JPH0612991A - Traveling wave tube - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a traveling wave tube in which the axial asymmetry of the central magnetic field is corrected to obtain an axially symmetric magnetic field and the electron beam transparency is improved. A traveling wave tube according to the present invention comprises a pole piece 8 having a plate-like cylindrical hub provided at the center on the outer periphery of a slow wave line connected to an input waveguide section 4 and an output waveguide section. A magnetic field concentrator in which the ring-shaped spacers 2 are alternately stacked and the ring-shaped magnet 5 is arranged between the pole pieces is provided, and the magnet corresponding to the input waveguide part or the output waveguide part is provided with U.
The letter-shaped notch 6 is provided, and the facing hub end surfaces 7b and 8b of the pole pieces 7 and 8 adjacent to the magnet are formed in a tapered shape, and the distance between the hub end surfaces is such that there is a notch in the magnet. It is narrow, and the above-mentioned purpose can be achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling wave tube, and more particularly to improvement of a magnetic field focusing device for the traveling wave tube.

[0002]

2. Description of the Related Art Generally, a traveling wave tube amplifies a high frequency by utilizing an interaction between an electron beam and a high frequency.
Participates in interaction with an electron gun unit that generates an electron beam, a slow-wave circuit (high-frequency acting unit) that interacts the electron beam with a high frequency, and a magnetic field focusing device that is provided on the outer periphery of the slow-wave circuit to focus a magnetic field It consists of a collector that captures the finished electron beam.

Since such a traveling wave tube uses an axially symmetric rod-shaped electron beam, the magnetic field for focusing the electron beam is also required to be axially symmetric. Therefore,
Basically, the shapes of the magnet and the pole piece (pole piece) of the magnetic field concentrating device that creates the magnetic field are also axially symmetric. But,
Since the input waveguide portion and the output waveguide portion are provided in the vicinity of both ends of the slow wave circuit, respectively, they have axially asymmetric portions. The affected magnets are often notched and mounted by avoiding axial asymmetry. At this time, in the conventional traveling wave tube, the pole piece adjacent to the asymmetric magnet, which is not affected by the axially asymmetric portion, has the axisymmetric structure.

[0004]

However, although the magnet is axially asymmetric by providing the notch, the pole piece adjacent to the magnet remains axially symmetric, so that the magnet having the notch is provided. The central magnetic field was axially asymmetric, and as a result, the axially symmetric electron beam was disturbed and the electron beam transparency was deteriorated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a traveling wave tube in which the axial asymmetry of the central magnetic field is corrected to obtain an axially symmetric magnetic field and the electron beam transparency is improved. And

[0006]

According to the present invention, there is provided a pole piece in which a cylindrical hub is provided in the center of a plate on the outer circumference of a slow wave line connected to an input waveguide section and an output waveguide section. A magnetic field concentrator in which ring-shaped spacers are alternately stacked and a ring-shaped magnet is arranged between pole pieces is provided, and a U corresponding to the magnet corresponding to the input waveguide section or the output waveguide section.
A traveling wave tube provided with a V-shaped notch, the facing hub end faces of the pole pieces adjacent to the magnet are formed in a tapered shape, and the distance between the hub end faces is narrow in the notched portion of the magnet. Is.

[0007]

According to the present invention, the axial asymmetry of the central magnetic field due to the axially asymmetrical shape of the magnet is corrected, and a substantially axially symmetrical magnetic field distribution can be provided. As a result, the electron beam transparency is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

The slow wave circuit of the traveling wave tube and the magnetic field concentrating device according to the present invention are constructed as shown in FIG. 1, and the pipe-shaped vacuum container in the slow wave circuit has excellent straightness and heat transfer property instead of the metal pipe. An IPP (Integral Pole Piece) structure is used. That is, a vacuum container is formed by alternately arranging pole pieces 1 and ring-shaped spacers 2 which are plate-shaped and through which a cylindrical hub 1a penetrates at the center, and a magnet 3 is arranged between the pole pieces 1. The magnetic field focusing device is constituted by these components.

