JP2861968B2 - Electron gun and microwave tube using cold cathode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun used in a device using an electron beam, such as a microwave tube such as a traveling wave tube, or a cathode ray tube. The present invention relates to a structure of an electron gun using a manufactured field emission cold cathode device and a microwave tube using such an electron gun.

[0002]

2. Description of the Related Art As a conventional technique, for example, Japanese Patent Laid-Open No. 5-3 is disclosed.
No. 4,3000, describes an "electron gun and a cathode ray tube", and Japanese Patent Application No. 7-282938 describes a "linear beam microwave tube".

A microwave tube is used as an amplifier or the like of a high-power microwave transmission device used for satellite communication or the like, and has a structure including an electron gun section for extracting a focused electron beam, an electron gun section, and the like. A high-frequency circuit unit that amplifies microwaves by the interaction between the unit and the high-frequency electric field, and a collector unit that captures the interacting electron beam and converts it into heat.
The main component is a focusing device that generates a magnetic field for focusing the electron beam.

FIG. 7 is a sectional view of a traveling wave tube using a conventional hot cathode.

A typical example of a microwave tube is a traveling wave tube, and FIG. 7 shows a longitudinal sectional view of an example of a spiral traveling wave tube which is one of the traveling wave tubes. In FIG. 7, the electron beam 18 extracted from the hot cathode 14 of the electron gun unit 11 is
Accelerated by the high voltage applied between the anode 25 and the hot cathode 14, the electric field distribution optimally formed by the focusing electrode 15 and the electric field generated by the focusing device formed by the plurality of magnets 20 and the magnetic poles 21. Of the high-frequency circuit section 12 as an electron beam 18
Guided into 9. A high frequency input unit 22 is provided on the helix 19
Is propagated at a speed substantially equal to that of the electron beam 18, so that the microwave is amplified and extracted from the high-frequency output unit 23. The electron beam 18 having completed the interaction with the microwave is captured by the collector 13 and converted into thermal energy and radiated out of the tube. The temperature of the hot cathode 14 of the electron gun section 11 is raised to about 1000 ° C. by heating by the heater 16, electrons in the metal are taken out as thermoelectrons, and accelerated by high voltage to obtain an electron beam 18.

In an electron gun using a hot cathode as an electron source, as in the traveling wave tube shown in FIG. 7, a preheating time required for heating is required in order to heat the cathode to a high temperature. Electricity reduces the efficiency of equipment, and the life of the cathode is usually limited to tens of thousands of hours due to evaporation of the cathode material. There is a need for an electron source.

On the other hand, in recent years, a field emission cold cathode in which a plurality of minute emitters and gates are formed and arranged on a silicon substrate by using a semiconductor manufacturing process and electrons are extracted by field emission has been developed, and a heater for heating the cathode has been developed. It is possible to improve efficiency, reliability, etc. by replacing cold cathode elements, which can be expected to have an infinite life in principle, with conventional hot cathodes for microwave tubes and cathode ray tube equipment. It is.

FIG. 11 is a partial sectional view of such a field emission cold cathode device.

In the field emission type cold cathode device 5 shown in FIG. 11, the cold cathode device 15 comprises a conical emitter 1 formed by laminating a metal such as molybdenum on a silicon substrate 3;
A gate 2 having a thickness of about 1 μm for applying an electric field to the tip of the emitter 1 and an insulating layer 4 for insulating the silicon substrate 3 and the gate 2 at the emitter potential are used as basic constituent elements. It has a structure in which a large number of the elements are arranged, and can be manufactured by applying a semiconductor manufacturing process. Gate 2 of field emission type cold cathode device 5
In addition, by applying a positive voltage of several volts to several tens of volts to the emitter 1, 2
A high electric field of about 5 × 10 ⁷ V / cm is generated, and electrons in the emitter 1 get energy exceeding the electron barrier on the metal surface and are emitted into a vacuum. The emitted electrons are focused by a focusing electrode and a focusing magnetic field, as in the case of a hot cathode, and are guided as an electron beam to a high frequency circuit in the case of a microwave tube.

FIG. 8 is a longitudinal sectional view of an electron gun using a conventional cold cathode. FIG. 9 is an enlarged view near the cathode of the electron gun of FIG.

