JPS63940A - Manufacture of cross spiral slow-wave structure of traveling wave tube - Google Patents

Abstract

PURPOSE:To obtain a cross spiral slow-wave structure easily and at a low cost, by winding the first and the second spirals on a core in parallel to each other with a fixed pitch, winding the third spiral as being superposed on and crossing them, and removing the second spiral afterwards. CONSTITUTION:The first and the second spirals 5 and 6 are wound on a core 8 closely and with a fixed pitch to each other. Then the third spiral 7 is wound being superposed on the spirals 5 and 6 in a way as crossing the spirals 5 and 6 with the same pitch as the first spiral 5 but in the opposite direction. And both ends of the first to the third spirals 5 to 7 are fixed to the core 8 by an adequate means. The whole spirals 5 to 7 in such a condition including the core 8 is annealed by heating in a hydrogen furnace or the like so as to eliminate an internal stress generated in winding the respective spirals on the core 8. Then, the whole spirals are cut in a necessary length and the core 8 and the second spiral 6 are removed. Thus, a cross spiral slow-wave structure can be easily obtained at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a traveling wave tube having a helical slow-wave circuit, and more particularly to a method for manufacturing an effective helical slow-wave circuit of a traveling wave tube.

BACKGROUND OF THE INVENTION A variety of traveling wave tubes are currently used in communications, broadcasting, and other fields. The traveling wave tube basically includes an electron gun that emits an electron beam, a collector that captures the electron beam from the electron gun, and a slow wave circuit placed between the electron gun and the collector. When the input signal wave applied to the slow-wave circuit from the input section travels along the slow-wave circuit, the electron beam is velocity-modulated, and the amplified electromagnetic wave is extracted at the output section on the downstream side of the slow-wave circuit. being done.

In recent years, there has been an increase in demand for such traveling wave tubes as power amplifier tubes at the final stage of repeaters for satellite communication earth stations.
In such applications, high output is essential. As the output increases, the operating voltage and current will naturally become higher and larger, but due to the necessity of ensuring insulation between electrodes, optimizing heat dissipation means, and securing the required beam power, it is natural that the external shape and dimensions will increase. increases. On the other hand, however, users' demands are for smaller, lighter, easier handling, and lower power consumption, including for mobile use such as on-vehicle or aircraft-mounted devices. Therefore, it has become essential to increase the output of the traveling wave tube without increasing its external dimensions and power consumption, that is, to develop some means for increasing its efficiency.

Under these circumstances, we focused on the fact that a spiral slow-wave circuit, which is formed by spirally forming wire or tape made of tungsten or molybdenum, etc., which have a high melting point, is small, lightweight, and easy to handle, as a slow-wave circuit for a traveling-wave tube. has been and is being used.

Furthermore, various improvements have been made to this spiral slow wave circuit in order to improve the efficiency of the traveling wave tube.

For example, there are those in which a speed taper pitch corresponding to the speed reduction of the electron beam is added to the output end of the spiral, and those in which the spiral is plated with gold to reduce high frequency loss at the output end spiral portion.

However, in order to further increase the output, it is necessary to create a helical structure that suppresses the electronic component of the spatial harmonics of the spiral to increase the coupling impedance of the fundamental wave, while at the same time reducing the backward wave component. .

One method is to combine a first spiral that propagates electromagnetic waves with a second spiral that is wound in the opposite direction to the first spiral and intersects with the first spiral at the same pitch. Spiral slow wave circuits are known.

Problems to be Solved by the Invention FIG. 2 illustrates a traveling wave tube slow wave circuit structure 1 having a conventionally known crossed spiral slow wave circuit. The intersecting spiral 2 consists of two spirals: a first spiral 2'' that propagates electromagnetic waves, and a second spiral 2'' that is wound in the opposite direction to the first spiral and intersects with the first spiral 2' at the same pitch. It is formed by combining the two, and the overall shape is cylindrical and cage-shaped. Further, the crossed spiral 2 is housed and fixed in a cylindrical metal envelope 4 via a plurality of dielectric columns 3.