Further, in this embodiment, a coaxial waveguide (not shown) is provided as an input waveguide section on the input side of the slow wave circuit, and a coaxial waveguide 4 is provided as an output waveguide section on the output side. It is set up. The magnet 5 corresponding to the coaxial waveguide 4 is configured as shown in FIG. 2, and is formed into a ring shape and a U-shaped notch 6 is provided so as to include the central hole. The pole pieces 7, 8 adjacent to the magnet 5 are different from the other pole pieces 1,
The hubs 7a and 8a are formed in a plate shape and are provided in the center, but as is apparent from FIG. 3, the hub end surfaces 7 facing each other are formed.
b and 8b are formed in a tapered shape, and the pole pieces 7 and 8 are arranged so that the distance between the opposing end faces of the hubs becomes narrower on the notch 6 side of the magnet 5. In other words, the hub of the narrowed portion is projected more than usual. As is apparent from FIG. 1, when the dimension between adjacent normal hubs is a, the dimension b between the hubs in the narrowed portion has a relationship of a> b. Hub end surface 7b,
A ring-shaped spacer 9 having a short length is arranged between 8b.

Although both pole pieces 7 and 8 have exactly the same shape, when they are used, the tapered hub end surfaces 7b and 8 are formed.
b are arranged so as to face each other. Further, although the portion corresponding to the output waveguide 3 has been described, the portion corresponding to the input waveguide portion has the completely same structure. Then, a slow wave line 10 made of a helix is inserted in a vacuum container formed of the pole piece 1 and the spacer 2, and is supported and fixed by a dielectric support rod (not shown). (Other embodiments)

The embodiment shown in FIG. 4 is an application of the present invention to a cavity-coupled traveling wave tube. The slow wave line is composed of a large number of cavity partition walls 12 that form a large number of cavities 11. Then, the rectangular waveguide 4 serving as the output waveguide section is replaced by the magnet 5
It is arranged at six notches. The hubs of the pole pieces 7 and 8 sandwiching this from both sides are cylindrical hubs 7 that taperly project at the notches 6 of the magnet 5 and have a narrow gap.
a and 8a. Reference numeral 13 in the drawing represents a cylindrical conductor for guiding the electron beam to a collector (not shown). Further, the present invention can be applied not only to a traveling wave tube having a magnetic field focusing device of an IPP structure, but also to a traveling wave tube having an independent pipe-shaped vacuum container.

[0013]

According to the present invention, the magnet corresponding to the input waveguide portion or the output waveguide portion is provided with a U-shaped notch, and the facing hub end faces of the pole pieces adjacent to the magnet are provided. Since it is formed in a taper shape and the distance between both hub end surfaces is narrowed in the notch of the magnet, the axial asymmetry of the central magnetic field due to the axial asymmetric shape of the magnet is corrected, and Axisymmetric magnetic field distribution can be provided. As a result, the electron beam transparency is improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a main part of a traveling wave tube according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a magnet taken along the line AA ′ in FIG.

FIG. 3 is a perspective view showing a pole piece used in the traveling wave tube of the present invention.

FIG. 4 is a vertical cross-sectional view showing the main parts of another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pole piece, 2 ... Spacer, 3 ... Magnet, 4 ... Coaxial waveguide, 5 ... Magnet, 6 ... Notch, 7,8 ... Pole piece, 7a, 8a ... Hub, 7b, 8b ... Hub end surface, 9 …Spacer.

Claims (1)

[Claims] 1. A pole piece having a plate-shaped cylindrical hub at the center and ring-shaped spacers are alternately stacked on the outer periphery of a slow-wave line connected to an input waveguide and an output waveguide. In the traveling wave tube provided with a magnetic field concentrator in which a ring-shaped magnet is arranged between the pole pieces, a U is added to the magnet corresponding to the input waveguide section or the output waveguide section.
In addition to providing a notch, the facing hub end faces of the pole pieces adjacent to the magnet are formed in a tapered shape, and the distance between the hub end faces is narrow at the notched portion of the magnet. Traveling wave tube characterized by.