JPH05325802A - Large power microwave tube - Google Patents

Abstract

PURPOSE:To shorten a length in a tube axial direction of a focussing circuit part by using a spacer for deciding an electromagnet coil position as a magnetic material, so as to decrease protrusion of a pole piece to an electron gun side and a collector side. CONSTITUTION:An electron beam emitted from a cathode 5 is focussed by an electric field between a Wehnelt electrode 3 and an anode electrode 6. The beam passing through the electrode 6 is left as focussed by a magnetic field of a magnetic circuit system, comprising an electromagnet coil 10, collector side pole piece 13, upper yoke 12, lower yoke 8, spacer 19 and an electron gun side pole piece 7, to pass through a high frequency circuit part 11, and captured by a collector part. Here by using a magnetic material for the spacer 19, protrusion of the pole pieces 7, 13 can be decreased, and a length in the tube axial direction of a focussing circuit part can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high power microwave tube having an electromagnet as a focusing device.

[0002]

2. Description of the Related Art As shown in FIG. 4, a high power microwave tube using a conventional electromagnet for a focusing device has an electron gun section for emitting an electron beam and a collector section for trapping the electron beam from the electron gun section. And a focusing circuit section for focusing the electron beam, and a high frequency circuit section arranged between the electron gun section and the collector section.

Next, the operation of each part will be described. The electron gun part
A cathode 5 that emits an electron beam, a cathode support 2 that supports the cathode 5, a Wehnelt electrode 3 and an anode electrode 6 that form an electric field for focusing and accelerating the electron beam, and the electrodes are electrically insulated from each other. It is composed of an insulating stone 4 and an electron gun support 1 that supports the electron gun portion.

The high frequency circuit section is composed of a high frequency circuit section 11 for speed-modulating the electron beam emitted from the electron gun section by a high frequency signal to collect the electron beam and convert the energy of the electron beam into a high frequency signal. The focusing circuit unit forms a magnetic field necessary for passing the electron beam emitted from the electron gun unit through the high frequency circuit unit while focusing the electron beam. The focusing circuit unit includes the electromagnet coil 10 and the electron gun side pole piece that is a magnetic body. 7, a lower yoke 8, an upper yoke 12, a collector side pole piece 13, and a spacer 9 used for positioning the electromagnet coil 10. This spacer 9 is lightweight
A bake plate was used for processing and other reasons, but there was no problem with the conventional high-power microwave tube.

The magnetic flux density distribution on the central axis of the high frequency circuit of the conventional high power microwave tube on the collector side is shown by the solid line in FIG. This magnetic flux density distribution determines the electron beam trajectory until it passes through the high frequency circuit and is captured by the collector section.

The magnetic flux density distribution on the central axis of the electron gun section is shown by the solid line in FIG. Since this magnetic flux density distribution influences the diameter and ripple rate of the electron beam passing through the high frequency circuit, the shape of the focusing circuit section is experimentally changed to obtain the optimum magnetic flux density distribution.

By the way, in order to realize the required magnetic flux density distribution, it is necessary to enhance the focusing or bunching of the electron beam with the recent trend toward higher frequency, higher efficiency and higher power of high power microwave tubes. As shown in (3), the electron gun side pole piece 7 and the collector side pole piece 13 of the focusing circuit portion were projected toward the electromagnet coil 10 in the tube axis direction. Thereby, the magnetic flux density distribution is set as shown by the broken lines in FIGS.

[0008]

In this conventional high-power microwave tube, the focusing circuit portion is formed so that the electron gun side pole piece 7 and the collector side pole piece 13 are projected toward the electromagnet coil 10 in the tube axis direction. There was a problem of stretching in the direction.

[0009]

The present invention has a structure in which a spacer for positioning and fixing an electromagnet coil is a magnetic body in a high power microwave tube using an electromagnet as a focusing device.

[0010]

As a result, the protrusion of the electron gun side pole piece and the collector side pole piece can be reduced, and the length of the focusing circuit portion in the tube axis direction can be made shorter than before.

[0011]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a high-power microwave tube according to an embodiment of the present invention. The electron beam emitted from the cathode 5 is focused by the electric field between the Wehnelt electrode 3 and the anode electrode 6. The electron beam that has passed through the anode electrode 6 remains focused by the magnetic field generated by the magnetic circuit system including the electromagnet coil 10, the collector side pole piece 13, the upper yoke 12, the lower yoke 8, the spacer 19 and the electron gun side pole piece 7, and the high frequency circuit It passes through the section 11 and is captured by the collector section.

In this embodiment, the spacer 19 is made of iron (magnetic material), which allows the electron gun side pole piece 7 to be formed.
The protrusion of the collector side pole piece 13 was made smaller than in the conventional case, and the magnetic flux density distribution close to the broken line in FIG. 2 was obtained. As for the magnetic flux density distribution of the electron gun part, a magnetic flux density distribution close to the broken line in FIG. 3 was obtained. As a result, the length of the focusing circuit section in the tube axis direction can be made shorter than before.

It should be noted that some effects can be expected if only one of the spacers is made of iron and the other is made of a baking plate.

[0014]

As described above, according to the present invention, the positioning fixing spacer of the electromagnet coil is made of a magnetic material,
Since the protrusions of the electron gun side pole piece and the collector side pole piece were made smaller than before, the length of the focusing circuit in the tube axis direction could be made shorter than before.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a magnetic flux density distribution diagram on the collector side of the present invention and a conventional high-frequency circuit unit.

FIG. 3 is a magnetic flux density distribution chart of the present invention and a conventional electron gun section.

FIG. 4 is a sectional view of an example of a conventional technique.

FIG. 5 is a cross-sectional view of another example in which a pole piece is projected in the conventional technique.

[Explanation of symbols]

 1 Electron Gun Support 2 Cathode Support 3 Wehnelt Electrode 4 Insulating Stone 5 Cathode 6 Anode Electrode 7 Electron Gun Side Pole Piece 8 Lower Yoke 9 Spacer (Bake Plate) 10 Electromagnetic Coil 11 High Frequency Circuit 12 Upper Yoke 13 Collector Side Pole Piece 14 Collector 19 Spacer (magnetic material)

Claims (1)

[Claims] 1. A high power microwave tube using an electromagnet as a focusing device, wherein at least one of positioning fixing spacers placed at both ends of the electromagnet coil is made of a magnetic material.