JPH0141148Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetron cathode, and more particularly to a so-called groove type cathode structure in which a groove is formed in the electron emitting portion of the cathode surface and the groove is filled with an electron emissive material.

In a magnetron cathode, the electrons emitted from the cathode undergo rotational motion due to the action of the magnetic field, so not all of the electrons emitted from the cathode reach the anode, but a certain percentage of the electrons return to the cathode and impact the cathode in reverse. For this reason, in a cathode coated with a powdered electron emissive material such as oxide, the electron emissive material is likely to be damaged by severe reverse bombardment of electrons. In addition, magnetrons are often operated in pulses, and in that case, the current density per unit area is extremely high. However, with a cathode coated with powdered electron radioactive material, the series resistance between the electron radioactive material layers becomes large, resulting in a high current density. In a magnetron cathode that requires density, it is not preferable to have only an electron-emitting substance coated and solidified on the cathode surface. Based on these reasons, we use a so-called cermet type in which metal pieces are mixed with an electron radioactive material and adhere it around the cathode sleeve, or we use a mesh that is glued around the cathode sleeve to release the electron radioactive material into the mesh of the mesh. A mesh type filled with carbon dioxide and a groove type in which a groove is formed around the cathode sleeve and an electron radioactive material is filled in the groove are considered.

Groove type cathodes were developed to improve the characteristics of mesh type cathodes because the adhesive strength between the cathode sleeve and the mesh was insufficient, and they have a structure, for example, as shown in the cross-sectional view of FIG. 1. That is, in FIG. 1, 1 is a cathode sleeve, 2 is a heater, 3 is a groove formed in the cathode sleeve 1, 4 is an electron radioactive material filled in the groove 3, and 5 is an end hat, which is formed integrally with the cathode sleeve 1. .
This type of cathode does not cause problems in use, such as peeling of the mesh adhered to the outer periphery of the cathode sleeve, unlike the mesh type, and provides good characteristics.
The machining process to form the groove requires extremely precise machining (the wall thickness of the cathode sleeve 1 itself is thin at approximately 0.5 to 1 mm, and the groove width is approximately 0.2 mm and depth is 0.1 mm, which is extremely small overall). .) It is difficult to process, and
Even if it could be manufactured, it required a lot of man-hours and was expensive.

The present invention was devised in view of this situation, and its purpose is to provide a cathode structure of a groove type cathode that is easy to manufacture and inexpensive. Specifically, large-diameter and small-diameter laminate plates made of thin plates of the same material as the cathode sleeve are glued to the outer periphery of the cathode sleeve, or large-diameter and small-diameter laminate plates that also serve as cathode sleeves are stacked and glued alternately. However, the groove is formed. This will be explained in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which a is a sectional view and b is a plan view. In FIG. 2, reference numerals 1 to 5 indicate the same parts as in FIG. 1, but the end hat 5 is not integral with the cathode sleeve 1, but is a plate formed in a ring shape and adhered to the outer shape of the cathode sleeve 1. 6
7 is a laminate plate whose inner diameter is the same as the outer diameter of cathode sleeve 1 and has a larger outer diameter, and 7 is a laminate plate whose inner diameter is the same as that of cathode sleeve 1.
8 is a ring for determining the mutual position of the end hat 5 and the laminate plates 6 and 7, and the inner diameter is the same as the outer diameter of the cathode sleeve 1. The outer diameter is the same as that of the small-diameter laminate plate 7, and a plurality of small-diameter laminate plates 7 may be stacked and used. These laminate plates 6, 7 and end hats 5
These can be easily formed by press working etc. because they are made of easy-to-process materials such as nickel plates, and after the end hat 5 ring 8, a large diameter laminate 6 and a small diameter laminate plate 7 are alternately overlapped to the extent that the required cathode area is obtained. Furthermore, a large diameter laminate plate 6, a ring 8,
Stack the end hats 5 and solder them with a waxing material such as nickel powder that does not adversely affect the emitter.
The sleeve is spun to fit tightly by hot compression bonding or cold. If the laminate plates are stacked and bonded without any gaps in this way, a groove 3 will be formed in the portion of the small-diameter laminate plate 7 surrounded by the large-diameter laminate plate 6, and if this groove 3 is filled with an electron radioactive material, A groove type cathode similar to the conventional one can be obtained.

Figure 3 is a sectional view of the cathode base part showing another embodiment of the present invention.In this example, a laminate plate is not glued to the outer peripheral surface of the cathode sleeve, but a laminate plate that also serves as the cathode sleeve. . That is, a large-diameter laminate plate 11, a small-diameter laminate plate 12, and an end hat 5 are made of thin plates such as nickel plates, and the inner diameter is the same as that of a conventional cathode sleeve. , a ring 10, a plurality of sets of small diameter laminates 12 and large diameter laminates 11,
The ring 10, end hat 5, and end ring 13 are stacked so that their inner diameters match and are bonded together by brazing or the like. This bonding method can be easily achieved by, for example, sequentially inserting these into a jig rod that matches the inner diameter and clamping them from both ends, brazing or welding. For the ring 10 and the end ring 13, a plurality of large-diameter laminate plates 11 or small-diameter laminate plates 12 may be used, or the pipe of the cathode sleeve base 9 may be cut to form a ring.

As explained above, according to the present invention, a groove-type cathode having grooves on the surface of the cathode can be obtained by simply stacking and gluing laminate plates of large diameter and small diameter, which can be easily formed by mold processing, alternately. Therefore, it can be manufactured at low cost, and since the width and depth of the groove can be freely adjusted by adjusting the thickness and outer diameter of the lamination, even small grooves can be easily formed, which greatly contributes to improving the characteristics of reliable magnetrons. There is something.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional groove type cathode, Figure 2 is a groove type cathode showing one embodiment of the present invention, with a being a sectional view and b being a plan view, and Figure 3 being another embodiment of the present invention. FIG. 3 is a cross-sectional view of a cathode base portion showing an example. 1... Cathode sleeve, 2... Heater, 3... Groove, 4...
Electron radioactive substance, 5... Endhat, 6, 11...
Large diameter laminate board, 7, 12...Small diameter laminate board.

Claims (1)

[Scope of utility model registration request] A cathode sleeve formed into a hollow cylindrical shape, a heater inserted into the hollow part of the cathode sleeve, and a groove formed in an electron emitting part on the outer periphery of the cathode sleeve.
In a magnetron cathode consisting of an electron emitting substance filled in the groove and end hats provided at both ends of the electron emitting portion, laminate plates having a large diameter and laminate plates having a small diameter are alternately stacked and bonded. A magnetron cathode characterized by having a groove formed therein.