JPH04332425A - Manufacture of slow wave circuit of traveling wave tube - Google Patents

Abstract

PURPOSE:To easily fix a helix supported on dielectric struts inside an envelope by the use of a plastically deformed spacer. CONSTITUTION:Manufacture of a wave delaying circuit of a traveling wave tube comprises the steps of: inserting a helix 4 supported on three dielectric struts 3 into an envelope; arranging a metal jig having a thermal expansion coefficient smaller than that of a spacer 2 at the outside surface of the spacer 2 constituting a part of the envelope; heating the envelope with the metal jig fixingly arranged therein; and cooling the heated envelope for fixing the helix 4 supported on the dielectric struts 3 inside the envelope.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for manufacturing a traveling wave tube slow wave circuit, and more particularly to a traveling wave tube slow wave circuit including a step of fixing a helix held by a dielectric support inside a slow wave circuit envelope. This invention relates to a method of manufacturing a circuit.

0002

[Prior Art] A traveling wave tube using a helix-type slow-wave circuit is an electron gun that emits an electron beam, a helix-type slow-wave circuit that amplifies a signal through the interaction between the electron beam and the signal, and a helix-type slow-wave circuit that amplifies the signal by the interaction between the electron beam and the signal. It consists of a collector, etc. that captures the electron beam.

[0003] When an electron beam passes through a helix, the electron beam spreads outward due to the influence of space charges and collides with the helix. When the amount of electrons that collide with the helix increases, the number of electrons that contribute to signal amplification in the helix type slow-wave circuit decreases, and the energy conversion efficiency of the traveling wave tube decreases. Furthermore, the helix is heated to a high temperature by the collision with the electron beam, releasing a large amount of gas and causing deterioration of the cathode, or the helix melting and rendering the traveling wave tube inoperable. A periodic magnetic field focusing device is used to prevent such problems from occurring and to focus the electron beam to a constant diameter throughout.

[0004] As a periodic magnetic field focusing device, the helix and dielectric are used to prevent the helix from shifting due to external forces such as vibrations and shocks, and to reduce the thermal resistance between the helix and the slow-wave circuit envelope. It is necessary to securely and precisely hold the pair of support columns within the slow-wave circuit envelope.

Conventionally, as a periodic magnetic field focusing device, as shown in FIG. The cylindrical envelope 9 is deformed into a substantially triangular shape by applying pressure from three directions of the support, the helix 4 supported from three directions is inserted into the dielectric support 3, and the helix is held by releasing the pressure. As shown in FIG. 5, a plurality of disc-shaped pole pieces 1 made of magnetic metal with a hole in the center are fitted onto the outer periphery of a helix-type slow-wave circuit manufactured by the so-called distortion squeeze method. A structure in which an annular permanent magnet 10 is arranged concentrically with the electron beam is known. The distortion squeeze method has been widely used because it does not require very high component precision and can easily and reliably hold the helix 4 within the slow wave circuit envelope.

[0006] However, as traveling wave tubes become more powerful at higher frequencies, periodic magnetic field focusing devices are also required to have higher magnetic flux density. In other words, as shown in Fig. 6, a disc-shaped pole piece 1 made of magnetic metal with a hole in the center and a cylindrical spacer 2 made of non-magnetic metal are stacked alternately, and are connected to the outside of the slow-wave circuit by brazing. A periodic magnetic field focusing device has been proposed that has a so-called pole piece integrated slow wave circuit envelope in which a permanent magnet 10 is arranged between pole pieces 1.

[0007]

[Problems to be Solved by the Invention] However, in the above-mentioned pole piece integrated slow-wave circuit envelope, it is difficult to deform the donut plate-shaped pole piece when inserting the helix into the slow-wave circuit envelope. Yes, distortion squeeze method cannot be used. For this reason, the inner diameter of the brazed slow-wave circuit envelope was first precisely ground with a gun drill, etc., and then the helix and dielectric support were press-fitted. The dimensional difference between the inner diameter of the slow-wave circuit envelope and the outer shape of the internal structure consisting of the helix and dielectric support must be suppressed to within several μm, and extremely high component dimensional accuracy is required. In addition, there were other problems such as the dielectric support being broken due to the strong press-fitting, and the need to bond the helix and the dielectric support to prevent displacement during press-fitting.

Furthermore, since the helix is held by a slight difference in the dimensions of the parts, the holding strength is weak, and there is also the problem that the position of the helix is likely to shift.

An object of the present invention is to provide a slow-wave traveling wave tube that does not require high component dimensional accuracy and allows a helix to be easily inserted and fixed into a slow-wave circuit envelope without damaging the dielectric support or shifting the helix position. An object of the present invention is to provide a method for manufacturing a circuit.

0010

[Means for Solving the Problems] The present invention provides three dielectric supports inside an envelope formed by alternately stacking and joining disc-shaped pole pieces having a hole in the center and cylindrical spacers. A method for manufacturing a traveling wave tube slow wave circuit in which a held helix is arranged, including the step of inserting the helix held by the dielectric support into the inside of the envelope, and forming a part of the envelope. a step of arranging and fixing a metal jig having a smaller thermal expansion coefficient than the spacer on the outer surface of the spacer, a step of heating the envelope in which the metal jig is arranged and fixed, and a step of cooling the heated envelope. fixing the helix held by the dielectric support inside the envelope by doing so.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) and 1(b) are partial sectional views illustrating a first embodiment of the present invention.

