Electron gun containing sectional insulating ceramic

Abstract

The invention relates to an electron gun containing sectional type insulating ceramics, which comprises an anode, the sectional type insulating ceramics, a cathode supporting piece, a cathode cylinder, a cathode and a focusing electrode, the sectional type insulating ceramics comprise a plurality of ceramic sections, suspension electrodes are arranged between the adjacent ceramic sections, and the suspension electrodes and the ceramic sections are alternately stacked. The direction from the anode to the cathode supporting piece is the top-to-bottom direction, the direction from the cathode cylinder to the sectional type insulating ceramic is the inside-to-outside direction, shielding rings are arranged on the lower end face of the anode and the inner sides of the suspension electrodes, and anti-corona rings are arranged on the outer sides of the suspension electrodes. Compared with the prior art, by designing the sectional insulating ceramic structure comprising the ceramic sections with different lengths and the shielding ring with the function of shielding electrons emitted by the cathode cylinder from bombarding the ceramic, the uniformity of an electric field on the surface of the electronic gun ceramic is improved, the peak electric field intensity on the surface of the ceramic is reduced, and the insulating capacity of the electronic gun shell is improved; the cable has the advantage of high insulating capacity.

Description

Technical Field

[0001] The invention belongs to the field of vacuum electronic technology, and relates to a solution to the problem of surface insulation of a magnetic ring of an electron gun, and in particular to an electron gun comprising segmented insulating ceramics. Background Art

[0002] Vacuum electronic devices such as klystrons and traveling wave tubes use the interaction between electrons and electromagnetic waves in a special vacuum environment to achieve energy conversion, and are widely used in high-power and high-frequency fields. The function of the electron gun in a vacuum electronic device is to generate an electron beam of a certain shape and energy, in which the cathode and anode generally need to be loaded with a voltage ranging from several thousand volts to several hundred kilovolts. The ceramic ring is an annular ceramic structure on the electron gun shell, located between the cathode support and the anode (the cathode support is connected to the cathode through the cathode tube, and the potential is the same as the cathode), which plays a supporting and insulating role. Surface flashover is a corona discharge phenomenon formed on the surface of the magnetic ring. The occurrence of surface flashover means that the insulation of the vacuum electronic device fails and cannot work normally. In severe cases, it may even directly damage the magnetic ring. The voltage of the magnetic ring when the surface flashover occurs is much smaller than the voltage required for the breakdown of the vacuum gap of the same size or the body breakdown inside the ceramic. Therefore, surface flashover is an important reason that restricts the insulation strength of the electron gun shell. As vacuum electronic devices develop towards high power and miniaturization, the electric field strength in the electron gun continues to increase, and the surface of the insulating ceramic surface is more prone to surface flashover, which is a problem that must be considered during design. .

[0003] Conventional electron guns use a single-section ceramic ring with a long length. It is generally believed that excessive field strength and electron bombardment are the main reasons for triggering surface flashover on insulating ceramics. To overcome this problem, previous studies generally used anti-corona rings to reduce the field strength at the intersection of ceramics, vacuum and metal. However, on the one hand, there is still the problem of uneven field strength distribution on the ceramic surface, resulting in a high peak field strength. On the other hand, it is impossible to shield the high-energy electrons emitted from the cathode tube from bombarding the ceramic surface, which limits the insulation capacity of the magnetic ring. Summary of the invention

[0004] An object of the present invention is to provide an electron gun including segmented insulating ceramics capable of improving the insulation capability of the electron gun.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] An electron gun including segmented insulating ceramics, comprising an anode, segmented insulating ceramics, a cathode support, a cathode tube, a cathode and a focusing electrode, wherein the anode, segmented insulating ceramics and cathode support are sequentially connected to form a gun shell of the electron gun, realizing the function of a vacuum sealed chamber, wherein the cathode tube, cathode and focusing electrode are located in the vacuum sealed chamber, the cathode tube is mounted on the cathode support, and the cathode and focusing electrode are mounted on the cathode tube, wherein:

[0007] The segmented insulating ceramic comprises a plurality of ceramic segments, and suspension electrodes are arranged between adjacent ceramic segments, and the suspension electrodes and the ceramic segments are alternately stacked.

[0008] With the direction from the anode to the cathode support as the top-to-bottom direction and the direction from the cathode tube to the segmented insulating ceramic as the inside-to-outside direction, the lower end surface of the anode and the inner side of each suspension electrode are provided with a shielding ring, and the outer side of each suspension electrode is provided with an anti-corona ring.

[0009] Furthermore, the pressure in the vacuum sealed chamber is less than or equal to 10 -5 Pa.