In this crossed spiral slow wave circuit, two spiral propagation modes exist in a superimposed manner. For this reason, it is also known that because the fundamental wave component electric field in the axial direction of the entire helical system is strong, the coupling impedance of the helix is also high, and high output can be obtained.

However, although such a crossed helical slow wave circuit is known to have the above-mentioned high efficiency characteristics,
Due to its complex shape, molding has a low yield and requires high precision and a long processing time, resulting in high manufacturing costs, and in the end, it is impossible to put it into practical use. Ta.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for manufacturing a crossed helical slow wave circuit, which allows the aforementioned crossed helical slow wave circuit to be manufactured easily and inexpensively.

A means for solving the problem, that is, a method for manufacturing a crossed spiral slow wave circuit of a traveling wave tube according to the present invention, is to wind first and second spirals on a winding core in parallel with each other at a predetermined pitch, It is characterized in that a third spiral is wound overlappingly so as to intersect with the first and second spirals, and the second spiral is later removed.

According to the method of the present invention as described above, the second spiral is wound, for example, around the core in parallel with the first spiral, so that the pitch of the first spiral can be made uniform, and at the same time, The cross section of the third spiral wound on top of the first and second spirals can also be made to be close to a perfect circle.

Therefore, according to the present invention, a high quality crossed helical slow wave circuit of a traveling wave tube can be manufactured easily and inexpensively.

Example Next, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1(a) is a three-dimensional diagram of a crossed spiral slow-wave circuit structure of a traveling wave tube according to the present invention, and FIG.
FIG. 1(C) is a three-dimensional view illustrating a method of forming the crossed spirals of the crossed spiral slow wave circuit in FIG. 1(a).

Referring to FIG. 1(a), the cylindrical and cage-shaped intersecting spiral 2 of the illustrated traveling wave tube consists of a plurality of cylinders located around the intersecting helix 2 and parallel to the central axis of the intersecting helix 2. shaped dielectric pillar 3
It is supported by and housed in a cylindrical metal envelope 4, and is fastened and fixed by the elasticity of the cylindrical metal envelope 4.

An electron gun unit (not shown) for emitting an electron beam is coupled to one end of the cylindrical metal envelope 4, and an electron gun unit (not shown) that emits an electron beam is connected to the other end of the cylindrical metal envelope 4. A collector section (not shown) is coaxially connected to the envelope 4 and has a function of capturing the kinetic energy of the heat energy, converting the kinetic energy into thermal energy, and dissipating it.

The crossed spiral 2 is composed of a spiral 5 that propagates electromagnetic waves, and a spiral 7 that is wound on top of the spiral 5 at the same pitch as the spiral 5 so as to intersect with the spiral 5. Necessary points of intersection between the spirals 5 and 7 are joined by, for example, welding.

Such a crossed spiral 2 is formed according to the present invention as follows. As shown in FIG. 1(C), first, a winding core 8 is prepared which has an outer diameter equal to the inner diameter of the intersecting spiral to be formed and is sufficiently longer than the entire length in the axial direction of the intersecting spiral to be formed.

The first and second spirals 5 and 6 are wound on the core 8 parallel to each other and densely at a predetermined pitch. Next, a third spiral 7 is wound over the spirals 5 and 6 in the opposite direction at the same pitch as the first spiral 5 so as to intersect with the spirals 5 and 6. and the first, second and third spirals 5, 6
, 7 are fixed to the winding core 8 using appropriate means.

The entire spirals 5, 6, and 7 including the winding core 8 in such a state are heated and annealed, for example, in a hydrogen furnace or the like, to remove the internal stress caused when each spiral is wound around the winding core 8.

Furthermore, the crossed spiral 2 can be formed by cutting the whole to a required length and removing the winding core 8 and the second spiral 6.

