An electron gun device for flushing and degassing a microchannel plate

Abstract

The present invention discloses an electron gun device for flushing and degassing a microchannel plate, which includes a pin flange, a cylindrical metal shielding cover, a fixed support rod, and a filament. The beneficial effects of the present invention are as follows: A mosquito coil-shaped filament structure is designed to make the flushing electrons emitted by the filament more uniform, achieving the effect of a surface electron source; the mosquito coil-shaped filament structure significantly increases the effective emission area of the filament, greatly improving the electron flushing efficiency of the MCP; a cylindrical metal shielding cover is added to form a closed space, which can effectively shield the influence of the external environment on the movement trajectory of the flushing electrons. At the same time, the metal shielding cover is divided into upper and lower layers, and an insulating ceramic ring connector is used for connection in the middle. By applying different high voltages to the upper and lower layers of the metal shielding cover respectively, a stable and uniform internal focusing electric field will be formed by the high voltage difference between the two, so that the flushing electron beam emitted by the filament vertically and uniformly flushes on the input surface of the MCP.

Description

Technical Field

[0001] The present invention relates to an electron gun device, specifically an electron gun device for flushing and degassing a microchannel plate, belonging to the field of vacuum electron technology. Background Art

[0002] A microchannel plate (MCP) is a large-area microchannel electron multiplier made of lead-containing glass with a high secondary electron emission coefficient. Due to its characteristics such as high gain, high resolution, small volume, and fast response, it is widely used in technical fields such as photon multiplication and counting, photon detection and imaging. In particular, the third-generation low-light-level image intensifier made of MCP has the ability to detect extremely weak light signals and has currently become an important part of low-light-level night vision instruments at home and abroad.

[0003] During the production process of MCP, a large amount of residual gases such as H2O, N2, CO, and CO2 will be adsorbed on the inner wall of its channels. These gases will cause the shortening of the life of MCP, the increase of noise, or the serious decline of the cathode sensitivity of the optoelectronic conversion device made therefrom. To obtain an MCP with excellent performance, it is necessary to flush and degas it. Electron flushing and degassing of the microchannel plate is a necessary degassing method in the production process of MCP and is also one of the key processes in the development process of low-light-level image intensifiers. At present, most of the electron flushing and degassing of MCP directly uses an electron gun as the electron emission source. Therefore, it is crucial to design an electron gun device with high uniformity. The existing electron gun devices mainly have the following problems: First, the shape and structure of the filaments in the electron gun are various, specifically including various forms such as "V" shape, "Z" shape, and "one" shape, but it is difficult to generate a highly uniform surface electron beam, resulting in uneven flushing during the electron flushing of MCP, thereby affecting the image quality when the low-light-level image intensifier forms an image; second, the effective emission area of the filaments in the electron gun is small, which determines that the electron emission current density is not high, thereby reducing the electron flushing and degassing efficiency; third, the single negative high bias voltage applied to the filaments in the electron gun causes the flushing electrons to deflect, disturbing the movement trajectory of the flushing electrons, thereby affecting the electron flushing uniformity. Summary of the Invention

[0004] The purpose of the present invention is to provide an electron gun device for flushing and degassing a microchannel plate in order to solve at least one of the above technical problems.

[0005] The present invention realizes the above purpose through the following technical solutions: An electron gun device for flushing and degassing a microchannel plate includes a lead-in pin flange, a cylindrical metal shielding cover, a fixed support rod, and a filament. The cylindrical metal shielding cover is fixed below the lead-in pin flange. A fixed support rod is vertically arranged on the outer side wall of the cylindrical metal shielding cover, and a filament is installed inside the cylindrical metal shielding cover;

[0006] The cylindrical metal shield is a multi-layer structure, each structure is connected into a whole by spot welding, and the layers from top to bottom are the filament fixing part, the first-level metal shield, the insulating ceramic ring connecting part and the second-level metal shield;

[0007] Four fixed support rods are provided, and they include two filament fixing member fixing support rods for supporting the filament fixing member, a first-level metal shield fixing support rod for supporting the first-level metal shield, and a second-level metal shield fixing support rod for supporting the second-level metal shield;

[0008] The filament is a self-winding mosquito coil type rhenium tungsten filament, and the two ends of the filament are respectively connected to the first sealing ring and the second sealing ring in the filament fixing member, and a lead port is designed outside each of the two sealing rings as a filament electrode.

