Photoelectric synergistic excitation nanometer cold cathode electron gun

Abstract

The invention discloses a photoelectric synergistic excitation nanometer cold cathode electron gun. The electron gun comprises a cathode structure, an anode structure, a focusing electrode structure, a laser and a focusing light path, after a laser beam emitted by the laser passes through a focusing light path, the laser beam is irradiated to the cathode structure with a conductive characteristic; the cathode structure with the conductive characteristic generates electrons through laser excitation, and the electrons are emitted through the anode structure and the focusing electrode structure. The focusing light path comprises a beam expander, a half-reflecting mirror, a first convex lens, a second convex lens and a reflecting mirror which are arranged in sequence; the cathode structure with the conductive characteristic is arranged between the first convex lens and the second convex lens; the cathode structure with the conductive property is provided with at least one emission tip; the optical centers of the beam expander, the half-reflecting mirror, the first convex lens, the second convex lens and the reflecting mirror and an emitting tip of the cathode structure with the conductive characteristic are all located on the same straight line; the laser emits a laser beam to enter the focusing light path from one end of the beam expander. The electron gun has the advantages of being low in power consumption, high in quantum efficiency, small in size, high in response speed and capable of being integrated.

Description

Technical Field

[0001] The present invention relates to the field of vacuum electron sources and vacuum optoelectronic devices, and more specifically, to a photoelectric cooperative excitation nano cold cathode electron gun. Background Art

[0002] With the rapid development of modern science and technology, high-efficiency vacuum optoelectronic devices have been widely used in many cutting-edge technology fields such as ultra-high spatiotemporal resolution characterization, vacuum photodetection, photomultiplier tubes, free electron lasers, and high-precision electron microscopy imaging. As the core device of these applications, electron guns need to have the characteristics of high spatiotemporal resolution, high current density, high electron yield, and high quantum efficiency.

[0003] At present, photocathode electron guns generally use a large-area planar cathode structure, which has a low enhancement factor for the laser electric field and often requires strong light excitation to produce multi-photon or light field electron emission, resulting in a high electron emission threshold and low quantum efficiency. On the other hand, the excitation laser mostly uses a small-angle oblique incidence excitation method, which has problems such as laser beam blocking the electron beam path, device structure size limitation, and small vertical component of polarization electric field, which leads to difficult device design, poor optical coupling efficiency, and low emission current.

[0004] The prior art discloses a picosecond ultrafast ultrashort pulse electron gun. The electron gun includes a light excitation component, a pulse electron beam emission component, a vacuum shell and an electrode line; the light excitation component includes an ultrafast laser and a reflector; the pulse electron beam emission component includes a cathode structure, a grid structure and an anode structure; the cathode structure, the grid structure, the anode structure and the reflector form a whole and are placed in the vacuum shell; the grid structure and the anode structure are arranged opposite to the cathode structure in sequence and are separated from each other to form a vacuum gap structure; the cathode structure is provided with a cold cathode; the centers of the grid structure and the anode structure are respectively provided with a first through hole and a second through hole; the reflector is arranged in the vacuum shell and is arranged opposite to the anode structure and is located on the side of the anode structure away from the grid structure; the center of the reflector is provided with a third through hole, and the first through hole, the second through hole, the third through hole and the center of the cathode structure are on the same horizontal line. The laser beam in the electron gun is not focused, so the light excitation is insufficient, the electron emission threshold is high, and the quantum efficiency is low. Summary of the invention

[0005] The present invention aims to provide a photoelectric cooperative excitation nano cold cathode electron gun to solve the defects of the prior art, such as high electron emission threshold, low quantum efficiency, difficult device design, poor optical coupling efficiency and small emission current. The electron gun has the characteristics of low power consumption, high quantum efficiency, small size, fast response speed and can be integrated.

[0006] The primary purpose of the present invention is to solve the above technical problems. The technical solution of the present invention is as follows:

[0007] A photoelectric cooperative excitation nano cold cathode electron gun, comprising: a cathode structure with conductive properties, an anode structure, a focusing electrode structure, a laser, and a focusing optical path;

[0008] After the laser beam emitted by the laser passes through the focusing optical path, the laser beam is irradiated onto the cathode structure with conductive properties; the cathode structure with conductive properties is excited by the laser to generate electrons, and the electrons are emitted through the anode structure and the focusing electrode structure;

[0009] The focusing optical path includes a beam expander, a semi-reflecting mirror, a first convex lens, a second convex lens, and a reflector arranged in sequence; the cathode structure with conductive properties is arranged between the first convex lens and the second convex lens;

[0010] The cathode structure having conductive properties has at least one emitting tip;

[0011] The optical centers of the beam expander, the semi-reflecting mirror, the first convex lens, the second convex lens, the reflector, and an emission tip of a cathode structure having conductive properties are all located on the same straight line;

[0012] The laser beam emitted by the laser enters the focusing light path from one end of the beam expander.

