JPH0222928Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a traveling wave tube device using a periodic magnetic field device for electron beam focusing.

In an electron tube that passes an electron beam through a relatively long slow wave circuit (high frequency circuit) such as a traveling wave tube device, a periodic magnetic field device is generally used as one means for focusing the electron beam. FIG. 1 is a sectional view showing an example of a conventional periodic magnetic field device used in a traveling wave tube device.
A conventional traveling wave tube device will be explained below with reference to FIG. The tube 1 includes an electron gun 11 that emits an electron beam,
It includes a slow wave circuit 12 that causes the electron beam to interact with a high frequency wave and a collecting electrode section 13 that captures the electron beam,
The slow wave circuit 12 is housed inside a tubular outer circumferential body 14 that forms a part of the envelope of the bulb 1 .
The periodic magnetic field device 2 has a cylindrical shape as a whole and is arranged coaxially along the axis of the outer circumferential tube body 14 . The periodic magnetic field device 2 is interposed between a plurality of permanent magnets 21 magnetized in the axial direction and the permanent magnets 21,
It consists of an annular magnetic pole piece 22 having an axial extension 23, which generates a periodic magnetic field for focusing the electron beam on the axis. The permanent magnet 21 is a semicircular permanent magnet 24, 25 as shown in FIG.
They are configured in a cylindrical shape as a pair.

In general, when it is desired to increase the allowable power of the collector electrode section 13 or when it is desired to lower the voltage of the collector electrode section 13 than the voltage of the slow wave circuit in order to improve the overall efficiency of the traveling wave tube device, the outer diameter of the collector electrode section 13 is is larger than the outer diameter of the outer circumferential tube 14. For this reason, the required number of annular magnetic pole pieces 22 are inserted in advance along the outer periphery of the outer circumferential tube 14 before the collector electrode part 13 is attached during the manufacturing process of assembling the tube 1, and the annular magnetic pole pieces 22 are inserted in advance in the required number along the outer circumference of the outer circumferential tube 14, and the annular magnetic pole pieces 22 are A pair of permanent magnets 2 made up of individual permanent magnet pieces 24 and 25 divided into semi-circular shapes
1 are interposed between the magnetic pole pieces 22, respectively, and a periodic magnetic field device 2 is disposed on the outer circumferential tube body 14.

However, such a structure has the following drawbacks. That is, in order to achieve good electron beam focusing and to stably fix the periodic magnetic field device 2 on the axis of the outer circumferential tube 14, the total length of the outer circumferential tube 14 that houses the slow wave circuit 12 and the total length of the periodic magnetic field device 2 must be Although it is necessary to match them as much as possible, the periodic magnetic field device 2 is formed of a large number of permanent magnets 21 and magnetic pole pieces 22, and the overall length of the periodic magnetic field device 2 varies within a certain dimension. On the other hand, regarding the bulb 1, if the outer circumferential tube body 14 is long, it is difficult to make it from a single thin metal tube. The overall length of the body 14 also tends to vary, and it is difficult to match the overall length of the outer circumferential tube 14 with the overall length of the periodic magnetic field device 2. For this reason, in the manufacturing process of combining the permanent magnet 21 with the tube 1, several types of permanent magnets 21 with different thicknesses are prepared and the periodic magnetic field device 2
However, it is necessary to prepare the permanent magnet 21 for dimension adjustment in advance, which is uneconomical, and the magnetic field strength of the part where the permanent magnet 21 is replaced with the permanent magnet 21 for dimension adjustment is taken. It was difficult to obtain the required magnetic field strength. Furthermore, if the total length of the periodic magnetic field device 2 is slightly shorter than the total length of the outer circumferential tube body 14, the periodic magnetic field device 2 is likely to be misaligned in the axial direction, making it difficult to obtain good electron beam focusing. There were drawbacks such as poor current transmittance, burning out of the slow wave circuit 12, and adversely affecting the life of the tube 1.

The purpose of this invention is to eliminate the above-mentioned drawbacks of the conventional device with a simple structure, to make it possible to adjust the axial position of the periodic magnetic field device and the tube without replacing the permanent magnet, and to make it possible to adjust the axial position of the periodic magnetic field device and the tube without replacing the permanent magnet. An object of the present invention is to provide a traveling wave tube device that can prevent directional positional deviation and stably maintain electron beam focusing of a tube for a long period of time.

