CN112271127A

CN112271127A - Open electron beam tube

Info

Publication number: CN112271127A
Application number: CN202011267759.8A
Authority: CN
Inventors: 方钢群; 潘朝俊
Original assignee: Huangshi Shangfang Inspection Equipment Co ltd
Current assignee: Huangshi Shangfang Inspection Equipment Co ltd
Priority date: 2020-11-13
Filing date: 2020-11-13
Publication date: 2021-01-26

Abstract

An open electron beam tube includes a housing having a cavity structure; one end of the shell is provided with an end cover, and the other end of the shell is provided with a sealing flange; the outer wall of the shell is provided with a window part, a high-pressure access part which extends outwards and is provided with a sealing cover and a vacuum extraction part which extends outwards; the window part is in positive correspondence with the high-voltage access part; the field emission device is positioned in the cavity of the shell; and an electron emission window assembly welded to the window portion; a titanium foil for closing the window part is arranged in the electron emission window assembly, and electrons emitted by the metal wire are evenly divided through the grid mesh, then strike the titanium foil and are transmitted outwards; through designing the electron beam tube into open structure to satisfy the needs to the electron beam tube in the existing market, satisfy the diversification of market demand, design the inner structure of electron beam tube simultaneously, guarantee the stable shaping of electron beam and stable efficient and jet out.

Description

Open electron beam tube

Technical Field

The invention relates to the field of electron acceleration, in particular to an open type electron beam tube.

Background

The electron beam irradiation technology is widely applied in the fields of material modification, coating preparation, sterile rapid disinfection and the like, wherein an electron beam tube is an important electronic device for realizing electron beam external irradiation, so the structure of the electron beam tube can influence the application range of the electron beam.

In the market, the application of electron beams in a small space is very rare because the structure of the current electron beam tube is almost standardized and the electron beam tube capable of adapting to the small space is very short, but in life, the design of the electron beam tube structure with miniaturization and lightweight is urgent, and the electron beam tube with various structures is needed to adapt to the requirement of consumers.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a new technical scheme, and the technical scheme is used for meeting the requirement of the market on the diversity of the electron beam tubes.

The technical scheme provided by the invention is as follows:

an open electron beam tube includes

A housing having a cavity structure; one end of the shell is provided with an end cover, and the other end of the shell is provided with a sealing flange; the outer wall of the shell is provided with a window part, a high-pressure access part which extends outwards and is provided with a sealing cover and a vacuum extraction part which extends outwards; the window part is in positive correspondence with the high-voltage access part;

a field emission device located within the cavity of the housing; the field emission device comprises a focusing head, a core column sealing cylinder, a cathode cover and a metal wire, wherein the focusing head is fixedly connected with the sealing cover through a hollow ceramic connector, the core column sealing cylinder and the focusing head are positioned outside the cathode cover, and the focusing head is sleeved on the core column sealing cylinder; the core column sealing cylinder is in conduction connection with the metal wire; a notch is formed in the outer wall of the cathode cover, a grid net is fixed in the notch, and the metal wire is arranged in the cathode cover and is positioned right below the grid net; and

the electron emission window assembly is welded on the window part and corresponds to the grid mesh; the electron emission window assembly is internally provided with a titanium foil for sealing the window part, and electrons emitted by the metal wire are evenly divided through the grid mesh, then hit the titanium foil and are transmitted outwards.

Further, the cathode cover comprises a cover body and a shielding cover, wherein the cover body is cylindrical, and the notch is formed in the cover body; the shielding cover has two and all is hemispherical, two the shielding cover sets up respectively the both ends of housing body and outside protrusion.

Further, the grid mesh is a molybdenum mesh.

Furthermore, a strip-shaped filament seat is arranged in the housing body, and the metal wire is fixed on the filament seat; the filament seat is fixed with the housing body through a fixing block, and the stem sealing-in barrel is fixed at the other end of the fixing block and is in conduction connection with the metal wire.

Further, be equipped with a plurality of blind holes on the filament seat, it is a plurality of the blind hole is along the length direction equidistance array distribution of filament seat, every all be provided with in the blind hole along its axial direction extension's knob insulator, every the knob insulator with wire fixed connection is in order to support the wire.

