placed in the collector fitting groove of the heat sink 41 via the insulating sheet 42 containing boron nitride, and further faces the surface fitted to the collector fitting groove on the circumferential outer surface of the collector 5. The circumferential outer surface is connected to the fixing member 4 via a similar insulating sheet 44.
The collector 5 is fixed to the heat sink 41 by fitting into the collector fitting portion 3 and tightening with the screw 13 . Further, the heat sink 41 is fixed to the case substrate 12. In this example, a metal plate with a thickness of 0.6 mm was used as the fixing member 43, and it was possible to obtain a highly reliable collector heat dissipation structure that was inexpensive, lightweight, and had a good heat dissipation effect. In the collector heat radiator structure according to this embodiment, since an insulating sheet having elasticity and flexibility is used, the collector 5 and the insulating sheet 42 and the insulating sheet 42 and the heat radiator 41
The effective contact area that contributes to heat conduction between the two is large. Therefore, the heat radiation path of the traveling wave tube, which generates a relatively small amount of heat in the collector 5, is from the collector 5 to the heat radiator 41 via the insulating sheet 42 in FIG.
In many cases, just the route leading to is sufficient. In such a case, it is not necessary to use a metal part as the fixing member 43, and it may be made of heat-resistant plastic or the like. Further, the structure may be such that the fitting area between the fixing member 43 and the collector 5 is small. When an electrically insulating material is used as the fixing member 43,
The insulating sheet 44 is not required, and the structure can be made simpler, lighter, and cheaper. As the insulating sheets 42 and 44, for example, sheets made of boron nitride and silicone rubber as main components and reinforced with glass fibers can be used.

As shown in the above embodiments, the present invention has the ability to:
It is possible to obtain a collector heat dissipation structure for a traveling wave tube that has superior voltage resistance characteristics than the conventional one and is inexpensive, small and lightweight.

Note that it is clear that the present invention is not limited by the shape and structure of each component or the shape of the insulating sheet.

[Brief explanation of the drawing]

Figures 1a and b are an axial cross-sectional view and an AA' cross-sectional view of a conventional traveling wave tube, respectively; Figure 2 is a cross-sectional view showing another example of the conventional type; and Figure 3 is a cross-sectional view of the present invention. FIG. 3 is a cross-sectional view of one embodiment of the invention. In the figure, 1 is a slow wave circuit, 5 is a collector, 7, 21, 41 are heat sinks, 42, 44 are insulating sheets containing boron nitride having elasticity and flexibility, and 43 is a fixing member.

Claims (1)

[Scope of utility model registration request] A substantially cylindrical collector 5 is fitted into a heat sink 41 having a collector fitting groove with a substantially semicircular cross section via an insulating sheet 42 containing boron nitride.
The fixing member 4 is inserted through the insulating sheet 44 from the top of the
A traveling wave tube characterized by being fixed by 3.