JPH0625878Y2 - Traveling wave tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to improvement of characteristics of a helix type traveling wave tube, particularly a slow wave circuit.

[Conventional technology]

A helix-type traveling-wave tube is a slow-wave circuit in which a metal conductor is formed into a helix shape, and usually three dielectric columns are arranged in a barrel-shaped stainless steel cylinder at 120 ° intervals in the axial direction. Is arranged so that the helix is held by mechanical pressure. A signal from the outside is input to the helix via the input coaxial waveguide, exchanges energy with the electron beam, and is extracted as an amplified signal to the outside via the output coaxial waveguide.

FIG. 2 (a) is a cross-sectional view showing the details of the high-frequency output section, in which 1 is a helix, 2 is a dielectric strut, and 3 is a barrel. It is assembled by the distortion squeeze method, and the helix 1 is fixed by utilizing the elasticity of stainless steel which is the material of the barrel 3. In the coaxial waveguide 7, the outer coaxial conductor 4 is connected to the barrel 3, and the inner coaxial conductor 5 is connected to the helix 1. A space between the coaxial outer conductor 4 and the coaxial inner conductor 5 is sealed with a vacuum sealing ceramic 6. In addition, 8 is a permanent magnet and 9 is a magnetic pole, and the combination thereof forms a periodic permanent magnet device.

[Problems to be solved by the invention]

In the conventional helix type traveling wave tube, the temperature of the helix during operation was abnormally high near the connection portion of the coaxial waveguide depending on the product. If this temperature rise occurs, accidents such as evaporation and fusing of the helix material are likely to occur, which causes a decrease in the reliability of the traveling wave tube.

The present inventor has found the following as a result of investigating the above-mentioned abnormal temperature rise of the helix. As mentioned above, the helix and the dielectric support are assembled in the barrel by the distortion squeeze method. However, the heat generated in the helix during the operation of the traveling wave tube makes contact as the mechanical contact pressure applied to the helix increases. The area is large and the heat that escapes from the helix is large. However, the work of connecting the coaxial waveguide to the barrel is usually performed by high-frequency brazing. At this time, the temperature of the barrel is heated to about 800 ° C in the vicinity of the brazing portion, so even if careful brazing is performed, the barrel material Of stainless steel is easily annealed, and as a result, the pressure applied to the helix is weakened. Therefore, it was found that the temperature of the helix during operation may rise abnormally depending on the manufacturing conditions.

An object of the present invention is to provide a traveling wave tube based on the above investigation results, which is provided with measures capable of reliably preventing an abnormal temperature rise during the operation of the helix.

[Means for solving problems]

The helix-type traveling-wave tube of the present invention is provided with a brazing connection portion of the coaxial waveguide near the connection portion of the barrel for holding the helix through the dielectric strut with the input / output coaxial waveguide. Grooves along the outer circumference of the barrel are provided on both outer sides.

[Action]

The coaxial waveguide is mounted on the barrel by high-frequency brazing as in the past.However, since the groove provided along the outer circumference of the barrel near the brazing portion, that is, the connection portion of the coaxial waveguide, the thickness of the barrel is reduced. It becomes thin and the heat resistance of this part is large. Therefore, the heat generated during the high frequency heating is limited to the brazing portion and the heating of the other portions of the barrel is suppressed, so that the annealing of the barrel can be prevented. As a result, the barrel retains sufficient resilience and provides the helix with sufficient contact pressure through the dielectric strut.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2B is an enlarged view of the brazing portion 10 for connecting the barrel 3 with the coaxial outer conductor 4 of the conventional example shown for comparison. The barrel 3 has a uniform thickness even in the brazing portion 10. Has become.

On the contrary, in the present embodiment, as shown in FIG. 1, the barrel 3 is provided with the grooves 11 on both outer sides in the vicinity of the brazing portion 10. The groove 11 is provided along the outer circumference of the barrel 3 and is formed in an annular shape. Due to the groove 11, the thermal resistance is large in this portion. Therefore, when the coaxial outer conductor 4 is brazed to the barrel 3, the resistance against the heat flow in the direction shown by the arrow in the figure is large. As a result, the heating during brazing can be limited to the brazing part 10.

[Effect of device]

As described above, the present invention has a simple structure in which a groove is formed along the outer circumference in the vicinity of the portion of the barrel that is connected to the coaxial waveguide, and prevents the temperature increase during operation of the conventional helix. I was able to. This makes it possible to obtain a highly reliable traveling wave tube.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, showing a situation in the vicinity of a connection portion with a barrel of a coaxial waveguide, and FIG. 2 shows a cross-sectional view of a conventional high-frequency output portion and a vicinity of the connection portion. It is a figure which shows the situation of. 1 ... Helix, 2 ... Dielectric support, 3 ... Barrel, 4 ... Coaxial outer conductor, 5 ... Coaxial inner conductor, 6 ... Vacuum sealing ceramic, 7 ... Coaxial waveguide, 10 ... … Brazing part, 11… Groove.

Claims (1)

[Scope of utility model registration request] 1. In a helix-type traveling wave tube, a brazing connection of the coaxial waveguide is provided in the vicinity of a connection portion of a barrel holding a helix via a dielectric strut with an input / output coaxial waveguide. Helix type traveling wave tube, characterized by having grooves along the outer circumference of the barrel on both outer sides of the section.