Further, the metal wire is a tungsten wire.

Furthermore, the electronic window ejection assembly further comprises a grid plate, the grid plate is welded and fixed on the window portion in a sealing mode, a honeycomb-shaped radiating net is arranged at the position, right opposite to the window portion, of the grid plate, and the titanium foil is attached to the grid plate through a pressing plate and covers the radiating net.

Furthermore, a cold circulation channel is further arranged in the grid plate and surrounds the heat dissipation net to cool the titanium foil attached to the grid plate.

Furthermore, the heat dissipation net is made of an oxygen-free copper material.

Furthermore, the thickness of the titanium foil is 0.015-0.02 mm.

The beneficial effect that adopts this technical scheme to reach does:

through designing into open structure with electron beam tube, external vacuum system compares in vacuum electron beam tube, can make things convenient for and efficient change wire and titanium paper tinsel as required to satisfy the needs to electron beam tube quick maintenance and reduce cost on the existing market, satisfy the diversification of market demand, design the inner structure of electron beam tube simultaneously, guarantee electron beam's stable shaping and stable efficient and jet out.

Drawings

FIG. 1 is a perspective view of a lateral vacuum electron beam tube.

Fig. 2 is an exploded view of a lateral vacuum electron beam tube.

Fig. 3 is an exploded view of the electronic launch window assembly.

Fig. 4 is a plan view of the ceramic joint.

Fig. 5 is a sectional view of a-a in fig. 4, showing an internal structure of the ceramic connector.

Fig. 6 is a plan view of the sealing flange.

Fig. 7 is a sectional structural view of B-B in fig. 6, showing the structure of the sealing flange.

Fig. 8 is an exploded view of a field emission device.

Fig. 9 is a partially enlarged view of C in fig. 8, showing a connection structure of the wire and the lamp wire holder.

Fig. 10 is a perspective view of a vertical vacuum electron beam tube.

Fig. 11 is an exploded view of a vertical vacuum electron beam tube.

Fig. 12 is a plan view of a vertical vacuum electron beam tube.

FIG. 13 is a sectional view of the electron beam tube D-D of FIG. 12, showing the internal structure of the vertical vacuum electron beam tube.

Fig. 14 is a perspective view of an open electron beam tube.

Wherein: 10 casing, 11 end cover, 12 sealing flange, 13 window part, 14 high-pressure access part, 15 sealing cover, 16 vacuum extraction part, 20 field emission device, 21 focusing head, 22 core column sealing cylinder, 23 cathode cover, 24 metal wire, 25 lamp wire base, 26 fixing block, 30 electronic emission window component, 31 titanium foil, 32 pressing plate, 33 grid plate, 34 sealing ring, 35 welding block, 40 ceramic connector, 41 through hole, 100 cavity, 211 end plate, 231 housing body, 232 shielding cover, 233 notch, 234 grid mesh, 251 blind hole, 252 porcelain column and 331 heat dissipation mesh.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

The embodiment provides an electron beam tube structure, and through the design of the electron beam tube structure, the diversified demands of the electron beam tube structure on the market are met, so that the competitiveness of enterprises is enhanced.

In the scheme, referring to fig. 1-2, the proposed electron beam tube comprises a housing 10, wherein the housing 10 is a cylindrical structure, an end cover 11 is arranged at one end of the housing 10, and a sealing flange 12 is arranged at the other end; a cavity 100 is formed inside the housing 10 by the cooperation of the end cap 11 and the sealing flange 12.

A field emission device 20 is disposed in the cavity 100, the field emission device 20 is used for emitting electrons, the emitted electrons form an electron beam under the action of an electric field and rapidly irradiate towards the window 13 on the wall of the housing 10, an electron emission window assembly 30 is disposed on the window 13, the electron emission window assembly 30 is welded on the window 13 and corresponds to the field emission device 20, a titanium foil 31 is disposed in the electron emission window assembly 30, and the titanium foil 31 can cover the window 13.

