JPS6348381B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a support structure for 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 part that generates an electron beam, a high-frequency circuit part (helix part) that interacts with the electron beam and electromagnetic waves, a collector part that captures the electron beam, and a collector part that focuses the electron beam.
Common components include the PPM and a case to hold and store the tube.

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 section, 2 is a high frequency circuit section and a PPM section, 3 is a collector section, 4 is a base plate forming part of the case,
5 represents a support for a high frequency circuit. Further, a cross section AA' in FIG. 1 is shown in FIG. 2. Second
In the figure, a part of the outer periphery of one magnet 2' constituting the PPM is supported by a support 5.
The support body 5 is fixed to the base plate 4 with screws or the like. Also, the magnet 2' is connected to the support 5.
A copper band 6, usually about 0.5 to 1 mm thick, is fixed to the support 5 with the magnet 2' in between to prevent it from floating. 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 for this is that a small magnetic body 7 is placed at an arbitrary position on the PPM to correct the biased magnetism of the magnet, so that the transmittance of the electron beam can be adjusted. In this case, placing the small magnetic body 7 outside the thick band 6 is of no use in adjusting the beam transmittance. This is because they are magnetically isolated by the thickness of the band, which significantly weakens the effect of correcting biased magnetism.

However, such a conventional structure has the following drawbacks. 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 causes the value to become smaller.

In view of the above-mentioned drawbacks of the structure, another high-frequency circuit support structure has been devised that allows beam transmittance to be easily adjusted while maintaining sufficient mechanical strength of the helix circuit.

An example of its structure is shown in FIG. As shown in the figure, in this structure, the first
Now, instead of the conventional supports installed at several locations in the axial direction, one support body is installed across the entire axial direction.
A long book support 8 is used. Also, secondly,
A very thin stainless steel cover 9 (0.1mm thick) is used instead of the traditional copper band (0.5~1mm thick).
~0.15 mm), which is in principle the same length as the long support described above. and,
Thirdly, the small magnetic body 7 for beam transmission adjustment is attached to the outside of the thin cover 9.

The first feature of this support structure is that because the high-frequency circuit is supported in the entire axial direction, there are no suspended parts as in conventional structures, making it mechanically extremely strong. . In addition, the second feature is that the thickness of the cover 9 can be made thinner by selecting the material, and the distance between the small magnetic material and the PPM can be reduced, thereby increasing the effect of the small magnetic material on the PPM, thereby increasing the mechanical strength. The point is that the beam can be easily adjusted from outside while maintaining the same position. In this structure, the small magnetic body 7 cannot be attached to the part where the support 8 is present, that is, the lower half of the PPM, but the beam transmission can be adjusted by the PPM.
It has been confirmed that simply placing a small magnetic material on the upper half of the device is sufficient for practical use.

However, it has been found that the above-described high frequency circuit support structure has the following drawbacks. In other words, when the cover 9 is screwed to the support 8, the high-frequency circuit is tightly sandwiched in the fixation at the beginning of assembly, but as the cover 9 is repeatedly operated as a traveling wave tube, the heat of the high-frequency circuit increases. It has become clear that the pinching force gradually weakens as the material expands and contracts.

An object of the present invention is to provide a helical traveling wave tube having a support structure that does not allow the support mechanism to loosen due to repeated thermal expansion and contraction.

According to 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 extends approximately equal to the entire length of the high-frequency circuit in the tube axis direction, and extends below the outer diameter of the magnet. Half or a part of the cover is supported in the tube axis direction by a support, and a very thin cover whose length in the tube axis direction is approximately equal to the support and has a large elastic modulus is sandwiched between magnets. A traveling wave tube is obtained, which is attached to a support within an elastic range and is characterized in that the magnetic field of the periodic permanent magnet is adjusted from outside the cover.

An example of the structure of the high frequency circuit support mechanism according to the present invention is shown in FIG. In Fig. 5, the cover 9 does not have an inverted U-shaped cross section, but has a structure in which both ends are bent horizontally from the middle, and both ends of the support 8 are also spread out accordingly. ing. For the cover 9, a non-magnetic material with a large elastic modulus such as stainless steel or phosphor bronze is selected.
As used within the elastic change of that material, the screw 1
It can be installed at 0. In such a configuration, even if the high frequency circuit undergoes thermal expansion and contraction, the probability that the support mechanism will become loose is greatly reduced.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a conventional high frequency circuit support structure of a helical traveling wave tube, Fig. 2 is a sectional view taken along line A-A' in Fig. 1, and Fig. 3 is a high frequency circuit support structure shown in Fig. 1. FIG. 4 is a perspective view showing an improved conventional high frequency circuit support mechanism, and FIG. 5 is a perspective view showing a high frequency circuit support mechanism according to the present invention. In the figure, 1 is the electron gun section, 2 is the high frequency circuit and PPM section, 3 is the collector section, 4 is the base plate that forms part of the case, and 5
is a high frequency circuit support body, 6 is a band, 7 is a small magnetic body, 8 is a high frequency circuit support body, 9 is a cover, and 10 is a screw.

Claims (1)

[Claims] 1. A high frequency circuit with a periodic permanent magnet on the outer periphery,
The high-frequency circuit is supported by a high-frequency circuit support member having a length approximately equal to the total length of the high-frequency circuit and provided with a groove for receiving approximately the lower half of the periodic permanent magnet, and is made of a non-magnetic material with a large elastic modulus. A thin cover that is approximately the same as the support and has a thin thickness is placed over the high-frequency circuit, and both ends of the cover are bent horizontally from the middle, and the high-frequency circuit support also conforms to the bending of both ends of the cover. The traveling cover has a protrusion extending in the horizontal direction, and both ends of the cover are fixed to the protrusion of the high-frequency circuit support within an elastic change of the material of the cover. tube.