JPS59228342A - Multiple-cavity klystron - Google Patents

Abstract

PURPOSE:To make a permanent magnet focusing device lightweight and facilitate handling and reduce production cost by comprising a part or the whole of at least either of cavity walls of the input and output resonant cavities in resonant cavities with a magnetic body. CONSTITUTION:An electron gun section 1 that generates an electron beam, a high frequency circuit section 2 that performs the interaction between the electron beam generated from this electron gun section 1 and high frequency power, and a collector section 3 that catches the electron beam for which the interaction between it and the high frequency power is completed, and a permanent magnet 4 that forms a magnetic field which focuses the electron beam are provided. The high frequency circuit section 2 in such a multiple cavity klystron is comprised with a number of resonant cavities 10 and a part or the whole of one or both cavity walls of the input and output resonant cavities in the resonant cavities is comprised with a magnetic body. For example, the opposed section of an input section magnetic pole piece 6 for an output section magnetic pole piece 7 is comprised with the cavity wall of the input resonant cavity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvement of a multi-cavity klystron. As is well known, a multi-cavity talistron includes an electron gun section that emits an electron beam, and an electron beam emitted from the electron gun section. and a collector section that captures the electron beam that has finished interacting with the radio frequency power in the radio frequency circuit section and converts it into thermal energy, and the electrons emitted from the electron gun section. It consists of a focusing device that generates a magnetic field to focus the beam and pass the electron beam through the high-frequency circuit section. Among these, the high frequency circuit section usually consists of 4 to 6 resonant cavities, a cheese mechanism for varying the resonant frequency of the resonant cavities, and a coupling section between the input and output circuits. Coupling is performed in the input cavity, which is the resonant cavity closest to the electron gun section, and coupling with the output circuit is performed in the output cavity, which is the resonant cavity located closest to the collector. Further, the focusing device is composed of an electromagnet or a permanent magnet, and magnetic pole pieces of an input section and an output section placed at both ends of the high frequency circuit section for leaking a magnetic field into the high frequency circuit.

In a multi-cavity talistron with a relatively low output of about 3 kW or less, the electron beam can be focused with a relatively weak magnetic field due to the miniaturization of the entire klystron and ease of operation, so permanent magnets are used. A focusing device is used.

FIG. 1 shows an example of a multi-cavity talistron using a conventional permanent magnet focusing device. In FIG. 1, 1 is an electron gun section that generates an electron beam, 2 is a high frequency circuit section, 3 is a collector section that captures the electron beam and converts it into thermal energy;
4 is a permanent magnet, 5 is a yoke, 6 is an input magnetic pole piece, 7 is an output magnetic pole piece, 8 is an input circuit, 9 is an output circuit, 10 is a resonant cavity constituting a high frequency circuit, and 11 is an electron beam path. Drift tube is shown. FIG. 1 shows a case where the input circuit 8 is a coaxial line and the output circuit 9 is a waveguide.

Now, in Figure 1, the strength of the magnetic field created by the permanent magnet 4 is
The magnitude of the electron beam current passing through the high frequency circuit, the diameter of the electron beam when passing through the drift tube 11, the length tg between the input magnetic pole piece 6 and the output magnetic pole piece 7, the input magnetic pole piece 6
It is determined by the opposing area Sg of the output magnetic pole piece 7, etc. The larger the electron beam current and the smaller the electron beam diameter, the stronger the magnetic field needs to be, so the permanent magnet 4 needs to be larger or made of a magnetic material that can produce a strong magnetic field. 0 If the distance tg between the magnetic pole pieces 6 and 7 becomes longer, the length tm of the permanent magnet 4 will normally be longer in proportion to Ag in order to obtain the magnetic field necessary to pass the electron beam through the high-frequency circuit. Is required. However, the distance tg between the input and output magnetic pole pieces 6°7 is required for a multi-cavity klystron, and the length of the high frequency circuit section is determined by the fc maximum output, the available bandwidth, and the electron beam voltage and current. cannot be made any shorter than necessary.

Further, the magnet cross-sectional area Sm needs to be large enough to pass the magnetic flux generated by the magnet 4 without saturating it.

In addition, in order to effectively obtain a magnetic field distribution between the input and output magnetic pole pieces 6.7, a certain amount of magnetic pole piece opposing area of 8 g is required,
Generally, the larger sg is, the larger the magnet cross-sectional area Sm is required19, and the magnet cross-sectional area cannot be made smaller than necessary.

In this way, the size of the permanent magnet 4 of the multi-cavity klystron is determined mostly by the strength of the magnetic field necessary for focusing the electron beam, the length of the high frequency circuit section, and the material of the permanent magnet 4. Furthermore, the larger the permanent magnet 4 becomes, the larger the yoke portion 5 that connects the upper and lower permanent magnets is required to pass the magnetic flux, so it is necessary to have a large cross-sectional area.

