JPS6240812B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention aims to improve the contact thermal resistance and mechanical adhesion between a pole piece and a metal cylinder passing through the pole piece in a periodic magnetic field device used in a traveling wave tube or the like. It is related to the device.

Conventionally, when using a periodic magnetic field device such as a traveling wave tube to focus an electron beam, the traveling wave tube is inserted into a periodic magnetic field device that is preassembled with a pole piece and a magnet, or the traveling wave tube is During the tube assembly process, a pole piece is placed through the slow wave circuit envelope such as a spiral.
After the traveling wave tube is completed, a ring-shaped magnet divided into two along the diameter is attached to complete the periodic magnetic field device, so the inner diameter of the pole piece and the outer diameter of the metal cylinder that makes up the slow wave circuit envelope are different from each other. A slight difference is provided between them so that the pole piece can be easily moved or rotated in the axial direction of the metal cylinder. As a result, when trying to obtain high output using a spiral slow-wave circuit, the output section of the spiral circuit is heated to a high temperature by the high-frequency current flowing through the spiral circuit, which limits the high-frequency output. It is the cause.

Conventionally, in order to solve this problem, a material with high thermal conductivity such as beryllia porcelain or boron nitride was used as the dielectric material for supporting the spiral circuit, and the spiral circuit and the support were used so that the envelope was tightly attached to the inside of the envelope. By inserting the body, the heat generated in the spiral is effectively conducted to the envelope and diffused in the axial direction of the envelope, and a small portion is also conducted from the contact part with the pole piece to the periodic magnetic field device. As a result, the spiral circuit was cooled, but the heat could not be effectively dissipated to the periodic magnetic field device, which has a much larger volume and heat dissipation surface area than a metal cylinder, and in the end, the high frequency output was significantly increased. could not increase. Furthermore, in the conventional type, the contact between the pole piece and the metal cylinder was insufficient, and in some cases, it was necessary to bond the two using epoxy resin or the like for mechanical reinforcement.

The purpose of the present invention is to eliminate such drawbacks of the conventional type, and to effectively conduct the heat generated inside the metal cylinder and led to the metal cylinder to the periodic magnetic field device, thereby reducing the heat inside the metal cylinder. It is an object of the present invention to provide a periodic magnetic field device that can lower the temperature of a heating substance and firmly fix the periodic magnetic field device and a metal cylinder.

In order to achieve the above object, the present invention provides a pole piece with a cutout having a cutout surface inclined with respect to its central axis, and after inserting this into the outer periphery of a metal cylinder, The pole piece is compressed so that the surfaces thereof come into close contact with each other, and the outer periphery of the metal cylinder and the inner periphery of the pole piece are thermally and mechanically brought into close contact.

The present invention will be explained in detail below using examples as well as conventional examples.

Figure 1 is a partial cross-sectional view of a conventional general periodic magnetic field device and a metal cylinder that passes through it.
is a pole piece, and 3 is a metal cylinder.

FIG. 2 is an explanatory view of the relationship between the pole piece 2 and the metal cylinder 3 of the periodic magnetic field device having the conventional structure, where FIG. 2A is a plan view of the pole piece portion, and FIG. 2B is a sectional view of the pole piece portion. A gap 4 is provided between the pole piece 2 and the metal cylinder 3 so that the metal cylinder 3 can be easily moved on the outer periphery thereof.
This shows that it is provided. For this reason, the conventional periodic magnetic field device has the above-mentioned drawbacks.

In order to eliminate such drawbacks, the present invention has made the following improvements.

