Packaging type electron source

Abstract

The invention relates to the technical field of electron sources, and discloses a packaged electron source, which comprises an electron source cathode, an electron source anode, an internal multi-stage focusing structure, a deflection structure, an electron beam film window, an external focusing structure and an insulating tube shell, and is characterized in that the electron beam film window divides the interior of the insulating tube shell into a sealed-off vacuum area and an external environment area; the electron source cathode, the electron source anode, the internal multi-stage focusing structure and the deflection structure are all arranged in the sealed-off vacuum area, and the external focusing structure is arranged in the external environment area. The electron source is a packaged integrated device, the size of the electron source is reduced, the use scene of the electron source is expanded, and the stability of an emergent electron beam is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electron sources, and particularly to an encapsulated electron source. Background Art

[0002] An electron gun, i.e., an electron source that generates a high-speed electron beam. In many electronic devices and physical experiments, the electron source is a key component that provides the "raw materials" for subsequent electron behaviors and processes. Common electron sources include: thermionic emission sources, field emission electron sources, photoemission sources, etc. The traditional electron source structure includes a cathode, a control stage, an anode, a focusing electrode, a deflection coil, etc. Such an electron gun requires a high-vacuum environment of at least 10 -3 Pa magnitude to maintain electron beam emission and ensure the cathode life. The emitter needs high-power heating, resulting in high energy consumption and low efficiency. The existing electron sources mainly have the following disadvantages:

[0003] (1) A vacuum pumping unit is required to maintain the vacuum environment. The three electron sources introduced above all need to work in a vacuum and require a vacuum environment of not less than 10 -3 Pa. Therefore, in the equipment using the electron source, it is usually required that the sample to be measured is also placed in the vacuum chamber, which limits the application scenarios of the electron source.

[0004] (2) The multi-stage vacuum structure design of the electron source and the sample is complex. Since a high-vacuum environment needs to be provided for the electron source, in most equipment, the method of designing a graded vacuum cavity may be adopted. For example, in a scanning electron microscope, the vacuum degree requirement for the electron gun part is high, and the vacuum degree requirement for the sample chamber position is low. Different vacuum degrees of the two vacuum chambers are realized through two sets of units, which greatly increases the complexity of the system design.

[0005] (3) It is difficult to reduce the volume. Due to the need for a complex vacuum environment, traditional electron sources are often huge in volume and cannot be miniaturized. Summary of the Invention

[0006] In view of this, the present invention provides an encapsulated electron source to solve the problems of complex structure and large volume of the existing electron sources.

[0007] The present invention provides an encapsulated electron source, including: an electron source cathode, an electron source anode, an internal multi-stage focusing structure, a deflection structure, an electron beam thin film window, an external focusing structure, and an insulating housing. Among them, the electron beam thin film window divides the inside of the insulating housing into a sealed-off vacuum area and an external environment area; the electron source cathode, the electron source anode, the internal multi-stage focusing structure, and the deflection structure are all arranged in the sealed-off vacuum area, and the external focusing structure is arranged in the external environment area.

[0008] The encapsulated electron source provided by the present invention is an encapsulated integrated device, which greatly expands the usage scenarios of the electron source, can effectively reduce the structural complexity of the equipment using the electron source, reduce the volume of the electron source, and can greatly improve the stability of the emitted electron beam.

[0009] In an alternative embodiment, the electron beam thin film window includes: a silicon substrate and a thin film. Among them, the silicon substrate divides the inside of the insulating shell into a sealed vacuum region and an external environment region and is hermetically connected to the inner wall of the insulating shell; the thin film completely covers the silicon substrate to form an integrated structure; holes are provided on the silicon substrate, and the diameter of the holes is larger than the diameter of the beam spot of the pulsed electron beam. After the electrons from the cathode of the electron source are heated by an external negative high-voltage filament power supply to become free electrons in space, they are emitted under the action of the cathode of the electron source and are accelerated by the negative high-voltage electric field between the anode of the electron source.

[0010] In an alternative embodiment, the thin film is one of a silicon nitride thin film or a diamond thin film.

[0011] For the encapsulated electron source provided by the present invention, the silicon nitride thin film or the diamond thin film hardly attenuates the intensity of the high-energy electron beam, and has a strong ability to withstand the pressure difference on both sides and high reliability.

[0012] In an alternative embodiment, the thickness of the thin film is in the order of hundreds of nanometers.