[0013] Furthermore, the material of the anode structure and the focusing electrode structure is metal.

[0014] Furthermore, the focal length range of the first convex lens and the second convex lens is 10mm to 100mm, the diameter range is 10mm to 100mm, the distance between an emitting tip of the cathode structure with conductive properties and the first convex lens is the focal length of the first convex lens, and the distance between an emitting tip of the cathode structure with conductive properties and the second convex lens is the focal length of the second convex lens.

[0015] Furthermore, the magnification of the beam expander is 1-50.

[0016] Furthermore, the wavelength of the laser emitted by the laser is in the range of 300nm to 2400nm, and the output spot diameter is in the range of 0.1mm to 2cm.

[0017] Furthermore, the distance between the cathode structure with conductive properties and the anode structure ranges from 0.01 mm to 10 mm, and the distance between the focusing electrode structure and the anode structure ranges from 0.01 mm to 10 mm.

[0018] Furthermore, the angle range of the laser beam irradiating the cathode structure having conductive properties is 30° to 90°, and the excitation light intensity range is 10 -3 W cm -2 ~10 12 W cm-2 .

[0019] Furthermore, the cathode structure with conductive properties includes: a nano cold cathode structure and a cathode substrate structure, one end of the cathode substrate structure is connected to the nano cold cathode structure;

[0020] The material of the nano cold cathode structure is any one of upright multi-walled carbon nanotubes, upright few-layer graphene, tungsten and its oxide nanoneedle tips, molybdenum and its oxide nanoneedle tips, and zinc oxide nanowires;

[0021] The material of the cathode substrate structure is metal.

[0022] Furthermore, a photoelectric cooperative excitation nano cold cathode electron gun also includes a vacuum housing;

[0023] The cathode structure, anode structure, focusing pole structure and focusing optical path with conductive properties are located inside the vacuum housing, and the laser is located outside the vacuum housing.

[0024] Furthermore, the vacuum housing includes a metal housing, an electrode flange, a glass window, and an exhaust flange;

[0025] The glass window is coaxially arranged with the focusing optical path and is located between the laser and the beam expander; the metal shell is respectively connected with the electrode flange, the exhaust flange and the glass window, and the electrode flange is connected with the control electrode.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention improves the light excitation intensity in the light path through a focusing light path composed of a beam expander, a semi-reflecting mirror, a first convex lens, a second convex lens, and a reflector arranged in sequence; a continuous laser beam or a pulsed laser beam after focusing and superposition is used to excite a cathode structure with conductive characteristics to which a DC bias electric field is applied. On the one hand, it avoids the problems of electrode shielding in the traditional photocathode electron gun structure, which makes it difficult for laser excitation to couple efficiently with the electric field, and the high gate absorption rate leads to a decrease in electron yield; on the other hand, it gives play to the advantages of photocathode electron guns and field emission electron guns in obtaining continuous electron beams or pulsed electron beams with low energy divergence, high spatiotemporal resolution, and high current density. In summary, multiple superposition and focusing of incident light and reflected light are achieved through the focusing light path structure, which effectively improves the laser intensity in the light path, especially at the focus; at the same time, the nano cold cathode with DC bias is set at the focus, which realizes the immersion excitation of the nano cold cathode by laser excitation, maximizes the coupling efficiency of laser excitation and DC electric field, and effectively improves the device performance of the photoelectric synergistic nano cold cathode electron gun. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1This is a structural diagram of a photoelectric cooperative excitation nano cold cathode electron gun provided in Example 1.

[0029] Figure 2 This is an electron microscope image of the upright multi-walled carbon nanotube nano cold cathode provided in Example 1.

[0030] Figure 3 This is a partial enlarged view of the upright multi-walled carbon nanotube nano cold cathode provided in Example 1.

[0031] Figure 4 This is an electron microscope image of the upright few-layer graphene nanocold cathode provided in Example 1.

[0032] Figure 5 This is a partially enlarged view of the upright few-layer graphene nanocold cathode provided in Example 1.

[0033] Figure 6 This is an electron microscope image of the polycrystalline tungsten needle-shaped nano cold cathode provided in Example 1.

[0034] Figure 7 This is a partial enlarged view of the polycrystalline tungsten needle-shaped nano cold cathode provided in Example 1.