Thus, the cavity 100 of the housing 10 forms a closed space under the combined condition of the titanium foil 31, the end cap 11 and the sealing flange 12, and then the whole electron beam tube is placed in a vacuum furnace and baked at a temperature of 500-600 ℃ to make the cavity 100 in a vacuum state, thereby forming the vacuum electron beam tube.

The thickness of the titanium foil 31 is between 0.015mm and 0.02mm, and the main purpose of providing such a thin titanium foil 31 is to enable the electron beam emitted from the field emission device 20 to penetrate the titanium foil 31, thereby achieving an improved treatment or sterilization treatment of external objects.

It should be noted that the electron beam can hit the surface of the titanium foil 31 for transmission, but the vacuum state of the cavity 100 is not affected, that is, the existence of the titanium foil 31 can not only effectively ensure the vacuum state in the cavity 100, but also enable the electron beam emitted by the field emission device 20 to smoothly transmit.

In order to ensure the stability of the connection of the titanium foil 31 on the electron emission window assembly 30, in the present embodiment, referring to fig. 3, the electron emission window assembly 30 further includes a pressing plate 32, a grid plate 33, a sealing ring 34 and a welding block 35 which are sequentially stacked, wherein the titanium foil 31 is disposed between the pressing plate 32 and the grid plate 33, and it can be understood that the pressing plate 32, the titanium foil 31, the grid plate 33, the sealing ring 34 and the welding block 35 are sequentially disposed from top to bottom in the order of the electron emission window assembly 30.

The main purpose of the pressing plate 32 is to stably press the titanium foil 31, so that the titanium foil 31 can be stably attached to the grid plate 33 to ensure the tightness of the connection; the sealing ring 34 is used for ensuring the sealing and the stability of the connection between the grid plate 33 and the welding block 35, the welding block 35 is welded and fixed on the window part 13, and the periphery of the window part 13 is ensured to be sealed; the replacement is conveniently realized by adopting a mode of overlapping the components.

As another embodiment, a scheme of only retaining the pressing plate 32, the titanium foil 31 and the grid plate 33 may also be adopted, that is, the electronic emission window assembly 30 is arranged in the order of the pressing plate 32, the titanium foil 31 and the grid plate 33 from top to bottom, and then the grid plate 33 is directly welded on the window portion 13 to ensure the sealing around the window portion 13; such a design is advantageous in reducing the number of assembly steps and has a certain promoting effect in ensuring the stability of the vacuum in the cavity 100.

The above two designs can both ensure that the electron beam generated by the field emission device 20 passes through the window 13 and finally reaches the titanium foil 31 to realize transmission.

Meanwhile, in a specific using process, it is found that the titanium foil 31 will generate a large amount of heat under the impact of a large amount of electron beams, and therefore, the heat dissipation mesh 331 having a honeycomb structure is disposed at a position on the grid plate 33 directly opposite to the titanium foil 31, where the heat dissipation mesh 331 not only has a certain promoting effect on the heat dissipation of the electron beams, but also has an effect of homogenizing the electric field, because electrons emitted from the field emission device 20 may have a certain concentration, so that after a part of concentrated electron beams are dispersed through the honeycomb heat dissipation mesh 331, a certain promoting effect on the uniform distribution of the electron beams and the transmission of the titanium foil 31 is achieved.

Optionally, heat sink mesh 331 is made of an oxygen free copper material.

In order to further achieve the effect of reducing the temperature of the titanium foil 31, in the present embodiment, a cold circulation channel is further designed on the baffle plate 33, where the cold circulation channel mainly refers to a channel for flowing a medium on the baffle plate 33, and the effect of reducing the temperature of the titanium foil 31 is achieved by utilizing the flow of the medium in the baffle plate 33.

Specifically, the cold circulation channel described herein is a water cooling channel, which is disposed around the heat dissipation mesh 331, that is, the water cooling channel is disposed around the heat dissipation mesh 331, and the water cooling channel is designed with a water inlet and a water outlet; when the field emission device 20 works, the water medium is injected into the water cooling channel, so that the whole grid plate 33 is in a lower temperature state, and the titanium foil 31 attached to the grid plate 33 can be effectively cooled.