[0013] In an alternative embodiment, the vacuum degree of the sealed vacuum region is better than 10 -4 Pa, and the pressure of the external environment region is the standard atmospheric pressure.

[0014] In an alternative embodiment, the frequency of the pulsed electron beam is 0 - 100 kHz.

[0015] In an alternative embodiment, the insulating shell is made of alumina ceramic.

[0016] In an alternative embodiment, the encapsulated electron source further includes: an exhaust pipe. Among them, one end of the exhaust pipe is connected to an external vacuum unit, and the other end of the exhaust pipe is inserted into the sealed vacuum region of the insulating shell. The exhaust pipe is used to extract the gas in the sealed vacuum region.

[0017] For the encapsulated electron source provided by the present invention, the method of pumping the sealed vacuum region with the exhaust pipe is simple and easy to implement.

[0018] In an alternative embodiment, the exhaust pipe is made of one of oxygen-free copper or red copper.

[0019] In an alternative embodiment, the encapsulated electron source further includes at least one non-evaporable getter, wherein the non-evaporable getter is disposed in the sealed vacuum region of the insulating envelope and is used to adsorb residual gas molecules in the sealed vacuum region. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 is a composition diagram of an encapsulated electron source according to an embodiment of the present invention;

[0022] Figure 2 is a composition diagram of an electron beam thin film window according to an embodiment of the present invention;

[0023] Figure 3 is a composition diagram of another encapsulated electron source according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and may also be the communication inside two components. It may be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0027] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] A hypersonic vehicle refers to a vehicle with a flight speed greater than Mach 5. When such a vehicle is flying, it has a violent dynamic and energy interaction with the high-altitude atmosphere, resulting in the "elusive" temperature, density and other parameters of the surrounding air flow field. These flow field parameters will directly affect the flight trajectory of the vehicle. Therefore, it is of great significance to calculate and simulate and experimentally test to obtain the flow field characteristic parameters for the design and control of the vehicle. Among them, experimental testing is the source and basis for obtaining high-precision flow field experimental data, and can provide important experimental data and technical support for the design and development of the vehicle.

[0029] Electron Beam Fluorescence (EBF) technology is an advanced local non-invasive optical diagnostic technology, which can accurately measure parameters such as density, vibrational temperature, rotational temperature, and velocity of a hypersonic flow field. The basic principle of EBF technology is to use a high-energy electron beam to excite gas molecules and atoms, generating a broadband fluorescence signal from the X-ray to the infrared spectral band. Different types of gas molecules and atoms (such as N2, NO, CO, CO2, and He) have EBF signals characterized by vibrational bands and rotational emission spectral lines. By combining components such as spectrometers and pulsed cameras to process and analyze the fluorescence signal, important parameters such as flow field temperature, velocity, and density can be obtained.

[0030] Using this technology for high-altitude flight tests can directly obtain more accurate experimental data in a real environment, further promoting the development of hypersonic technology. The development trend of EBF technology flight tests mainly lies in the difficulties in the requirements of its test system device, which are restricted by aspects such as the payload, external dimensions, and power consumption of the vehicle, and at the same time need to adapt to complex test environments. The EBF technology test system mainly includes: an electron gun, an ICCD camera, a spectrometer device, and a data acquisition, storage, and processing module, etc. The electron gun, as the core component of the test system, is responsible for providing the high-energy electron beam required for testing. A set of electron gun systems with small size, light weight, and low energy consumption is of great significance for promoting EBF technology flight tests.

[0031] An electron gun is an electron source that generates high-speed electrons. In many electronic devices and physical experiments, the electron source is a crucial component that provides the "raw materials" for subsequent electron behaviors and processes. Common electron sources include: thermionic emission sources, field emission electron sources, photoemission sources, etc.

[0032] Thermionic emission sources are based on the phenomenon of thermionic emission. When a metal is heated to a sufficiently high temperature, the electrons in the metal gain enough energy to overcome the potential barrier at the metal surface and escape into the vacuum, becoming free electrons. For example, in old-fashioned electron tubes, when the filament (usually a tungsten filament) is heated, thermionic emission occurs. The filament is equivalent to a thermionic emission source. It's like heating a pot of water to boiling, and the water molecules (analogous to electrons) gain enough energy to turn into water vapor and escape from the water surface. In traditional cathode ray tube displays and televisions, thermionic emission sources are used to generate electron beams. The electron beams are controlled by electric and magnetic fields and strike the fluorescent screen, causing the screen to emit light and thus display images.

