JPH04229932A - Traveling wave tube provided with coupling device between delay line and outer microwave circuit - Google Patents

Abstract

PURPOSE: To provide a traveling wave tube having a configuration which decreases and/or simplifies operations of machining, assembling and brazing in fabrication by arranging a dielectric layer between a delay line and a support and connecting an end of the delay line to a part of the support. CONSTITUTION: A dielectdc layer 22 is intervened between a spiral 2 of a delay line 1 and three supports 20 and 21. Further an end of the spiral 2 is connected to a part 25 of the support 21 and a part 23 of the support 21 is arranged so as to face against an inner conductor core 12 of a transmission line 6. By this configuration, operations of machining, assembling and brazing can be reduced and/or simplified and therefore the configuration can be applied to a wide-band power traveling wave tube. Moreover, the coupling of the delay line 1 to the support 21 is preferably achieved by brazing these prior to introduction thereof into an interior of a sheath 3.

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 which is provided with a coupling device between its delay line and an external microwave circuit. The invention applies in particular to broadband traveling wave tubes with helical or helical-derived delay lines.

0002

2. Description of the Related Art This type of traveling wave tube mainly consists of: an electron gun that emits an electron beam in a substantially linear direction; A delay line placed downstream of the electron gun. The delay line is housed in a cylindrical metal sheath in coaxial relationship with the delay line and centered in the metal sheath by a support. The electron beam traverses the delay line from one end of the line to the other. Interaction between the microwaves guided by the delay line and the electrons occurs within the metal sheath. The delay line is provided with a device for injecting microwaves and a device for extracting microwave energy. The metal sheath is usually connected to earth. A focusing device equipped with a permanent magnet and coaxially connected to the sheath. This focusing device extends along the length of the delay line. Within the sheath, a focusing device generates a magnetic field that has the effect of keeping the path of the electron beam in a straight line. A collector that collects the electron beam downstream of the delay line. The support member is in the form of a rod. These rods are often made of quartz, alumina, glucina, or boron nitride. The rods are clamped or brazed to the delay line and sheath. This configuration limits the operating band on the high frequency side of the traveling wave tube.

[0003] In order to widen the zone, it has hitherto been proposed to use as a support a metal member which radiates inwardly from the inner wall of the sheath. These metal members are covered with a dielectric layer. This structure is disclosed in French patent application no. 89/07,081 filed on May 30, 1989 by the applicant. This configuration allows the traveling wave tube to operate over a very wide band and also allows effective cooling of the delay line. Traveling wave tubes are usually connected to external microwave circuitry via connecting parts at the input and output sides of the delay line. On the input side, this connecting part that allows the injection of microwave energy usually has a coaxial line structure and the level of the injected energy is low. At the output side of the delay line, the connecting part for extracting the amplified microwave energy has the structure of a coaxial line or a ridge waveguide, depending on the level of energy to be extracted.

[0004] A coupling device between a traveling wave tube delay line and an external microwave circuit has been proposed, for example, on June 27, 1980.
French Patent No. 2,485,801 filed on
Known by the number. In this patent, the external microwave circuits each have a transmission line with an internal conductor core. The connection between the delay line and the transmission line is implemented by coupling pins. The coupling pin is fixedly connected to the inner conductor core on one side and fixedly connected to the end of the delay line on the other side. Therefore, 2
The two parts are mechanically interrelated. Therefore,
During the assembly of traveling wave tubes, difficulties arise in making the joint between the coupling pin and the end of the delay line. The size of the coupling pin and delay line is small. On the other hand, measurements taken to ensure that the traveling wave tube meets specifications can only be performed after the joint is formed. This joint is typically brazed and cannot be disassembled. A defect in one of the components belonging to the structure of the delay line will lead to the disposal of the external microwave circuit or the focusing device and thus the entire device.

