JPH0228596Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] This invention is based on an electron cyclotron maser-type microelectronic cyclotron (gyromonotron), gyroklystron, gyroscope traveling wave tube, peniotron, and gyropeniotron. Concerning improvements to wave tube devices.

[Technical background of the invention and its problems]

In the microwave tube device described above, which generates high-power microwaves by utilizing the coupling between the cyclotron mode of a hollow electron beam and a predetermined mode of a resonant circuit consisting of a cylindrical resonant cavity, electrons are placed downstream of the electron gun. A cylindrical beam introduction section, a small diameter cutoff section, a resonant cavity section, a collector section, and a high frequency output section are arranged along the beam path. During the operation of this device, gas is emitted from the collector electrode that captures the electron beam, and the resulting ions travel back toward the electron gun, causing unnecessary modes and unstable operation. On the other hand, in this type of device, in order to reduce variations in electron beam energy, the cathode is generally operated in a temperature limited region and the beam current is controlled by the cathode temperature. By the way, a part of the high frequency power generated in the high frequency interaction section consisting of a resonant cavity or high frequency power generated in an undesired mode may proceed to the cathode side and heat the cathode. It is well known that a cut-off section with a reduced diameter is provided in the circuit wall mainly for the purpose of blocking the transmission of high-frequency power in the fundamental wave mode (TEon mode, where n is an integer) to the cathode side. It is difficult to completely block the high-frequency components of other modes by using only one mode, and it is thought that unstable operation or runaway phenomena may often occur due to instability of the cathode temperature.

Therefore, an invention has already been proposed in Japanese Patent Laid-Open No. 1983-1972 in which ring-shaped high-frequency absorbers and conductor rings are alternately arranged in the resonant cavity or in the electron beam introduction part on the electron gun side to suppress the generation and propagation of unnecessary modes.
It is disclosed in Publication No. 113240. Although this technique is effective in its basic concept, there is room for further improvement. In particular, if there are irregularities on the inner surface of the circuit wall, the efficiency of the interaction between the electron beam and the high-frequency electromagnetic field and the absorption efficiency of electromagnetic waves in unwanted modes cannot be increased beyond a certain level, and further improvements are needed in practical terms.

[Purpose of invention]

This idea reliably absorbs and attenuates high-frequency currents that attempt to proceed from the resonant cavity toward the electron gun, or high-frequency waves of unnecessary modes that occur in the circuit along the way, thereby suppressing the instability of the cathode temperature. The present invention provides a microwave tube device based on the principle of an electron cyclotron maser that can perform the following steps.

[Summary of the idea]

This idea provides a resistive layer that absorbs high-frequency current on almost the entire inner surface of the tube wall constituting the electron beam introduction section and cutoff section located downstream of the electron gun section, and also flattens the inner surface of this resistive layer. It is a continuous surface. This resistance layer is formed to have a surface resistance layer with a direct current resistance in the range of 10Ω/cm to 1KΩ/cm at room temperature, thereby stabilizing the absorption effect of high frequency current and the predetermined beam energizing electric field. can be formed into In this way, unstable heating of the cathode due to undesired high frequency waves can be reliably suppressed.

[Example of idea]

Examples of this invention will be described below with reference to the drawings. Note that the same parts are represented by the same symbols.

FIG. 1 is a schematic diagram of an example in which the present invention is implemented in a gyroscope. In the same figure, reference numeral 11 denotes an electron gun part that emits a hollow electron beam, 12 a reduction tapered electron beam introducing part, 13 a cut-off part with the smallest inner diameter, 14 a first enlarged taper part, and 15
16 is a resonant cavity portion, 16 is a second enlarged taper portion, and 17 is a resonant cavity portion.
18 is an output section, 19 is a dielectric output window, 20 is an electron gun solenoid of the magnetic field device, and 21 is a main solenoid. Therefore, a resistance layer 22 that absorbs high frequency current, which will be described later, is formed on the inner surface of the cut-off section 13 and the inner wall surface of the tapered electron beam introducing section 12.
These surfaces form a continuous flat surface.

The specific structure will be explained with reference to FIGS. 2 and 3. In the electron gun section 11, a cathode 23 and an accelerating anode 24 are insulated by ceramic insulating cylinders 25 and 26 and coaxially supported around a tube axis C. Tube walls 31, 32 divided in the longitudinal direction from the electron beam introduction section 12 to the resonance cavity section 15,
33 are hermetically sealed in sequence at fitting connection portions 34, 34, . The second enlarged taper portion 16 is fitted and connected by a pair of connecting flanges 37, and vertically connected by a heliar arc weld portion 38.