[0033] Field emission sources cause electrons to be emitted from the material surface by applying a very strong electric field. Under the action of a strong electric field, the energy state of electrons changes, enabling them to penetrate the potential barrier at the material surface and be emitted. This emission method does not require heating the material as in thermionic emission. For example, field emission sources are used in some new types of electron microscopes and vacuum microelectronic devices. Figuratively speaking, it's as if there is a powerful external force (electric field) pulling electrons out of a "cage" (material surface). Field emission displays are an important application area of field emission sources. It is expected to become a new generation of flat panel display technology, with advantages such as high brightness, high contrast, and fast response.

[0034] Photoemission sources utilize the photoelectric effect. When photons irradiate the surface of certain materials, the electrons in the materials absorb the energy of the photons. If the photon energy is large enough, the electrons can overcome the binding at the material surface and escape, generating photoelectrons. For example, the photocathode in a photomultiplier tube is a photoemission source. When light irradiates the photocathode, electron emission occurs, and these electrons are amplified in the photomultiplier tube and used to detect weak optical signals. It's like using a small "optical signal trigger device" to generate electrons and then letting these electrons play a greater role. It is applied in devices such as photodetectors and solar cells. In optical communication systems, photodetectors use photoemission sources to convert optical signals into electrical signals to achieve signal detection and processing.

[0035] Existing electron sources have the following disadvantages:

[0036] (1) A vacuum pump unit is required to maintain a vacuum environment. The three types of electron sources introduced above all need to operate in a vacuum and require a vacuum environment of no less than 10-3 Pa for the electron source. Therefore, in devices using electron sources, it is usually required that the sample to be measured be placed in the vacuum chamber together, which limits the application scenarios of the electron source.

[0037] (2) The multi-stage vacuum structure design of the electron source and the sample is complex. Since a high-vacuum environment needs to be provided for the electron source, in most devices, a method of designing a hierarchical vacuum cavity may be adopted. For example, in a scanning electron microscope, the vacuum degree requirement is high in the electron gun part and low in the sample chamber position. Two vacuum pumps are used to achieve different vacuum degrees in the two vacuum chambers, which greatly increases the complexity of the system design.

[0038] (3) It is difficult to reduce the volume. Due to the need for a complex vacuum environment, traditional electron sources are often huge in volume and cannot be miniaturized.

[0039] This embodiment provides a packaged electron source, as Figure 1 shown, including: an electron source cathode 13, an electron source anode 4, an internal multi-stage focusing structure 5, a deflection structure 7, an electron beam thin film window 8, an external focusing structure 9, and an insulating tube shell 10.

[0040] Figure 1 In, the electron beam thin film window 8 divides the inside of the insulating tube shell 10 into a sealed-off vacuum region 11 and an external environment region 12.

[0041] Specifically, Figure 1 in, during the production process of the packaged electron source, after the electron beam thin film window 8 is sealed and fixed inside the insulating tube shell 10, an air extraction tube can be inserted into the left region of the electron beam thin film window 8. After using a vacuum pump unit to extract the air in the left region of the electron beam thin film window 8 to form a vacuum environment, the air extraction tube is immediately sealed to prevent the air outside the insulating tube shell 10 from entering the left region of the electron beam thin film window 8 through the air extraction tube, so that the left region of the electron beam thin film window 8 forms a sealed-off vacuum region 11. The pressure in the external environment region 12 is atmospheric pressure or greater than the pressure in the sealed-off vacuum region 11.

[0042] Figure 1 In, the electron source cathode 13, the electron source anode 4, the internal multi-stage focusing structure 5, and the deflection structure 7 are all arranged in the sealed-off vacuum region 11, and the external focusing structure 9 is arranged in the external environment region 12.

[0043] Figure 1In [the device], electrons emitted from the electron source cathode 13 are accelerated into an electron beam by the electron source anode 4 under the action of an external negative high voltage. After that, the electron beam successively passes through the internal multi-stage focusing structure 5 and the deflection structure 7 to be converted into a pulsed electron beam. Then, the pulsed electron beam is shot into the external focusing structure 9 through the electron beam thin film window 8 and corrected into a high-energy electron beam before being emitted.