There is also a known device described in European Patent Application Publication No. 0,341,107, filed on April 14, 1989. This is a contactless coupling device between a delay line and an external microwave circuit. For this purpose, the conductor parts must be brazed to the ends of the sheath. This conductor part is a coupling pin fixed to the corresponding end of the delay line. The inner conductor core of the transmission line has an end opposite the outer surface of the conductor portion. An electromagnetic coupling is made between the delay line and the inner conductor core via the outer surface of the conductor part. When assembling,
Measurements can be taken before final assembly, so
If there is a defect in a component forming part of the structure of the delay line or focusing device or any of the outer microwave circuitry, the defect can be identified. However, the connection of the delay line and the coupling pin by laser welding is a complex operation and can only be carried out if the delay line is introduced into the sheath, surrounded by an insulating support. Coupling pin alignment must be performed beforehand.

[0006]

SUMMARY OF THE INVENTION The present invention aims to solve the above problems by means of a mechanically independent connection between the delay line and the inner conductor core. The invention has the advantage realized by a non-contact coupling,
By eliminating conductor parts with coupling pins fixed to the ends of the delay line, machining, assembly and brazing operations can be reduced and/or simplified. The end of the delay line is connected directly to one of the supports designed to hold the end of the delay line within the sheath. This support is a conductor. The connection of the delay line to the support is carried out, for example by brazing, before introduction into the sheath. The reliability of the braze can be tested before introduction into the sheath.

[0007]

SUMMARY OF THE INVENTION The present invention comprises a delay line held within a cylindrical conductor sheath by a plurality of conductor supports and an external microwave circuit coupled to the delay line by a capacitor effect. The external microwave circuit is a traveling wave tube including a transmission line having an inner conductor core disposed near an end of the delay line, and a dielectric material is disposed between the delay line and the support. a layer is arranged, one of the ends of the delay line is connected to a portion of one of the supports, the portion of the support facing the inner conductor core; This invention provides a traveling wave tube characterized in that it is arranged as follows.

[0008] The ends of the delay line can be brazed to a portion of the support. According to one embodiment, the sheath has an incision, thereby forming a space around the part of said support connected to the end of the delay line. According to another embodiment, the sheath may cover a portion of said support connected to the end of the delay line. According to a third embodiment, the part of the support connected to the end of the delay line has two perpendicular flanges, the first flange being in the extension of the support and the second flange being in the extension of the support. This first
on the flange and fixed to the end of the delay line. According to a fourth embodiment, the sheath has two longitudinal grooves. The grooves are radially curved and are located on either side of the portion of the support to which the end of the delay line is connected. In these third and fourth embodiments it is possible to match the coupling between the delay line and the transmission line.

[0009] The delay line is preferably helical. It is also brazed to the dielectric layer. The conductor support may be a rib that projects inside the sheath and forms part of the sheath. The transmission line is preferably a ridge waveguide or a coaxial line. A hermetically sealed microwave window can be inserted between the part of the support connected to the end of the delay line and the inner conductor core.

The present invention will become more apparent from the following description of embodiments with reference to the accompanying drawings. In the accompanying drawings, corresponding parts have been provided with the same reference numerals. Also, to simplify the drawing, the dimensions of each part do not correspond to their actual values.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a longitudinal sectional view of a portion of a prior art traveling wave tube. Figure 2 shows the plane AA of the traveling wave tube shown in Figure 1.
' is a cross-sectional view along . FIG. 1 is also a longitudinal section along the plane BB' of FIG. Traveling wave tube has delay line 1
and an external circuit 1 for extracting microwave energy.
0. The delay line 1 is a helix 2 with an axis XX' and is made of copper, for example. This helix 2 is held in the center of a cylindrical conductor sheath 3 by three insulating supports 4 spaced at 120° to each other. The support 4 is a rod whose cross section is trapezoidal. These supports are formed, for example, from quartz, alumina, glucina or boron nitride. They are clamped or brazed to the helix 2. The supports 4 are each preferably inserted into a hollow groove 17 formed in the inner wall of the sheath 3. The end of the sheath 3 on the output side of the delay line 1 (the end shown in FIG. 1) abuts the end of a cylindrical tube 5 which extends to a collector (not shown). In Figures 1 and 2, an external microwave circuit 10 for microwave energy extraction comprises a ridge waveguide transmission line 6 with an internal conductor core. The ridge waveguide is a rectangular waveguide. This waveguide is arranged so as to traverse the axis XX' until it comes into contact with the sheath 3. This waveguide includes a main body 7 and a lid 8. The cross section of the main body 7 includes a bottom 9, two walls 11 perpendicular to this bottom, and these two walls 1.
E formed by ridges 12 equidistant from 1
It is a glyph. This ridge 12 acts as an inner conductor core. A focusing device surrounds the sheath 3, but this device is not shown.

