Cascade coaxial virtual cathode reflection triode array and assembling method thereof

Abstract

The invention relates to a coaxial reflection triode and an assembling method thereof, in particular to a cascade coaxial virtual cathode reflection triode array and an assembling method thereof, and solves the problems that the utilization efficiency of pulse hard X rays of a planar reflection triode is low, application is limited, series connection is difficult to achieve, and the like. Or a coaxial reflection triode is complex in structure, and the utilization efficiency of the pulse hard X-ray is low. On the basis of a coaxial reflection triode, an inner side cathode is removed, and in the working process, electrons penetrating through an anode foil form a virtual cathode on the inner side of an anode; a two-stage series triode array is formed by the anode foil mounted on the anode base, the round hole in the suspension electrode, the anode foil mounted on the suspension electrode and the round hole in the grounding cathode; by adopting array arrangement, the radiation field distribution can be adjusted, and the utilization efficiency of pulse hard X-rays is improved; through series connection work, the device can be applied to a large-scale high-voltage pulse source, and the radiation intensity of pulse hard X-rays is further improved.

Description

Technical Field

[0001] The invention relates to a coaxial reflection triode and an assembly method thereof, in particular to a cascade coaxial virtual cathode reflection triode array and an assembly method thereof. Background Art

[0002] Pulsed hard X-rays with photon energies of 10keV to 100keV have important applications in the study of system electromagnetic pulse effects. Using high-current pulsed electron beams to bombard high-Z materials (high atomic coefficient materials) to produce bremsstrahlung is the basic means of obtaining pulsed hard X-rays. Currently, single-gap electron beam diodes are the main technical approach to generating pulsed hard X-rays. However, since the generation of pulsed hard X-rays requires electron energy to be lower than 300keV, the efficiency of generating pulsed hard X-rays through bremsstrahlung is low, and the injection power density is limited by the electron energy. The energy injection of pulsed hard X-rays cannot meet the application requirements. Therefore, it is necessary to develop a new type of hard X-ray conversion load to improve the injection power density, energy conversion efficiency, and hard X-ray utilization efficiency.

[0003] In order to obtain pulsed hard X-rays with higher energy injection, technicians have successively developed electron beam diode series-parallel technology and reflection triode series-parallel technology. If the electron beam diode uses a thick target, it will seriously absorb low-energy rays, greatly reducing the radiation output of pulsed hard X-rays; if a thin target is used, the remaining electron energy after the electron interacts with the target material once cannot be used, resulting in a decrease in the conversion efficiency of pulsed hard X-rays. In the reflection triode, the electrons are reflected multiple times in the gap between the cathode and the anode to hit the target, which can efficiently utilize the kinetic energy of the electrons and improve the efficiency of converting electrons into pulsed hard X-rays.

[0004] According to the structure, the reflection transistor can be divided into a planar reflection transistor and a coaxial reflection transistor. The working principle of the planar reflection transistor is as follows: Figure 1 As shown, the electron beam 13 is reflected by the two cathodes 11 and penetrates the anode target 12 to generate pulsed hard X-rays, which are symmetrically radiated in the axially forward and backward directions. Therefore, only one direction can be used in the irradiation test, and the utilization efficiency of pulsed hard X-rays is low. At the same time, it is difficult for the planar structure to achieve series operation. Under the limitation of the pulsed hard X-ray energy spectrum, it cannot be applied to high-voltage and high-power pulse sources, which has limitations.

[0005] The coaxial reflection triode can improve the conversion efficiency and utilization efficiency of pulsed hard X-rays, and solves the problem of series-parallel operation in structure. However, it has two cathodes 11 and an anode target 12. The electron beam 13 penetrates the anode target 12 under the action of the cathode 11 to generate two sets of parallel pulsed hard X-rays. The structure is complex, and the series voltage division needs to be achieved by finely adjusting the gap between the cathode and the anode, which is difficult to control. The working principle is as follows: Figure 2Another problem with the coaxial reflectotransistor is that it is difficult to effectively focus the pulsed hard X-rays outside the target on the effector irradiation area when using a single large-sized coaxial anode target, resulting in low efficiency in the utilization of pulsed hard X-rays. Summary of the invention

