JPH0142107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for supporting a high frequency circuit of a helical traveling wave tube using a periodic permanent magnet (PPM) as an electron beam focusing device.

A helical traveling wave tube consists of an electron gun section that generates an electron beam, a high-frequency circuit section (helix section) that interacts between the electron beam and electromagnetic waves, a collector section that captures the electron beam, a PPM that focuses the electron beam, and a tube. A common component is a case that holds and stores the ball.

As is well known, the helical traveling wave tube has a relatively simple high-frequency circuit structure and a relatively small outer diameter, so it has the great feature that electron beam focusing by PPM can be easily performed.

An example of the structure of a typical conventional helical traveling wave tube is shown in FIG. In Fig. 1, 1 is an electron gun part, 2 is a high frequency circuit and PPM part, 3 is a collector part, 4 is a base plate forming part of the case, and 5
indicate the supports of the high-frequency circuit, respectively. Further, a cross section AA' in FIG. 1 is shown in FIG. 2. In FIG. 2, a part of the outer periphery of one magnet 2' constituting the PPM is supported by a support 5, and the support 5 is fixed to the base plate 4 with screws or the like. In order to prevent the magnet 2' from floating off the support 5, a copper band 6 with a thickness of approximately 0.5 to 1 mm is usually placed between the magnet 2' and the support 5.
is fixed to. The reason why the band 6 is made of copper is to conduct the heat generated in the high-frequency circuit to the support body and release it. If only the support body 5 and band 6 are taken out and shown three-dimensionally, the result will be as shown in FIG. In the conventional structure, such support mechanisms were installed at several locations along the tube axis, leaving spaces between each support. The reason is that at any position on the PPM,
This is to make it possible to adjust the transmittance of the electron beam by placing a small magnetic body 7 for correcting the biased magnetization of the magnet. In this case, if the small magnetic material 7 is placed outside the thick band 6,
Not useful for beam transmittance adjustment. because,
This is because the band is magnetically isolated by the thickness of the band, which significantly weakens the effect of correcting biased magnetism.

The inventor found the following drawbacks in such a conventional structure. That is, a helical traveling wave tube generally has a long overall circuit length despite its small circuit outline, and its mechanical strength is originally very weak. Therefore, even if such a circuit is supported by several supports, the mechanical strength of the portions not supported by the supports is very weak. In addition, even if the circuit has good straightness at the manufacturing stage, unexpected impacts during transportation or mounting may deform part of the circuit (the part not supported by the support) and deteriorate the beam transmission characteristics. can also occur. However, increasing the number of supports will increase the cost, making it difficult to center each support, and where to place the small magnetic material for adjusting the biased magnetism mentioned above. This is not desirable as it also results in a decrease in

An object of the present invention is to provide a traveling wave tube equipped with a new high-frequency circuit support structure that eliminates the drawbacks of the conventional structure and allows easy adjustment of beam transmittance while maintaining sufficient mechanical strength of the helix circuit. That's true.

In the present invention, a periodic permanent magnet is used as an electron beam focusing device, and the high-frequency circuit support member forming a part of the case is approximately equal to the entire length of the high-frequency circuit in the tube axis direction, and the lower half of the outer diameter of the magnet or A part of it is received by the support body in the tube axis direction, and further, the length in the tube axis direction is approximately equal to the support body,
It is characterized in that a very thin cover is attached to a support with a magnet in between, and the magnetic field of the periodic permanent magnet is adjusted from outside the cover.

An example of a support structure according to the present invention is shown in FIG. As seen in the figure, in the present invention,
First of all, instead of conventional supports that are installed at several locations in the axial direction, one long support 8 is used that extends throughout the axial direction. Secondly, conventional copper bands (0.5-1mm thick)
Instead, use a very thin stainless steel presser plate 9.
(thickness: 0.1 to 0.15 mm), which is designed to have the same length as the long support 8 described above in principle. Thirdly, the small magnetic body 7 for beam transmission adjustment is attached to the outside of the thin holding plate 9.

The first feature of the support structure of the present invention is that since the high frequency circuit is supported in the entire axial direction, there is no suspended part as in the conventional structure, and the structure is mechanically extremely strong. It is. Also, the second
The feature is that the thickness of the holding plate 9 is made thinner by selecting the material, and the distance between the small magnetic material and the PPM is brought closer to increase the effect of the small magnetic material on the PPM, while maintaining mechanical strength. , the beam can be easily adjusted from outside. In the structure of the present invention, the portion where the support body 8 is present,
In other words, although it is not possible to attach the small magnetic material 7 to the lower half of the PPM, the beam transmission can be adjusted.
It has been confirmed that simply placing a small magnetic material in the upper half of the PPM is sufficient for practical purposes.

In addition, as another structure of the present invention, the support and PPM
The joint portion may not be arcuate but may be linear as shown in FIG. 5, or may have an intermediate structure as shown in FIG. 6.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing an example of the structure of a conventional helical traveling wave tube, and FIG.
A′ sectional view, FIG. 3 is a perspective view of the high frequency circuit support mechanism section of FIG. 1, FIG. 4 is a side view of the high frequency circuit support mechanism according to the present invention, and FIGS. FIG. 3 is a perspective view showing another embodiment of the invention. 1 is the electron gun section, 2 is the high frequency circuit section and PPM section, 3 is the collector section, 4 is the base plate that forms part of the case,
5 is a high frequency circuit support body, 6 is a band, 7 is a small magnetic body, 8 is a support body, and 9 is a presser plate.

Claims (1)

[Claims] 1. A high-frequency circuit using periodic permanent magnets is supported over almost its entire length by a support, and
A traveling wave tube, characterized in that the tube is attached to the support by a very thin holding plate extending in the tube axis direction, and a small magnetic body is directly provided on the holding plate.