The coupling between the delay line 1 and the transmission line 6 is realized by a conductor part 13 . This conductor part 13 is fixed at the end of the delay line 1 on the side of the microwave energy extraction external circuit 10 . The illustrated conductor part 13 is in the form of a ring. This conductor part is fitted into the outer wall of the sheath 3. The coupling pin 14 is
Fixedly connected to the ring. The coupling pin 1
4 protrudes into the interior of the sheath 3 and is brazed to the end of the helix 2. A notch 15 is formed in the sheath 3 near the coupling pin 14 to form a space around the component 13. A narrow space 16 is formed between the end of the ridge 12 located next to the delay line 1 and the outer surface of the conductor part 13 . Even without contact, an electromagnetic coupling is formed due to the capacitor effect between the outer surface of the conductive part 13 and the ridge 12. This conductor component 13 and transmission line 6 are mechanically unrelated.

FIG. 3 is a longitudinal cross-sectional view of a portion of a waveguide according to the invention. FIG. 4 is a cross-sectional view of the tube shown in FIG. 3 in plane AA'. FIG. 3 also shows the plane BB′ of FIG.
FIG. The delay line 1 has a spiral with an axis XX', which spiral includes three conductor supports 20,
21 at the center of the conductor sheath 3. The microwave energy extraction circuit 10 includes a waveguide-shaped transmission line 6 having a ridge 12 as shown in FIGS. 1 and 2.
has. The transmission line is placed near the end of the helix 2 shown in FIG. three supports 20, 21
are 120 degrees apart. Helix 2 and support 2
A dielectric layer 22 is interposed between 0 and 21. This dielectric layer serves as an insulator for the spiral 2 and can be made of alumina. The ends of the helix 2 are connected to a portion of one support 21. This support 21
The above-mentioned portion of the transmission line 6 faces the inner conductor core of the transmission line 6. The above-mentioned portion of the support body 21 and the inner conductor core 12 are
Mechanically independent. This connection 23 is performed, for example, by laser welding or brazing. Connection 23 is a direct connection to said part of support 21. Said part of the support 21 connected to the helix 2 is exposed and without dielectric. Said part of the support 21 connected to the helix 2 provides a coupling between the helix 2 and the conductor core 12 of the transmission line.

As can be seen in FIG. 3, the sheath 3 is provided with an incision 25, thereby forming a space around the support 21 connected to the end of the helix 2. space 1
6 is a ridge 1 on the outer surface from the above part of the support 21.
It separates the 2. Between the outer surface of the part of the support 21 and the ridge 12, due to the capacitor effect,
Electromagnetic coupling is ensured. Said part of the support 21 plays the same role as the conductor part with the coupling pin of the prior art. The supports 20, 21 are in the form of rods with a rectangular cross section. These cross sections were sometimes trapezoidal. These rods are preferably made of metal, such as copper or its alloys. These rods are clamped or brazed. Each of the supports 20 and 21 is
It is inserted into a hollow groove 24 formed in the inner wall of the sheath 3. These grooves make it easier to attach the helix 2 to the sheath 3. The supports 20 and 21 can be a part of the sheath 3 and have a rib shape that protrudes into the interior of the sheath 3. It is also possible not to form a cut in the sheath 3. In this case, a space 16 is formed between the outer surface of the sheath 3 and the ridge 12. In this case, the conductor support 2
1 is in contact with the sheath 3 over its entire length. This sheath 3 also provides a coupling between the delay line and the inner conductor core. Using the device shown in Figure 3, the standing wave ratio obtained in a passband larger than one octave is 1
．． Less than 7.