[0035] Figure 8 This is an electron microscope image of the polycrystalline molybdenum needle-shaped nano cold cathode provided in Example 1.

[0036] Fig. 9 This is a partial enlarged view of the polycrystalline molybdenum needle-shaped nano cold cathode provided in Example 1.

[0037] Fig.10 This is an electron microscope image of the zinc oxide nanowire nano cold cathode provided in Example 1.

[0038] Fig.11 This is a partially enlarged view of the zinc oxide nanowire nano cold cathode provided in Example 1.

[0039] Fig.12 This is a front view of the cylindrical nano cold cathode structure provided in Example 1.

[0040] Fig.13 A side view of the cylindrical nano cold cathode structure provided in Example 1.

[0041] Fig.14 This is a top view of the cylindrical nano cold cathode structure provided in Example 1.

[0042] Fig.15 This is a front view of the elliptical cylindrical nano cold cathode structure provided in Example 1.

[0043] Fig.16 This is a side view of the elliptical cylinder nano cold cathode structure provided in Example 1.

[0044] Fig.17 This is a top view of the elliptical cylindrical nano cold cathode structure provided in Example 1.

[0045] Fig.18 This is a front view of the prismatic nano cold cathode structure provided in Example 1.

[0046] Fig.19 This is a side view of the prismatic nano cold cathode structure provided in Example 1.

[0047] Fig. 20 This is a top view of the prismatic nano cold cathode structure provided in Example 1.

[0048] Fig.21 This is the front view of the conical nano cold cathode structure provided in Example 1.

[0049] Fig. 22 A side view of the conical nano cold cathode structure provided in Example 1.

[0050] Fig.23 This is a top view of the conical nano cold cathode structure provided in Example 1.

[0051] Fig.24 This is a front view of the pyramidal nano cold cathode structure provided in Example 1.

[0052] Fig.25 This is a side view of the pyramidal nano cold cathode structure provided in Example 1.

[0053] Fig.26 This is a top view of the pyramidal nano cold cathode structure provided in Example 1. DETAILED DESCRIPTION

[0054] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0055] In order to better illustrate the present embodiment, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product;

[0056] It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0057] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0058] Example 1

[0059] like Figure 1 As shown, a photoelectric cooperative excitation nano cold cathode electron gun includes: a cathode structure 11 with conductive properties, an anode structure 12, a focusing electrode structure 13, a laser 22, and a focusing optical path 21;

[0060] After the laser beam emitted by the laser 22 passes through the focusing optical path 21, the laser beam is irradiated onto the cathode structure 11 with conductive properties; the cathode structure 11 with conductive properties generates electrons after being excited by the laser, and the electrons are emitted through the anode structure 12 and the focusing electrode structure 13;

[0061] The focusing optical path 21 includes a beam expander 211, a semi-reflecting mirror 212, a first convex lens 213, a second convex lens 214, and a reflector 215 arranged in sequence; the cathode structure with conductive properties is arranged between the first convex lens 213 and the second convex lens 214;

[0062] The cathode structure 11 having conductive properties has at least one emission tip;

[0063] The optical centers of the beam expander 211, the semi-reflective mirror 212, the first convex lens 213, the second convex lens 214, the reflective mirror 215 and an emission tip of the cathode structure 11 with conductive properties are all located on the same straight line;

[0064] The laser 22 emits a laser beam which enters the focusing optical path 21 from one end of the beam expander 211 .

[0065] It should be noted that the semi-reflective mirror 212 has a one-way transmission characteristic for the laser light emitted by the laser 22, wherein the laser light incident from the side close to the laser 22 can be transmitted through the semi-reflective mirror 212, and the laser light incident from the side far from the laser (22) will be reflected by the semi-reflective mirror (212);

[0066] A first through hole and a second through hole are respectively provided at the centers of the anode structure (12) and the focusing electrode structure (13), and the center of the nano cold cathode structure 112, the center of the first through hole, and the center of the second through hole are located on the same straight line;

[0067] The emission tip of the nano cold cathode structure 112 is located at the common focus of the first convex lens 213 and the second convex lens 214 included in the light excitation component 20 .