[0009] As a further solution of the present invention: a lead pin flange with a specially customized structure for maintaining the cavity vacuum has a flange diameter of 110 mm and an effective blade diameter of 100 mm, and is used in conjunction with a 100 mm standard copper ring, and four penetrating lead pins are designed at the center position of the lead pin flange as lead pin interfaces for applying a high-voltage power supply, two of which are connected to the electrodes of the filament, and the other two are respectively connected to the first-stage metal shielding cover and the second-stage metal shielding cover.

[0010] As a further solution of the present invention: the filament fixing part is a multi-layer sealing structure, and the structure layers from top to bottom are respectively a first I-shaped part, a first ceramic ring, a first sealing ring, a second ceramic ring, a second sealing ring, a third ceramic ring and a second I-shaped part, wherein the diameter of the I-shaped part is 42 mm and the thickness is 3 mm, the diameter of the ceramic ring is 42 mm and the thickness is 3 mm, the diameter of the sealing ring is 42 mm and the thickness is 0.1 mm.

[0011] As a further solution of the present invention: the first-stage metal shielding cover is fixed below the filament fixing member, and the first-stage metal shielding cover is a metal cylinder made of stainless steel, with an inner diameter of 40 mm, an outer diameter of 42 mm, and a height of 90 mm.

[0012] As a further solution of the present invention: an insulating ceramic ring connector is fixedly connected below the first-level metal shielding cover, and the insulating ceramic ring connector is a three-layer sealing structure of a third I-shaped piece, a fourth ceramic ring, and a fourth I-shaped piece.

[0013] As a further solution of the present invention: the second-stage metal shielding cover is fixed below the insulating ceramic ring connector, and the second-stage metal shielding cover is a metal round wall made of stainless steel, with an inner diameter of 40 mm, an outer diameter of 42 mm, and a height of 30 mm.

[0014] As a further solution of the present invention: The fixing support rod of the filament fixing part is a metal long rod made of stainless steel, with a diameter of 5 mm, a length of 10 mm, two in number and exactly the same shape, and an internal threaded hole with a diameter of 3 mm is machined at one end of the fixing support rod of the filament fixing part.

[0015] As a further solution of the present invention: The fixing support rod of the first-stage metal shielding cover and the fixing support rod of the second-stage metal shielding cover are both metal long rods made of stainless steel and include fastening screws that cooperate with them. Their diameters are 5 mm, and their lengths are 50 mm and 90 mm respectively. And internal threaded holes with a diameter of 3 mm are machined at both ends of the fixing support rod of the first-stage metal shielding cover and the fixing support rod of the second-stage metal shielding cover.

[0016] The beneficial effects of the present invention are as follows:

[0017] 1) This device changes the previous filament shape structure, and ingeniously designs a mosquito coil-shaped filament structure, making the scouring electrons emitted by the filament more uniform, achieving the effect of a surface electron source;

[0018] 2) The mosquito coil-shaped filament structure in this device significantly increases the effective emission area of the filament, greatly improving the electron scouring efficiency of the MCP;

[0019] 2) This device additionally adds a cylindrical metal shielding cover on the basis of the existing device, thereby forming a closed space, which can effectively shield the influence of the external environment on the movement trajectory of the scouring electrons. At the same time, the metal shielding cover is divided into upper and lower layers, and an insulating ceramic ring connector is used for connection in the middle. By applying different high voltages on the upper and lower layers of the metal shielding cover respectively, the high voltage difference between the two will form a stable and uniform internal focusing electric field, so that the scouring electron beam emitted by the filament vertically and uniformly scours on the input surface of the MCP. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of the electron gun of the present invention;

[0021] Figure 2 It is a cross-sectional view of the electron gun of the present invention;

[0022] Figure 3 It is a physical diagram of the mosquito coil-shaped structure adopted by the filament in the electron gun of the present invention.

[0023] In the figure: 1. Pin flange, 2. Cylindrical metal shielding cover, 3. Fixing support rod, 4. Filament, 5. Filament fixing part, 6. First-stage metal shielding cover, 7. Insulating ceramic ring connector, 8. Second-stage metal shielding cover, 9. Fixing support rod of the filament fixing part, 10. Fixing support rod of the first-stage metal shielding cover, 11. Fixing support rod of the second-stage metal shielding cover. Detailed Implementation Manner

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0025] Embodiment 1

[0026] As Figures 1 to 3 shown, an electron gun device for flushing and degassing a microchannel plate includes a lead pin flange 1, a cylindrical metal shielding cover 2, a fixed support rod 3, and a filament 4. The cylindrical metal shielding cover 2 is fixed below the lead pin flange 1. A fixed support rod 3 is vertically arranged on the outer side wall of the cylindrical metal shielding cover 2, and a filament 4 is installed inside the cylindrical metal shielding cover 2;