[0006] The purpose of the present invention is to solve the technical problems that the planar reflection triode has low pulse hard X-ray utilization efficiency, application limitations, and difficulty in series connection, and the coaxial reflection triode has a complex structure and low pulse hard X-ray utilization efficiency, and to provide a cascaded coaxial virtual cathode reflection triode array and an assembly method thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A cascade coaxial virtual cathode reflective triode array, which is special in that it comprises a coaxially arranged anode foil group, an anode base, a suspension electrode, a suspension electrode insulating support, a grounded cathode and a grounded outer cylinder;

[0009] The anode foil group includes a first anode foil group and a second anode foil group, wherein the first anode foil group and the second anode foil group include anode foils of the same number and arranged in parallel;

[0010] The anode base is used to realize the introduction of electric power, and its lower end is coaxially fixed on the output end face of the positive polarity pulse source. A through hole is provided at the center of the anode base, and the floating electrode insulating support passes through the through hole. Its lower end is fixed at the center of the output end face of the positive polarity pulse source, and its upper end is fixedly connected to the center of the floating electrode.

[0011] The suspension electrode is provided with circular holes corresponding to the anode foils of the first anode foil group; the upper ends of the anode foils of the first anode foil group pass through the corresponding circular holes on the suspension electrode, and the lower ends are fixed on the anode base;

[0012] The lower end of the grounded outer cylinder is fixed on the grounded end surface of the positive polarity pulse source and is coaxially arranged with the anode base;

[0013] The grounded cathode is coaxially mounted on the upper end of the grounded outer cylinder, and is provided with circular holes corresponding to the anode foils of the second anode foil group; the upper ends of the anode foils of the second anode foil group pass through the corresponding circular holes on the grounded cathode, and the lower ends are fixed on the floating electrode;

[0014] The electrons are gathered inside the anode foil to form a virtual cathode, and the corresponding circular hole forms a coaxial virtual cathode reflection triode; the anode foil of the first anode foil group and the circular hole on the suspended electrode form a first-level coaxial virtual cathode reflection triode array, and the anode foil of the second anode foil group and the circular hole on the grounded cathode form a second-level coaxial virtual cathode reflection triode array;

[0015] The first-stage coaxial virtual cathode reflection triode array and the second-stage coaxial virtual cathode reflection triode array are connected in series through a suspended electrode to form a cascade coaxial virtual cathode reflection triode array.

[0016] Furthermore, the anode foils in the first anode foil group are in a double ring shape and are evenly installed on the upper end of the anode base.

[0017] Furthermore, the number of anode foils in the first anode foil group and the second anode foil group is 30.

[0018] Furthermore, the working environment of the anode base, the suspended electrode, the grounded cathode, the suspended electrode insulation support and the grounded outer cylinder is a vacuum environment of less than 1×10 -2 Pa vacuum environment.

[0019] Furthermore, the anode foil comprises a fixedly connected cylindrical body and a threaded cylindrical base; the cylindrical base is used to connect the anode base or the suspended electrode;

[0020] The cylindrical body is made of high-purity tantalum foil with a thickness of 10 μm to 20 μm, a diameter of 2 cm to 4 cm, and a length of 6 cm to 10 cm;

[0021] The cylindrical base is made of aluminum and has a length of less than 2 cm.

[0022] Furthermore, the material of the anode base is a non-ferromagnetic metal material.

[0023] Furthermore, the suspension electrode is made of high-purity graphite electrode with a thickness of 2 mm to 5 mm;

[0024] The grounded cathode is made of graphite material with a thickness of 2 mm to 5 mm.

[0025] Furthermore, the suspension electrode insulation support is a polyethylene or organic glass columnar insulation material, and the average surface electric field strength is less than 50 kV / cm.

[0026] Furthermore, the grounded outer cylinder is a cylindrical cylinder made of stainless steel or aluminum.