FIG. 8 is disclosed in Japanese Patent Application Laid-Open No. 5-343000. The electron gun 112 shown in FIG. 8 is mainly used for a cathode ray tube. The formed gate 117 is connected to a plate-shaped conductor 122, which is a gate potential power supply component, and is connected to the emitter 11
By applying a positive voltage to the gate 117 with respect to 9, electrons are emitted from the tip of the emitter 119 by field emission. Above the gate 117, the first electron beam focusing electrode 125 and the second electron beam focusing electrode 1
A method of applying an independent voltage to these focusing electrodes to focus an electron beam emitted from the emitter 119 to obtain an electron gun structure with less aberration is disclosed.

In this example, power is supplied to the gate 117 by connecting a plate-shaped conductor 122 having a hole formed in the center, and a gate stem 123 is connected to both ends of the plate-shaped conductor 122. Then, a potential is supplied from outside. Power is supplied to the first electron beam focusing electrode 125 and the second electron beam focusing electrode 128 by rod-shaped lead terminals 126 and 129 connected thereto, respectively, and the plate-shaped conductor 122 and the first electron beam focusing electrode 12
The fifth and second electron beam focusing electrodes 128 are insulated from each other by the insulating layer 124 and the insulating material 127 because independent voltages are applied.

FIG. 10 is a longitudinal sectional view of another electron gun using a conventional cold cathode.

FIG. 10 shows an example of an electron gun structure using a cold cathode device disclosed in Japanese Patent Application No. 7-282938. In this electron gun structure, the electron emission region 25 of the cold cathode device 239
A structure is shown in which the focusing electrode 212 having an opening smaller than 7 is fixed in contact with the gate layer extending to the outside of the electron emission region 257. In this example, the electron beam is focused on the electrons emitted from the electron emission region 257 by devising the shape of the thin plate-shaped focusing electrode 212 connected to the gate layer.

In this example, the power supply to the gate potential and the focusing of the electron beam 202 are combined by one component. However, the component shape is extremely complicated in order to form an optimal electric field distribution on the front surface of the cold cathode 244. It has a shape.

[0016]

In such an electron gun using a cold cathode as an electron source, particularly in an electron gun used as an electron source for a microwave tube, a cold cathode element is fixed on a tube axis with high precision, and a cold cathode is used. It is necessary to provide a means for supplying a voltage to the gate potential layer formed on the surface of the cathode element and a means for obtaining a thin electron beam by focusing an electron beam emitted from the cathode by a focusing electrode provided near the cathode. .

In addition, a tube such as a traveling-wave tube is usually heated to 500 ° C. in an evacuation process such as a manufacturing process in which the inside of the tube is evacuated.
In order to experience the process of heating back and forth to release gas adhering to the inside of the tube,
It is necessary to devise a technique for avoiding the destruction of the minute gate / emitter structure due to the thermal expansion of the support for supporting the focusing electrode and the cathode. For example, for a cold cathode device fixed to a support, if the gate potential feeding component is a solid metal mass fixed to the gate layer, these components are not affected by a temperature rise of several hundred degrees.
A slight difference in thermal expansion of about [mu] m causes the focusing electrode to bite into the gate layer or a force for peeling the gate layer from the substrate, thereby causing a problem of destruction of the gate layer.

In the electron gun 112 using the conventional cold cathode device shown in FIG. 8, a component 1 for supplying power to the gate 117 is used.
Reference numeral 22 denotes a thin plate, which has plasticity, and has gate 11 against thermal expansion or external impact.
7 is maintained, but it is impossible to carry out the focusing action of the electron beam with this component, and by applying a voltage to the other focusing electrodes 125 and 128 installed thereon, The electron beam is focused. Also,
Due to the presence of the power supply component 122 to the gate, the focusing electrode 1
Some distance from the cathode surface at 25,128 is required for insulation, and for focusing of the electron beam, a lower negative potential is required for the cathode, and such a microwave tube requires The adoption of a simple structure causes the complexity of the power supply device and offsets the advantages of the cold cathode electron source.

In the structure of the conventional electron gun using the cold cathode device shown in FIG. 10, a power supply component for the gate layer also serves as a focusing electrode.
Is formed of a thin plate to have plasticity, thereby similarly absorbing thermal expansion. However, the focusing electrode 212 must be formed of a plate-shaped component, and the shape is complicated to obtain a required electric field distribution, which is difficult to design and manufacture.

