JP2603976B2 - Helix slow wave circuit type traveling wave tube - Google Patents

Description

Description of the Invention [Object of the Invention] (Industrial application field) The present invention relates to a helix slow wave circuit type traveling wave tube for oscillating or amplifying a microwave, and in particular, a vacuum vessel divided into a plurality of pieces in advance. The present invention relates to a traveling wave tube having a structure integrally joined at a predetermined position.

(Prior Art) As is well known, a helix slow wave circuit type traveling wave tube has a structure in which a helix conductor constituting a slow wave circuit is arranged around an electron beam path to cause an interaction between an electron beam and a high frequency wave. The helical conductor is generally formed by winding, for example, a molybdenum wire having a circular cross section in a spiral shape at a predetermined pitch, or a ribbon-shaped conductor having a rectangular cross section. The helical conductor is mounted in a long pipe-shaped vacuum vessel by three helical support rods made of beryllia ceramic. As such a helix slow-wave circuit structure, there is known a structure in which, in order to enhance the assembling accuracy, the helix slow-wave circuit structure is divided into a plurality of members in advance in an axial direction, and a support rod and a helix conductor are inserted into each of the members and integrally joined. Have been. According to this structure, a considerably long slow-wave circuit structure can be relatively easily assembled.

(Problems to be Solved by the Invention) However, according to such a conventional structure, discontinuity of high-frequency characteristics is likely to occur at an integrally joined portion of the divided portions. In other words, in the case where the high-frequency attenuation film is formed on the outer peripheral surface near the split portion of the helix support rod, rubbing due to thermal expansion and contraction occurs between the open helix conductor and the attenuation film, and the attenuation film gradually becomes There is a risk of peeling off or incomplete contact between the two. Further, in the case where a solid attenuator is attached to each vacuum vessel end of the divided portion, a small space is likely to be formed in both united portions, and discontinuity occurs. Thus, an unstable phenomenon of the operation of the traveling wave tube is likely to occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a helical slow wave circuit type traveling wave tube which solves the above-mentioned disadvantages, facilitates assembly of an integral joint of a vacuum vessel, and hardly causes unstable phenomenon of high frequency characteristics. And

[Means for Solving the Problems] According to the present invention, an attenuator arranged around a helical conductor is built in a region including a joint of a vacuum vessel, has a generally cylindrical shape, and has two openings. It has a tapered inner surface whose inner diameter gradually decreases from the end to the center, and a holding hole or slit is formed to fit the helix support rod, and the end of the helix support rod is inserted and held in this holding hole. The helix slow wave circuit type traveling wave tube has an end portion of the helix conductor inserted and disposed in a small-diameter through hole at the center of the attenuator.

(Operation) According to the present invention, the end of the vacuum vessel divided in advance with the end of the helix support rod inserted and held in the helix support rod holding hole of the attenuator having a generally cylindrical and tapered inner surface. The vacuum container can be integrally joined by being inserted into the inside of the unit, and assembly can be easily performed with high precision. Also, while the helix conductor is inscribed in the center through hole of the attenuator,
Since the integral joint of the vacuum vessel is located at the center of the attenuator, a traveling wave tube having a stable high-frequency characteristic without a discontinuous structure can be obtained.

(Example) Hereinafter, the example is described with reference to drawings. The same parts are denoted by the same reference numerals.

As shown in FIGS. 1 to 4, a small and long stainless steel pipe-shaped vacuum vessel is composed of two divided vessel sections 11 and 12 prepared in advance, and the outer periphery is welded in a vacuum-tight manner. It is integrally connected at the joined portion 13. A generally cylindrical attenuator 14 is inscribed inside the vacuum vessel including the joint 13. This attenuator 14 is made of a solid high-frequency absorber such as silicon carbide (SiC), and has a tapered inner surface 14b whose inner diameter is gradually reduced from both open ends 14a, 14a to the vicinity of the center. . The central inner surface 14c is formed to have the same inner diameter as the helical outer diameter of the helix conductor 15.
In the attenuator 14, holding holes 14d, 14d... Into which the ends of three helix support rods 16, 16. ing. These holding holes 14d terminate at a position separated from the center of the attenuator by a predetermined distance in the axial direction, and three helix support rods 16 are mounted and held in these holding holes. The helix conductors 15 are mounted inside the helix support rod 16 and the attenuator 14 such that their free ends terminate near the center of the attenuator. In particular, each end 15a, 15a of the helix conductor is located at the center of the attenuator 14.
It is inscribed on the inner surface of 14c. Attenuator tapered inner surface 14b
Is gradually approaching and completely in contact with the end 15a of the helix conductor. As a result, there is no electrical discontinuity in the axial direction of the slow wave circuit, no high-frequency reflection occurs, and the integral joint 13 of the vacuum vessel is positioned at a position where the helix of the attenuator 14 and its supporting rod are not present. With the configuration on the outer periphery, the shape of the joint does not affect the high-frequency transmission characteristics at all.

The cylindrical attenuator 14 is, for example, 2
It may be divided into two parts, which makes the assembly easier. The helix support rod may have a fan-shaped cross section. In this case, a slit is formed in the attenuator so that the support rod can be fitted.

[Effects of the Invention] As described above, according to the present invention, a helix support rod can be inserted and held in a cylindrical attenuator, and a helix conductor-mounted one can be inserted into a vacuum vessel and integrally joined. The assembly can be easily performed with high precision. In addition, the helix conductor is inscribed in the center hole of the attenuator, and the integral joint of the vacuum vessel is located almost at the center of the attenuator. A wave tube is obtained. In particular, even if the end of the helix conductor slightly moves during operation, the contact with the attenuator can be reliably obtained, and there is no possibility that the operation becomes unstable. In addition, an unnecessary high-frequency electric field such as a coaxial mode can be reliably absorbed by the central portion of the attenuator.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an essential part showing an embodiment of the present invention, and FIGS. 2 and 3 are 2-2 and 3-3 of FIG. 1, respectively.
FIG. 4 is a partially cutaway perspective view of a main part of FIG. 11, 12… Vacuum vessel, 13… Integral joint, 14… Attenuator, 14b… Tapered inner surface, 14c …… Central inner surface, 15…
Helix conductor, 14d: Hold hole, 16: Helix support rod.

Claims (1)

(57) [Claims] 1. A vacuum vessel in which a long pipe divided in advance in the axial direction is integrally joined in a vacuum-tight manner, a helix conductor arranged on a central axis of each of the divided vacuum vessel portions, and a helix. Helix slow-wave circuit type including at least three dielectric helix support rods interposed between a conductor and an inner wall of a vacuum vessel, and an attenuator composed of a high-frequency absorber disposed around the helix conductor In the traveling wave tube, the attenuator has a generally cylindrical shape built in a region including a joint of a vacuum vessel, and is formed on a tapered surface whose inner diameter gradually decreases from both open ends to the center. A holding hole or slit into which the helix support rod fits is formed, the end of the helix support rod is inserted and held in the holding hole, and the end of the helix conductor is A helix slow-wave circuit type traveling-wave tube, wherein the helix-slow-wave traveling-wave tube is inserted into a small-diameter through hole at the center of the attenuator.