[0068] The continuous laser beam or pulsed laser beam emitted by the laser 22 is expanded by the beam expander 211 and then transmitted through the semi-reflective mirror 212 to be incident on the first convex lens 213, and is focused by the first convex lens 213 to the common focus of the first convex lens 213 and the second convex lens 214, and then diverges and is incident on the second convex lens 214 to be refocused into parallel light and then is incident on the surface of the reflector 215 and is reflected, and the reflected light generated by the reflector 215 is incident on the second convex lens 214 and is focused to the common focus of the first convex lens 213 and the second convex lens 214, and then diverges and is incident on the first convex lens 213 to be focused into parallel light and then is incident on the side surface of the semi-reflective mirror 212 away from the laser 22 and is reflected; this process is repeated until the continuous laser beam or pulsed laser beam emitted by the laser 22 is almost completely consumed;

[0069] The cathode structure 11, anode structure 12 and focusing electrode structure 13 with conductive properties are connected to an external driving circuit through a control electrode 40. Under the action of a DC bias electric field, the nano cold cathode structure 112 on the cathode structure 11 with conductive properties generates electron emission. At the same time, after the continuous laser beam or pulsed laser beam emitted by the laser 22 is focused at the common focus of the first convex lens 213 and the second convex lens 214, the nano cold cathode structure 112 on the cathode structure 11 with conductive properties is stimulated by an immersion method at a certain angle and light intensity. The nano cold cathode structure 112 generates a continuous electron beam or a pulsed electron beam stimulated by the continuous laser beam or the pulsed laser beam and regulated by the DC bias electric field. The generated continuous electron beam or pulsed electron beam passes through the first through hole and the second through hole at the center of the anode structure 12 and the focusing electrode structure 13 in turn, and is respectively extracted and accelerated by the anode structure 12 and focused by the focusing electrode structure 13, and then emitted from the through hole of the vacuum housing 31.

[0070] It should be noted that, during the propagation of the continuous laser or pulsed laser emitted by the laser 22 in the focusing optical path structure 21, after multiple focusing by the first convex lens 213 and the second convex lens 214, and multiple reflections by the half-reflecting mirror 212 away from the laser 22 and the reflector 215, the incident light and the reflected light are superimposed on each other in the optical path by interference and the like, and an illumination area with high power density and strong polarization electric field is formed near the common focus of the first convex lens 213 and the second convex lens 214, and the cross-sectional area of ​​the illumination area on a plane perpendicular to the optical path is much larger than the cross-sectional area of ​​the top emission tip of the nano cold cathode structure 112 on the same plane, thereby realizing immersion excitation of the top emission tip of the nano cold cathode structure 112;

[0071] The geometric center of the top emitting tip of the nano cold cathode structure 112 coincides with the common focus of the first convex lens 213 and the second convex lens 214. The cross-sectional area of ​​the nano cold cathode structure 112 on a plane perpendicular to the optical path is much smaller than the cross-sectional area of ​​the laser irradiation area on the plane, thereby ensuring that the laser can achieve immersion excitation of the top emitting tip of the nano cold cathode structure 112.

[0072] The central axis of the cathode electron beam emitting component 10 is perpendicular to the central axis of the optical excitation component 20; the central axis of the cathode electron beam emitting component 10 passes through the center of the through hole of the vacuum housing 31; the central axis of the optical excitation component 20 passes through the center of the glass window 311. The laser 22 is a laser capable of emitting continuous laser light, or a laser based on mode locking technology such as SESAM and Kerr lens, capable of emitting pulsed laser light with a pulse width as narrow as fs level.

[0073] The present invention uses a focusing optical path structure 21 to focus the continuous laser beam or pulsed laser beam emitted by the laser 22, and at the same time, the laser intensity in the optical path, especially at the focus of the first convex lens 213 and the second convex lens 214, is increased by multiple superposition of the incident light and the reflected light. The focused and superimposed continuous laser beam or pulsed laser beam is then used to excite the nano cold cathode structure 112 to which a DC bias electric field is applied, thereby directly emitting a continuous electron beam or pulsed electron beam modulated by the continuous laser beam or pulsed laser beam: on the one hand, it avoids the problem of the traditional photocathode electron gun structure having electrode shielding that makes it difficult for the laser excitation to couple with the electric field, and the high gate absorption rate that leads to a low electron yield. On the other hand, it plays the advantages of photocathode electron gun and field emission electron gun in obtaining continuous electron beam or pulse electron beam with low energy divergence, high spatiotemporal resolution and high current density. Innovatively, the multiple superposition and focusing of incident light and reflected light are realized by focusing the optical path structure 21, which effectively improves the laser intensity in the optical path, especially at the focus. Furthermore, the nano cold cathode structure 112 with DC bias is set at the focus, which realizes the immersion excitation of the nano cold cathode structure 112 by laser excitation, maximizes the coupling efficiency of laser excitation and DC electric field, and effectively improves the device performance of the optoelectronic synergistic nano cold cathode electron gun.