The present invention has been made in view of the above points, and has made it possible to secure the stability of the cold cathode and the power supply with respect to a change in environmental temperature and obtain a good electron beam focusing. It is another object of the present invention to provide an electron gun using a cold cathode device as an electron source and a microwave tube using the same.

[0021]

In order to achieve the above object, the present invention provides an electron gun using a field emission type cold cathode device formed by arranging a plurality of emitters and gates on a plane as an electron source. The field emission cold cathode device includes a focusing electrode disposed in contact with a gate layer surface formed around an electron emission region on the field emission type cold cathode device, and a support for supporting the cold cathode device. And a metal part having elasticity provided between these two supports. The lower part of the support supporting the cold cathode is pressed to maintain contact between the gate layer and the focusing electrode, and the focusing electrode The power is supplied to the gate layer through the gate electrode.

Further, the present invention relates to an electron gun using a field emission type cold cathode device formed by arranging a plurality of emitters and gates on a plane as an electron source. A focusing electrode disposed in contact with the surface of the gate layer formed around the region, and a support for supporting the cold cathode element, wherein the focusing electrode is fitted with another support for supporting the cold cathode element; A metal part having elasticity is provided between the support and the focusing electrode, and the focusing electrode is pressed from above the cold cathode gate layer to maintain contact between the gate layer and the focusing electrode,
Power is supplied to the gate layer through the focusing electrode.

The microwave tube according to the present invention is characterized in that the above-mentioned electron gun is used as an electron beam source.

The present invention having the above configuration has the following operations.

The elastic spring metal disposed between the two supports of the cold cathode element is in a contracted state in a fixed state, and the cold cathode element is forced to expand in the axial direction by the spring metal. A force is applied in the direction of the focusing electrode, and good contact is maintained between a contact portion between the gate power supply layer and the focusing electrode, which is formed to extend to the periphery of the electron emission region of the cold cathode device.

Alternatively, the above-mentioned contact portion is formed by another means, ie, the spring electrode disposed between the focusing electrode and its support, which is also likely to extend in the axial direction. It is pressed against the surface gate feed layer, these contacts are maintained, and mechanical fixation and electrical contact are maintained.

The focusing electrode itself does not need to have a spring property as in the conventional example, and can take any shape, and can select an optimum shape for focusing the electron beam.

Also, when an electron gun using such a cold cathode device is used for a microwave tube such as a traveling wave tube, the temperature of the microwave tube may be changed during the manufacturing process or during use. The dimensional change between the cold cathode support and the focusing electrode occurs due to the thermal expansion or thermal contraction of the support portion, the focusing electrode support portion and their peripheral members, but due to the action of the springy metal, the gate power supply layer of the cold cathode device. And the focusing electrode is maintained in electrical contact and mechanically fixed.

Further, by processing the focusing electrode into an optimum shape, the potential distribution around the cathode and anode of the electron gun can be optimized, so that the electron beam can be focused well.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment of an electron gun using a cold cathode according to the present invention. FIG. 2 is a perspective view of the cold cathode device shown in FIG.

The electron gun of FIG. 1 has a rotationally symmetric structure with respect to the central axis. In this electron gun, the field emission cold cathode device 5
Are used as electron sources. The cold cathode device 5 is formed on a normal semiconductor silicon substrate by a semiconductor manufacturing process, and is cut into a rectangular shape from a silicon wafer. FIG. 11 shows a cross-sectional structure of the emitter and the gate, which are the electron-emitting portions. FIG. 2 shows a perspective view of the cold cathode element 5.

As described above with reference to FIG. 11, the cold cathode element 5 has a conical emitter 1 formed by laminating a metal such as molybdenum on a silicon substrate 3, and a thickness of 1 μm for applying an electric field to the tip of the emitter 1. Gate 2 and a silicon substrate 3 having an emitter potential and an insulating layer 4 for insulating the gate 2
Is a basic constituent element, and a large number of thousands or more of these elements are usually arranged at intervals of several μm, and the electron emission region 6 shown in FIG.
Is formed. The gate electrode is formed as a gate power supply layer 7 extending to the outside of the electron emission region 6, and is insulated from the silicon substrate 3 by an insulating layer extended to the outer periphery in the same manner.