[0010] Furthermore, the axial lengths of the ceramic segments are non-uniform, so that the suspension electrodes are arranged at non-uniform intervals.

[0011] Furthermore, along the direction from the anode to the cathode support, the axial length of the first ceramic segment is the longest, the second is the second, and the remaining ceramic segments are shorter.

[0012] Furthermore, the remaining ceramic segments have the same axial length.

[0013] Furthermore, the thickness of the shielding ring near the anode is smaller than the thickness of the shielding ring far from the anode, and the thinner portion is closer to the ceramic segment.

[0014] Furthermore, in the shielding ring connected to each suspension electrode, the upper end surface of the shielding ring close to the anode is higher than the upper end surface of the suspension electrode connected thereto.

[0015] Furthermore, all corners of each shielding ring are rounded.

[0016] Furthermore, there is a gap between the anti-corona ring and the segmented insulating ceramic.

[0017] Furthermore, the end of the anti-corona ring is in a smooth arc shape.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention optimizes the shell structure of the electron gun, designs a segmented insulating ceramic separated by a suspended electrode, and designs a shielding ring structure on the suspended electrode, thereby improving the uniformity of the electric field on the surface of the electron gun ceramic, reducing the peak electric field intensity on the surface of the ceramic, and solving the problem of easy surface flashover of the ceramic caused by electric field concentration in the traditional shielding ring design, effectively improving the insulation capacity, having the advantages of strong insulation capacity, etc., which is of great significance to increasing the power capacity and reliability of microwave devices.

[0020] 2. The segmented insulating ceramic designed by the present invention has different lengths of each ceramic segment. Since the electric potential of the focusing electrode outside the cathode is not much different from that of the cathode, and the distance between the focusing electrode and the anode is usually small, the position with the strongest electric field in the electron gun is usually between the focusing electrode and the anode. The segmented insulating ceramic designed by the present invention has two longer segments close to the anode, and the corresponding shielding ring length is also longer. Due to the influence of the focusing electrode and the anode, the electric field near the shielding ring close to the anode is stronger than the shielding ring far away from the anode. When the spacing between the shielding rings is not much different, this will lead to a greater potential difference between the shielding rings closer to the anode. The potential difference between the upper and lower ends of the magnetic ring is the same as the potential difference between the shielding rings connected to its upper and lower ends, so the potential difference between the two ends of the magnetic ring close to the anode is higher. Under this condition, if the length of each magnetic ring is the same, the electric field on the surface of the magnetic ring close to the anode will be stronger. The present invention lengthens the length of the magnetic ring close to the anode, which can reduce the electric field strength on the corresponding magnetic ring surface, thereby forming a more uniform electric field distribution on the entire segmented insulating ceramic surface and reducing its peak electric field.

[0021] 3. The main function of the shielding ring designed in the present invention is to shield the high-energy electrons emitted by the cathode tube from bombarding the ceramic to avoid breakdown. All corners of the shielding ring are rounded to form a smooth arc surface to avoid the occurrence of sharp corners and other structures that lead to electric field concentration and prevent the electric field at the end of the shielding ring from being too large.

[0022] 4. The anti-corona ring of the present invention is arranged outside the lower end of the suspension electrode and the anode and the upper end of the cathode support to reduce the electric field strength at the position of the ceramic, vacuum and metal junction nearby. In addition, the upper part of the anti-corona ring is also located near the ceramic, vacuum and metal junction, which also plays a role in reducing the electric field strength at the position of the nearby three junctions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a stereogram of an electron gun of the present invention;

[0024] Figure 2 is an axial cross-sectional view of the electron gun of the present invention;

[0025] Figure 3 yes Figure 2 The enlarged view of point A in the middle;

[0026] Figure 4 yes Figure 2 The enlarged view of point B in the middle;

[0027] Figure 5 It is a simulation diagram of the electric field strength on the inner surface of insulating ceramics;

[0028] Description of reference numerals:

[0029] 1. Electron gun; 2. Anode; 3. Segmented insulating ceramic; 31. Ceramic segment; 32. Suspended electrode; 33. Shielding ring; 331. First ring segment; 332. Second ring segment; 34. Anti-corona ring; 4. Cathode; 5. Cathode support; 6. Cathode tube; 7. Focusing electrode. DETAILED DESCRIPTION

[0030] Now, with reference to the accompanying drawings, a schematic scheme of the electron gun disclosed in the present invention is described in detail. Although the accompanying drawings are provided to present some embodiments of the present invention, the accompanying drawings do not have to be drawn according to the size of the specific implementation scheme, and certain features may be enlarged, removed or partially cut away to better illustrate and explain the disclosure of the present invention. Some components in the accompanying drawings may be adjusted in position according to actual needs without affecting the technical effect. The phrase "in the accompanying drawings" or similar terms appearing in the specification do not necessarily refer to all drawings or examples.