FIGS. 5 and 6 are longitudinal and cross-sectional views, respectively, of a portion of a traveling wave tube according to the invention. 5 is a longitudinal cross-sectional view taken along plane BB' in FIG. 6, and FIG. 6 is a cross-sectional view taken along plane AA' in FIG. The supports 20 and 21 are
It is a rod with a rectangular cross section. Said part of the support 21 connected to the end of the helix 2 and facing the ridge 12 can be given a suitable shape. Impedance matching can be obtained by this suitable shape, which shape is chosen as a function of the desired frequency and passband. Thus, material can be added to or removed from said portion of the support 21. In FIGS. 5 and 6, said part of the support 21 has two perpendicular planar flanges 5
0.51. A first rectangular flange 50 is in the extension of the support 21 . This flange is thinner than the support 21 but projects on both sides of the support. The second flange 51 is on top of the first flange 50. This second flange is fixed to the helix 2, for example by brazing. Further, the sheath 3 has a notch 25 to form a space around the above-mentioned portion of the support body 21.

FIGS. 7 and 8 are longitudinal and cross-sectional views, respectively, of a portion of a traveling wave tube according to the invention. 7 is a longitudinal cross-sectional view taken along plane BB' in FIG. 8, and FIG. 8 is a cross-sectional view taken along plane AA' in FIG. The sheath 3 can also be used to align the coupling. In these drawings,
The length of the sheath 3 is approximately the same as that of the support body 21. This sheath has substantially longitudinal grooves 70, 71 in a radial direction.
, and these grooves completely penetrate the wall of the sheath 3. Grooves 70, 71 are arranged on both sides of support 21. The depth of the grooves 70 and 71 is approximately equal to the height of the ridge 12. These two grooves 70, 71 delimit the sheath part that participates in the coupling with said part of the support 21 connected to the end of the helix 2. This configuration given to the sheath 3 makes it possible to improve the heat dissipation between the helix 2 and the outside of the sheath via the support 21. The sheath 3 and the support 21 remain in intimate contact throughout their length. Since the end of the helix 2 is on the output side of the traveling wave tube, the temperature increases particularly.

FIGS. 9 and 10 are longitudinal and cross-sectional views, respectively, of a portion of a traveling wave tube according to the present invention. 9 is a longitudinal cross-sectional view taken along plane BB' in FIG. 10, and FIG. 10 is a cross-sectional view taken along plane AA' in FIG. In these figures, the transmission line is a coaxial line 90. This coaxial line comprises a central conductor 91 and an outer conductor 92 in the form of a coaxial cable. This center conductor 91 is not hollow. Two conductors 91 and 92 are separated by a dielectric 93. Coupling is performed between the delay line 1 and the center conductor. The conductor supports 20, 21 are an integral part of the sheath 3. These conductor supports are formed in the form of ribs projecting inward from the inner wall of the sheath 3. The sheath 3 including the ribs is formed by, for example, broaching. Said part of the support 21 is connected directly to the end of the helix 2. The above-mentioned part of this support body 21 is connected to the coaxial line 9
It is arranged so as to face the center conductor 91 of No. 0. A dielectric layer 2 is provided between the supports 20 and 21 and the spiral 2.
2 is placed. This dielectric layer insulates the helix 2 from the conductor supports 20,21. The sheath 3 is provided with an incision 25 forming a space around said part of the support 21 connected to the end of the helix 2 . A microwave window extends between the outer surface of the portion of support 21 and the end of center conductor 91 . The microwave window 94 is transparent to microwave energy but impermeable to gas. This window is hermetically secured to the traveling wave tube. The use of microwave windows is described, for example, in French patent application No. 88/13, filed on October 11, 1988,
It is described in No. 342.

