JPH01309237A - Traveling-wave tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a traveling wave tube with an improved beam focusing device.

(Prior Art) Fig. 5 is an axial cross-sectional view showing a beam focusing device near the coaxial plug of a conventional traveling wave tube. A spacer, 3 is a vacuum envelope constructed by stacking the periodic pole pieces 1 and periodic spacers 2 alternately, 4 is a periodic permanent magnet for providing magnetic field density distribution, and 5 is a coaxial plug for inputting and outputting high frequency signals. Inner conductor 6, outer conductor 7 and ceramic high frequency window 8
9 has an end welded to the inner conductor 6,
The helix 10 serving as a slow wave circuit is a support rod that holds the helix 9 inside the vacuum envelope 3. 8th
The figure is a sectional view of a conventional traveling wave tube disclosed in, for example, Japanese Utility Model Application Publication No. 53-106658, in which numeral 13 represents an electron gun that generates an electron beam, and numeral 14 represents a collector that captures the electron beam.

Next, the operation will be explained. The electron beam generated by the electron gun 13 is preferably captured by the collector 14 after contributing to the amplification of the high frequency signal without being captured inside the helix 9 which serves as a slow wave circuit. In order to avoid being captured, it is necessary to provide an appropriate magnetic field density distribution around the helitus 9, and generally a configuration as shown in FIG. 5 is used to provide a magnetic field density distribution. Since the electrons that make up the electron beam repel each other and tend to spread, periodic permanent magnets 4 are arranged periodically to increase the magnetic flux density parallel to the electron beam passing through the inside of the helix 9 in the axial direction. The electron beam is focused by providing a distribution to prevent it from being captured by the helix 9.

[Problem to be solved by the invention]

Since the conventional traveling wave tube is constructed as described above, it is physically impossible to attach the periodic permanent magnet 4 to the coaxial plug 5 that inputs and outputs high frequency waves, as shown in FIG. As shown in FIG. 7, the magnetic flux density in the axial direction on the circumference of the beam focusing device at the position where the coaxial plug part 5 is provided is higher than the magnetic flux density distribution in other parts shown by the solid line. There was a problem that the distribution became non-uniform (as shown by the broken line in FIG. 7), and the electron beam was likely to be captured by the helix 9. Further, there were other problems such as it was extremely difficult to make adjustments to focus the electron beam while preventing it from being captured by the helix 9.

This invention was made to solve the above-mentioned problems, and it is possible to make the axial magnetic flux density distribution on the circumference of the beam focusing device more uniform at the position where the coaxial plug part is provided,
The purpose of the present invention is to obtain a traveling wave tube in which electron beams are less likely to be captured by helices, and the focusing of the electron beams can be easily adjusted.

[Means to solve the problem]

In the traveling wave tube according to the present invention, divided periodic permanent magnets obtained by dividing an annular permanent magnet in the axial direction and circumferential spacers made of non-magnetic material are arranged alternately on the circumference on which the coaxial plug part of the beam focusing device is attached. It was placed in

[Effect]

The beam focusing device of the traveling wave tube in this invention uses divided periodic permanent magnets and circumferential spacers arranged alternately.
Even on the circumference of the position where the coaxial plug is attached,
Make the axial magnetic flux density distribution more uniform.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a circumferential sectional view of the coaxial plug portion 5 of the beam focusing device for a traveling wave tube according to the present invention, and FIG. 2 is an axial sectional view taken along line A--A in FIG. In the figure, 1 is a periodic pole piece made of a magnetic material, 2 is a periodic spacer made of a non-magnetic material, 3 is a vacuum envelope configured by stacking the periodic pole pieces 1 and the periodic spacers 2 alternately, and 4 is a magnetic field density distribution. 5 is a coaxial plug for inputting and outputting high-frequency signals, and is composed of an inner conductor 6, an outer conductor 7, and a ceramic high-frequency window 8, 21 is a non-magnetic circumferential spacer, 41 is a divided periodic permanent magnet obtained by dividing an annular permanent magnet in the axial direction.

Although traveling wave tube parts such as helices are omitted, the configuration is exactly the same as the conventional example shown in FIG. 5.