The cold cathode device 5 having such an emitter-gate structure formed on the surface is fixed so that the silicon substrate 3 is in contact with the cathode support 27 made of metal shown in FIG. At a contact portion of the cathode support 27 with the cold cathode device 5, a cathode holding portion 27H, which is a rectangular or circular concave portion fitted with the outer diameter of the cold cathode device 5, is formed. It is fixed by contact or adhesion. From the bottom of the cathode holding portion 27H, a column-shaped cathode support pillar 27S extending integrally therewith is formed. Cathode support column 2
The lower part of 7S is a second metal support 2 for supporting it.
8 is fitted. The second support body 28 has a portion in which a cylindrical component is provided with a circular hole for fitting with the cathode support body 27,
Flange 28F integrally extending from outer diameter of bottom of cylinder
It is a shape having. Cathode support 27 and second support 2
It is preferable that the fitting portion 8 is fitted with a slight dimensional difference in order to prevent radial displacement between them.
A hole 28H for bleeding air from the fitting portion is formed below the fitting portion of the second support 28. A helical spring 29 is inserted between the cathode support 27 and the second support 28 at the outer periphery of the cathode support 27S. The helical spring 29 is formed by spirally winding a metal wire having a high melting point and having a spring property, and in a fixed state, the helical spring 29 is in a contracted state. On the other hand, a gate power supply layer 7 extending from the gate electrode is formed around the electron emission region 6 on the surface of the cold cathode element 5, and is made of metal so as to be in contact with the gate power supply layer 7. A focusing electrode 15 is provided. The focusing electrode 15 is an annular component having a hole in the center thereof through which the electron beam 18 passes, and has a surface shape such that a potential distribution between the focusing electrode 15 and the anode 25 is optimized. The focusing electrode 15 is fixed to a cylindrical focusing electrode support 30 that supports the focusing electrode 15 by welding or the like.
The opposite side of the focusing electrode support 30 to which the focusing electrode 15 is connected has a flange portion 30F. Between the flange portion 30F and the flange portion 28F of the support body 28, a cylindrical insulator 26 usually made of ceramic is provided. And are hermetically bonded to them. Further, another cylindrical insulator 17 made of ceramic is disposed between the flange portion 30F of the focusing electrode support 30 and the anode 25, and is air-tightly joined to the flange portion 30F of the focusing electrode support 30. The anode 25 is an annular component having a hole in the center thereof through which the electron beam 18 passes. The anode 25 and the insulator 17 are air-tightly joined via another metal member. The insulators 17 and 26, the cathode support 27 and the focusing electrode support 30 are operated so that the inside of the insulators 17 and 26 of these electron guns is operated in vacuum.
Are hermetically joined by brazing.

The operation of the first embodiment of the electron gun using the cold cathode according to the present invention having the above structure will be described with reference to FIG.

A voltage of several volts to several tens of volts is applied to the gate 2 of the field emission type cold cathode element 5 with respect to the emitter 1 by applying a positive voltage to the emitter 1.
A high electric field intensity of 10 ⁷ V / cm is generated, and the electrons in the emitter 1 gain energy exceeding the electron barrier on the metal surface and are emitted into a vacuum. Since the emitter 1 is formed on the silicon substrate 3 of the cold cathode device 5, it has the same potential as the silicon substrate 3 and has a cathode support 27 supporting the cold cathode device 5 and a second support 28 fitted with the cathode support 27. , An emitter potential is supplied from outside. On the other hand, the gate potential is supplied from the outside via the focusing electrode 15 in contact with the gate power supply layer 7 and the focusing electrode support 30 joined to the focusing electrode 15, and between the second support 28 and the focusing electrode support 30, It is electrically insulated by an insulator 26 made of ceramic or the like. The focusing electrode 15 is fixed to the gate power supply layer 7 on the surface of the cold cathode element 5 by contact, and the contact portion is a spiral spring inserted between the cathode support 27 and the second support 28 supporting the cathode support 27. 29 is brought into pressure contact with the force to be extended, and is electrically stably contacted.

In an electron gun used for a tube such as a traveling wave tube, in the manufacturing process, the temperature is set to about 500 ° C. in order to completely remove gas molecules adhering to the inner wall of the tube while performing vacuum evacuation. Experience the process of being heated. Further, under actual operating conditions, there is a possibility that the semiconductor device is usually exposed to a temperature condition of about −30 ° C. to about 150 ° C.