[0027] The present invention also provides an assembly method of the above-mentioned cascade coaxial virtual cathode reflective triode array, which is special in that it includes the following steps:

[0028] Step 1, assembling n anode foils, wherein n is an even number greater than 10;

[0029] Step 2, fix the suspension electrode insulation support at the center of the output end face of the positive polarity pulse source as an installation reference;

[0030] Step 3, fix the anode base on the output end face of the positive polarity pulse source so that it is coaxial with the suspension electrode insulation support;

[0031] Step 4: Install n / 2 anode foils on the anode base, then fix the suspension electrode on the upper end surface of the suspension electrode insulation support, and precisely adjust the position of the suspension electrode so that the error between the gap between the anode foil and the corresponding circular hole on the suspension electrode 3 and the preset coaxial anode-cathode gap is less than 0.2 mm;

[0032] Step 5: Install the grounding outer cylinder on the grounding end face of the pulse source, ensuring that it is coaxial with the anode base;

[0033] Step 6: Install the remaining n / 2 anode foils on the suspended electrode, then fix the grounded cathode on the upper end surface of the grounded outer cylinder, and precisely adjust the position of the grounded cathode so that the error between the gap between the anode foil and the corresponding circular hole on the grounded cathode and the preset coaxial cathode-cathode gap is less than 0.2 mm;

[0034] Step 7: seal the anode foil, anode base, suspension electrode, suspension electrode insulation support, grounded cathode and grounded outer cylinder in a vacuum less than 1×10 -2 Pa vacuum environment, the assembly of the cascade coaxial virtual cathode reflection triode array was completed.

[0035] Compared with the prior art, the present invention has the following beneficial technical effects:

[0036] 1. In the cascaded coaxial virtual cathode reflective triode array provided by the present invention, a virtual cathode is formed on the inner side of the anode foil, thereby simplifying the coaxial reflective triode structure;

[0037] 2. The cascaded coaxial virtual cathode reflection triode array provided by the present invention adopts an array structure, which not only realizes series connection in structure, but also realizes series connection in the circuit when the coaxial virtual cathode reflection triode is working. By adjusting the number and impedance of the coaxial virtual cathode reflection triode, power matching and voltage division control with the pulse source are realized, which greatly reduces the difficulty of series connection and improves the transmission coupling efficiency of electric power.

[0038] 3. In the cascade coaxial virtual cathode reflective triode array provided by the present invention, electrons repeatedly move between the cathode and the virtual cathode and hit the target multiple times. Compared with the single-gap electron beam diode, the kinetic energy of electrons can be fully utilized, and the conversion efficiency of pulsed hard X-rays can be greatly improved. At the same time, the reflected low-energy electrons are conducive to reducing the energy spectrum of pulsed hard X-rays;

[0039] 4. In the cascaded coaxial virtual cathode reflective triode array provided by the present invention, the radiation field distribution of pulsed hard X-rays can be flexibly arranged and optimized by adjusting the positions of the anode foil and its corresponding circular hole, thereby reducing the loss of pulsed hard X-rays outside the target and improving the radiation intensity of pulsed hard X-rays;

[0040] 5. In the cascaded coaxial virtual cathode reflective triode array provided by the present invention, voltage division control can be achieved by adjusting the number of anode foils, greatly reducing the difficulty of cascade operation;

[0041] 6. The cascaded coaxial virtual cathode reflector triode array provided by the present invention can be applied to large-scale high-voltage pulse sources. Under the premise of ensuring the fidelity of the pulse hard X-ray energy spectrum, the energy injection of the pulse hard X-ray can be further improved through spatial superposition;

[0042] 7. In the cascade coaxial virtual cathode reflective triode array provided by the present invention, the anode foils in the first anode foil group are evenly distributed in a double ring shape, which can make the radiation field of the pulse hard X-ray evenly distributed, and evenly divide the pressure between each level, reduce the target electron energy, and ensure the fidelity of the energy spectrum of the pulse hard X-ray;

[0043] 8. In the cascade coaxial virtual cathode reflective triode array provided by the present invention, the length of the cylindrical base is less than 2 cm, so as to avoid blocking the movement of electrons inside the anode foil;

[0044] 9. In the cascade coaxial virtual cathode reflective triode array provided by the present invention, the material of the anode base is a non-ferromagnetic metal material, which can avoid the generation of additional magnetic fields that interfere with the movement of electrons. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is the working principle diagram of the existing planar reflection triode;

[0046] Figure 2 It is the working principle diagram of the existing coaxial reflection triode;