[0074] The present invention adopts a nano cold cathode structure 112 with field electron emission characteristics, which can obtain electron emission with high quantum efficiency, large current, high brightness, and low energy dispersion, reduce the power consumption and size of the device, and greatly improve the integration and miniaturization of the device. At the same time, through the coupling arrangement of the nano cold cathode structure 112 and the focusing optical path structure 21, the high requirements of the electron gun on the excitation light source are greatly reduced, and the light intensity is reduced by at least 4 orders of magnitude, further improving the current density, energy efficiency, and spatiotemporal resolution of the electron beam of the electron gun, while reducing the electron emission threshold, and improving the integration and miniaturization of the device.

[0075] Furthermore, the anode structure 12 and the focusing electrode structure 13 are made of metal.

[0076] Furthermore, the focal length range of the first convex lens 213 and the second convex lens 214 is 10 mm to 100 mm, and the diameter range is 10 mm to 100 mm. The distance between an emitting tip of the cathode structure 11 with conductive properties and the first convex lens 213 is the focal length of the first convex lens 213, and the distance between an emitting tip of the cathode structure with conductive properties and the second convex lens 214 is the focal length of the second convex lens 214.

[0077] Furthermore, the magnification of the beam expander 211 is 1-50.

[0078] Furthermore, the wavelength of the laser emitted by the laser 22 is in the range of 300 nm to 2400 nm, and the output spot diameter is in the range of 0.1 mm to 2 cm.

[0079] The laser 22 can output continuous laser light or pulsed laser light.

[0080] Furthermore, the distance between the cathode structure 11 having conductive properties and the anode structure 12 is in the range of 0.01 mm to 10 mm, and the distance between the focusing electrode structure 13 and the anode structure 12 is in the range of 0.01 mm to 10 mm.

[0081] The maximum cross-sectional diameter of the light output by the beam expander 211 is not greater than the minimum value of the diameters of the first convex lens 213, the second convex lens 214, and the reflector 215;

[0082] Furthermore, the angle range of the laser beam irradiating the cathode structure 11 having conductive properties is 30° to 90°, and the excitation light intensity range is 10 -3 W cm -2 ~10 12 W cm -2 .

[0083] Furthermore, the cathode structure 11 having conductive properties includes: a nano cold cathode structure 112 and a cathode substrate structure 111, and one end of the cathode substrate structure 111 is connected to the nano cold cathode structure 112;

[0084] like Figure 2 to Figure 11 As shown, the material of the nano cold cathode structure 112 is any one of upright multi-walled carbon nanotubes, upright few-layer graphene, tungsten and its oxide nanoneedle tips, molybdenum and its oxide nanoneedle tips, and zinc oxide nanowires;

[0085] The cathode substrate structure 111 is made of metal.

[0086] The nano cold cathode structure 112 is a cold cathode with a high aspect ratio and a nano-scale tip emission structure on the top and has field electron emission characteristics.

[0087] The nano cold cathode structure 112 achieves electron output by means of a field-induced electron emission mechanism. In theory, the nano cold cathode can obtain high-quality electron emission with a temporal and spatial characteristic that highly follows the trend of the potential barrier change, almost no time hysteresis, and high electron yield and current density, making it easy to achieve device integration and miniaturization. At the same time, commonly used nano cold cathode materials such as upright multi-walled carbon nanotubes, upright few-layer graphene, tungsten and other metals and their oxide nanomaterials have good interaction characteristics with lasers, providing an excellent solution for cathode selection and device development of photocathode electron guns. Specifically, through the synergistic excitation of nano cold cathode and photoelectricity, a DC bias is applied to the nano cold cathode, and the width and height of the cathode surface barrier are compressed, so that the electrons in the cathode can be more easily emitted under laser excitation; at the same time, through the appropriate device structure and laser coupling path, the cathode is fully immersed in laser excitation, so that a large number of electrons can transition to higher energy levels and form an emission current through above-threshold emission or tunneling emission, thereby effectively solving the defects of traditional photocathode electron gun devices such as low electron yield, low current density, low quantum efficiency, high emission threshold, high working environment requirements and short life.

[0088] Further, it also includes a vacuum housing 31;

[0089] The cathode structure 11 , the anode structure 12 , the focusing electrode structure 13 , and the focusing optical path 21 having conductive properties are located inside the vacuum housing, and the laser 22 is located outside the vacuum housing 31 .