Due to such a change in the external temperature of the electron gun, the cathode support 27 and the second support 2 supporting the same are supported.
8. When the dimensional change occurs in the tube axis direction due to thermal expansion or contraction of the focusing electrode support 30 or the like, each dimensional change differs depending on their material and temperature. It appears as a dimensional change in the element portion, causing a change in the contact state between the gate power supply layer 7 and the focusing electrode 15. That is, it becomes a force for compressing or pulling the cold cathode element 5 in the axial direction.
The gate power supply layer 7 having a slightly small thickness may be broken. However, in the present invention, such a dimensional change is
The cathode support 27 and the second support 28 supporting the cathode support 27 are movable in the axial direction only by being fitted to each other so as to absorb. Moreover, the gate power supply layer 7 and the focusing electrode 15 can always maintain a good contact state by the force of the spiral spring 29.

Electrons emitted from the emitter 1 of the cold cathode device 5 in a vacuum are focused by the focusing electrode 15 and the focusing magnetic field, and in the case of a microwave tube, are guided as an electron beam to the high frequency circuit. The shape of the focusing electrode 15 is
The potential distribution on the front surface of the cathode is determined by computer simulation or the like so as to be optimal for the focusing of the electron beam 18. In this embodiment, the focusing electrode 15
The shape of the portion facing the electron beam 18 can be almost determined only by optimizing this potential distribution. As in the conventional example, the focusing electrode 15 is provided with a spring property to make contact with the gate layer 7. Therefore, it is not necessary to devise a method for securing the electron beam, and good electron beam focusing characteristics can be obtained.

Next, the first embodiment of the electron gun according to the present invention will be described in more detail.

The cold cathode element 5 is manufactured by forming an emitter 1, a gate 2 and the like on a silicon wafer by a semiconductor process, and then cutting out a rectangular chip having a thickness of about 0.5 mm and a width of about 2 mm. 5000 or more emitters 1 and gates 2 are arranged at intervals of several μm and have a diameter of 1 m.
An electron emission region 6 of about m is formed. On the cold cathode element surface outside the electron emission region 6, the gate power supply layer 7 is extended as it is. This cold cathode element 5 is installed on a cathode support 27 made of a metal such as molybdenum. At this time, it may be fixed with an adhesive or the like. Further, the cathode support 27 is provided with this and o. Second support 2 made of metal such as Kovar which fits with a slight dimensional difference of about 05 mm
8 so as to be mutually movable in the axial direction. The second support 28 is formed with a hole 28H having a diameter of about 1 mm for bleeding air from the fitting portion. Further, the second support 28 is joined to the insulator 26 made of ceramic such as alumina by brazing, and is vacuum-sealed and simultaneously insulated from the focusing electrode support 30. The potential of the emitter 1 is connected to a lead wire or the like outside the vacuum of the second support 28 and supplied with power. The helical spring 29 is made of a material having a spring property even at a high temperature, such as a tungsten wire having a thickness of about 0.5 mm.
It is used after being annealed at about 1000 ° C. In the fixed state, the helical spring 29 is slightly contracted, and presses the cathode support 27 and the cold cathode element 5 in the direction of the focusing electrode 15. The focusing electrode 15 is made of a metal such as molybdenum, and a contact portion with the gate power supply layer 7 is preferably plated with gold to reduce contact resistance. The focusing electrode 15 is fixed at its outer diameter to a focusing electrode support 30 made of metal such as Kovar by welding.

The surface shape of the focusing electrode 15 is adjusted so that the electric field distribution formed between the focusing electrode 15 and the anode 25 for applying the acceleration voltage of the electron beam is optimal for the focusing of the electron beam 18.
It is open to 5. This is because it is desirable that the shape is close to a shape well-known as a pierce-type electron gun.

By applying a voltage of about 10 V to 100 V (positive with respect to the emitter 1) to the gate 2 of the cold cathode, electrons are obtained from the conical tip of the emitter 1 by field emission. The voltage to be applied depends on the sharpness of the tip of the conical shape and the distance from the gate, and the value is usually determined for the required amount of current in the above range. Electrons that have jumped out of the emitter 1 are accelerated by a high voltage of several KV applied to the anode 25 and are focused by a focusing electric field created between the focusing electrode 15 and a focusing magnetic field given from the outside, so that a central hole of the anode 25 is formed. Pass through. The accelerating voltage applied to the anode 25 varies greatly depending on the application in which the electron beam 18 is used. In the case of a traveling wave tube or the like, a voltage of 3 KV or more is usually used.