[0027] The cylindrical metal shielding cover 2 is a multi-layer structure, and each structure is connected into a whole by spot welding. And from top to bottom, each layer structure is a filament fixing part 5, a first-stage metal shielding cover 6, an insulating ceramic ring connecting part 7, and a second-stage metal shielding cover 8 in sequence;

[0028] Four fixed support rods 3 are provided, and it includes two filament fixing part fixed support rods 9 for supporting the filament fixing part 5, one first-stage metal shielding cover fixed support rod 10 for supporting the first-stage metal shielding cover 6, and one second-stage metal shielding cover fixed support rod 11 for supporting the second-stage metal shielding cover 8;

[0029] The filament 4 is a self-wound mosquito coil-shaped rhenium-tungsten filament, and both ends of the filament 4 are respectively connected to the inside of the first sealing ring and the second sealing ring in the filament fixing part 5. At the same time, a lead port is designed outside each of the two sealing rings as a filament electrode.

[0030] Embodiment 2

[0031] As Figures 1 to 3 shown, in addition to including all the technical features in Embodiment 1, this embodiment further includes:

[0032] The flange diameter of the lead pin flange 1, which adopts a special customized structure and is used to maintain the cavity vacuum, is 110 mm, the effective knife-edge diameter is 100 mm, and it is used in cooperation with a standard copper ring of 100 mm. And four through lead pins are designed at the center position of the lead pin flange 1 as lead pin interfaces for applying high-voltage power supplies. Two of them are connected to the electrodes of the filament 4, and the other two are respectively connected to the first-stage metal shielding cover 6 and the second-stage metal shielding cover 8.

[0033] The filament fixing part 5 has a multi-layer sealing structure. From top to bottom, each layer structure is respectively a first I-shaped part, a first ceramic ring, a first sealing ring, a second ceramic ring, a second sealing ring, a third ceramic ring, and a second I-shaped part. Among them, the diameter of the I-shaped part is 42 mm, the thickness is 3 mm, the diameter of the ceramic ring is 42 mm, the thickness is 3 mm, and the diameter of the sealing ring is 42 mm, the thickness is 0.1 mm.

[0034] The first-stage metal shielding cover 6 is fixed below the filament fixing part 5, and the first-stage metal shielding cover 6 is a metal cylinder made of stainless steel. Its inner diameter is 40 mm, the outer diameter is 42 mm, and the height is 90 mm.

[0035] An insulating ceramic ring connecting part 7 is fixedly connected below the first-stage metal shielding cover 6, and the insulating ceramic ring connecting part 7 has a three-layer sealing structure of a third I-shaped part, a fourth ceramic ring, and a fourth I-shaped part.

[0036] The second-stage metal shielding cover 8 is fixed below the insulating ceramic ring connecting part 7, and the second-stage metal shielding cover 8 is a metal circular wall made of stainless steel. Its inner diameter is 40 mm, the outer diameter is 42 mm, and the height is 30 mm.

[0037] Embodiment Three

[0038] As Figures 1 to 3 shown, in this embodiment, in addition to including all the technical features in Embodiment One, it further includes:

[0039] The filament fixing part fixing support rod 9 is a metal long rod made of stainless steel. Its diameter is 5 mm, the length is 10 mm, and the number is two and the shapes are exactly the same. And one end of the filament fixing part fixing support rod 9 is processed with an internal threaded hole with a diameter of 3 mm, so as to be able to achieve threaded cooperation with the pin of the pin flange 1.

[0040] The first-stage metal shielding cover fixing support rod 10 and the second-stage metal shielding cover fixing support rod 11 are both metal long rods made of stainless steel and include fastening screws matching with them. Their diameters are 5 mm, and the lengths are 50 mm and 90 mm respectively. And both ends of the first-stage metal shielding cover fixing support rod 10 and the second-stage metal shielding cover fixing support rod 11 are processed with internal threaded holes with a diameter of 3 mm. One end can be in threaded cooperation with the pin of the pin flange 1, and the other end fixes the first-stage metal shielding cover 6 and the second-stage metal shielding cover 8 respectively through screws.

[0041] Embodiment Four

[0042] An electron gun device for flushing and degassing a microchannel plate, the specific structural schematic diagram is as Figure 1 shown. The electron gun device of the present invention includes a pin flange 1, a cylindrical metal shielding cover 2, a fixing support rod 3, and a filament 4.