[0047] Figure 3 It is a structural schematic diagram of an embodiment of the present invention;

[0048] Figure 4 is a working principle diagram of an embodiment of the present invention;

[0049] The following are the descriptions of the reference numerals:

[0050] 1- anode foil, 2- anode base, 3- suspension electrode, 4- suspension electrode insulation support, 5- grounded cathode,

[0051] 6-grounded outer cylinder, 7-first anode foil group, 8-second anode foil group;

[0052] 11- cathode, 12- anode target, 13- electron beam, 14- virtual cathode. DETAILED DESCRIPTION

[0053] The following is a further detailed description of a cascade coaxial virtual cathode reflective triode array and its assembly method proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0054] A cascaded coaxial virtual cathode reflective triode array comprises a coaxially arranged anode foil group, an anode base 2, a suspension electrode 3, a suspension electrode insulating support 4, a grounded cathode 5 and a grounded outer cylinder 6. Figure 1 As shown, the anode base 2, the suspended electrode 3, the grounded cathode 5, the suspended electrode insulating support 4 and the grounded outer cylinder 6 are coaxially arranged. The anode foil group includes a first anode foil group 7 and a second anode foil group 8, and the first anode foil group 8 and the second anode foil group 8 each include 30 parallel anode foils 1. The series and parallel connection between the anode foils 1 determines the impedance, so the number of anode foils 1 is determined by the required array impedance. The anode foil 1 includes a fixedly connected cylindrical body and a threaded cylindrical base, and the cylindrical base is used to connect the anode base 2 or the suspended electrode 3. The cylindrical body is made of high-purity tantalum foil with a thickness of 10μm to 20μm, a diameter of 2cm to 4cm, and a length of 6cm to 10cm, and its surface is required to be flat. The material of the cylindrical base is aluminum, and threads are arranged on the outer surface. In order to avoid the cylindrical base blocking electrons and pulsed hard X-rays and reducing the conversion efficiency of pulsed hard X-rays, its length is less than 2cm. If the cylindrical base is too long, it will block the movement of electrons inside the cylindrical anode foil 1. The diameter and length of the cylindrical body and the thickness of the tantalum foil directly affect the working impedance of the coaxial virtual cathode reflection triode formed by the cylindrical body. The limitation on the size here can maintain the impedance of the coaxial virtual cathode reflection triode within a suitable range.

[0055] The anode base 2 is used to realize the introduction of electric power. Its lower end is coaxially fixed to the output end face of the positive polarity pulse source by screws, and a double annular evenly distributed threaded hole is opened at the upper end, and the threaded hole is used to install the first anode foil group 7. The material of the anode base 2 is a non-ferromagnetic metal material. In this embodiment, stainless steel or aluminum is used. A through hole is provided in the center of the anode base 2, and the suspension electrode insulating support 4 passes through the through hole. Its lower end is fixed to the center of the output end face of the positive polarity pulse source by screws, and the upper end is fixedly connected to the center of the suspension electrode 3, so that the suspension electrode 3 is in an insulated and potential suspended state. The suspension electrode insulating support 4 is a polyethylene or organic glass columnar insulating material, and the average surface electric field strength is less than 50kV / cm to avoid insulation breakdown during operation. If necessary, grooves can be opened on its surface to increase the insulation distance.

[0056] The suspension electrode 3 is provided with circular holes corresponding to the anode foils of the first anode foil group 7, and the edge is provided with threaded holes for installing the second anode foil group 8. The upper end of the anode foil 1 of the first anode foil group 7 passes through the corresponding circular hole on the suspension electrode 3 to form a coaxial cathode-cathode gap, and the lower end is fixed on the anode base 2. The suspension electrode 3 adopts a high-purity graphite electrode with a thickness of 2mm to 5mm. If the thickness of the suspension electrode 3 is too low, the emission current will be small, making the working impedance of the coaxial virtual cathode reflection triode high, and if the thickness is too high, the electric field strength on the cathode surface will be reduced.

[0057] The grounded outer cylinder 6 is a cylindrical cylinder made of stainless steel or aluminum, the lower end of which is fixed to the grounded end surface of the positive polarity pulse source through a flange, and is coaxially arranged with the anode base 2 , and a threaded hole for fixing the grounded cathode 5 is opened at the upper end.