FIG. 3 is a sectional view of an electron gun using a cold cathode according to a second embodiment of the present invention. FIG. 4 is a perspective view of a leaf spring used in the electron gun of FIG.

The electron gun shown in FIG. 3 has a rotationally symmetric structure with respect to the central axis. The members used in the second embodiment of FIG. 3 are given the same numbers as those used for the same members in the first embodiment of FIG. The second embodiment differs from the first embodiment in FIG. 1 in that a metal member having a spring property inserted between a cathode support 27 and a second support 28 fitted thereto is a helical spring. This is not a leaf spring 31. As an example of the shape of the leaf spring 31, as shown in the perspective view of FIG. 4, it has a stepped disc shape having a hole at the center.
In a fixed state, the leaf spring 31 is in a contracted state. A plurality of seats 32 are formed on the circumference of the leaf spring 31 to facilitate the deformation of the spring.

The operation of the second embodiment is the same as that of the first embodiment described above. However, since the plate spring 31 is used, the axial direction of the entire electron gun is smaller than that of the first embodiment. The length can be shortened, but conversely a larger dimension is required in the radial direction. As a material of the plate-like spring 31, an inconel or a molybdenum-rhenium alloy which does not deteriorate even at a high temperature like a spiral spring is used, and is manufactured by drawing and cutting from a plate having a thickness of about 0.1 mm.
It is arranged between the cathode support 27 and the second support 28 fitted thereto, and serves to keep the contact between the gate layer of the cold cathode device 5 and the focusing electrode 15.

FIG. 5 is a sectional view of a third embodiment of the electron gun using the cold cathode according to the present invention. The electron gun of FIG. 5 has a rotationally symmetric structure with respect to the central axis. The members used in the third embodiment of FIG. 5 are given the same numbers as those used for the same members in the first embodiment of FIG.

In FIG. 5, the cold cathode element 5 is the same as that shown in FIGS.
It is fixed so that a silicon substrate part contacts on it. At a contact portion of the cathode support 27 with the cold cathode device 5, a cathode holding portion 27H, which is a rectangular or circular concave portion fitted with the outer diameter of the cold cathode device 5, is formed. It is fixed by contact or adhesion. Cathode holder 27H
A column-shaped cathode support pillar 27S extending integrally therefrom is formed from the bottom of the cathode support pillar 27S. Further, the cathode support pillar 27S has a flange portion 27F at an end thereof, and the flange portion 27F is formed of a cylindrical insulator 26. And airtight. On the other hand, a gate power supply layer extending from the gate electrode is formed around the electron emission region on the surface of the cold cathode element 5, and the focusing electrode 15 made of metal is brought into contact with the gate power supply layer. Is installed. The focusing electrode 15 is an annular component having a hole at the center portion through which the electron beam 18 passes, and the surface shape is determined so that the potential distribution between the focusing electrode 15 and the anode 25 is optimal. , Which are fitted with a cylindrical metal focusing electrode support 30 that supports this. The focusing electrode support 30 has a cylindrical portion having a fitting portion with the focusing electrode 15 and a flange portion 30F at an end opposite to the cylindrical portion. The flange portion 30F is hermetically bonded to the cylindrical insulators 26 and 17 at the flange portion 30F. Have been.

The fitting portion between the focusing electrode 15 and the focusing electrode support 30 is desirably fitted with a slight dimensional difference in order to prevent the mutual displacement in the radial direction. Further, between the focusing electrode 15 and the focusing electrode support 30, a plate-like spring 31 having one joined to the focusing electrode support 30 is provided,
The plate-shaped spring 31 is in a contracted state in a fixed state, and presses the focusing electrode 15 against the gate layer of the cold cathode element 5.
The plate-shaped spring 31 has the shape shown in FIG. 4 as described in the embodiment of FIG.

The space between the focusing electrode support 30 and the cathode support 27 is joined to a cylindrical insulator 26 usually made of ceramic. Further, a cylindrical insulator 17 made of another ceramic or the like is provided between the focusing electrode support 30 and the anode 25.
It is joined by. The insulator 17 of these electron guns as a whole,
Insulator 17, so that the inside is operated in vacuum from 26,
26 and the cathode support 27 and the focusing electrode support 30 are hermetically joined by brazing.