[0044] Specifically, Figure 1 In [the device], the dotted arrow represents the electron beam trajectory. Electrons on the electron source cathode 13 are emitted from the material surface by passing through the potential barrier on the material surface under the action of the external negative high voltage electric field. The divergent electrons pass through the channel at the center of the electron source anode 4 and enter the central channel of the internal multi-stage focusing structure 5 for focusing, so that the divergent electrons are focused into an approximately parallel beam. After the parallel electron beam adjusts the pulse frequency through the central channel of the deflection structure 7, it passes through the electron beam thin film window 8 and enters the external focusing structure 9 in the external environment area 12 from the sealed vacuum area 11. The electron beam thin film window 8 can transmit the electron beam without causing attenuation of the electron beam. After the external focusing structure 9 corrects the divergence that may occur after the pulsed electron beam passes through the electron beam thin film window 8, the pulsed electron beam forms a high-energy electron beam and is emitted through the outlet of the insulating tube shell 10.

[0045] Optionally, Figure 1 In [the device], the internal multi-stage focusing structure 5 may include multiple focusing structures, which can reliably focus the electron beam into an approximately parallel beam for multiple times and then emit it.

[0046] It should be noted that after the electron beam thin film window is installed, the vacuum unit can be closed. The encapsulated electron source does not need to use the vacuum unit to continuously maintain the vacuum environment during subsequent use, nor does it need to be placed in the vacuum environment together with the sample to be measured, making the use method of the electron source simple and the application scenario flexible.

[0047] The encapsulated electron source provided in this embodiment is an encapsulated integrated device, which greatly expands the usage scenarios of the electron source, can effectively reduce the structural complexity of the equipment using the electron source, reduce the volume of the electron source, and can greatly improve the stability of the emitted electron beam.

[0048] In some alternative embodiments, as Figure 2 shown, the electron beam thin film window includes: a silicon substrate 81 and a thin film 82. Among them, the silicon substrate 81 divides the inside of the insulating tube shell 10 into a sealed vacuum area 11 and an external environment area 12 and is hermetically connected to the inner wall of the insulating tube shell 10; the thin film 82 completely covers the silicon substrate 81 to form an integrated structure; holes are provided on the silicon substrate 81, and the diameter of the holes is larger than the diameter of the beam spot of the pulsed electron beam. The pulsed electron beam is obtained after the electrons from the electron source cathode become free electrons in space under the heating of the external negative high voltage filament power supply, and are then emitted under the action of the electron source cathode 13 and accelerated by the negative high voltage electric field between the electron source cathode 13 and the electron source anode 4.

[0049] Specifically, Figure 2 In, the thin film 82 first completely covers one side of the silicon substrate 81 and is combined with the silicon substrate 81 into an integral structure. When a pulsed electron beam needs to pass through, an etching process is used at the position where the pulsed electron beam passes through to open a hole in the silicon substrate 81 at the corresponding position below the thin film 82 in a manner that does not damage the integrity of the thin film. The size of the hole should meet the requirements according to the spot diameter of the passing pulsed electron beam, generally about 1 mm, so that the thin film 82 and the silicon substrate 81 present a window structure with a support structure. When assembling the electron source, the thin film 82 is located on the side of the sealed vacuum region 11 to prevent the gas molecule exchange between the sealed vacuum region 11 and the external environment region 12 from damaging the vacuum degree. The silicon substrate 81 is bonded to the base on the inner wall of the insulating tube shell 10 using silicon wafer bonding technology to achieve vacuum sealing, or vacuum sealing glue can also be used for bonding.

[0050] Optionally, Figure 2 In, the thin film 82 can be a silicon nitride thin film or a diamond thin film, or other thin films that can transmit electron beams and hardly attenuate the intensity of the passing high-energy electron beams. The thin film 82 has a strong ability to withstand the pressure difference on both sides and high reliability.

[0051] Optionally, Figure 2 In, the thickness of the thin film 82 is in the order of hundreds of nanometers.

[0052] Optionally, Figure 2 In, the insulating tube shell 10 is made of vacuum insulating materials such as 95 alumina ceramics or 99 alumina ceramics that can be used for vacuum electronic devices.

[0053] In some optional embodiments, the vacuum degree of the sealed vacuum region is better than 10 -4 Pa, and the pressure of the external environment region is the standard atmospheric pressure.

[0054] Optionally, the vacuum degree of the sealed vacuum region is better than 10 -4 Pa, 12 is the external environment, and the external environment region can be an atmospheric environment or a vacuum environment with a relatively high vacuum degree (such as 10 - 100 Pa).