[0031] Certain directional terms used to describe the drawings below, such as "inside", "outside", "above", "below" and other directional terms, will be understood to have their normal meanings and refer to those directions involved when the drawings are normally viewed. Unless otherwise specified, the directional terms described in this specification are basically in accordance with the conventional directions understood by those skilled in the art.

[0032] The terms "first", "first", "second", "second" and the like used in the present invention do not indicate any order, quantity or importance, but are used to distinguish one component from other components.

[0033] like Figure 1 and Figure 2 As shown, this embodiment provides an electron gun 1 including segmented insulating ceramics, including an anode 2, a segmented insulating ceramic 3, a cathode support 5, a cathode tube 6, a cathode 4 and a focusing electrode 7. The anode 2, the segmented insulating ceramic 3 and the cathode support 5 are connected in sequence to form a vacuum sealed chamber for accommodating other components of the electron gun. As a gun shell of the electron gun, the cathode tube 6 with the cathode 4 and the focusing electrode 7 connected to the upper end is installed on the cathode support 5 and is located in the vacuum sealed chamber. The pressure in the vacuum sealed chamber is less than or equal to 10 -5 In this embodiment, the segmented insulating ceramic 3 is made of alumina ceramic.

[0034] In this embodiment, the direction from the anode 2 to the cathode support 5 is taken as the top-to-bottom direction, and the segmented insulating ceramic 3 has two upper and lower end faces, the anode 2 has a lower end face welded to the upper end face of the segmented insulating ceramic 3, and the cathode support 5 has an upper end face welded to the lower end face of the segmented insulating ceramic 3.

[0035] The segmented insulating ceramic 3 is cylindrical and includes a plurality of ceramic segments 31. Metal suspension electrodes 32 are arranged between adjacent ceramic segments 31. The suspension electrodes 32 and the ceramic units 31 are alternately stacked. By using different lengths of the ceramic segments, the uniformity of the electric field strength on the surface of the insulating ceramic can be improved. Figure 5 The comparison of electric field strength on the ceramic surface using non-uniform segmented insulating ceramics, uniform segmented insulating ceramics, and without suspended electrodes and shielding rings is shown. The use of non-uniform segmented insulating ceramics can improve the uniformity of the electric field strength on the insulating ceramic surface.

[0036] In this embodiment, five non-uniformly arranged suspension electrodes 32 are provided, each suspension electrode having two upper and lower end faces and two inner and outer surfaces. The axial length of each ceramic segment is non-uniform, so that each suspension electrode 32 is arranged at a non-uniform interval. In this embodiment, along the direction from the anode 2 to the cathode support 5, the axial length of the first ceramic segment is the longest, followed by the second ceramic segment, and the lengths of the remaining ceramic segments are shorter. The lengths of the remaining ceramic segments in this embodiment are the same.

[0037] In this embodiment, with the cathode tube pointing towards the segmented insulating ceramic as the inside-to-outside direction, a shielding ring 33 is provided on the lower end surface of the anode 2 and the inner side of each suspended electrode 32. The shielding ring 33 is designed to be a gradient structure with rounded ends. The portion close to the anode is thin and close to the ceramic, and the portion away from the anode is thick and away from the ceramic. On the one hand, it is used to shield the high-energy electrons emitted by the cathode from bombarding the ceramic, and on the other hand, it is used to reduce the electric field strength of the nearby triple junction. Figure 4 FIG. 2 shows an enlarged view of the structure of the shielding ring according to the present embodiment. Figure 4 As shown, the shielding ring 33 includes a first ring segment 331 and a second ring segment 332 connected along the radial direction of the electron gun 1. The first ring segment is thin and close to the ceramic segment 31, the second ring segment 332 is thick and far away from the ceramic segment 31, and the end of the shielding ring 33 is rounded to prevent stress concentration at the end and excessive electric field strength.

[0038] In this embodiment, six shielding rings 33 are provided, wherein the first shielding ring is welded to the lower end surface of the anode 2, and the second to sixth shielding rings are correspondingly welded to the lower end surfaces of the suspension electrodes 32. Among the shielding rings 33 connected to the suspension electrodes 32, the upper end surface of the shielding ring 33 close to the anode 2 is slightly higher than the upper end surface of the suspension electrode 32 connected thereto, which effectively increases the effect of the shielding rings.