[0090] Furthermore, the vacuum housing includes a metal housing 313, an electrode flange 312, a glass window 311, and an exhaust flange 314;

[0091] The glass window 311 is coaxially arranged with the focusing optical path 21 and is located between the laser 22 and the beam expander 211 ; the metal housing 313 is respectively connected to the electrode flange 312 , the exhaust flange 313 , and the glass window 311 .

[0092] The inner wall of the metal shell 313 is provided with an insulating layer or an insulating liner; the metal shell 313 is exhausted and vacuum-packaged to form the vacuum shell 31; the laser 22 is arranged outside the vacuum shell 31, and the laser 22 emits a continuous laser beam or a pulsed laser beam through the glass window 311 and through the focusing optical path 21, and then immerses and excites the nano cold cathode structure 112 on the cathode structure 11.

[0093] It should be noted that the collector 50 is connected to the metal shell to collect the generated electrons. If the electrons need to be output to other components for use, the collector 50 may not be provided, and the electrons may be connected to other components through a vacuum pipe.

[0094] The electron gun further comprises an outer gun body shell 32 , and the vacuum shell 31 and the laser 22 are placed inside the outer gun body shell 32 .

[0095] The side wall of the outer gun body shell 32 is provided with an electrode interface; the control electrode 40 is connected to an external driving and control circuit via the electrode interface.

[0096] The control electrode 40 is used to connect to an external driving circuit. When a positive voltage is used, the voltage applied to the anode structure 12 is no more than 5 kV, the voltage applied to the focusing electrode structure 13 is no more than 10 kV, and the cathode structure 11 is grounded.

[0097] When negative voltage driving is used, the voltage applied to the cathode structure 11 is not less than -10 kV at least, the voltage applied to the anode structure 12 is not less than the voltage applied to the cathode structure 11 at least and does not exceed the voltage applied to the focusing electrode structure 13 at most, and the voltage applied to the focusing electrode structure 13 is not less than the voltage applied to the anode structure 12 at least and does not exceed 0 V at most;

[0098] The DC bias electric field between the cathode structure 11 and the anode structure 12 acts on the nano cold cathode structure 112 on the cathode structure 11 , causing the nano cold cathode structure 112 to enter a critical electron emission state or an electron emission state.

[0099] In a specific embodiment, the electron gun further comprises a gun body housing 32, and the vacuum housing 31 and the laser 22 are placed inside the gun body housing 32. The housing of the electron gun in this embodiment comprises a gun body housing 32 and a vacuum housing 31; wherein the vacuum housing 31 and the laser 22 are placed inside the gun body housing 32; and the laser 22 is placed outside the vacuum housing 31.

[0100] In this embodiment, the side wall of the gun housing 32 is provided with an electrode interface; the electrode line 40 is connected to the external drive and control circuit through the electrode interface. The laser control line and power line 41, cathode electrode line 42, anode electrode line 43, and focusing electrode line 44 are electrically connected to different electrode interfaces respectively, and the laser control line and power line 41, cathode electrode line 42, anode electrode line 43, and focusing electrode line 44 are electrically connected to the external drive and control circuit through the electrode interface.

[0101] In this embodiment, the gun body shell 32 can be made of insulating materials such as plastic, ceramic, etc., or a composite insulating material containing multiple materials.

[0102] In this embodiment, Figure 12 to Figure 26 As shown, the nano cold cathode structure 112 is made of upright multi-walled carbon nanotubes with low work function and high aspect ratio, and its structure can be a cylinder, an elliptical cylinder, a prism, a cone, or a pyramid. Under the synergistic excitation of a focused continuous laser beam or a pulsed laser beam and a DC bias electric field, the nano cold cathode structure 112 can emit a large number of continuous electron beams or pulsed electron beams.

[0103] In a specific embodiment, the vacuum distance between the nano cold cathode structure 112 and the anode structure 12 is 1 mm; the vacuum distance between the focusing electrode structure 13 and the anode structure 12 is 0.5 mm.

[0104] In a specific embodiment, the electrode line 40 is used to connect to an external driving circuit. When a positive voltage is used for driving, the voltage applied to the anode structure 12 is 3 kV, the voltage applied to the focusing electrode structure 13 is 5 kV, and the cathode structure 11 is grounded (~0 V);

[0105] When negative voltage driving is used, the voltage applied to the cathode structure 11 is -5 kV, the voltage applied to the anode structure 12 is -2 kV, and the focusing pole structure 13 is grounded (~0 V);

[0106] The DC bias electric field between the cathode structure 11 and the anode structure 12 acts on the nano cold cathode structure 112 on the cathode structure 11, so that the nano cold cathode 112 structure enters a critical electron emission state or an electron emission state.

