JPS6391935A - Traveling-wave tube - Google Patents

Abstract

PURPOSE:To interrupt the permeation of a brazing material into an external conductor by connecting an internal conductor with a spiral transmission line surrounded with a magnetic circuit functioning to focus electron beams and surrounding the internal conductor with an external conductor so as to form an coaxial circuit and at that time inserting a sleeve into the lower part of a ceramic window with which the internal and external conductors are fixed. CONSTITUTION:An internal conductor 5 formed perpendicularly to a spiral transmission line 2 and made to pass through a magnetic circuit 1 is connected with an end part of the line 2 surrounded with the circuit 1. A cylindrical external conductor 10 in parallel with the internal conductor 5 is connected with a cylinder inside the circuit 1 so that a coaxial circuit 3 is formed. Terminal parts of them are sealed with a ceramic window 4, and a cap 6 is inserted into the periphery of the window. When this part is sealed with a brazing material 9 thereafter, an upper end part of the external conductor 10 is made larger than conventionally and a sleeve 11 is inserted between the internal conductor 5 and the external conductor 10. When this window block 7 is brazed with the external conductor 10 in this way, the permeation of the brazing material toward the external conductor 10 is interrupted by the sleeve 11, so that a change in impedance of a traveling-wave tube can be prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the structure of a coaxial circuit.

[Conventional technology]

Figure @2 is a partial sectional view of a conventional traveling wave tube disclosed in, for example, Japanese Utility Model Application Publication No. 54-25062. (1) is a magnetic circuit that focuses the electron beam, (2) is a spiral circuit that is a microwave transmission line, and (3) is connected to the end of the spiral circuit (2) to form the spiral circuit (2). - It is a coaxial circuit responsible for transmitting and receiving signals to and from the window assembly (7) consisting of the ceramic window (4), inner conductor (5) and camp (6), and the outer conductor (8
) and are assembled by brazing.

A conventional coaxial circuit is assembled by brazing the window assembly (7) and the outer conductor (8) with a brazing filler metal (9) as shown in Figure 2. The brazed f-twisted window assembly (7) and the outer conductor (8) form a coaxial circuit and maintain vacuum tightness within the traveling wave tube.

[Problem that the invention seeks to solve]

Conventional coaxial circuits are assembled as described above,
Depending on the brazing conditions or the number of times brazing is performed, the G brazing material may sag into the coaxial circuit as shown in Figure 3, resulting in problems such as impedance mismatch in the coaxial circuit. Ta.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain a coaxial circuit having a structure that prevents deterioration of impedance matching caused by brazing.

[Means for solving problems]

In the coaxial circuit according to the present invention, a sleeve is installed between the outer conductor and the camp.

[Effect]

In this invention, by installing the sleeve between the outer conductor of the coaxial circuit and the camp, irregular changes in impedance caused by the brazing filler metal dripping into the coaxial circuit can be suppressed.

A detailed explanation is given in the embodiments of the invention.

〔Example〕

The coaxial circuit (3) according to the present invention will be explained below with reference to the drawings. In the cross-sectional view f shown in FIG. 1(a),
+1) to (9) are the same as in the conventional example. FIG. 1(B) is a cross-sectional view of the coaxial circuit (3) according to the present invention, where αQ is an outer conductor having an inner diameter a' larger than that of the conventional example, and (6) is an inner diameter a that is equal to the inner diameter of the outer conductor of the conventional example. It is a sleeve with.

The wall thickness of the sleeve 0υ and the inner diameter a' of the outer conductor 00 are determined by f so that an appropriate gap g is created.
Attach υ concentrically within the outer conductor 0Q.

As described above, by installing a sleeve with an inner diameter equal to the inner diameter of the conventional outer conductor in advance within the frosted outer conductor,
When brazing the window assembly and the outer conductor, even if the filler metal sometimes flows into the two outer conductors, the gap between the outer conductor and the sleeve can absorb the flow of filler metal, and the solder metal does not flow. This suppresses changes in impedance caused by

In other words, the inner wall of the outer conductor as seen from the microwave power 1 is the inner wall of the sleeve, and irregular changes in the inner diameter of the outer conductor due to the brazing filler metal as in the conventional example are suppressed, and the characteristics of the coaxial circuit determined by the equation 0 are suppressed. Impedance is kept constant.

ξr: Relative permittivity of spatial medium A: Outer conductor radius B: Inner conductor radius [Effects of the Invention] As described above, according to the present invention, changes in the impedance of the coaxial section due to the brazing filler metal dripping into the coaxial circuit can be suppressed. This makes it possible to suppress deterioration of RF performance due to brazing of the coaxial circuit.

A high gain traveling wave tube can be provided.

[Brief explanation of the drawing]

FIG. 1(A) is a partial sectional view of a traveling wave tube according to an embodiment E of the present invention, FIG. 1(B) is a sectional view of a coaxial circuit, and FIG. 2 is a partial sectional view of a conventional traveling wave tube. Figure @3 is a cross-sectional view of a conventional coaxial circuit. In the figure, (2) is a spiral circuit, (3) is a coaxial circuit, (
4) is a ceramic window, (5) is an inner conductor, (6) is a camp, (7) is an assembly of windows, (8) is an outer conductor, (9) is a brazing material, αQ is an outer conductor with a different inner diameter. , 0sukema sleeve. Note that the same line numbers in Figure 1 indicate the same line or the monk part.

Claims (1)

[Claims] An input and output coaxial circuit is connected to the end of the spiral circuit and is responsible for transmitting and receiving signals between this spiral circuit and an external circuit, and the other end of the inner conductor of this coaxial circuit is a ceramic input window and output window that are vacuum-sealed. What is claimed is: 1. A traveling wave tube that is taken out of a vacuum through a tube, characterized in that a sleeve is installed between an inner conductor and an outer conductor that constitute a coaxial circuit.