In order to meet the diversified demands of the market on the electron beam tube structure, the present embodiment provides two structures of vacuum electron beam tubes, the shapes of the shells of the two structures of vacuum electron beam tubes are different, but the working principles of the two structures of vacuum electron beam tubes are basically the same, in order to distinguish the two types of vacuum electron beam tubes, one design is defined as a horizontal vacuum electron beam tube, the other design is defined as a vertical vacuum electron beam tube, and the structures of the two types of vacuum electron beam tubes are further described below.

The transverse vacuum electron beam tube defines a transverse direction as an input flow direction of an external high pressure parallel to a central axis of the housing 10.

The ability of field emission device 20 to generate electrons is accomplished using high voltages, specifically those voltages in the range of about 50KV to about 200 KV.

Specifically, referring to fig. 2, 4-5, in the transverse vacuum electron beam tube, a ceramic connector 40 with a hollow structure is disposed between the field emission device 20 and the sealing flange 12, wherein one end of the ceramic connector 40 is fixedly sleeved with the field emission device 20, and the other end is fixed with the sealing flange 12 and penetrates out of the sealing flange 12; the field emission device 20 is suspended in the cavity 100 of the housing 10 through the ceramic connector 40.

Here, the ceramic connector 40 is arranged and the field emission device 20 is suspended in the cavity 100, which is mainly used for insulation and avoiding direct contact between the field emission device 20 and the housing 10; meanwhile, the ceramic connector 40 is designed to be hollow, and an external high-voltage connecting wire can penetrate into the ceramic connector 40 and is in conductive connection with the field emission device 20, so that the field emission device 20 is promoted to generate electron beams under the action of high voltage.

Optionally, the ceramic connector 40 has a tapered shape, and the outer surface of the ceramic connector 40 is corrugated, and the diameter of the cross section of the end, which is sleeved with the field emission device 20, of the ceramic connector 40 is smaller than the diameter of the cross section of the other end of the ceramic connector 40; meanwhile, the hollow ceramic connector 40 can be understood as a through hole 41 formed inside the ceramic connector 40, that is, the through hole 41 makes the ceramic connector 40 have a hollow structure, wherein the through hole 41 has a tapered structure with the same shape as the ceramic connector 40, and the aperture of the end of the through hole 41 close to the field emission device 20 is smaller than the aperture of the end of the through hole 41 close to the sealing flange 12.

The surface of the ceramic connector 40 is designed to be corrugated, and the same conical structure design is made for the appearance of the ceramic connector 40 and the through hole 41, so that the pressure-resistant grade of the ceramic connector 40 is enhanced, and the safety of the whole electron beam tube is improved; on the other hand, the corrugated design makes the ceramic connector 40 have more excellent heat dissipation performance.

Meanwhile, in the transverse vacuum electron beam tube, because the ceramic connector 40 is directly and fixedly connected with the sealing flange 12, the structure of the sealing flange 12 is further designed, see fig. 2, 6-7, that is, the sealing flange 12 is in a disc shape and is used for closing one end of the shell 10; the center of the sealing flange 12 is provided with a through hole, the ceramic connector 40 penetrates through the through hole to realize the sealing and fixed connection with the sealing flange 12, meanwhile, one surface of the sealing flange 12 facing the cavity 100 is of a concave structure with a low middle part and a high periphery, and the through hole is arranged at the center of the concave structure.

By designing the sealing flange 12 into a concave structure, the center of the sealing flange 12 becomes thinner, the contact area of the joint of the ceramic connector 40 and the sealing flange 12 is reduced, and the influence of high pressure on the diffusion of the housing 10 is reduced as much as possible.

The insulation of the ceramic connector 40 enables the field emission device 20 to stably generate and emit electron beams under high voltage.

Referring to fig. 8, the field emission device 20 is composed of a focusing head 21, a stem sealing cylinder 22, a cathode cover 23, and a wire 24 disposed inside the cathode cover 23.

Here, the focusing head 21 is sleeved on the stem sealing cylinder 22, which is mainly used for improving the focusing power, and meanwhile, one end of the focusing head 21 connected with the ceramic connector 40 is designed into a horn shape, so that at least part of the ceramic connector 40 is sleeved in the focusing head 21, and it should be noted that the end with a smaller cross-sectional area of the ceramic connector 40 is sleeved in the focusing head 21.