[0107] In a specific embodiment, the focal length of the first convex lens 213 and the second convex lens 214 in the focusing optical path structure 21 is 35.1 mm; the diameter of the first convex lens 213 and the second convex lens 214 is 25.4 mm; the first convex lens 213 and the second convex lens 214 are arranged coaxially facing each other, and the spacing along the straight line formed by the optical center is the sum of the focal lengths of the first convex lens 213 and the second convex lens 214; the magnification of the beam expander 211 is 10;

[0108] In a specific embodiment, the wavelength range of the laser emitted by the laser 22 is 400nm-2000nm, wherein the central wavelength is 1064nm; the output spot diameter of the laser 22 is 1mm; the laser 22 can output continuous laser or pulsed laser.

[0109] The continuous laser beam or pulsed laser beam emitted by the laser 22 passes through the focusing optical path structure 21 with an irradiation angle of 90° and an excitation light intensity of 10 7 W cm -2 The nano cold cathode structure 112 on the immersion-type excitation cathode structure 11 is made to generate a continuous electron beam or a pulse electron beam jointly regulated by a focused continuous laser beam or a pulse laser beam and a DC bias electric field.

[0110] The overall size of the photoelectric cooperative excitation nano cold cathode electron gun described in this embodiment after vacuum packaging is about 40cm×10cm×10cm, which is suitable for portable, integrated and miniaturized device equipment applications. Among them, an electrode interface is provided on one side of the gun body shell 32, and the electrode wires 40 (including laser control wires and power wires 41, focusing electrode wires 44, anode electrode wires 43, and cathode electrode wires 42) are connected to the external drive and control circuit through the electrode interface to apply a driving electric field and control to the small laser 22, the focusing electrode structure 13, the anode structure 12, and the cathode structure 11 respectively.

[0111] The cathode electron beam emission component 10 of the photoelectric cooperative excitation nano cold cathode electron gun described in this embodiment includes a cathode substrate structure 111, an anode structure 12, and a focusing electrode structure 13, which are machined using stainless steel with a machining accuracy of 0.05 mm. The diameter of each component is 2 cm, and the thickness is 2 mm, 1 mm, and 1 mm, respectively. Four assembly holes with a diameter of 2 mm are punched at the same position on each emission component, and electrode interfaces with a length of 5 mm and a width of 2 mm are extended at non-overlapping positions. The vacuum spacing between the tip of the nano cold cathode structure 112 and the center of the anode structure 12 is 200 μm, and the vacuum spacing between the anode structure 12 and the focusing electrode structure 13 is 2 mm. The diameters of the first through hole and the second through hole in the center of the anode structure 12 and the focusing electrode structure 13 are 2 mm and 1 mm, respectively.

[0112] The photoelectric cooperative excitation nano cold cathode electron gun described in this embodiment uses a focusing optical path structure to focus a continuous laser beam or a pulsed laser beam, and at the same time, the laser intensity in the optical path, especially at the focus of the first convex lens and the second convex lens, is increased by multiple superposition of incident light and reflected light, and then the nano cold cathode structure to which a DC bias electric field is applied is excited by the focused and superimposed continuous laser beam or pulsed laser beam, thereby directly emitting a continuous electron beam or a pulsed electron beam modulated by the continuous laser beam or the pulsed laser beam: on the one hand, it avoids the problem that the laser excitation is difficult to couple with the electric field due to electrode shielding in the traditional electron gun structure, and the gate absorption rate is high. On the other hand, it plays the advantages of photocathode electron gun and field emission electron gun in obtaining continuous electron beam or pulsed electron beam with low energy divergence, high temporal and spatial resolution and high current density. Innovatively, it realizes multiple superposition and focusing of incident light and reflected light through focusing optical path structure, effectively improving the laser intensity in the optical path, especially at the focus. Furthermore, it sets the nano cold cathode with DC bias at the focus, realizing immersion excitation of nano cold cathode by laser excitation, maximizing the coupling efficiency of laser excitation and DC electric field, and effectively improving the device performance of optoelectronic synergistic nano cold cathode electron gun.

[0113] The photoelectric cooperative excitation nano cold cathode electron gun described in this embodiment adopts a nano cold cathode structure with field-induced electron emission characteristics, which can obtain electron emission with high quantum efficiency, large current, high brightness, and low energy dispersion, reduce the power consumption and size of the device, and greatly improve the integration and miniaturization of the device. At the same time, through the coupling setting of the nano cold cathode structure and the focusing optical path structure, the high requirements of the electron gun on the excitation light source are greatly reduced, and the light intensity is reduced by 4 orders of magnitude, which further improves the current density, energy efficiency, and spatiotemporal resolution of the electron beam of the electron gun, and reduces the electron emission threshold.

