JPH04333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a support structure for a traveling wave tube using a periodic permanent magnet (hereinafter referred to as PPM) as a beam focusing device.

As is well known, a traveling wave tube includes an electron gun section that generates an electron beam, a high frequency circuit section that interacts with the electron beam, a collector section that captures the electron beam, and a high frequency input/output circuit section. It consists of a beam focusing device that focuses the electron beam, a tube support part (part of the case), etc.

Figure 1 shows the structure of a typical high-frequency circuit of a conventional PPM focused traveling wave tube. FIG. 1a shows a cross section of one of the high-frequency circuits, in which 1 is a helix, 2 is an insulating column, and 3 is a barrel. Barrel 3 also serves as a vacuum envelope. 4
Figure 1a shows the magnets that make up the PPM.
If the cross section in the direction perpendicular to is shown for only the PPM part, it will look like Figure 1b. In figure b, 4
is the magnet and 8 is the pole piece. a again
Returning to the diagram, 5 is the tube support, 6 is the clamp, 7
indicates a set screw. A three-dimensional view of 5 is shown in Figure 1c. As described above, the conventional method of supporting the high-frequency circuit section of the bulb has generally been through the pole piece or magnet that constitutes the PPM.

However, recently there has been a strong demand to increase the output of traveling wave tubes, and in such cases it has been found that the following problems occur with the conventional support structure shown in FIG. Problem number one
As the power of the tube increases, the loss within the tube (high frequency loss and DC loss) generally increases accordingly, so the heat generated in the helix and insulating struts is transferred to the barrel, making the barrel extremely hot. This heat is transferred to the support base 5 through the magnet 4, but in the process raises the temperature of the magnet, which weakens the magnetic field of the magnet and adversely affects beam transmission. The second problem is the existence of a gap between the barrel and the pole piece. In a normal traveling wave tube, the pole piece 8 is not fixed to the barrel 3, and there is a gap of 2/100 to 5/100 mm in the radial direction between them, but this is due to the fact that the pole piece 8 is not fixed to the barrel 3. This is undesirable because it acts in the direction of hindering the transfer of heat to the helix, causing an increase in the temperature of the helix. The third problem is that unless the outside diameter accuracy of the magnet and the eccentricity of the inside and outside diameters are strictly controlled, the surface of the magnet 4 and the surface of the support base 5 will not come into surface contact over the entire section in the tube axis direction. The problem is that it impairs heat transfer.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new tube support structure that is effective in high-power traveling wave tubes and eliminates the drawbacks of the conventional structures as described above.

The present invention provides a traveling wave tube that uses a periodic permanent magnet as a beam focusing device, in which a high-frequency circuit support component that forms a part of the case has a comb-shaped cross section, and the upper surface of the comb teeth is arc-shaped. The diameter of the circular arc matches the outer diameter of the barrel, which is the vacuum envelope of the high-frequency circuit section of the traveling wave tube, and the tube and the supporting parts are It is characterized by being closely fixed to.

FIG. 2 shows the structure of the high frequency circuit of the traveling wave tube according to the present invention. In FIG. 2a, the inside of the barrel 3 is the same as the conventional one, but it is shown that the tube support structure is different from the conventional one. That is,
As shown in FIG. 2c, a three-dimensional view of the support base 5', the support base directly receives the barrel. Support stand 5'
The comb tooth-shaped protrusions provided on the upper surface of the barrel are machined into an arcuate shape so that the upper surface is just in surface contact with the barrel. The pole piece 8 is inserted into the gap between the teeth of the comb, and a magnet having a c-shaped cross section as shown in FIG. 2b is fitted into the teeth of the comb from above. In such a new support structure, firstly, most of the heat generated within the barrel is transmitted to the support stand side without passing through the magnet, so that the temperature of the magnet itself can be prevented from increasing. Secondly, since the support base 5' and the barrel 3 are in complete contact with each other with no space between them, the thermal resistance between them can be extremely small, and the temperature rise in the barrel can be kept relatively low. Thirdly,
There is no need to worry as much about the magnet's outer diameter accuracy and eccentricity of the inner and outer diameters as before. Fourth, as an additional effect, the C-shaped magnet does not require the conventional procedure of breaking it into two pieces and fitting them into the barrel.
The time required to incorporate the magnet is short.
What you need to be careful about here is the risk of biased magnetism occurring in the circumferential direction due to the C-shaped magnet, but since the pole piece itself maintains perfect axial symmetry, it will not be seen in the axial magnetic field. If the biased magnetism is relaxed,
This is not a problem in practice.

Although the above explanation has taken a helical traveling wave tube as an example of a traveling wave tube, it is clear that the present invention can also be applied to a coupled cavity traveling wave tube for PPM focusing. Further, in view of the gist of the invention, it is clear that copper or aluminum, which has good thermal conductivity, is optimal as the material for the support base 5'.

[Brief explanation of drawings]

FIG. 1 shows a conventional traveling wave tube support structure. Figure a shows a cross section, figure b shows a longitudinal cross section of the PPM, and figure c shows a three-dimensional view of the tube support. FIG. 2 shows a tube support structure for a traveling wave tube according to the present invention.
Figure a shows a cross section, figure b shows a side view of the magnet, and figure c shows a three-dimensional view of the tube support. 1...Helix, 2...Insulating strut, 3...Barrel,
4... Magnet, 5, 5'... Tube support stand, 6... Clamp, 7... Set screw, 8... Pole piece.

Claims (1)

[Claims] 1. In a traveling wave tube that is equipped with a periodic permanent magnet as a beam focusing device around the high-frequency circuit section of the tube and is supported by a support component, the high-frequency circuit section support component that forms part of the case has a comb-shaped cross section. The upper surface of the teeth of the comb is machined into an arc shape, and the diameter of the arc matches the outer diameter of the barrel, which is the vacuum envelope of the high frequency circuit section, and the arc part of the support part and the barrel are The pole pieces constituting the periodic permanent magnet are inserted into each gap between the teeth of the comb.
1. A traveling wave tube characterized in that the tube and the support component are closely fixed as a whole in the tube axis direction of the high frequency circuit section by fitting C-shaped magnets into the teeth of the comb.