The focusing head 21 and the stem sealing cylinder 22 mentioned here are both disposed outside the cathode cover 23 to reduce the influence on the metal wire 24, and of course, the metal wire 24 needs to be conductively connected to the stem sealing cylinder 22 to ensure that the external high voltage can be smoothly connected to the metal wire 24, so that the metal wire 24 is heated to generate high-energy electron cloud and emit the electron beam.

The cathode cover 23 comprises a cover body 231 and a shielding cover 232, wherein the cover body 231 is cylindrical, and a notch 233 is formed in the cover body 231, so that electron cloud generated by the metal wire 24 can be smoothly emitted outwards; the focusing head 21 is welded at one end of the cathode cover 23 and ensures the conduction of the core column sealing cylinder 22 and the metal wire 24; the shield can 232 is located at the other end of the housing body 231, and the shield can 232 has a hemispherical shape such that an arc-shaped convex portion of the shield can 232 faces outward when mounted on the housing body 231.

Here, the housing body 231 is designed to be cylindrical so as to collect the electron cloud generated by the wire 24, and the hemispherical shielding cover 232 is disposed on the housing body 231 to ensure that the generated electron cloud can be sufficiently collected at the cut 233 to be emitted.

Meanwhile, in consideration of the fact that the density distribution of the high-energy electron cloud generated by the temperature rise of the metal wire 24 is not uniform, in order to enable electrons to be uniformly distributed to shoot into the electron emission window assembly 30 to achieve the field equalizing effect, a grid mesh 234 is further arranged at the position of the notch 233, the grid mesh 234 is fixed in the notch 233, and the metal wire 24 is located right below the grid mesh 234, so that after the metal wire 24 generates the electron cloud, the electron cloud is guided and distributed through the grid mesh 234, and the generated electron beams can be distributed more uniformly.

Optionally, the grid mesh 234 is a molybdenum mesh.

The heat dissipation mesh 331 in the electron emission window assembly 30 has the same function of equally distributing the electric field, that is, after the metal wire 24 generates the electron cloud, the electron cloud is guided and distributed for the first time through the grid mesh 234, so that the electrons are dispersed, then the electrons are emitted into the electron emission window assembly 30 under the function of the high-voltage electric field, and when passing through the heat dissipation mesh 331 on the grid plate 33, the electrons are uniformly dispersed for the second time, and finally, the electrons are emitted onto the titanium foil 31, so that the transmission is realized.

Through twice dispersion, the density of the electron cloud is reduced, and the generated electron beams are more uniform.

Referring to fig. 8-9, the metal wire 24 is disposed on the casing body 231 through the filament holder 25, the filament holder 25 is in a strip shape and is fixedly disposed in the casing body 231, the metal wire 24 is disposed on the filament holder 25, specifically, the filament holder 25 is provided with a plurality of blind holes 251, the blind holes 251 are equidistantly distributed along the length direction of the filament holder 25, meanwhile, each blind hole 251 is provided with a knob insulator 252 extending along the axial direction thereof, each knob insulator 252 is fixed with the metal wire 24, and thus the knob insulators 252 support the metal wire 24 together.

The knob insulator 252 is provided to ensure the straight and complete metal wire 24, and the knob insulator 252 can be used for insulation to avoid the contact between the metal wire 24 and the filament seat 25, so that after the metal wire 24 and the stem sealing cylinder 22 are electrically conducted, electron cloud can be generated smoothly under the action of high voltage.

Optionally, the wire 24 is tungsten wire.

The vertical vacuum electron beam tube defines the vertical direction as the input flow direction of the external high pressure vertical to the central axis of the shell.

