JPH0673280B2 - Method of manufacturing traveling wave tube - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for electrically connecting a helix conductor of a traveling wave tube, particularly a slow wave circuit structure, and an inner conductor of a coaxial line.

[Technical background of the invention and its problems]

As is well known, the body of the traveling wave tube is an electron gun section that emits an electron beam, a slow wave circuit structure provided downstream of the beam,
Further, it has a collector electrode portion provided downstream thereof. As a slow wave circuit structure, a structure including a helix conductor is widely known, and a high frequency input is connected to one end thereof and a high frequency output coaxial line is connected to the other end thereof. The connection between the helix conductor and the inner conductor of the coaxial line is generally made as shown in FIG. That is, inside a vacuum container 11 made of a metal pipe such as a slender stainless steel, a metal ribbon such as molybdenum supported by three helix support rods 12 made of beryllia ceramic at intervals of 120 degrees is coiled. The wound helix conductor 13 is inserted. In addition, a part of the vacuum container 11 is provided with an outer conductor end portion of a coaxial line 16 composed of an inner conductor 14 and an outer conductor 15 that is hermetically joined and protrudes in a direction perpendicular to the slow wave circuit axis. Then, when connecting the end portion 13a of the helix conductor 13 and the inner conductor 14, insert the tip portion 13a of the helix conductor 13 into the axial hole 14a at the tip of the inner conductor, and fit the two in a state that the figure is turned upside down. The brazing filler metal 17 is placed on the part and heated at a high temperature for brazing.
Alternatively, they are electrically and mechanically connected by arc welding or laser welding.

Thereby, the connection between the helix conductor and the conductor in the coaxial line can be sufficiently obtained, but the following inconveniences are likely to occur. That is, when the helix conductor and the inner conductor are brazed in this manner, a part of the brazing material flows along the surface of the helix conductor and onto the slow wave circuit region. In this way, if the brazing material adheres to the helix conductor part on the slow wave circuit where the electron beam passes, when the traveling beam tube is operated and a part of the electron beam collides with this helix conductor, the brazing material evaporates. This causes the wax vapor to adhere to the surface of the helix support rod or the like, which may deteriorate the high frequency transmission characteristics. Further, in the case of welding, splash and steam due to welding may similarly adhere to the helix conductor portion and the helix support rod on the slow wave circuit. In an extreme case, it is expected that a part of the helix support rod will be electrically short-circuited. In order to prevent this, special precautions must be taken, especially with a traveling wave tube with an extremely small size for operating frequencies of 10 GHz and above, workability is poor and it is difficult to obtain a reliable connection structure. There is.

[Object of the Invention]

The present invention eliminates the above inconveniences, and the metal vapor and splash at the time of welding do not scatter to the helix support rod or the helix conductor portion on the slow wave circuit, and a highly reliable slow wave circuit structure is obtained. A method of manufacturing a wave tube is provided.

[Outline of Invention]

According to the present invention, a relay conductor made of a metal having a melting point lower than that of the helix conductor is previously joined to the end of the helix conductor, and an axial hole along the conductor center axis is formed at the end of the coaxial line conductor on the vacuum vessel side. A lateral hole reaching this axial hole is formed, the end of the relay conductor is inserted into the axial hole of the inner conductor so as to reach at least the lateral hole, and a laser beam is irradiated through this lateral hole. It is a method of manufacturing a traveling wave tube in which a relay conductor in an axial hole is melted and welded.

Example of Invention

An embodiment will be described below with reference to the drawings. The same parts are represented by the same symbols.

As shown in FIGS. 1 and 2, between the end portion 13a of the helix conductor, which is inserted together with the helix support rod 12 in the vacuum vessel 11 made of a metal pipe, and the coaxial line inner conductor 14, approximately L. Platinum-like helix shaped like a letter
Electrical connection is made via a relay conductor 21 made of a metal material having a lower melting point than 13. Then, in accordance with a preferred assembly procedure, this relay conductor 21 is provided with one end 21a in advance.
Is wound around a helix end 13a made of molybdenum and electrically connected by brazing or welding. The middle part is extended parallel to the tube axis, bent at a right angle, and inserted into the coaxial line conductor as it is in a cylindrical shape.

The coaxial line 16 projectingly provided in a part of the vacuum container 11 has an axial hole 14a which is previously formed halfway along the central axis at the inner end of the inner conductor 14 made of molybdenum or an equivalent high melting point material.
Has been formed. Further, a lateral hole 14b reaching the axial hole 14a is formed on the side wall thereof. Therefore, the cylindrical end portion 21b of the relay conductor 21 is inserted into the axial hole 14a of the inner conductor, and in this state, as shown by the arrow L, the laser beam is irradiated through the lateral hole 14b to irradiate the axial hole The relay conductor end 14b of is melted and welded to the inside of the inner conductor. The two are thus welded in the axial bore and electrically and mechanically connected.

By connecting in this way, the relay conductor with a low melting point itself contributes to welding and is welded inside the axial and lateral holes formed in the inner conductor, and the metal vapor and splash during welding are the main components of the helix. A highly reliable joining state can be obtained without reaching the portion. In the figure, reference numeral 18 represents an electron beam incident body electrode on the electron gun side. The portion of the relay conductor 21 parallel to the tube axis is formed to have a size slightly larger than the inner diameter of the main part of the helix.
As a result, the electron beam does not collide with this relay conductor, and there is no possibility that this relay conductor will melt due to the beam collision.

〔The invention's effect〕

As described above, according to the present invention, the electrical connection between the helix conductor and the conductor in the coaxial line is surely easy, and the splash at the time of joining is scattered on the surface of the helix conductor and the helix support rod in the slow wave circuit region. Therefore, there is no risk of adhesion and the high-frequency characteristics of the slow wave circuit will not deteriorate. Thus, a highly reliable traveling wave tube is obtained.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential portion showing an embodiment of the present invention, FIG. 2 is an enlarged perspective view showing the essential portion thereof, and FIG. 3 is a longitudinal sectional view of an essential portion showing a conventional structure. 13 ... Helix conductor, 13a ... Helix conductor end, 14 ... Coaxial line inner conductor, 14a ... Axial hole at inner conductor end, 14b ... Side wall lateral hole, L ... Laser beam, 16 …… Coaxial line, 21 …… Relay conductor.

Claims (1)

[Claims] 1. A helix conductor supported by a plurality of helix support rods is inserted into an elongated pipe vacuum container,
In a method of manufacturing a traveling wave tube in which the end of the helix conductor is electrically connected to an inner conductor of a coaxial line that is vertically provided on a part of the vacuum vessel, the end of the helix conductor is previously attached to the end of the helix conductor from the helix conductor. In addition, a relay conductor made of a metal having a low melting point is joined, and an axial hole along the conductor center axis and a lateral hole reaching the axial hole are formed at the end of the coaxial line inner conductor on the side of the vacuum container. The end portion of the relay conductor is inserted into the axial hole of the inner conductor so as to reach at least the lateral hole, and a laser beam is radiated through the lateral hole so that the relay conductor in the axial hole is fixed. A method of manufacturing a traveling wave tube, which comprises melting and welding.