[0058] The ground cathode 5 is made of graphite material with a thickness of 2 mm to 5 mm, and is provided with circular holes corresponding to the anode foils of the second anode foil group 8, and the edge is coaxially mounted on the upper end of the ground outer cylinder 6 by screws. The upper end of the anode foil 1 of the second anode foil group passes through the corresponding circular hole on the ground cathode 5, and the lower end is fixed on the floating electrode 3. If the thickness of the ground cathode 5 is too low, the emission current will be small and the working impedance of the triode will be high. If the thickness is too high, the electric field strength on the cathode surface will be reduced.

[0059] Electrons gather inside the anode foil 1 to form a virtual cathode 14, and the corresponding circular hole constitutes a coaxial virtual cathode reflection triode. The anode foil 1 is the anode of the coaxial virtual cathode reflection triode, and the corresponding circular hole is the cathode of the coaxial virtual cathode reflection triode. The gap between the anode foil 1 and the corresponding circular hole is the coaxial cathode-cathode gap of the coaxial virtual cathode reflection triode. Under the action of a high voltage pulse, the cathode of the coaxial virtual cathode reflection triode emits electrons, and after penetrating the anode, the electrons gather on the inside of the anode to form a virtual cathode 14. The electrons reflect back and forth between the cathode and the virtual cathode for multiple times, which can fully utilize the electron energy and improve the efficiency of pulse hard X-ray generation. Under the action of the beam self-magnetic field, the electrons obtain axial motion speed, and the average incident direction angle of the electrons on both sides is less than 180 degrees. The pulsed X-rays generated by the electrons on both sides are then superimposed in space, thereby improving the utilization efficiency of pulsed hard X-rays.

[0060] The anode foil 1 of the first anode foil group 7 and the circular hole on the floating electrode 3 constitute a first-stage coaxial virtual cathode reflection triode array, and the anode foil 1 of the second anode foil group 8 and the circular hole on the grounded cathode 5 constitute a second-stage coaxial virtual cathode reflection triode. The first-stage coaxial virtual cathode reflection triode array and the second-stage coaxial virtual cathode reflection triode array are connected in series through the floating electrode 3 to form a two-stage series circuit, which together constitute a cascade coaxial virtual cathode reflection triode array.

[0061] By changing the number of single tubes in the cascaded coaxial virtual cathode reflection triode array, the load impedance and the power source impedance are matched, and the arrangement is adjusted to adjust the radiation field so that it is evenly distributed. At the same time, the pulsed hard X-rays generated by each coaxial virtual cathode reflection triode are superimposed on the effective radiation area, reducing the loss of pulsed hard X-rays outside the target, thereby improving the utilization efficiency of pulsed hard X-rays. In this embodiment, the cascaded coaxial virtual cathode reflection triode array adopts a coaxial ring layout, and can work in series in multiple stages in the axial direction. The series voltage is divided between each stage to reduce the target electron energy and ensure the energy spectrum fidelity of the pulsed hard X-ray.

[0062] The working principle of the coaxial virtual cathode reflection triode provided in this embodiment is as follows: Figure 4 As shown, a positive high voltage pulse is loaded onto a two-stage coaxial virtual cathode reflection triode. Under the action of the high voltage pulse, an electron beam 13 is emitted from the surface of the circular hole (cathode 11 of the coaxial virtual cathode reflection triode). The electron beam 13 is accelerated by the coaxial positive and negative gap electric field and obtains energy. The high-energy electrons bombard the anode foil 1 to produce pulsed hard X-rays. After penetrating the anode foil 1 (anode 12 of the coaxial virtual cathode reflection triode), the electrons form a virtual cathode 14 inside the anode foil 1, and reflect the subsequent incident electrons to penetrate the anode foil 1 again. The electrons reciprocate between the cathode 11 and the virtual cathode 14, and reflect the target multiple times until the energy is zero. The layout of multiple single-tube arrays is conducive to optimizing the radiation uniformity of pulsed hard X-rays, reducing the loss of pulsed hard X-rays outside the target, thereby improving the efficiency of electron energy conversion and utilization. The two-stage array is connected in series to reduce the voltage to ensure the fidelity of the hard X-ray energy spectrum, and the pulsed hard X-rays are superimposed in space, thereby improving the radiation intensity.