The working principle of the vertical vacuum electron beam tube is the same as that of the transverse vacuum electron beam tube, and the structural design is different; specifically, the structure of the shell 10 of the first, vertical vacuum electron beam tube is slightly different from that of the horizontal vacuum electron beam tube; secondly, the structure of the field emission device 20 is slightly different; the following further introduces the above two differences:

referring to fig. 10 to 13, the housing 10 of the vertical vacuum electron beam tube is structurally different from the housing of the horizontal vacuum electron beam tube in that the vertical vacuum electron beam tube is provided with a high voltage connection part 14 extending outward on the outer wall of the housing 10, where the high voltage connection part 14 is used for installing a ceramic connector 40; it will be appreciated that in a transverse vacuum electron beam tube, the ceramic connector 40 is fixedly connected directly to the sealing flange 12; however, in the vertical vacuum electron beam tube, since the high voltage connection portion 14 extending outward is specially provided on the outer wall of the housing 10, the ceramic connector 40 is directly and fixedly connected to the high voltage connection portion 14, and the presence of the sealing flange 12 in the vertical vacuum electron beam tube is mainly used to facilitate the replacement of the wires 24.

Meanwhile, in order to ensure the stable sealing connection between the ceramic connector 40 and the high-pressure access part 14, a sealing cover 15 is arranged on the high-pressure access part 14, the sealing cover 15 is disc-shaped, and one surface of the sealing cover 15 facing the cavity 100 is of a concave structure with a low middle part and high periphery; meanwhile, a through hole is formed in the center of the sealing cover 15, and the ceramic connector 40 penetrates through the through hole and is fixed with the sealing cover 15 in a sealing mode.

The sealing cover 15 is set to be a concave structure with a low middle part and a high periphery, so that the center of the sealing cover 15 is thinned, the contact area of the joint of the ceramic connector 40 and the sealing cover 15 is reduced, and the influence of high pressure on the shell 10 is reduced as much as possible.

In the field emission device 20 in the vertical electron beam tube, the focusing head 21 is vertically disposed with the housing body 231, and in the horizontal electron beam tube, the focusing head 21 is disposed in parallel at one end of the housing body 231; when the focusing head 21 is perpendicular to the housing body 231, the two ends of the housing body 231 are required to be respectively provided with the shielding cases 232, and the two shielding cases 232 are in mirror symmetry, so that effective collection of electron cloud is ensured.

Meanwhile, in the vertical electron beam tube, the filament holder 25 is fixed with the housing body 231 through the fixing block 26, the fixing block 26 is arranged here, which is also beneficial to the installation of the focusing head 21, i.e. the focusing head 21 in the vertical electron beam tube is also provided with the end plate 211, the end plate 211 is fixed with the fixing block 26 through screws, and the fixation of the focusing head 21 and the housing body 231 is realized.

Here through designing horizontal vacuum electron beam tube and vertical electron beam tube, when having horizontal space, vertical space in to practical application's the scene, can be direct use horizontal vacuum electron beam tube, vertical electron beam tube, convenient and fast has very big promotion effect to electron beam tube's lightweight and diversified use.

In this embodiment, a further design is made on the structure of the horizontal or vertical vacuum electron beam tube, and an open type electron beam tube is designed, see fig. 14.

The use of the horizontal or vertical vacuum electron beam tube has to have a requirement, namely, the vacuum state in the cavity 100 needs to be ensured, and the requirement makes the vacuum electron beam tube be placed in a vacuum furnace after being assembled, and the vacuum electron beam tube is baked at the temperature of 500-600 ℃, so that the cavity 100 is in the vacuum state.

Therefore, in consideration of convenience of use, the vacuum pumping part 16 may be directly formed on the housing of the horizontal or vertical vacuum electron beam tube, where the vacuum pumping part is substantially a flange port for vacuum pumping, and after the vacuum pumping part 16 exists, it is no longer necessary to ensure that the cavity 100 is in a vacuum state, that is, when the vacuum pumping part 16 is used, the cavity 100 is communicated with the outside through the vacuum pumping part 16, only when the vacuum pumping part 16 is used, a vacuum pump (not shown) is directly installed, air inside the cavity 100 is pumped by the vacuum pump in real time, and the vacuum state inside the cavity is continuously ensured, and then the vacuum pump is carried to the field emission device 20 to generate electrons by high pressure, and release the electron beam.