Therefore, if the distance between the magnetic pole pieces 6 and 7 of the input/output section can be shortened without changing the shape of the high-frequency circuit section, it can be used as one of the effective means for creating a permanent magnet structure.

The present invention provides a multi-cavity talistron that solves the above problems.

FIGS. 2 and 3 show an embodiment of a multi-cavity klystron employing the present invention. Similarly to FIG. 1, 1 is an electron gun section;
2 is a high frequency circuit section, 3 is a collector section, 4 is a permanent magnet, 5
is the yoke, 6 is the input pole piece, 7 is the output pole piece, 8 is the input circuit, 9 is the output circuit, 10 is the resonance cavity, and 11 is the drift tube. is that the portion of the input magnetic pole piece 6 facing the output magnetic pole piece 7 serves as a cavity wall of the input resonant cavity. Further, in FIG. 3, the opposing portion of the output magnetic pole piece 70 also serves as the cavity wall of the output resonant cavity. As a result, in Figure 1,
The gap distance tg between the input magnetic pole piece 6 and the output magnetic pole piece 7 is 6.
In Fig. 2 or 3, the thickness Δt of the conductor plate constituting the resonant cavity of the input section or the output section is
The multi-gap distance shorter by g is tg - Δtg.

To give an example of a multi-cavity klystron with 5 cavities in the 5 GHz band, the distance tg between the magnetic pole pieces 6 and 7 is about 65 mm, and the thickness of the plate separating the resonant cavity and each magnetic pole piece of the input and output cavities. The thickness Δtg of the cavity wall between 6 and 7 is about 2.5 m, and if the present invention is adopted, the gap, distance tg - Δtg = 62
．． 5m, which is a decrease in the gap distance of about 4%. This makes it possible to create the same magnetic field in the high frequency circuit section 2 in the gap even if the length of the permanent magnet 4 is shortened by 4 inches. Furthermore, if the gap length between the magnetic pole pieces 6 and 7 is shortened, the leakage of unnecessary magnetic fields to other parts will be reduced accordingly. -It makes it possible to make it as short as 11m.

Furthermore, since it is possible to reduce the total magnetic flux generated by the magnet 4, it is also possible to reduce the cross-sectional area of the yoke part 5.As a result, the combined weight of the permanent magnet 4 and the yoke part 5 can be reduced. 10% for on structure (Fig. or 3)
In addition, by combining the structures shown in FIGS. 2 and 3, the cavity walls on the electron gun 1 side and the collector 3 side of the input resonance wall and output resonance cavity are used as the input section and the output section, respectively. If the magnetic pole piece of the part doubles as the shape, the distance between the magnetic pole pieces is tg-2Δ
tg, and the gap length is reduced by about 8 inches, which ultimately makes it possible to reduce the weight of the permanent magnet device by about 20%. 50
For example, take the values for a Hz band 5-cavity klystron,
As explained above, it goes without saying that multi-cavity klystrons using other frequency bands will also produce similar results, and as with 0 or more, multi-cavity klystrons employing the present invention have a permanent magnet focusing device. Significant weight reduction! This makes the multi-cavity klystron easier to handle and reduces manufacturing costs.0 In addition, the range of multi-cavity klystrons employing the present invention includes a magnetic pole piece at the input or output section. Needless to say, this includes those whose surfaces are plated with Ou, etc.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of an example of a conventional multi-cavity klystron, and FIGS. 2 and 3 are cross-sectional views showing the structure of a multi-cavity klystron employing the present invention. 0 1...Electron gun section, 2...High frequency circuit section, 3...Collector, 4...Permanent magnet,
5...Yoke, 6-...Input section magnetic pole piece,
7...Output pole piece, 8...Input circuit, 9...Output circuit, 10...Resonance window 8
Same, 11... Drift tube.

Claims (1)

[Claims] An electron gun section that generates an electron beam, a high frequency circuit section that causes the electron beam generated from the electron gun section to interact with high frequency power, and an electron beam that has finished interacting with the high frequency power in the high frequency circuit section. In the multi-cavity klystron, which is composed of a collector section that captures and converts it into thermal energy, and a permanent magnet that creates a magnetic field for focusing the electron beam, the high-frequency circuit section is composed of a plurality of resonant cavities, and the high-frequency circuit section is composed of a plurality of resonant cavities, A multi-cavity klystron characterized in that a part or the entire cavity wall of at least one of an input resonant cavity and an output resonant cavity is made of a magnetic material.