Now, the cut-off part 13 consists of a plurality of high frequency absorbing ceramic rings 41, 41... and a conductor ring 4.
2, 42, etc. are arranged alternately. The ceramic ring 41 is made of silicon carbide (SiC) ceramic and has a sheet resistance of 10Ω/cm to 1KΩ/cm, and the conductive ring 42 is made of a copper ring.
The thickness (t) in the axial direction is approximately 1/2 of the tube wavelength (λg) of the fundamental mode. Each of these rings is disposed in thermally and electrically close contact with the tube walls 32 and 33, and has a flat continuous inner surface.

Note that the connecting portion 34 of each tube wall 32, 33 is located at the cut-off portion consisting of alternating layers of absorbent ceramic rings and conductor rings, thereby preventing discontinuous surfaces or gaps in the connecting portion. Even if this occurs, it is preferable because it does not disturb the rotational movement of the electron beam or generate unnecessary high-frequency waves.

Of the electron beam introducing section 12 having a reduced tapered shape,
The part adjacent to the cut-off part 13 has a cylindrical shape whose inner surface has a tapered surface that matches the taper angle of the introduction part.
A SiC ceramic cylinder 43 is inserted into the tube wall. This ceramic cylinder also has a sheet resistance.
It has a value of 10Ω/cm to 1KΩ/cm and is in thermally conductive contact with the tube wall 32. A high frequency lossy coating 44 is applied to the remaining inner surface of the beam introduction section. The sheet resistance of this coating 44 is also 10Ω/cm to 1KΩ/
It is formed to have a resistance value of cm. This coating may be, for example, a coating made of stainless metallicon, or a mixture of alumina (Al ₂ O ₃ ) powder and carbon or other metal powder, sprayed to a thickness of 100 μm.
As mentioned above, a film deposited to a thickness of preferably 200 μm to 500 μm is suitable, but the material is not limited to these and any non-magnetic material may be used. As mentioned above, the resistance layer 22 consisting of a continuous layer of the absorbent ceramic 41, the ceramic cylinder 43, and the coating 44 has an internal DC resistance of 10Ω/cm to 1KΩ/cm, particularly preferably 20Ω/cm to 200Ω/cm. It was found that a value in between was appropriate.

[Effect of idea]

According to this invention, by having the above structure, the high frequency current that attempts to proceed toward the electron gun section is almost completely absorbed by the resistance layer 22, and the heat is transferred to the outside through the tube wall. is dissipated into. In particular, a plurality of high-frequency absorber rings and a plurality of conductor rings are alternately and closely arranged on the inside of the electron beam passage wall between the electron gun section and the resonant cavity section so as to form a flat continuous inner surface, and Since the internal surface resistance of the high-frequency absorber ring has a value in the range of 10Ω/cm to 1KΩ/cm, the inner surface of the high-frequency absorber ring is not charged, and an accelerating electric field for the electron beam can be reliably applied. Moreover, since the conductor ring and the absorber ring are alternately in close contact with each other, the heat generated in the absorber ring is quickly conducted to the electron beam passage wall via the conductor ring and dissipated. The high-frequency absorption capacity can be increased, and the propagation of high-frequency waves toward the electron gun section can be effectively suppressed. Furthermore, since both rings are alternately stacked, assembly is easy.

The material of the absorbent ceramic ring 41 or the ceramic cylinder 43 is not limited to SiC ceramic, but may be any non-magnetic material that contains a substance that absorbs high frequency current and releases relatively little gas.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal sectional view showing an embodiment of the present invention;
FIG. 2 is an enlarged sectional view of the main part, and FIG. 3 is an enlarged sectional view of the main part. DESCRIPTION OF SYMBOLS 11...Electron gun part, 12...Electron beam introducing part, 13...Cut-off part, 15...Resonance cavity part, 22...Resistance layer, 31, 32, 33...Tube wall, 41...Absorptive property Ceramic ring, 42...
Conductor ring, 43...Ceramic cylinder, 44...
...Resistance coating.

Claims (1)

[Claims for Utility Model Registration] An electron gun section that emits a hollow electron beam, a cylindrical electron beam passage wall disposed downstream of the beam of the electron gun section, and an electron beam passage wall disposed downstream of the electron beam passage wall. A cylindrical resonant cavity that interacts with the beam, a magnetic field device provided to impart swirling kinetic energy to the electron beam, and a collector electrode and a high frequency output section provided downstream of the resonant cavity. In the electron cyclotron maser type microwave tube device, a plurality of high frequency absorber rings and a plurality of conductor rings are alternately and closely arranged on the inner periphery of the cylindrical electron beam passage wall so as to form a flat continuous inner surface. The above microwave tube device is characterized in that the high frequency absorber ring has an inner circumferential surface resistance ranging from 10Ω/cm to 1KΩ/cm.