[0055] In some optional embodiments, the frequency of the pulsed electron beam is 0 - 100 kHz.

[0056] Specifically, Figure 1 In, the deflection of the electron beam is realized by using the deflection structure 7 to achieve the pulsed emission of the electron beam, so that the encapsulated electron source can achieve the pulsed electron beam emission with an energy of 50 keV and a beam current reaching the mA level.

[0057] In some optional embodiments, such as Figure 3As shown, the encapsulated electron source further includes: an evacuation tube 2. One end of the evacuation tube 2 is connected to an external vacuum unit, and the other end of the evacuation tube 2 is inserted into the sealed vacuum area of the insulating tube shell 10. The evacuation tube 2 is used to extract the gas in the sealed vacuum area.

[0058] Specifically, Figure 3 After the encapsulated electron source is assembled, the sealed vacuum area 11 is connected to the vacuum unit through the evacuation tube 2 for evacuation. After the evacuation is completed, a hydraulic clamp with an obtuse-edge is used to pinch and cut off the evacuation tube 2 while sealing the evacuation tube 2.

[0059] Optionally, the evacuation tube 2 is made of oxygen-free copper or red copper.

[0060] In some alternative embodiments, as Figure 3 shown, the encapsulated electron source further includes: at least one non-evaporable getter 3.

[0061] Specifically, Figure 3 in this case, the non-evaporable getter 3 is arranged in the sealed vacuum area of the insulating tube shell 10 and is used to adsorb the residual gas molecules in the sealed vacuum area. The encapsulated electron source further includes a cathode negative high-voltage electrode 1, which is used to provide a negative high-voltage potential for the electron source cathode 13.

[0062] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A packaged electron source, characterized in that: include: An electron source cathode (13), an electron source anode (4), an internal multi-stage focusing structure (5), a deflection structure (7), an electron beam film window (8), an external focusing structure (9) and an insulating tube shell (10), wherein: The electron beam film window (8) divides the interior of the insulating tube shell (10) into a sealed vacuum area (11) and an external environment area (12); The electron source cathode (13), the electron source anode (4), the internal multi-stage focusing structure (5) and the deflection structure (7) are all arranged in the sealed vacuum area (11), and the external focusing structure (9) is arranged in the external environment area (12).

2. The packaged electron source according to claim 1, characterized in that: The electron beam thin film window (8) comprises: a silicon substrate (81) and a thin film (82), wherein: The silicon substrate (81) divides the interior of the insulating tube shell (10) into a sealed vacuum area (11) and an external environment area (12), and is sealedly connected to the inner wall of the insulating tube shell (10); The film (82) completely covers the silicon substrate (81) to form an integrated structure; A hole is provided on the silicon substrate (81), the diameter of the hole being larger than the diameter of the beam spot of the pulsed electron beam. The pulsed electron beam is obtained by accelerating the electrons of the electron source cathode (13) and the electron source anode (4) after the electrons are heated by an external power source to become free electrons in space.

3. The packaged electron source according to claim 2, characterized in that: The film (82) is a silicon nitride film or a diamond film.

4. The packaged electron source according to claim 2, characterized in that: The film (82) has a thickness of hundreds of nanometers.

5. The packaged electron source according to claim 1, characterized in that: The vacuum degree of the sealed vacuum area (11) is better than 10 -4 Pa, the pressure of the external environment area (12) is standard atmospheric pressure.

6. The packaged electron source according to claim 2, characterized in that: The frequency of the pulsed electron beam is 0-100 kHz.

7. The packaged electron source according to claim 1, characterized in that: The insulating tube shell (10) is made of one of 95 alumina ceramics and 99 alumina ceramics.

8. The packaged electron source according to claim 1, characterized in that: Also includes: The exhaust pipe (2) includes: One end of the exhaust pipe (2) is connected to an external vacuum unit, and the other end of the exhaust pipe (2) is inserted into the sealed vacuum area (11) of the insulating tube shell (10). The exhaust pipe (2) is used to extract gas from the sealed vacuum area (11).

9. The packaged electron source according to claim 8, characterized in that: The exhaust pipe (2) is made of one of oxygen-free copper and red copper.

10. The packaged electron source according to claim 1, characterized in that: Also includes: At least one non-evaporable getter (3), wherein The non-evaporable getter (3) is arranged in the sealed vacuum region (11) of the insulating tube shell (10) and is used to adsorb residual gas molecules in the sealed vacuum region (11).

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