[0043] The specific installation method of this electron gun is as follows: For the filament fixing part 5 and the insulating ceramic ring connecting part 7, copper sealing is carried out according to the designed structural level. After the sealing, the finished product needs to be cleaned and its insulation property checked. Then, the filament fixing part 5, the first-stage metal shielding cover 6, the insulating ceramic ring connecting part 7, and the second-stage metal shielding cover 8 can be combined into a cylindrical metal shielding cover 2. The connection method between each part is in the form of nickel strip spot welding. For the convenience of later disassembly, the number of spot welding positions should not be too many. It is recommended to have four spot welds spaced 90 degrees apart in each circumference.

[0044] After that, both ends of the mosquito coil-shaped rhenium-tungsten wire filament 4 can be welded inside the two sealing rings in the filament fixing part 5. Among them, the mosquito coil-shaped rhenium-tungsten wire filament 4 is self-wound. First, the rhenium-tungsten wire is wound around an ultra-fine iron wire to form a filament 4 with a spiral structure. The diameter of the ultra-fine iron wire is about 1 mm. Then, the spiral-shaped filament is bent in the shape of a mosquito coil to form the mosquito coil-shaped rhenium-tungsten filament 4.

[0045] In order to further fasten each part in the electron gun device, prevent the components from falling off during use, and at the same time apply negative high voltage to the filament 4 and the cylindrical metal shielding cover 2 respectively, filament fixing part fixing support rods 9, first-stage metal shielding cover fixing support rods 10, and second-stage metal shielding cover fixing supports 11 are provided. The two filament fixing part fixing support rods are respectively fixed to a pair of pins of the pin flange 1 through thread fitting, and the other ends are respectively spot welded to the two sealing rings in the sealing structure of the filament fixing part 5 through nickel strips. The two metal shielding cover fixing support rods are respectively fixed to the other pair of pins of the pin flange 1 through thread fitting, and the other ends are respectively fixedly connected to the first-stage metal shielding cover 6 and the second-stage metal shielding cover 8 through screws. In addition, these four fixing support rods also act as electrode connection wires for applying different high voltage to the filament 4 and the cylindrical metal shielding cover 2 respectively.

[0046] During use, if a certain component needs to be repaired or replaced, the spot welds between adjacent components can be cut with a surgical blade and the four fixing support rods can be screwed out, then all components can be separated, and thus the specific component can be repaired or replaced. This solution is simple and practical, and effectively solves the problems of non-adjustability after welding and cumbersome replacement.

[0047] Working principle: First, fix the tube housing with the microchannel plate to be flushed under the cylindrical metal shield 2 of the electron gun device. Generally, it is appropriate that the upper surface of the microchannel plate is about 3 cm away from the outlet of the cylindrical metal shield 2. Then, apply different high voltages to each electrode. Without special circumstances, generally set the input surface of the microchannel plate as the reference zero potential, that is, the common ground potential. In addition, there are 4 high voltages that can be set, and the potentials from high to low are: the first high voltage is the high voltage of the microchannel plate, the second high voltage is the negative high voltage of the second-stage metal shield 8, the third high voltage is the negative high voltage of the first-stage metal shield 6, and the fourth high voltage is the negative high voltage of the filament 4. In this device, we choose to set the high voltage of the microchannel plate to 800 V and the negative high voltage of the filament to -500 V. Correspondingly, the negative high voltages of the first-stage metal shield 6 and the second-stage metal shield 8 can be set to any value between -500 V and 0 V. According to the results of our simulation and experimental analysis, when the negative high voltage of the first-stage metal shield 6 is set to -400 V and the negative high voltage of the second-stage metal shield 8 is set to -100 V, the experimental effect is the best.

[0048] Use a current source to heat the filament 4. When reaching a specific power, a large number of thermoelectrons can be emitted from the surface of the filament 4. These thermoelectrons, that is, the flushing electrons, move towards the microchannel plate under the action of the high-voltage electric field. Generally, the electrons emitted by the filament 4 move in all directions. When the flushing electrons reach the surface of the microchannel plate, it is in a divergent form, which is not conducive to the uniformity of the flushing and degassing of the microchannel plate. In this electron gun device, due to the additional two-stage metal shields, the high-voltage difference between the two will form a focusing electric field at the interface, which has the function of focusing electrons. Therefore, the divergent flushing electrons emitted by the filament 4 are in a convergent state under the action of the focusing electric field. By adjusting the high-voltage values of the first-stage metal shield 6 and the second-stage metal shield 8, the function of precisely controlling the movement trajectory of the flushing electrons can be realized. Thus, the flushing electron beam emitted by the filament 4 vertically and uniformly flushes on the input surface of the microchannel plate.