[0039] like Figure 2As shown, a total of 6 ceramic segments are provided in this embodiment. Among them, the axial length of the first shielding segment is the largest, the axial length of the second shielding ring is smaller than the axial spacing of the first shielding ring, and the axial lengths of the third to sixth shielding rings are the same, which are smaller than the axial lengths of the first and second shielding rings. At the same time, in order to avoid excessive field strength at the ends of the first and second shielding rings, the distance between the first and second shielding rings and the inner surface of the segmented insulating ceramic 3 is increased.

[0040] Figure 3 An enlarged view of the structure of the anti-corona ring according to this embodiment is shown. The anti-corona ring 34 is welded to the outer surface of the suspension electrode 32, the outer side of the upper end surface of the cathode support 5, and the outer side of the lower end surface of the anode 2. There is a gap between the anti-corona ring 34 and the ceramic segment 31. The upper and lower end surfaces of the anti-corona ring 34 are rounded to avoid too high field strength at the end surfaces.

[0041] Figure 3 The enlarged view of the structure of the suspension electrode according to the present embodiment is shown. The outer surface of the suspension electrode 32 is welded to the inner surface of the anti-corona ring 34. The shielding ring 33 is welded to the inner surface of the suspension electrode 32. The lower end of the upper shielding ring and the upper end of the lower shielding ring are exactly overlapped in the axial direction, thereby preventing the high-energy electrons emitted by the cathode tube 6 from bombarding the ceramic segment 31.

[0042] The electron gun provided in this embodiment, which includes segmented insulating ceramics, can effectively avoid the situation where the field strength on the surface of the insulating ceramics and the three intersection points is high, and can shield the bombardment of the ceramics by electrons emitted by the cathode tube.

[0043] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. An electron gun comprising a segmented insulating ceramic, characterized in that: The invention comprises an anode (2), a segmented insulating ceramic (3), a cathode support (5), a cathode tube (6), a cathode (4) and a focusing electrode (7); the anode (2), the segmented insulating ceramic (3) and the cathode support (5) are connected in sequence to form a gun shell of an electron gun, realizing the function of a vacuum sealed chamber; the cathode tube (6), the cathode (4) and the focusing electrode (7) are located in the vacuum sealed chamber; the cathode tube (6) is mounted on the cathode support (5); the cathode (4) and the focusing electrode (7) are mounted on the cathode tube (6); wherein: The segmented insulating ceramic (3) comprises a plurality of ceramic segments (31), wherein a suspension electrode (32) is arranged between adjacent ceramic segments (31), and the suspension electrodes (32) and the ceramic segments (31) are alternately stacked. With the direction from the anode (2) pointing toward the cathode support (5) as the top-to-bottom direction and the direction from the cathode tube (6) pointing toward the segmented insulating ceramic (3) as the inside-to-outside direction, a shielding ring (33) is provided on the lower end surface of the anode (2) and the inner side of each of the floating electrodes (32), and an anti-corona ring (34) is provided on the outer side of each of the floating electrodes (32).

2. The electron gun comprising segmented insulating ceramic according to claim 1, characterized in that: The pressure in the vacuum sealed chamber is less than or equal to 10 -5 Pa.

3. The electron gun comprising segmented insulating ceramic according to claim 1, characterized in that: The axial lengths of the ceramic segments are non-uniform, so that the suspension electrodes (32) are arranged at non-uniform intervals.

4. The electron gun comprising segmented insulating ceramic according to claim 3, characterized in that: Along the direction from the anode (2) to the cathode support (5), the axial length of the first ceramic segment is the longest, followed by the second, and the remaining ceramic segments are shorter.

5. The electron gun comprising segmented insulating ceramic according to claim 4, characterized in that: The remaining ceramic segments have the same axial length.

6. The electron gun comprising segmented insulating ceramic according to claim 1, characterized in that: The thickness of the shielding ring (33) at a portion close to the anode (2) is smaller than the thickness of the portion far from the anode (2), and the thinner portion is closer to the ceramic segment (31).

7. The electron gun comprising segmented insulating ceramic according to claim 1, characterized in that: In the shielding ring (33) connected to each suspension electrode (32), the upper end surface of the shielding ring (33) close to the anode (2) is higher than the upper end surface of the suspension electrode (32) connected thereto.

8. The electron gun comprising segmented insulating ceramic according to claim 1, characterized in that: All corners of each shielding ring (33) are rounded.

9. The electron gun comprising segmented insulating ceramic according to claim 1, characterized in that: There is a gap between the anti-halo ring (34) and the segmented insulating ceramic (3).

10. The electron gun comprising segmented insulating ceramic according to claim 1, characterized in that: The end of the anti-corona ring (34) is in a smooth arc shape.

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