JPS5841716Y2 - electron gun device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron gun device that can easily improve assembly accuracy when assembling an electron gun used in a traveling wave tube or the like.

In electron guns used in traveling wave tubes, klystrons, etc.
The electron beam emitted from the cathode needs to pass through the slow-wave circuit, which has a relatively small inner diameter, without colliding with the slow-wave circuit, so that the electron beam diameter correctly matches the desired value and the position of the minimum electron beam diameter is It is also required to form an electron beam at a desired location.

Further, it is also necessary to reduce the power consumption of the heating wire (heater) for heating the cathode in order to reduce the total power consumption of traveling wave tubes, klystrons, etc.

Conventionally, various efforts have been made to reduce the power consumption of heating wires (heaters), but one of the most effective of these is to use multiple cathodes with low thermal conductivity, as shown in Figure 1. The structure is defined by support lines.

In FIG. 1, 1 is a cathode, 2 is a hot wire, 3 is a plurality of support wires, 4 is a cylindrical support body, and 5 is a cathode assembly assembled from these.

In this cathode assembly, since the cathode 1 is supported by a support wire with poor thermal conductivity, the heat of the cathode 1 is hardly lost, so that heating efficiency is high and low power is required.

Furthermore, as mentioned above, it is necessary for the electron gun to form an electron beam in which the positions of the electron beam diameter and the minimum electron beam diameter are precisely regulated. It needs to be fixed.

The above will be explained using the electron gun section of a traveling wave tube used for amplifying microwaves as shown in FIG.

Reference numeral 8 denotes an electron gun, which includes a cathode assembly 5, a focusing electrode 6, and an accelerating electrode 7.

Reference numeral 9 denotes a slow wave circuit in which the microwave is amplified by the interaction between the microwave and the electron beam, through which the electron beam passes.

10 is an electron beam formed by the electron gun 8, and point A indicates the minimum beam diameter point of the electron beam 10.

11 shows the vacuum envelope including the bottom stem.

In addition, the electron gun 8 requires parts for fixing each electrode, parts for insulating the electrodes from each other, and a magnetic focusing circuit around the slow wave circuit 9, but these are omitted from the figure.

The electrons emitted from the cathode form an electron beam 10, which has a minimum beam diameter at point A, and passes through the slow wave circuit 9 while being focused by a magnetic focusing circuit.

In this case, it is clear that if the beam diameter at point A is large, it will not be able to pass through the slow wave circuit 9, but if it is too small, the focusing by the magnetic focusing circuit will not be performed effectively, and the electrons will not be able to pass through the slow wave circuit 9. The collision may damage the slow-wave circuit 9, which has a relatively small heat capacity, resulting in a shortened lifespan, and even if the slow-wave circuit 9 is not damaged, it may impede the amplification action.

This is true even if the position of point A is not appropriate.

As mentioned above, the positions of the electron beam diameter and the minimum electron beam diameter need to be accurate, but both of these are
It is important to assemble the electron gun to the designed dimensions, especially the positional relationship between the cathode 1 and the focusing electrode 6. Accurate assembly is important.

This is also important from the perspective of preventing large variations in perveance among traveling wave tubes.

This invention adjusts the relative position of the cathode and focusing electrode to the designed dimensions.
In particular, it is an object of the present invention to provide an electron gun device that is easy to assemble with a dimension G indicating a relative position in the axial direction having an accurate value as designed.

Conventionally, in order to assemble the dimension G to the designed value, it has depended on the dimensional accuracy of the jigs and tools.

FIG. 3 shows a conventional method. Reference numeral 12 denotes a jig for determining the dimensions. The focusing electrode 6 and the cathode assembly 5 are combined, and the jig 12 and the cathode assembly 5 are pressed together while applying force in the direction of the arrow 15. Weld part B.

This is the conventional method, but it has the following problems.

One is that the support wire 3 is thin and elastic, so when the jig 12, focusing electrode 6, and cathode assembly 5 are combined, the support wire 3 is deformed, and after welding the B part and removing the jig 12, the dimension G. When measured, there are often large differences from the design values.

Therefore, one of the problems is that this work requires a certain degree of skill.

Another drawback is that even if the dimension G of part B is measured after welding and it deviates significantly from the design value, it is difficult to correct it.

This also applies to the case where portion B is welded with the cathode 1 and the focusing electrode 6 being largely eccentric.

The problems of the conventional methods described above can be easily solved according to the present invention.

FIG. 4 is a diagram of the cathode assembly 5 and the focusing electrode 6 combined according to the present invention.

The difference from the conventional structure in terms of structure is that a spacer 13 is present between the cathode assembly 5 and the focusing electrode 6.

The assembly method in this case is to measure the dimension G while applying force in the direction of the arrow 15, and if the dimension G differs from the design value, replace the spacer 13 with one of a different dimension (thickness), and Part B can be welded only after passing the test.

In other words, in this case, unlike the case in Fig. 3, the jig 12
This is possible because the dimension G can be measured with a microscope-type dimension measuring device.

Another advantage of the present invention is that even if a force is applied in the direction of the arrow 15, no force is applied to the support line 3, so there is no deformation of the support line.

As described above, the present invention has a simple structure and allows the relative positions of the cathode and focusing electrode to be assembled according to the designed values without using any special parts, resulting in high dimensional accuracy and less variation in perveance. You can get an electron gun.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a cathode assembly of a low-power cathode, and FIG. 2 is a sectional view showing the vicinity of an electron gun of a traveling wave tube. FIG. 3 is a sectional view for explaining a conventional method of relative positioning of a cathode and a focusing electrode, and FIG. 4 is a sectional view showing a main part of an embodiment of the present invention. 1...Cathode, 3...Support line, 4...
...Cylindrical support, 5...Cathode assembly, 6...
... Focusing electrode, 7... Acceleration electrode, 8...
...electron gun, 13...spacer.

Claims (1)

[Scope of utility model registration request] In an electron gun device in which a cathode assembly that emits an electron beam is fitted and fixed to a cylindrical portion of an electrode that focuses an electron beam emitted from the cathode, a spacer is inserted between the cathode assembly and the focusing electrode to adjust the relative position. An electron gun device characterized by being regulated and fixed.