JPH0513010A - Coupled-cavity type traveling wave tube - Google Patents

Abstract

PURPOSE:To prevent the central magnetic field from being weakened, by sectioning a high frequency circuit constituting the traveling wave tube by severing portions into a plurality of sections, and making the inside diameter of a pole piece in the severing portion different for each severing portion to thereby make uniform the field distribution on a tube axial to reduce local field distributions at the severing portions. CONSTITUTION:Cavity portions 1 and pole pieces 2a are alternately bonded by brazing to construct a high frequency circuit, at both ends of which are provided high frequency window portions 5 as input/output portions. Inside the circuit are provided severing portions 4 each containing a high frequency absorber to thereby divide the circuit into a plurality of sections. At the respective outer ends of the window portions 5 are mounted an electron gun portion 6 and a collector 7, respectively, to construct a vacuum envelope. In this structure, the inside diameter of a pole piece 2b held between the severing portions 4 is made 70 to 95% of the inside diameter of the pole pieces 2a at other positions, and magnets 3a, 3b are provided from outside between the pieces 2a, 2b to construct a focusing field device. In this way, the unevenness of the central field attributable to shaping of the magnet 3b like a horse shoe is avoided by making small the inside diameter of the piece 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupled cavity type traveling wave tube mainly used as a microwave amplifier in a microwave transmitter or the like.

[0002]

2. Description of the Related Art Conventionally, a coupled cavity type traveling wave tube has an electron gun section for generating an electron beam, a high frequency circuit section for amplifying the high frequency power by interacting the electron beam with the high frequency power, and an electron gun. Focusing magnetic field device that focuses the electron beam emitted from the high-frequency circuit and generates a magnetic field for passing through the high-frequency circuit with a substantially constant beam diameter, and collects the electron beam that has completed the interaction in the high-frequency circuit. It consists of a collector part that converts into heat energy.

FIG. 2 is a sectional view of a conventional coupled cavity type traveling wave tube. The cavity member 1 and the pole piece 2 are alternately joined by brazing to form a high frequency circuit, and a high frequency window 5 which is an input / output unit of high frequency power is attached to both ends thereof. The high-frequency circuit is divided into a plurality of parts by disposing a seber part 4 including a high-frequency absorber inside the high-frequency circuit, and an electron gun part 6 and a collector 7 are attached to both ends of the high-frequency window part 5, respectively. It constitutes the enclosure. Further, the magnets 3a and 3b are attached between the pole pieces 2 to form a focusing magnetic field device together with the pole pieces 2.

[0004]

In the conventional coupled cavity type traveling wave tube described above, the high frequency circuit is divided into a plurality of parts by the seber part 4 as shown in FIG. Since the sectional structure is as shown in FIG. 3 which is a view taken along the line AA ', the magnet 3b attached to the portion of the severs 4 must be horseshoe-shaped. Therefore, the central magnetic field on the tube axis of the sever portion 4 is weakened, and there is a problem that demagnetization occurs near the tube axis through which the electron beam passes.

The electron beam is disturbed by the nonuniformity of the magnetic field distribution on the tube axis and the demagnetization, and the interaction between the electron beam and the high frequency power is disturbed and the operation becomes unstable. Further, when the electron beam concentrates and collides with a portion on the inner wall of the high-frequency circuit, the high-frequency circuit becomes hot and gas is generated, which deteriorates the vacuum degree in the tube and adversely affects the service life. It may be damaged due to melting.

[0006]

SUMMARY OF THE INVENTION The coupled cavity type traveling wave tube of the present invention is constructed by reducing the inner diameter of the pole piece of the severs portion to 70% to 95% of the inner diameter of the pole piece of the other portion. It is characterized in that the central magnetic field on the axis is made equal to that of the other portions to make it uniform and the demagnetization of the seber portion is reduced.

[0007]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention. The cavity member 1 and the pole piece 2a are alternately joined by brazing or the like to form a high-frequency circuit, and a high-frequency window portion 5 which is an input / output portion of high-frequency power is attached to both ends thereof. The high-frequency circuit is divided into a plurality of parts by disposing a sever portion 4 containing a high-frequency absorber inside the high-frequency circuit, and an electron gun portion 6 and a collector are attached to both ends of the high-frequency window portion 5, respectively, to form a vacuum envelope. Make up the vessel.

A pole piece 2b sandwiched between the severs 4
The inner diameter of 70% of the inner diameter of the pole piece 2a of the other part is
The size is 95%. Pole pieces 2a, 2b
Magnets 3a and 3b are attached from the outside between them to form a focusing magnetic field device. As shown in FIG. 3, the nonuniformity of the central magnetic field on the tube axis caused by the horseshoe-shaped magnet 3b reduces the inner magnetic field of the pole piece 2b so that the central magnetic field of the severs part is different from other parts. Since it can be made the same, it is eliminated, and it is possible to weaken the demagnetization in the vicinity of the tube axis of the severs portion.

The electron beam generated in the electron gun section 6 amplifies the high frequency power by interaction in the high frequency circuit section, is then collected by the collector 7, and operates as a coupled cavity type traveling wave tube. Has been done.

[0010]

As described above, in the coupled cavity type traveling wave tube of the present invention, the inner diameter of the pole piece of the severs portion is set to 70% to 95% of the inner diameter of the pole piece of the other portion. By this, the magnetic field distribution on the tube axis can be made uniform and the demagnetization in the severs can be reduced, so that the disturbance of the electron beam can be prevented and the electron beam can be prevented from concentrating on a part of the inner wall of the high frequency circuit. .. Therefore, it is possible to prevent deterioration of the degree of vacuum in the tube, prevent damage to the high frequency circuit, stabilize the operation, and improve the reliability of the coupled cavity type traveling wave tube.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a conventional coupled cavity type traveling wave tube.

FIG. 3 is an A- for showing a cross-sectional structure of the severs portion of FIG.
FIG.

[Explanation of symbols]

 1 Cavity member 2, 2a, 2b Pole piece 3a, 3b Magnet 4 Sever part 5 High frequency window part 6 Electron gun part 7 Collector

Claims (1)

Claim: What is claimed is: 1. An electron gun section for generating an electron beam, a high frequency circuit section for amplifying high frequency power by interacting between the electron beam and the high frequency power, and an electron beam passing through the high frequency circuit. In a coupled cavity type traveling wave tube comprising a collector part for collecting and converting the energy into heat energy, and a focusing magnetic field device part for generating a magnetic field for concentrating an electron beam, a severs part constituting the focusing magnetic field device part. Inner diameter of pole piece of 70% to 95% of inner diameter of pole piece of other parts
A coupled-cavity traveling-wave tube characterized by the size of.