The above examples are merely illustrative of some embodiments of the invention. Other devices can be devised within the scope of the invention. In particular, the other end of the helix located at the input of the delay line can likewise be coupled to a transmission line capable of radiating microwaves.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a portion of a conventional traveling wave tube using a non-contact coupling device between a helical delay line and a ridge waveguide.

FIG. 2 is a cross-sectional view of the traveling wave tube shown in FIG. 1.

FIG. 3 is a longitudinal cross-sectional view of a portion of a traveling wave tube according to the invention using a non-contact type coupling device between a helical delay line and a ridge waveguide;

FIG. 4 is a cross-sectional view of the traveling wave tube shown in FIG. 3;

FIG. 5 is a longitudinal sectional view of a portion of a traveling wave tube according to the invention using another non-contact type coupling device;

6 is a cross-sectional view of the traveling wave tube shown in FIG. 5. FIG.

FIG. 7 is a longitudinal sectional view of a portion of a traveling wave tube according to the invention using yet another non-contact type coupling device;

8 is a cross-sectional view of the traveling wave tube shown in FIG. 7. FIG.

FIG. 9 is a longitudinal sectional view of a portion of a traveling wave tube according to the invention using a hermetically sealed non-contact type coupling device between the helical delay line and the coaxial line;

10 is a cross-sectional view of the traveling wave tube shown in FIG. 9. FIG.

[Explanation of symbols]

1 delay line
2 Helix 3 Conductor sheath
4 Insulating support 5 Cylindrical conductor
6 Transmission line 7 Main body 8
Lid 9 Bottom
10 External microwave circuit 11 Wall part
12 Ridge 13 Conductor parts
14 Coupling pin 17
groove
20, 21 Support 22 Dielectric layer
23 Connections 50, 51
Flange 70, 71
Groove 90 Coaxial line
91, 92 conductor 93 dielectric layer

Claims (12)

[Claims] 1. A delay line held within a cylindrical conductor sheath by a plurality of conductor supports, and an external microwave circuit coupled to the delay line by a capacitor effect;
The external microwave circuit is a traveling wave tube comprising a transmission line having an inner conductor core disposed near an end of the delay line, and a dielectric layer is provided between the delay line and the support. one of the ends of the delay line is connected to a portion of one of the supports;
A traveling wave tube characterized in that a portion of the support is disposed to face the inner conductor core. 2. The traveling wave tube according to claim 1, wherein the end of the delay line is brazed to a portion of the support. 3. The traveling wave tube according to claim 1, wherein the sheath has a notch forming a space around a portion of the support connected to an end of the delay line. . 4. The traveling wave tube according to claim 1, wherein the sheath covers a portion of the support connected to an end of the delay line. 5. A portion of the support connected to an end of the delay line has two perpendicular flanges, a first flange extending toward the support and a second flange extending toward the support. Process according to claim 1, characterized in that a flange is on said first flange and is fixed to said end of said delay line, said two flanges allowing alignment of the coupling. Wave tube. 6. The sheath has two radially extending longitudinal grooves disposed on opposite sides in a portion of the support connected to the end of the delay line, the two grooves providing a means for achieving
The traveling wave tube according to claim 4 or 5, characterized in that it enables coupling matching. 7. The traveling wave tube according to claim 1, wherein the delay line is a spiral. 8. The traveling wave tube according to claim 1, wherein the delay line is brazed to the dielectric layer. 9. The traveling wave tube according to claim 1, wherein the support is a rib forming a part of the sheath and protruding inside the sheath. 10. The transmission line is a ridge waveguide,
The traveling wave tube according to claim 1, wherein the inner conductor core is a protrusion. 11. The traveling wave tube according to claim 1, wherein the transmission line is a coaxial line, and the inner conductor core is a center conductor of the coaxial line. 12. A microwave window according to claim 1, further comprising a hermetically sealed microwave window extending between the portion of the support connected to the delay line and the inner conductor core. traveling wave tube.