[0063] This embodiment removes the inner cathode on the basis of the coaxial reflection triode. During operation, the electrons passing through the anode target form a virtual cathode 14 on the inner side of the anode, so that the electrons reflect the target multiple times, which can greatly improve the conversion efficiency of pulsed hard X-rays. It not only has the characteristics of a coaxial reflection triode, but also greatly simplifies the structure of the coaxial reflection triode. By adopting a small-sized anode conversion target and array arrangement, the radiation field distribution of the pulsed hard X-ray can be flexibly arranged and optimized, and the loss of the pulsed hard X-ray outside the target can be reduced, thereby improving the utilization efficiency and energy injection of the pulsed hard X-ray; by adjusting the number and impedance of single tubes, it is easy to achieve power matching with the pulse source and improve the transmission coupling efficiency of the electric power; by achieving uniform voltage division of the array with the same number of single tubes, the difficulty of series operation is greatly reduced, and it can be used for large-scale high-voltage pulse sources. Under the premise of ensuring the fidelity of the pulsed hard X-ray energy spectrum, the energy injection of the pulsed hard X-ray can be further improved through spatial superposition.

[0064] The cascaded coaxial virtual cathode reflector triode array provided in this embodiment is used to generate pulsed hard X-rays, and its working process mainly includes the following steps:

[0065] Step 1, turn on the positive polarity pulse source, and the positive polarity pulse voltage wave generated by it is first loaded into the first-stage coaxial virtual cathode reflection triode array. Under the action of the positive polarity pulse voltage wave, the circular hole opened on the suspension electrode 3 forms a plasma emission center on its surface in an explosive electron emission manner, and emits a high-current electron beam. The beam current size of the high-current electron beam is limited by the space charge, so that the impedance of the first-stage coaxial virtual cathode reflection triode array drops rapidly.

[0066] Step 2, in the initial stage of the first-stage coaxial virtual cathode reflection triode array emitting a high-current electron beam, the second-stage coaxial virtual cathode reflection triode array is in an open circuit state. As the impedance of the first-stage coaxial virtual cathode reflection triode array decreases, the voltage divided by the first-stage coaxial virtual cathode reflection triode array is rapidly loaded onto the second-stage coaxial virtual cathode reflection triode array, and electrons begin to be emitted from the circular hole on the grounded cathode 5, forming a series loop with the first-stage coaxial virtual cathode reflection triode array.

[0067] Step 3: With the increase of the voltage division and the beam current, under the control of the space charge limited current, the first-stage coaxial virtual cathode reflection triode array and the second-stage coaxial virtual cathode reflection triode array enter the dynamic voltage division stage.

[0068] Step 4: The electrons are accelerated by the cathode-cathode gap electric field formed between the anode foil 1 and the circular hole and gain energy to form high-energy electrons. The high-energy electrons bombard the anode foil 1 to generate pulsed hard X-rays.

[0069] Step 5: Some of the high-energy electrons penetrate the anode foil 1 and gather inside it, and the electron density increases to form a virtual cathode 14. The virtual cathode 14 reflects the electrons gathered in the anode foil 1, so that the high-energy electrons are reflected multiple times between the cathode and the anode and penetrate the anode foil 1, continuously generating pulsed hard X-rays until the high-energy electrons are absorbed by the anode foil 1.

[0070] The self-magnetic field of the beam makes the electrons have axial velocity during the reflection process. The pulsed hard X-rays radiated by the electrons on both sides can be superimposed on each other in the effect experimental area, forming a large-area, high-intensity, and realistic energy spectrum pulsed hard X-ray radiation field, thereby improving the conversion efficiency and utilization efficiency of pulsed hard X-rays.

[0071] This embodiment also provides a method for assembling the above-mentioned cascade coaxial virtual cathode reflective triode array to form a series structure, which is characterized by comprising the following steps:

[0072] Step 1: Calculate the circumference of the anode foil 1 according to its radius and cut the tantalum foil to keep it intact and flat. Paste the tantalum foil onto a threaded aluminum cylinder to ensure that the radius of the anode foil is uniform and the surface has no wrinkles. Prepare 30 anode foils.