The operation of the third embodiment shown in FIG. 5 is the same as the operation of the embodiment shown in FIG. However, the focusing electrode 15 is pressed against the gate power supply layer of the cold cathode element 5 by the plate-shaped spring 31 so that the gate potential is supplied, and the cathode support 27 and the focusing electrode support 30 are heated by external heating or the like. When thermal expansion occurs, the focusing electrode 15 and the focusing electrode support 30 move axially with each other, absorb the difference in thermal expansion therebetween, and apply an unreasonable force to the cold cathode element 5. Has been prevented. Also, as in the embodiment shown in FIG. 3, the axial length is not required as compared with the embodiment in FIG.
A radial space for disposing the plate spring 31 is required. Further, as an example, the plate spring is processed from a plate material having a high-temperature spring strength such as Inconel or molybdenum rhenium alloy as in the embodiment shown in FIG. 3, and the outer peripheral portion of the plate spring is formed on the focusing electrode support 30. They are joined by welding or the like.

FIG. 6 is a sectional view of a traveling wave tube which is a typical example of a microwave tube incorporating the electron gun of the embodiment shown in FIG.

In the traveling wave tube shown in FIG. 6, the main components of the high-frequency circuit section 12 are arranged around an electron beam 18 which exits from the electron gun section 11, passes through the center hole of the anode 25, and linearly advances on the axis. Spiral 19 is installed. The spiral 19 is formed by winding a wire having a high melting point such as molybdenum or tungsten in a spiral shape. Helix 19
A plurality of annular magnets 20 located outside thereof and an annular magnet 21 installed between the respective magnets are supported by a dielectric support rod 24 in a cylinder of a focusing device formed by stacking, and The dielectric support rod 24 is usually made of three rod-shaped ceramics. On both sides of the helix 19, a high-frequency input section 22 and a high-frequency output section 23 forming a coaxial line are provided.
9 is connected. In addition, an annular ceramic 34 is arranged in the middle of the coaxial line for vacuum sealing. Further downstream of the high frequency circuit, a cylindrical collector 13 made of metal is arranged. An insulator 35 made of an annular ceramic is provided between the collector section 13 and the high-frequency circuit section 12.
Are provided and insulated from the high-frequency circuit unit 12. A focusing device in which a plurality of annular magnets 21 are alternately joined is installed around the spiral 19, and generates a periodic focusing magnetic field in the path of the electron beam 18.

Next, the operation of the traveling wave tube shown in FIG. 6 will be described.

The electron beam 18 taken out from the cold cathode element 5 of the electron gun section 11 is accelerated by a high voltage, and the electric field distribution optimally formed by the focusing 15 and the plurality of annular magnets 20 Are focused by a magnetic field generated by a focusing device formed by an annular magnet 21 disposed between the magnets, and are guided as an electron beam 18 into a spiral 19 of the high-frequency circuit section 12. The microwave guided from the high frequency input unit 22 propagates on the helix 19 and travels along the helix 19. The diameter and pitch of the helix 19 are determined according to the operating frequency of the traveling wave tube so that the electron beam 18 and the microwave traveling along the helix 19 are almost equal in speed. The microwave is energized by the electron beam 18 by propagating at approximately the same speed as the electron beam 18 and after being amplified,
It is taken out from the high frequency output unit 23. The electron beam 18 having completed the interaction with the microwave is captured by the collector 13 and converted into thermal energy and radiated out of the tube.

Although FIG. 6 shows an embodiment incorporating the electron gun shown in FIG. 1, the same operation can be obtained by using another electron gun of the present invention.

[0057]

According to the present invention as described above, the following excellent effects can be obtained. (1) A spring is provided between the cathode support and the second support fitted to the cathode support or between the focusing electrode and the focusing electrode support to press the cold cathode element and the focusing electrode. Since the contact between the gate power supply layer of the cold cathode device and the focusing electrode is maintained,
Even when a bulb using an electron gun such as a traveling-wave tube is exposed to a temperature of about 500 ° C., the cold cathode device is not destroyed and the fixation of the cold cathode device is not loosened. There is an effect that the gates and their supports or electrodes come into contact with each other, and the potential can be stably supplied. (2) A spring metal is provided on the cold cathode support or the support of the focusing electrode without providing spring properties to the focusing electrode itself or installing a power supply part to the gate separately from the focusing electrode. The contact between the gate power supply layer and the focusing electrode is maintained, and there is no restriction on the shape of the focusing electrode itself, such as the need to form a thin plate to prevent poor contact. Since the shape of the focusing electrode can be determined so as to be optimal for beam focusing, the shape of the focusing electrode that comes in contact with the gate power supply layer of the cold cathode and supplies its potential is determined by the optimal electric field distribution for electron beam focusing. It can be designed to give a good linear beam with little ripple and the like, and has the effect of realizing a tube with good characteristics. (3) Since an electron gun using a cold cathode as an electron source is used, and an electron gun having good electron beam characteristics and stable against environmental characteristics such as temperature can be realized, a traveling wave having a high efficiency without a cathode preheating time is required. There is an effect that a microwave tube such as a tube can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of an electron gun using a cold cathode according to the present invention.