Hereinafter, an embodiment of the present invention will be explained based on FIG. The tube 1 includes an electron gun section 11, a slow wave circuit 12, and a collecting electrode section 13 in an outer peripheral container, just like the conventional type. The periodic magnetic field device 2 includes a plurality of permanent magnets 21 and magnetic pole pieces 22-1 to 11, which are made up of permanent magnet pieces 24 and 25 divided into semicircular shapes.
and magnetic pole pieces 26-1 and 26-2, and the magnetic pole piece 2
2-1 to 11 are annular and have an axially extending portion 23 on the inner circumferential portion thereof, similar to the conventional type. On the other hand, as shown in FIG. It is also possible to incorporate it into the outer circumferential tube body 14. That is, a plurality of magnetic pole pieces 22-
1 to 11 are inserted in advance in required quantities along the outer periphery of the outer circumferential tube body 14 before the collector electrode part 13 is attached during the manufacturing process of assembling the tube 1, and are inserted at the end of the electron gun 11 on the collector electrode part 13 side. The magnetic pole pieces 22-1 and 22-11 arranged in the central part and the magnetic pole piece 22-6 arranged in the central part are fixed at predetermined positions by the outer circumferential tube 14 and a fixing member 29. After completion, the permanent magnet 21 paired with the individual permanent magnetic pieces 24 and 25 divided into semicircular shapes is interposed between the magnetic pole pieces 22-1 to 11 and the magnetic pole pieces 26-1 to 2, and the outer circumferential tube is body 1
4, a periodic magnetic field device 2 is arranged. The dimension of the periodic magnetic field device 2 in the axial direction is adjusted by adjusting the thickness of the magnetic pole pieces 26-1 and 26-2. In practice, magnetic pole pieces 26-1 and 26-2 with different thicknesses are prepared in advance, with the thickness of the magnetic pole pieces 26-1 and 26-2 being changed at intervals of approximately 0.2 to 0.5 mm around the standard dimensions. 1
The dimensional adjustment in the axial direction is carried out by the exchange of .about.2. The magnetic pole piece 30 in FIG. 4b is another example of a magnetic pole piece for adjusting the axial dimension, and is a plate-shaped magnetic pole piece having a notch approximately equal to the outer diameter of the outer circumferential tube body 14.
It is also possible to use a magnetic pole piece 30 instead of 2, and the thickness of the magnetic pole piece 30 is about half of the thickness of the magnetic pole pieces 26-1 and 26-2, and two magnetic pole pieces 30 are stacked with the notches shifted. It is practical to use the However, with this structure, it is possible to adjust the axial dimensions of the periodic magnetic field focusing device without replacing the permanent magnets, and there is no need to separately prepare permanent magnets with different thicknesses, which is economical, and also reduces the size of the magnetic pole piece. By adjusting the thickness, there is little change in the magnetic field distribution, and a pre-adjusted magnetic field distribution of the periodic magnetic field device can be provided on the tube axis.

In addition, some of the magnetic pole pieces, including the magnetic pole pieces arranged at both ends, are firmly held by the outer circumferential tube, so there is no axial displacement of the periodic magnetic field device, and the tube is stable. Current transmittance can be obtained.

In order to hold the periodic magnetic field device even more firmly,
Of course, it is possible to coat the outer circumference of the periodic magnetic field device with resin or the like.

As explained above, according to the present invention, it is possible to easily adjust the dimensions of the periodic magnetic field device and the tube in the axial direction, and also to securely hold and fix them, maintain stable current transmittance over a long period of time, and increase the overall length. It exhibits great effects when applied to high-gain traveling wave tubes.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional traveling wave tube device, FIG. 2 is a perspective view of the permanent magnet shown in FIG. 1, and FIG. 3 is a longitudinal sectional view of a traveling wave tube device according to the present invention. 4a and 4b are perspective views of the embodiment of the plate-shaped pole piece shown in FIG. 3; FIG. 1... Tube, 2... Periodic magnetic field device, 11... Electron gun, 12... Slow wave circuit, 13... Collector electrode section, 1
4... Outer circumferential tube body, 21... Cylindrical permanent magnet, 2
2... A magnetic pole piece having an extended portion 23, 23... An extended portion protruding in the axial direction on the inner circumference of the magnetic pole piece 22, 24,
25... Individual permanent magnet pieces obtained by dividing the cylindrical permanent magnet 21 into semicircular shapes, 26... Disc-shaped magnetic pole piece, 2
7, 28... Individual magnetic pole pieces obtained by dividing the disc-shaped magnetic pole piece 26 into semicircular shapes, 29... Fixing material, 30... Disc-shaped magnetic pole piece having a notch.

Claims (1)

[Scope of utility model registration request] A tube including an electron gun, a slow wave circuit, a collecting electrode section, and an elongated outer circumferential tube surrounding the slow wave circuit, and a plurality of permanent magnets and magnetic pole pieces coaxially located outside the outer circumferential tube. and an annular magnetic pole piece having an axially extending portion is disposed at both ends and the center of the outer circumferential tube, and is held and fixed on the outer circumferential tube by a fixing member. A traveling wave tube device characterized in that at least one of the magnetic pole pieces interposed between the annular magnetic pole pieces having extended portions held and fixed therein is a disc-shaped magnetic pole piece.