[0114] The same or similar reference numerals correspond to the same or similar components;

[0115] The terms used in the drawings to describe positional relationships are only used for illustrative purposes and should not be construed as limiting this patent;

[0116] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A photoelectric synergistic excitation nano cold cathode electron gun, characterized in that: include: A cathode structure (11) having conductive properties, an anode structure (12), a focusing electrode structure (13), a laser (22), and a focusing optical path (21); After the laser (22) emits a laser beam through a focusing optical path (21), the laser beam is irradiated onto a cathode structure (11) having a conductive property; the cathode structure (11) having a conductive property generates electrons through laser excitation, and the electrons are emitted through an anode structure (12) and a focusing electrode structure (13); The focusing optical path (21) comprises a beam expander (211), a semi-reflecting mirror (212), a first convex lens (213), a second convex lens (214), and a reflecting mirror (215) arranged in sequence; the cathode structure having conductive properties is arranged between the first convex lens (213) and the second convex lens (214); The cathode structure (11) having conductive properties has at least one emission tip; The optical centers of the beam expander (211), the semi-reflecting mirror (212), the first convex lens (213), the second convex lens (214), the reflecting mirror (215) and an emission tip of the cathode structure (11) having conductive properties are all located on the same straight line; The laser (22) emits a laser beam which enters the focusing optical path (21) from one end of the beam expander (211).

2. The photoelectric cooperative excitation nano cold cathode electron gun according to claim 1, characterized in that: The materials of the anode structure (12) and the focusing electrode structure (13) are metal.

3. The photoelectric cooperative excitation nano cold cathode electron gun according to claim 1, characterized in that: The focal lengths of the first convex lens (213) and the second convex lens (214) are in the range of 10 mm to 100 mm, and the diameters are in the range of 10 mm to 100 mm. The distance between an emission tip of the cathode structure (11) having conductive properties and the first convex lens (213) is the focal length of the first convex lens (213), and the distance between an emission tip of the cathode structure having conductive properties and the second convex lens (214) is the focal length of the second convex lens (214).

4. The photoelectric cooperative excitation nano cold cathode electron gun according to claim 1, characterized in that: The magnification of the beam expander (211) is 1-50.

5. The photoelectric cooperative excitation nano cold cathode electron gun according to claim 1, characterized in that: The wavelength range of the laser emitted by the laser (22) is 300nm to 2400nm, and the output light spot diameter range is 0.1mm to 2cm.

6. The photoelectric cooperative excitation nano cold cathode electron gun according to claim 1, characterized in that: The spacing between the cathode structure (11) having conductive properties and the anode structure (12) is in the range of 0.01 mm to 10 mm, and the spacing between the focusing electrode structure (13) and the anode structure (12) is in the range of 0.01 mm to 10 mm.

7. The photoelectric cooperative excitation nano cold cathode electron gun according to claim 1, characterized in that: The angle range of the laser beam irradiating the cathode structure (11) with conductive properties is 30° to 90°, and the excitation light intensity range is 10 -3 W cm -2 ~10 12 W cm -2 .

8. The photoelectric cooperative excitation nano cold cathode electron gun according to claim 1, characterized in that: The cathode structure (11) having conductive properties comprises: a nano cold cathode structure (112) and a cathode substrate structure (111), wherein one end of the cathode substrate structure (111) is connected to the nano cold cathode structure (112); The material of the nano cold cathode structure (112) is any one of upright multi-walled carbon nanotubes, upright few-layer graphene, tungsten and its oxide nano needle tips, molybdenum and its oxide nano needle tips, and zinc oxide nano wires; The material of the cathode substrate structure (111) is metal.

9. The photoelectric cooperative excitation nano cold cathode electron gun according to claim 1, characterized in that: Also includes a vacuum housing (31); The cathode structure (11) with conductive properties, the anode structure (12), the focusing electrode structure (13), and the focusing optical path (21) are located inside the vacuum housing, and the laser (22) is located outside the vacuum housing (31).

10. The photoelectric cooperative excitation nano cold cathode electron gun according to claim 9, characterized in that: The vacuum housing comprises a metal housing (313), an electrode flange (312), a glass window (311), and an exhaust flange (314); The glass window (311) is coaxially arranged with the focusing optical path (21) and is located between the laser (22) and the beam expander (211); the metal housing (313) is respectively connected to the electrode flange (312), the exhaust flange (313), and the glass window (311).

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