FIG. 2 is a perspective view of the cold cathode device shown in FIG.

FIG. 3 is a sectional view of an electron gun using a cold cathode according to a second embodiment of the present invention;

FIG. 4 is a perspective view of a leaf spring used in the electron gun of FIG. 3;

FIG. 5 is a sectional view of an electron gun using a cold cathode according to a third embodiment of the present invention.

6 is a cross-sectional view of a traveling wave tube which is a typical example of a microwave tube incorporating the electron gun of the embodiment shown in FIG.

FIG. 7 is a sectional view of a traveling wave tube using a conventional hot cathode.

FIG. 8 is a longitudinal sectional view of an electron gun using a conventional cold cathode.

FIG. 9 is an enlarged view of the vicinity of the cathode of the electron gun of FIG.

FIG. 10 is a vertical sectional view of another electron gun using a conventional cold cathode.

FIG. 11 is a partial sectional view of a field emission cold cathode device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Emitter 2 Gate 3 Silicon substrate 4 Insulating layer 5 Cold cathode device 6 Electron emission area 7 Gate feeding layer 11 Electron gun section 12 High frequency circuit section 13 Collector section 14 Hot cathode 15 Focusing electrode 16 Heater 17 Insulator 18 Electron beam 19 Spiral 20 Magnet 21 Magnetic pole 22 High frequency input unit 23 High frequency output unit 24 Dielectric support rod 25 Anode 26 Insulator 27 Cathode support 27H Cathode holding unit 27S Cathode support column 28 Support 28F Flange 28H Hole 29 Spiral spring 30 Focusing electrode support 30F Flange part 31 Plate spring 32 Slit 33 Inner conductor 34 Ceramic 35 Insulator 111 Glass container 112 Electron gun 113 Laramic substrate 114 Substrate 115 Cathode conductor 116 Insulating layer 117 Gate 119 Emitter 120 Field emission cold cathode 121 Caso Stem 122 Gate feeding component 123 Gate stem 124 Insulating layer 125 First electron beam focusing electrode 126 Lead terminal 127 Insulating material 128 Second electron beam focusing electrode 129 Lead terminal 202 Electron beam 211 Anode 212 Focusing electrode 239 Cold cathode device 243 Cold cathode support Body 244 Cold cathode 257 Electron emission area

Claims (4)

(57) [Claims] 1. An electron gun using, as an electron source, a field emission cold-cathode device formed by arranging a plurality of emitters and gates on a plane, and surrounding an electron emission region on the field emission cold-cathode device. A focusing electrode arranged in contact with the surface of the gate layer formed on the substrate, and a support for supporting the cold-cathode device, the support further fitted with a second support, and these two supports A metal part having elasticity is provided therebetween, and the lower part of the support supporting the cold cathode is pressed to maintain contact between the gate layer and the focusing electrode, and power is supplied to the gate layer via the focusing electrode. An electron gun using a cold cathode. 2. An electron gun using, as an electron source, a field emission type cold cathode device formed by arranging a plurality of emitters and gates on a plane. A focusing electrode disposed in contact with the surface of the gate layer formed on the substrate, and a support for supporting the cold cathode element, wherein the focusing electrode is fitted with another support for supporting the cold cathode element, A metal part having elasticity is provided between the focusing electrode and the focusing electrode, and the focusing electrode is pressed from above the cold cathode gate layer to maintain contact between the gate layer and the focusing electrode, and to supply power to the gate layer via the focusing electrode. An electron gun using a cold cathode. 3. A microwave tube using the electron gun according to claim 1 as an electron beam source. 4. A microwave tube using the electron gun according to claim 2 as an electron beam source.