The open electron beam tube provided by the embodiment is formed by additionally arranging the vacuum extraction part 16 on the vertical vacuum electron beam tube, and in actual application, the vacuum extraction part 16 can be additionally arranged on the horizontal vacuum electron beam tube, so that diversification of electron beam tube structures can be formed, and different requirements of users can be met.

The open electron beam tube provided herein eliminates the need for baking in a vacuum oven, providing more options for the user, who can hang the horizontal vacuum electron beam tube, the vertical vacuum electron beam tube, or the open electron beam tube depending on the actual situation.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. An open electron beam tube, comprising

A housing (10) having a cavity (100) configuration; one end of the shell (10) is provided with an end cover (11), and the other end is provided with a sealing flange (12); a window part (13), a high-pressure access part (14) which extends outwards and is provided with a sealing cover (15) and a vacuum extraction part (16) which extends outwards are arranged on the outer wall of the shell (10); the window part (13) is in positive correspondence with the high-voltage access part (14);

a field emission device (20) located within the cavity (100) of the housing (10); the field emission device (20) comprises a focusing head (21), a core column sealing cylinder (22), a cathode cover (23) and a metal wire (24), wherein the focusing head (21) is fixedly connected with the sealing cover (15) through a hollow ceramic connector (40), the core column sealing cylinder (22) and the focusing head (21) are positioned outside the cathode cover (23), and the focusing head (21) is sleeved on the core column sealing cylinder (22); the stem sealing cylinder (22) is in conductive connection with the metal wire (24); a notch (233) is formed in the outer wall of the cathode cover (23), a grid net (234) is fixed in the notch (233), and the metal wire (24) is arranged in the cathode cover (23) and is positioned right below the grid net (234); and

an electron emission window assembly (30) welded to the window portion (13) and corresponding to the grid mesh (234); the electron emission window assembly (30) is internally provided with a titanium foil (31) for closing the window part (13), and electrons emitted by the metal wire (24) are uniformly distributed through a grid mesh (234), then strike the titanium foil (31) and are transmitted outwards.

2. The open electron beam tube according to claim 1, wherein the cathode housing (23) comprises a housing body (231) and a shield housing (232), the housing body (231) having a cylindrical shape, the slit (233) being opened in the housing body (231); the shielding cover (232) has two and all is hemispherical, and two shielding cover (232) set up respectively the both ends of housing body (231) and outside protrusion.

3. The open electron beam tube of claim 2, wherein the grid mesh (234) is a molybdenum mesh.

4. The open electron beam tube according to claim 2, wherein an elongated filament mount (25) is provided in the housing body (231), the wire (24) being fixed to the filament mount (25); the lamp wire seat (25) is fixed with the housing body (231) through a fixing block (26), and the stem sealing cylinder (22) is fixed at the other end of the fixing block (26) and is in conduction connection with the metal wire (24).

5. The open electron beam tube according to claim 4, wherein the filament holder (25) is provided with a plurality of blind holes (251), the plurality of blind holes (251) are distributed in an equidistant array along the length direction of the filament holder (25), each blind hole (251) is provided with a blind hole (251) extending along the axial direction thereof, and each blind hole (251) is fixedly connected with the metal wire (24) to support the metal wire (24).

6. The open electron beam tube according to claim 5, wherein the metal wire (24) is a tungsten wire.

7. The open electron beam tube according to claim 1, wherein the electron emission window assembly further comprises a grid plate (33), the grid plate (33) is welded and fixed on the window portion (13) in a sealing manner, a honeycomb-shaped heat dissipation mesh (331) is disposed at a position where the grid plate (33) faces the window portion (13), and the titanium foil (31) is attached to the grid plate (33) through a pressing plate (32) and covers the heat dissipation mesh (331).

8. The tube of claim 7, wherein the louver (33) further comprises a cold circulation channel disposed around the heat dissipation mesh (331) for cooling the titanium foil (31) attached to the louver (33).

9. The open electron beam tube of claim 8, wherein the heat-dissipating mesh (331) is a heat-dissipating mesh (331) made of an oxygen-free copper material.

10. The open electron beam tube according to claim 1, wherein the titanium foil (31) has a thickness of 0.015mm to 0.02 mm.