[0073] Step 2: Fix the suspension electrode insulating support 4 to the center of the output end face of the positive polarity pulse source by means of screws as an installation reference.

[0074] Step 3: fix the anode base 2 on the output end face of the positive polarity pulse source so that it is coaxial with the suspension electrode insulating support 4 to avoid affecting the anode-cathode gap of the coaxial virtual cathode reflection triode.

[0075] Step 4, 15 of the anode foils 1 are installed on the anode base 2 by threading, and then the suspension electrode 3 is fixed on the upper end surface of the suspension electrode insulating support 4, and the position of the suspension electrode 3 is precisely adjusted so that the error between the gap between the anode foil 1 and the corresponding circular hole on the suspension electrode 3 and the preset coaxial cathode and cathode gap is less than 0.2mm. When installing the anode foil 1, it is necessary to avoid the anode foil 1 and the corresponding circular hole on the suspension electrode 3 from scratching, thereby damaging the anode foil 1. The circular hole on the suspension electrode 3 serves as the cathode of the coaxial virtual cathode reflective triode that emits electrons inward, and forms the first-level coaxial virtual cathode reflective triode array with the anode foil 1 installed on the anode base 2.

[0076] Step 5: Install the grounded outer cylinder 6 on the grounded end surface of the pulse source through a flange to ensure that it is coaxial with the anode base 2.

[0077] Step 6: Install the remaining 15 anode foils 1 on the corresponding positions of the suspension electrode 3 through threads, then fix the grounded cathode 5 on the upper end surface of the grounded outer cylinder 6, and precisely adjust the position of the grounded cathode 5 so that the error between the gap between the anode foil 1 and the corresponding circular holes on the grounded cathode 6 and the preset coaxial cathode-cathode gap is less than 0.2 mm. The circular hole on the grounded cathode 5 serves as the cathode of the coaxial virtual cathode reflective triode that emits electrons inward, and together with the anode foil 1 installed on the suspension electrode 3, forms a second-stage coaxial virtual cathode reflective triode array.

[0078] Step 7: seal the anode foil 1, the anode base 2, the suspended electrode 3, the suspended electrode insulating support 4, the grounded cathode 5 and the grounded outer cylinder 6 in a vacuum less than 1×10 -2 The assembly of the triode array is completed in a vacuum environment of Pa.

Claims

1. A cascaded coaxial virtual cathode reflective triode array, characterized in that: It comprises a coaxially arranged anode foil group, an anode base (2), a suspended electrode (3), a suspended electrode insulating support (4), a grounded cathode (5) and a grounded outer cylinder (6); The anode foil group comprises a first anode foil group (7) and a second anode foil group (8), wherein the first anode foil group (7) and the second anode foil group (8) comprise anode foils (1) of the same number and arranged in parallel; The anode base (2) is used to realize the introduction of electric power, and its lower end is coaxially fixed on the output end face of the positive polarity pulse source. A through hole is provided at the center of the anode base (2), and the suspension electrode insulating support (4) passes through the through hole. Its lower end is fixed at the center of the output end face of the positive polarity pulse source, and its upper end is fixedly connected to the center of the suspension electrode (3); The floating electrode (3) is provided with circular holes corresponding to the anode foils (1) in the first anode foil group (7); the upper end of the anode foil (1) in the first anode foil group (7) passes through the corresponding circular hole on the floating electrode (3), and the lower end is fixed on the anode base (2); The lower end of the grounded outer cylinder (6) is fixed on the grounded end surface of the positive polarity pulse source and is coaxially arranged with the anode base (2); The grounded cathode (5) is coaxially mounted on the upper end of the grounded outer cylinder (6), and is provided with circular holes corresponding to the anode foils (1) of the second anode foil group (8) one by one; the upper end of the anode foil (1) of the second anode foil group (8) passes through the corresponding circular hole on the grounded cathode (5), and the lower end is fixed on the floating electrode (3); The electrons are gathered inside the anode foil (1) to form a virtual cathode (14), and the circular hole corresponding thereto forms a coaxial virtual cathode reflection triode; the anode foil (1) of the first anode foil group (7) and the circular hole on the suspended electrode (3) form a first-level coaxial virtual cathode reflection triode array, and the anode foil (1) of the second anode foil group (8) and the circular hole on the grounded cathode (5) form a second-level coaxial virtual cathode reflection triode array; The first-stage coaxial virtual cathode reflection triode array and the second-stage coaxial virtual cathode reflection triode array are connected in series via a suspended electrode (3), and together form a cascaded coaxial virtual cathode reflection triode array.