However, in this state, the spirals 5 and 7 are merely in contact with each other at the points where they intersect every half turn. Therefore, it is easy to lose its shape mechanically. Therefore, in order to mechanically stabilize the entire crossed spiral, 2
Necessary points of intersection where the spirals 5 and 7 of the book intersect every half turn are joined by, for example, welding.

In the above-mentioned method for manufacturing a traveling wave tube crossed spiral slow wave circuit structure, the dimensions of the second spiral 6 are determined by the pitch and wire diameter (width and thickness in the case of tape) of the first spiral 5. Ru. That is,. When the first spiral 5 is a wire rod, the wire diameter of the first spiral is d1, the pitch is p, the width of the second spiral 6 is A, and the thickness is B, then A≦p-a, B =d. However, in the case of Δ〉B, the second spiral 6
A wire having the same wire diameter as B may be used.

That is, according to the manufacturing method of the present invention, the first spiral 5 has a uniform pitch because it has the second spiral 6, and the pitch of the first spiral 5 and the second spiral 6 becomes uniform. The cross section of the third spiral 7 wound over the top can also be formed into a substantially perfect circle.

Here, if the second spiral 6 is eliminated and the third spiral 7 is wound directly on top of the first spiral 5, at all the intersections where the two spirals intersect, a portion of the length of one spiral will be partially overlapped. It bulges in the outer circumferential direction by the thickness.

In other words, the spiral 7 comes into direct contact with the outer periphery of the winding core 8 only at each position offset by ±90 degrees with respect to the central axis of the crossed spiral 2 from the intersection point where the two spirals intersect, and the spiral 7 The cross section of is almost elliptical. If this is the case, various problems may occur in the electrical characteristics of the crossed helical slow wave circuit itself or in the case of storing and fixing it inside the cylindrical metal envelope 4.

Therefore, as described above, according to this embodiment, the crossed helical slow wave circuit, which is conventionally known to be able to generate a large output fG, but has not been put to practical use because it is difficult to mold and the manufacturing cost is high, can be easily realized. It can be realized easily and inexpensively, and the cross sections of the two inner and outer spirals can be formed into a substantially perfect circle. Therefore, it goes without saying that the crossed helical slow wave circuit has electrically stable characteristics.
4. Cylindrical metal envelope. The dielectric support column 3 to be housed and fixed inside can also be stably and easily arranged. Therefore, problems such as breakage of the dielectric support pillars and disturbance of the pitch of the spiral can be minimized, and a crossed spiral slow wave circuit structure with a well-balanced mechanical point can be realized.

Effects of the invention As is clear from the above explanation, according to the present invention,
A high-quality crossed helical slow wave tube that can realize a small, lightweight, highly reliable, and highly efficient traveling wave tube can be manufactured inexpensively and easily.

[Brief explanation of drawings]

FIG. 1(a) is a three-dimensional view of a crossed spiral slow wave circuit structure of a traveling wave tube according to the present invention, FIG. 1(a) is a sectional view of FIG. 1(a), and FIG.
C) is a three-dimensional view illustrating the method of forming the crossed spirals of the crossed spiral slow wave circuit in FIG. 1(a); FIG. FIG. 3 is a three-dimensional diagram illustrating a slow wave circuit structure of a wave tube. (Main reference numbers) 1...Cross spiral slow wave circuit structure, 2, 2", 2", 5, 6.7...Spiral 3...Dielectric support column, 4...Cylindrical metal envelope , 8... Core patent applicant
NEC Corporation (a) (b) 1...Spiral 3.
・Dielectric support 4. Cylindrical metal envelope 8. 1 core

Claims (1)

[Claims] The first and second spirals are wound on a winding core in parallel with each other at a predetermined pitch, a third spiral is wound so as to intersect with the first and second spirals, and the second spiral is later removed. A method for manufacturing a traveling wave tube crossed spiral slow wave circuit.