As shown in FIG. 1(a), the first embodiment has an outer diameter of 9 mm, an inner diameter of 1.8 mm, and a diameter of 1.8 m.
Thickness of 4.5 mm from m is 1.6 mm, diameter 4.5
A T-shaped pure iron disk-shaped pole piece 1 with a thickness of 1 mm at the part from 9 mm in diameter to 9 mm in diameter, and a cylindrical spacer made of Monel metal with an outer diameter of 4.5 mm, an inner diameter of 1.8 mm, and a thickness of 2.5 mm. 2 were stacked alternately with JISBAu-1V brazing plates interposed therebetween and heated to 1020° C. in a hydrogen atmosphere to obtain an envelope.

Next, as shown in FIG. 1(b), the helix 4 supported by the dielectric support 3 from three directions is inserted into the envelope, and then the helix 4 with an inner diameter of 4.5 mm, an outer diameter of 10 mm, An annular jig 5, which is a molybdenum ring halved with a thickness of 3 mm and a chamfered inner circumference and an axial thickness of 2.3 mm on the inner circumferential surface after chamfering, is attached to each pole. piece 1
A pair of each were arranged on the outer circumferential side of the spacer 2 between them. Furthermore,
A cylindrical jig 6, which is a molybdenum cylinder with an inner diameter of 10 mm and an outer diameter of 16 mm, halved in the axial direction, is placed on the outer peripheral side of the annular jig 5 so as to cover all the annular jigs 5, and the cylinder Several locations on the outer periphery of the shaped jig 6 were secured with molybdenum wires having a diameter of 0.8 mm.

The slow wave circuit thus assembled was heated to 800° C. in a hydrogen atmosphere and then cooled to room temperature. During this heating, since the coefficient of thermal expansion of the spacer 2 is larger than that of the annular jig 5 and the cylindrical jig 6, the spacer 2 is prevented from thermal expansion by the annular jig 5 and the cylindrical jig 6, and the diameter of the spacer 2 is The inner diameter of the spacer 2, which was plastically deformed toward the center of the spacer and cooled, became smaller than the inner diameter before heating, and the helix 4 supported by the dielectric support column 3 was firmly fixed inside the envelope. As can be seen from the above explanation, the virtual outer diameter of the structure in which three dielectric pillars 3 are arranged around the outer periphery of the helix 4 is smaller than the inner diameter of the spacer 2 before heating, and larger than that after heating. In this example, the virtual outer diameter of the structure of the helix 4 and the dielectric support 3 is set to 1.785 m.
It was set as m.

FIG. 2 is a partial sectional view illustrating a second embodiment of the present invention, and FIG. 3 is a perspective view of a fixing jig used in the second embodiment of the present invention.

In the second embodiment, a slow wave circuit was manufactured using the same parts and manufacturing method as in the first embodiment, but as shown in FIG. A jig in which an annular jig 5 and a cylindrical jig 6 made of molybdenum were integrated was used.

That is, as shown in FIG. 3, the inner diameter is 4.5 mm.
, Cut a molybdenum cylinder with an outer diameter of 16 mm in half in the axial direction, and insert pole piece 1 into the part where pole piece 1 will fit.
Semicircular grooves with a diameter of 10 mm and a width of 1.2 mm are provided at a pitch of A fixing jig 8 was prepared, and the annular jig 5 of the first embodiment was manufactured.
and the cylindrical jig 6 was used instead.

According to this method, although the jig becomes expensive, it is easy to assemble and can be used for mass production. Furthermore, if a cylinder made of molybdenum that fits on the outside of the fixing jig 8 is used instead of the molybdenum wire 7 secured to the outer periphery of the fixing jig 8, the assembly will be further facilitated.

On the other hand, when the number of slow-wave circuits to be manufactured is very small, such as when making a prototype, the outer periphery of the spacer 2 is directly and firmly attached without using the annular jig 5, the cylindrical jig 6, or the fixing jig 8. The same effect as in the above-mentioned embodiment can also be obtained by lashing with a molybdenum wire having a diameter of 1 mm or more.

[0021]

Effects of the Invention As explained above, according to the present invention, a helix held by a dielectric support is inserted into an envelope in which disk-shaped pole pieces and cylindrical spacers are stacked alternately and bonded together. After fixing a metal jig with a coefficient of thermal expansion smaller than that of the previous spacer to the outer surface of the spacer, it is heated to plastically deform the spacer inward, and then cooled to easily form an envelope with the plastically deformed spacer. This has the effect of fixing the helix held by the dielectric support inside.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view illustrating a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view illustrating a second embodiment of the present invention.

FIG. 3 is a perspective view of a fixing jig used in a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a helix insertion method using the conventional distortion squeeze method.

FIG. 5 is a partial cross-sectional view of an example of a conventional slow wave circuit.

FIG. 6 is a partial cross-sectional view of a conventional pole piece integrated slow wave circuit.

[Explanation of symbols]

1 Pole piece 2 Spacer 3 Dielectric support 4 Helix 5 Annular jig 6 Cylindrical jig 7 Molybdenum wire 8 Fixing jig 9 Cylindrical envelope 10 Permanent magnet 11 Blade jig

Claims (1)

[Claims] Claim 1: A progression device in which a helix held by three dielectric supports is placed inside an envelope formed by alternately stacking and joining disc-shaped pole pieces with a hole in the center and cylindrical spacers. In the method for manufacturing a wave tube slow wave circuit, the step of inserting the helix held by the dielectric support into the inside of the envelope, and the step of inserting the spacer on the outer surface of the spacer forming a part of the envelope. A step of arranging and fixing a metal jig with a smaller coefficient of thermal expansion, a step of heating the envelope with the metal jig arranged and fixed, and cooling the heated envelope to improve the temperature of the envelope. A method for manufacturing a traveling wave tube slow wave circuit, comprising the step of fixing a helix held by the dielectric support inside.