2. The cascaded coaxial virtual cathode reflective triode array according to claim 1, characterized in that: The anode foil (1) in the first anode foil group (7) is in the form of a double ring and is evenly mounted on the upper end of the anode base (2).

3. The cascaded coaxial virtual cathode reflective triode array according to claim 2, characterized in that: The number of anode foils (1) in the first anode foil group (7) and the second anode foil group (8) are both 30.

4. A cascaded coaxial virtual cathode reflective triode array according to any one of claims 1 to 3, characterized in that: The working environment of the anode foil group, the anode base (2), the suspended electrode (3), the grounded cathode (5), the suspended electrode insulating support (4) and the grounded outer cylinder (6) is a vacuum environment with a degree of less than 1×10 -2 Pa vacuum environment.

5. The cascaded coaxial virtual cathode reflective triode array according to claim 4, characterized in that: The anode foil (1) comprises a fixedly connected cylindrical body and a threaded cylindrical base; the cylindrical base is used to connect the anode base (2) or the suspended electrode (3); The cylindrical body is made of high-purity tantalum foil with a thickness of 10 μm to 20 μm, a diameter of 2 cm to 4 cm, and a length of 6 cm to 10 cm; The cylindrical base is made of aluminum and has a length of less than 2 cm.

6. The cascaded coaxial virtual cathode reflective triode array according to claim 5, characterized in that: The material of the anode base (2) is a non-ferromagnetic metal material.

7. The cascaded coaxial virtual cathode reflective triode array according to claim 6, characterized in that: The suspension electrode (3) is a high-purity graphite electrode with a thickness of 2 mm to 5 mm; The grounded cathode (5) is made of graphite material with a thickness of 2 mm to 5 mm.

8. The cascaded coaxial virtual cathode reflective triode array according to claim 7, characterized in that: The suspension electrode insulating support (4) is a polyethylene or organic glass columnar insulating material, and its surface average electric field strength is less than 50 kV / cm.

9. The cascaded coaxial virtual cathode reflective triode array according to claim 8, characterized in that: The grounded outer cylinder (6) is a cylindrical cylinder made of stainless steel or aluminum.

10. A method for assembling the cascaded coaxial virtual cathode reflective triode array according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1, assembling n anode foils (1), wherein n is an even number greater than 10; Step 2, fix the suspension electrode insulation support (4) at the center of the output end face of the positive polarity pulse source as an installation reference; Step 3, fix the anode base (2) on the output end face of the positive polarity pulse source so that it is coaxial with the suspension electrode insulation support (4); Step 4, installing n / 2 anode foils (1) on the anode base (2), then fixing the suspension electrode (3) on the upper end surface of the suspension electrode insulation support (4), and precisely adjusting the position of the suspension electrode (3) so that the error between the gap between the anode foil (1) and the corresponding circular hole on the suspension electrode (3) and the preset coaxial anode-cathode gap is less than 0.2 mm; Step 5, install the grounded outer cylinder (6) on the grounded end surface of the pulse source, ensuring that it is coaxial with the anode base (2); Step 6, installing the remaining n / 2 anode foils (1) on the suspended electrode (3), then fixing the grounded cathode (5) on the upper end surface of the grounded outer cylinder (6), and precisely adjusting the position of the grounded cathode (5) so that the error between the gap between the corresponding circular holes on the anode foil (1) and the grounded cathode (6) and the preset coaxial anode-cathode gap is less than 0.2 mm; Step 7: seal the anode foil (1), the anode base (2), the suspended electrode (3), the suspended electrode insulating support (4), the grounded cathode (5) and the grounded outer cylinder (6) in a vacuum of less than 1×10 -2 Pa vacuum environment, the assembly of the cascade coaxial virtual cathode reflection triode array was completed.

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