Next, the operation will be explained with reference to FIGS. 1 and 2. As shown in FIG. 1, two circumferential spacers 21 having the same cross-sectional shape as the outer circumference of the beam focusing device of the coaxial plug part 5 are arranged at equal intervals, and divided into pieces that match the dimensions of the gaps. Since three periodic permanent magnets 41 are arranged between the coaxial plug part 5 and the two circumferential spacers 21, the axial direction on the circumference of the position where the coaxial plug part of the beam focusing device is provided is The magnetic flux density distribution is more symmetrical than that of a conventional traveling wave tube, so it is more uniform on the cross-sectional circumference, which improves the focusing of the electron beam, and the helix (not shown in Figure 1) It becomes difficult to be captured. In FIG. 2, dashed arrows indicate that the magnetic flux density distribution in the axial direction is symmetrical between the coaxial plug portion 5 and the position where the circumferential spacer 21 is attached. The solid arrow indicates the axial magnetic flux density distribution at the position where the periodic permanent magnet 4 is attached, which is the same as the axial magnetic flux density distribution directly below the divided periodic permanent magnet 41. The above explanation is effective if applied in a case where it is necessary to alleviate the non-uniformity of the magnet by the periodic pole piece 1 which is generally possible.

In addition, in the above embodiment, periodic spacer 2 and circumferential spacer 2 are used.
1 is shown as an individual unit, it may be integrated into a single unit, and when integrated, the effect of facilitating the heat dissipation of the heat generated by the helix to the outside of the vacuum envelope 3 is added. Furthermore, as shown in FIG. 3, a flow path 11 for passing the cooling medium is provided in the integrated spacer 22, and a base 12 is arranged at the entrance and exit position of this flow path 11. When a cooling medium is passed through the helix, another effect is produced in that the heat generated by the helix can be released to the outside of the vacuum envelope 3 more efficiently.

〔Effect of the invention〕

As described above, according to the present invention, the traveling wave tube is configured such that a circumferential spacer made of a non-magnetic material is arranged between the divided periodic permanent magnets on the circumference where the coaxial plug part of the beam focusing device is attached. Therefore, it is possible to make the magnetic flux density distribution in the axial direction more uniform even on the circumference of the position where the coaxial plug of the beam focusing device is attached, making it difficult for the electron beam to be captured by the helix. This makes it easier to adjust the focusing of the electron beam, and has the effect of providing a traveling wave tube with high performance and long life.

[Brief explanation of the drawing]

FIG. 1 is a circumferential sectional view of a coaxial plug part of a traveling wave tube beam focusing device according to an embodiment of the present invention, and FIG.
-A is an axial sectional view of a conventional traveling wave tube, FIG. 3 is a sectional view of a main part of another embodiment of the present invention, FIG. An axial sectional view showing the beam focusing device near the coaxial plug, FIG. 6 is a circumferential sectional view of the coaxial plug in FIG. 5, FIG. 7 is an axial sectional view of the coaxial plug in FIG. 5, FIG. 8 is an axial sectional view of a conventional traveling wave tube. 1 is a periodic pole piece, 2 is a periodic spacer, 21 is a circumferential spacer, 22 is an integrated spacer, 4 is a periodic permanent magnet,
41 is a divided periodic permanent magnet, 5 is a coaxial plug, 11 is a flow path, and 12 is a cap. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent Applicant: Mitsubishi Electric Corporation 1"'- (2 others) 1: Periodic hole O-S 4: Periodic permanent magnet 2゛ Circulation prohibited :lff Matashin・-Sun 4 Luke 嘗 "J Zhou @ Eternal Stone 6 11° Liquid Hiroshi 12: Mouth ke 22:-I Song Yi (, S'<-゛su. Sub figure 6, ministers etc.

Claims (1)

[Claims] a beam focusing device comprising a combination of a periodic permanent magnet, a magnetic periodic pole piece, and a non-magnetic periodic spacer;
In a traveling wave tube having a coaxial plug attached to the beam focusing device, an annular permanent magnet is divided in the axial direction on the circumference to which the coaxial plug of the beam focusing device is attached. A traveling wave tube characterized by alternately arranging periodic permanent magnets and non-magnetic circumferential spacers.