[0049] In practical applications, the electron gun device of the present invention needs to be used in cooperation with a specific high-voltage power supply. The high-voltage power supply is: DW-QL type, main parameters: the maximum output power of the current source is 24 V; it has multiple high-voltage outputs, and its voltage output ranges are: 0~-500 V; 0~-500 V; 0~3 kV; 0~4 kV; it can be purchased on the market.

[0050] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0051] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An electron gun device for flushing and degassing a microchannel plate, Features: It comprises a lead pin flange (1), a cylindrical metal shielding cover (2), a fixed support rod (3) and a filament (4), wherein the cylindrical metal shielding cover (2) is fixed below the lead pin flange (1), the outer side wall of the cylindrical metal shielding cover (2) is vertically provided with a fixed support rod (3), and the inside of the cylindrical metal shielding cover (2) is provided with a filament (4); The cylindrical metal shield (2) is a multi-layer structure, each structure is connected into a whole by spot welding, and the layers of structure from top to bottom are, in order, a filament fixing part (5), a first-stage metal shield (6), an insulating ceramic ring connecting part (7), and a second-stage metal shield (8); Four fixed support rods (3) are provided, and include two filament fixing member fixing support rods (9) for supporting the filament fixing member (5), a first-stage metal shield fixing support rod (10) for supporting the first-stage metal shield (6), and a second-stage metal shield fixing support rod (11) for supporting the second-stage metal shield (8); The filament (4) is a self-winding mosquito coil type rhenium tungsten filament, and the two ends of the filament (4) are respectively connected to the inside of a first sealing ring and a second sealing ring in a filament fixing member (5), and a lead port is designed on the outside of each of the two sealing rings as a filament electrode; The lead pin flange (1) adopts a specially customized structure and is used to maintain the vacuum of the cavity. The flange diameter is 110 mm, the effective blade diameter is 100 mm, and it is used in conjunction with a 100 mm standard copper ring. Four lead pins are designed to penetrate the center of the lead pin flange (1) as lead pin interfaces for applying a high voltage power supply, two of which are connected to the electrodes of the filament (4), and the other two are respectively connected to the first-stage metal shielding cover (6) and the second-stage metal shielding cover (8); The filament fixing member (5) is a multi-layer sealing structure, wherein the layers from top to bottom are respectively a first I-shaped member, a first ceramic ring, a first sealing ring, a second ceramic ring, a second sealing ring, a third ceramic ring and a second I-shaped member, wherein the diameter of the I-shaped member is 42 mm and the thickness is 3 mm, the diameter of the ceramic ring is 42 mm and the thickness is 3 mm, and the diameter of the sealing ring is 42 mm and the thickness is 0.1 mm; The first-stage metal shielding cover (6) is fixed below the filament fixing member (5), and the first-stage metal shielding cover (6) is a metal cylinder made of stainless steel, with an inner diameter of 40 mm, an outer diameter of 42 mm, and a height of 90 mm; An insulating ceramic ring connector (7) is fixedly connected below the first-stage metal shield (6), and the insulating ceramic ring connector (7) is a three-layer sealing structure of a third I-shaped part, a fourth ceramic ring, and a fourth I-shaped part; The second-stage metal shielding cover (8) is fixed below the insulating ceramic ring connector (7), and the second-stage metal shielding cover (8) is a metal round wall made of stainless steel, with an inner diameter of 40 mm, an outer diameter of 42 mm, and a height of 30 mm.

2. The electron gun device according to claim 1, Features: The filament fixing support rod (9) is a long metal rod made of stainless steel, with a diameter of 5 mm, a length of 10 mm, two in number and exactly the same shape. An internal threaded hole with a diameter of 3 mm is machined at one end of the filament fixing support rod (9), so as to enable threaded cooperation with the pin of the pin flange (1).

3. The electron gun device according to claim 1, characterized in that: The first-stage metal shielding cover fixing support rod (10) and the second-stage metal shielding cover fixing support rod (11) are both long metal rods made of stainless steel and include fastening screws cooperating therewith, with a diameter of 5 mm and lengths of 50 mm and 90 mm respectively. Internal threaded holes with a diameter of 3 mm are machined at both ends of the first-stage metal shielding cover fixing support rod (10) and the second-stage metal shielding cover fixing support rod (11). One end can be in threaded cooperation with the pin of the pin flange (1), and the other end fixes the first-stage metal shielding cover (6) and the second-stage metal shielding cover (8) respectively through screws.

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