FIG. 3 is an explanatory view of the relationship between the shape of the pole piece for a periodic magnetic field device according to the present invention before compression processing and the metal cylinder, and figures a, b, and c are a side view, a plan view, and a cross section of the pole piece portion, respectively. It is a diagram. The pole piece 5 is provided with a slit (cutout) 6 that is inclined with respect to its axis, and a gap 4 is provided between the outer diameter of the metal cylinder 3 and the inner diameter of the pole piece 5. The structure is such that the pole piece 5 can be easily moved on the outer periphery of the pole piece 3. This slit 6
The width of and the inclination of the pole piece 5 with respect to the central axis are:
When the pole piece 5 is compressed with the slit 6 in between so that the opposing surfaces are completely in contact with each other, the inner diameter of the pole piece 5 becomes very slightly smaller than the outer diameter of the metal cylinder 3 passing through it, and as shown in FIG. As shown,
The selection is made so that the opposing surfaces of the slit 6 are in close contact with each other, and at the same time, there is no gap between the pole piece 5 and the metal cylinder 3, so that they are in complete contact with each other. Therefore, thermal contact resistance is significantly reduced compared to conventional structures, and sufficient mechanical strength can also be ensured. In addition, in Figure 4, Figures a,
b and c are a side view, a plan view, and a sectional view of the pole piece portion, respectively. Incidentally, the slit portion 6', in which the opposing surfaces of the slit are held in close contact by compression, may be spot welded by being held from both sides with spot electric welding electrodes 7 as shown in FIG.
Moreover, it will be more complete if they are joined by brazing or adhesive such as resin.

Furthermore, by providing a slit in the pole piece, the distribution of the axial magnetic field intensity generated by the periodic magnetic field device may be biased in the magnetic field strength, that is, biased magnetism may occur, but in the present invention, by providing the slit diagonally, Even if biased magnetism occurs, it can be suppressed to a minimum.

As is clear from the above detailed description, by implementing the present invention, the strength of the thermal and mechanical contact between the metal cylinder and the periodic magnetic field device circumscribing the metal cylinder is improved. When applied to , it becomes possible to effectively guide the heat of the helix heated by high-frequency power to a periodic magnetic field device with a large volume and surface area, keeping the output of the traveling wave tube at the same value as before. In some cases, the helix temperature is lowered, which reduces losses and improves efficiency;
If you want to increase the output, while keeping the helical temperature in the same range as for the output in the conventional structure,
It has the advantage of being able to significantly increase output.

Furthermore, the generation of biased magnetism due to the provision of slits in the pole pieces of the periodic magnetic field device can be minimized because the slits are provided diagonally, and the effect on the focusing of the electron beam is extremely small.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view of a conventional general periodic magnetic field device, Fig. 2 is an explanatory diagram of the relationship between the pole piece and the metal cylinder inscribed therein in the conventional periodic magnetic field device shown in Fig. 1; FIG. 3 is an explanatory diagram of the relationship between the pole piece of the periodic magnetic field device according to the present invention and the metal cylinder before compression processing, and FIG. 4 is an explanatory diagram of the relationship between the pole piece of the periodic magnetic field device according to the present invention and the metal cylinder after compression processing. An explanatory diagram of the relationship, FIG. 5 is a diagram showing an embodiment of the spot electric welding process as an example of a method of closely joining the opposing surfaces of the slit provided in the pole piece of the periodic magnetic field device according to the present invention. It is. In the figure, 1... Magnet, 2... Pole piece, 3... Metal cylinder, 4... Gap between pole piece and metal cylinder, 5... Pole piece according to the present invention, 5''... After compression processing Pole piece, 6...
Slit provided in pole piece 5, 6'... slit after compression processing, 7... electrode for spot electric welding.

Claims (1)

[Claims] 1. In a periodic magnetic field device in which a plurality of pole pieces and ring-shaped magnets are alternately arranged in contact with the outer periphery of a metal cylinder, the pole piece is provided with a cutout having a cutout surface inclined with respect to the central axis. After the pole piece is inserted into the outer periphery of the cylinder, the pole piece is compressed so that the opposing surfaces of the incision are in close contact with each other, and the outer periphery of the metal cylinder and the inner periphery of the pole piece are thermally and mechanically brought into close contact. A periodic magnetic field device characterized by: