A cascade coaxial virtual cathode reflex triode array and method of assembling same

Abstract

The present application relates to coaxial reflection triode and its assembling method, specifically relates to a kind of coaxial virtual cathode reflection triode array and its assembling method, solve the pulse hard X-ray utilization efficiency of plane type reflection triode is lower, application exists limitation, it is difficult to realize series connection, or the technical problems, such as the structure of coaxial reflection triode is complex, pulse hard X-ray utilization efficiency is lower.The present application is based on the coaxial reflection triode to remove the inner cathode, in the working process, electron passing through anode foil forms virtual cathode in the inside of anode;Through the circular hole of anode foil and suspension electrode installed on anode pedestal, and the circular hole of anode foil and ground cathode installed on suspension electrode, form two-stage series-connected triode array;Array arrangement is used to adjust radiation field distribution, improve the utilization efficiency of pulse hard X-ray;Through series connection work, it can be applied to large high-voltage pulse source, further improve the radiation intensity of pulse hard X-ray.

Description

Technical Field

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

[0002] Pulsed hard X-rays with photon energies ranging from 10keV to 100keV have important applications in the study of systematic electromagnetic pulse effects. The fundamental method for generating pulsed hard X-rays is to bombard high-Z materials (high atomic constant materials) with an intense pulsed electron beam to generate bremsstrahlung radiation. Currently, single-gap electron beam diodes are the primary method for generating pulsed hard X-rays. However, since the electron energy required for generating pulsed hard X-rays is below 300keV, the efficiency of generating pulsed hard X-rays via bremsstrahlung is low, and the injected power density is limited by the electron energy. Consequently, the energy flux of pulsed hard X-rays cannot meet application requirements. Therefore, it is necessary to develop new hard X-ray conversion loads to improve the injected power density, energy conversion efficiency, and hard X-ray utilization efficiency.

[0003] To achieve higher energy flux pulsed hard X-rays, researchers have developed series-parallel technology for electron beam diodes and reflective triodes. Using thick targets for electron beam diodes significantly absorbs low-energy radiation, significantly reducing the output of pulsed hard X-rays. Using thin targets, the remaining energy after a single interaction between the electrons and the target material remains unused, reducing the efficiency of pulsed hard X-ray conversion. In reflective triodes, electrons are repeatedly reflected between the cathode and anode, effectively utilizing their kinetic energy and improving the efficiency of converting electrons into pulsed hard X-rays.

[0004] According to the structure, the reflection transistor can be divided into planar reflection transistor and coaxial reflection transistor. The working principle of the planar reflection transistor is as follows: Figure 1 As shown, the electron beam 13, reflected by the two cathodes 11, penetrates the anode target 12 to generate pulsed hard X-rays. These pulsed hard X-rays radiate symmetrically in the forward and backward directions along the axis. Therefore, only one direction can be utilized in the irradiation test, resulting in low efficiency of pulsed hard X-ray utilization. Furthermore, the planar structure is difficult to implement in series operation. Due to the limited energy spectrum of the pulsed hard X-rays, it cannot be used as a high-voltage, high-power pulse source, thus presenting limitations.

[0005] The coaxial reflector triode can improve the conversion efficiency and utilization efficiency of pulsed hard X-rays, and solves the problem of series and 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, generating 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 coaxial reflectotransistors is that using a single large-sized coaxial anode target makes it difficult to effectively focus the pulsed hard X-rays outside the target onto the effector irradiation area, 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 of low utilization efficiency of pulsed hard X-rays of planar reflection transistors, limited application, and difficulty in series connection, as well as the complex structure and low utilization efficiency of pulsed hard X-rays of coaxial reflection transistors, and to provide a cascaded coaxial virtual cathode reflection transistor array and an assembly method thereof.

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

[0008] A cascaded coaxial virtual cathode reflective triode array is characterized in that it comprises a coaxially arranged anode foil group, an anode base, a suspension electrode, an insulation support for the suspension electrode, 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 the same number of anode foils arranged in parallel;

[0010] The anode base 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. A through hole is provided in the center of the anode base. The floating electrode insulating support passes through the through hole. Its lower end is fixed to 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 floating 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 floating electrode, and the lower ends are fixed to the anode base;

[0012] The lower end of the grounded outer cylinder is fixed to 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 in the grounded cathode, and the lower ends are fixed to the floating electrode.

[0014] The electrons gather inside the anode foil to form a virtual cathode, and the corresponding circular hole forms a coaxial virtual cathode reflective triode; the anode foil of the first anode foil group and the circular hole on the floating electrode form a first-stage coaxial virtual cathode reflective triode array, and the anode foil of the second anode foil group and the circular hole on the grounded cathode form a second-stage coaxial virtual cathode reflective 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 via a floating electrode to form a cascade coaxial virtual cathode reflection triode array.

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

[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 suspension electrode, the grounded cathode, the suspension electrode insulation support and the grounded outer cylinder is a vacuum degree of less than 1×10 -2 Pa vacuum environment.

[0019] Furthermore, the anode foil comprises a fixedly connected cylindrical body and a cylindrical base with threads; the cylindrical base is used to connect to 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 anode base is made of a non-ferromagnetic metal material.

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

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

[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 cascaded 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 to the upper end surface of the suspension electrode insulation support. Precisely adjust the position of the suspension electrode so that the gap between the anode foil and the corresponding circular hole on the suspension electrode 3 and the preset coaxial anode-cathode gap have an error of 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 to the upper end surface of the grounded outer cylinder, and precisely adjust the position of the grounded cathode so that the gap between the anode foil and the corresponding circular hole on the grounded cathode is less than 0.2 mm from the preset coaxial cathode-cathode gap.

[0034] Step 7: Seal the anode foil, anode base, suspension electrode, suspension electrode insulation support, grounded cathode and grounded outer cylinder 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.

[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, the 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 reflective triode array provided by the present invention adopts an array structure. Not only is the array structure realized in series, but when the coaxial virtual cathode reflective triodes are in operation, they are also connected in series in the circuit. By adjusting the number and impedance of the coaxial virtual cathode reflective triodes, power matching and voltage division control with the pulse source are achieved, which greatly reduces the difficulty of series operation and improves the transmission coupling efficiency of electric power.

[0038] 3. In the cascaded coaxial virtual cathode reflector 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, this can fully utilize the electron kinetic energy and greatly improve the conversion efficiency of pulsed hard X-rays. At the same time, the reflected low-energy electrons help to reduce the energy spectrum of the pulsed hard X-rays.

[0039] 4. In the cascaded coaxial virtual cathode reflector triode array provided by the present invention, the radiation field distribution of pulsed hard X-rays can be flexibly optimized by adjusting the position 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 series connection;

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

[0042] 7. In the cascaded 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 pulsed hard X-rays evenly distributed, and evenly divide the voltage between each level, thereby reducing the energy of the target electrons and ensuring the fidelity of the energy spectrum of the pulsed hard X-rays;

[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, which can prevent it from blocking the movement of electrons inside the anode foil;

[0044] 9. In the cascaded 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 This is a working principle diagram of an existing planar reflective triode;

[0046] Figure 2 This is a working principle diagram of an existing coaxial reflective triode;

[0047] Figure 3 Schematic diagram of the structure of an embodiment of the present invention;

[0048] Figure 4 This 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 assembly, 8-second anode foil assembly;

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

[0053] The following is a further detailed description of a cascaded 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 merely 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, floating electrode 3, grounded cathode 5, and floating electrode insulating support 4 are coaxially arranged with a grounded outer cylinder 6. The anode foil assembly includes a first anode foil assembly 7 and a second anode foil assembly 8, each of which consists of 30 parallel anode foils 1. The series and parallel connections between the anode foils 1 determine the impedance, so the number of anode foils 1 is determined by the required array impedance. The anode foil 1 consists of a fixed cylindrical body and a threaded cylindrical base. The cylindrical base is used to connect to the anode base 2 or the floating 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. It must have a smooth surface. The cylindrical base is made of aluminum and has threads on its outer surface. To prevent the cylindrical base from blocking electrons and pulsed hard X-rays, thereby reducing the conversion efficiency of pulsed hard X-rays, its length should be less than 2cm. If the cylindrical base is too long, it will block the movement of electrons within the cylindrical anode foil 1. The diameter, length and thickness of the cylindrical body and the tantalum foil directly affect the operating impedance of the coaxial virtual cathode reflection triode formed therefrom. The limitation on the size here can maintain the impedance of the coaxial virtual cathode reflection triode within an appropriate 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 the upper end is provided with double annular evenly distributed threaded holes, which are 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 its upper end is fixedly connected to the center of the suspension electrode 3, so that the suspension electrode 3 is insulated and in a potential suspension state. The suspension electrode insulating support 4 is a polyethylene or organic glass cylindrical insulating material with an average surface electric field strength of less than 50kV / cm to avoid insulation breakdown during operation. If necessary, grooves can be cut on its surface to increase the insulation distance.

[0056] The floating electrode 3 is provided with circular holes corresponding to the anode foils of the first anode foil assembly 7, and its edge is provided with threaded holes for mounting the second anode foil assembly 8. The upper end of the anode foil 1 of the first anode foil assembly 7 passes through the corresponding circular holes in the floating electrode 3, forming a coaxial cathode-cathode gap, and the lower end is fixed to the anode base 2. The floating electrode 3 is made of high-purity graphite with a thickness of 2mm to 5mm. A too thin floating electrode 3 will result in a low emission current and a high operating impedance of the coaxial virtual cathode reflector transistor. A too thick floating electrode 3 will reduce the electric field strength on the cathode surface.

[0057] The grounded outer cylinder 6 is a cylindrical cylinder made of stainless steel or aluminum. Its lower end 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. A threaded hole is opened at the upper end for fixing the grounded cathode 5.

[0058] The grounded cathode 5 is made of graphite with a thickness of 2mm to 5mm. It has circular holes corresponding to the anode foils of the second anode foil assembly 8. Its edges are coaxially mounted to the upper end of the grounded outer cylinder 6 using screws. The upper end of the anode foil 1 of the second anode foil assembly passes through the corresponding circular hole in the grounded cathode 5, and the lower end is fixed to the floating electrode 3. A too thin grounded cathode 5 will result in a low emission current and a high triode operating impedance. A too thick grounded cathode 5 will reduce the electric field strength on the cathode surface.

[0059] Electrons gather inside the anode foil 1 to form a virtual cathode 14, and the corresponding circular hole forms a coaxial virtual cathode reflective triode. The anode foil 1 is the anode of the coaxial virtual cathode reflective triode, and the corresponding circular hole is the cathode of the coaxial virtual cathode reflective triode. The gap between the anode foil 1 and the corresponding circular hole is the coaxial cathode-cathode gap of the coaxial virtual cathode reflective triode. Under the action of a high-voltage pulse, the cathode of the coaxial virtual cathode reflective triode emits electrons. 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 multiple times to hit the target, 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 acquire axial motion speed, and the average incident direction angle of the electrons on both sides is less than 180 degrees. The pulse X-rays generated by the electrons hitting the targets on both sides are then spatially superimposed, thereby improving the utilization efficiency of pulse hard X-rays.

[0060] The anode foil 1 of the first anode foil group 7 and the circular hole on the floating electrode 3 form a first-stage coaxial virtual cathode reflective 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-stage coaxial virtual cathode reflective triode array. The first-stage coaxial virtual cathode reflective triode array and the second-stage coaxial virtual cathode reflective triode array are connected in series via the floating electrode 3, forming a two-stage series circuit, together forming a cascaded coaxial virtual cathode reflective triode array.

[0061] By varying the number of individual tubes in the cascaded coaxial virtual cathode reflector transistor array, the load impedance and power source impedance are matched, and the arrangement is adjusted to uniformly distribute the radiation field. Simultaneously, the pulsed hard X-rays generated by each coaxial virtual cathode reflector transistor are superimposed on the effective radiation area, reducing the loss of pulsed hard X-rays outside the target and thereby improving the efficiency of pulsed hard X-ray utilization. In this embodiment, the cascaded coaxial virtual cathode reflector transistor array employs a coaxial ring layout, enabling multiple stages to operate in series in the axial direction. The series voltage divider between each stage reduces the energy of the target electrons and ensures the fidelity of the energy spectrum of the pulsed hard X-rays.

[0062] The working principle of the coaxial virtual cathode reflective triode provided in this embodiment is as follows: Figure 4 As shown, a positive high-voltage pulse is applied to a two-stage coaxial virtual cathode reflector. Under the action of the high-voltage pulse, an electron beam 13 is emitted from the surface of the circular aperture (cathode 11 of the coaxial virtual cathode reflector). Electron beam 13 is accelerated and energized by the electric field between the coaxial cathode and cathode. The high-energy electrons bombard anode foil 1, generating pulsed hard X-rays. Electrons that penetrate anode foil 1 (anode 12 of the coaxial virtual cathode reflector) form a virtual cathode 14 within anode foil 1, which reflects subsequent incident electrons and re-penetrates anode foil 1. Electrons travel back and forth between cathode 11 and virtual cathode 14, reflecting and hitting the target multiple times until their energy reaches zero. The multiple single-electrode array layout optimizes the uniformity of pulsed hard X-ray radiation and reduces pulsed hard X-ray losses outside the target, thereby improving electron energy conversion and utilization efficiency. Connecting the two-stage array in series reduces voltage, ensuring the fidelity of the hard X-ray energy spectrum. The pulsed hard X-rays are spatially superimposed, thereby increasing radiation intensity.

[0063] This embodiment removes the inner cathode from a coaxial reflectotransistor. During operation, electrons passing through the anode target form a virtual cathode 14 on the inner side of the anode, causing the electrons to reflect multiple times and hit the target, significantly improving the conversion efficiency of pulsed hard X-rays. This embodiment not only possesses the characteristics of a coaxial reflectotransistor but also significantly simplifies its structure. By using a small-sized anode conversion target and array arrangement, the radiation field distribution of pulsed hard X-rays can be flexibly optimized, reducing the loss of pulsed hard X-rays outside the target, thereby improving the utilization efficiency and energy flux of pulsed hard X-rays. By adjusting the number and impedance of individual tubes, power matching with the pulse source is easily achieved, improving the transmission coupling efficiency of electrical power. By achieving uniform voltage division in the array with the same number of individual tubes, the difficulty of series operation is significantly reduced. This embodiment can be used in large, high-voltage pulse sources. While ensuring the fidelity of the pulsed hard X-ray energy spectrum, the energy flux of pulsed hard X-rays 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 pulse source. The positive pulse voltage wave it generates is first loaded into the first-stage coaxial virtual cathode reflective triode array. Under the action of the positive pulse voltage wave, the circular hole opened in the floating electrode 3 forms a plasma emission center on its surface by explosive electron emission, and emits a high-current electron beam. The beam size of the high-current electron beam is limited by the space charge, causing the impedance of the first-stage coaxial virtual cathode reflective triode array to drop rapidly.

[0066] Step 2: In the initial stage of emitting a high-current electron beam from the first-stage coaxial virtual cathode reflection triode array, 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: As the voltage divider increases and the beam current increases, under the control of the space charge limited current, the first-stage coaxial virtual cathode reflective triode array and the second-stage coaxial virtual cathode reflective triode array enter the dynamic voltage divider stage.

[0068] Step 4: The electrons are accelerated by the electric field between the cathode and anode formed between the anode foil 1 and the circular hole and gain energy, forming high-energy electrons. The high-energy electrons bombard the anode foil 1 and 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, causing the high-energy electrons to reflect 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 further provides a method for assembling the above-mentioned cascaded coaxial virtual cathode reflective triode array to form a series structure, characterized by comprising the following steps:

[0072] Step 1: Cut the tantalum foil according to the radius of the anode foil 1, keeping it intact and flat. Attach the tantalum foil to a threaded aluminum cylinder, ensuring that the anode foil has a uniform radius and no wrinkles on the surface. Prepare 30 anode foils.

[0073] Step 2: Fix the floating electrode insulating support 4 to the center of the output end face of the positive polarity pulse source by 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 remains coaxial with the floating electrode insulating support 4 to avoid affecting the anode-cathode gap of the coaxial virtual cathode reflection triode.

[0075] Step 4: Thread 15 of the anode foils 1 onto the anode base 2. Then, secure the floating electrode 3 to the upper end surface of the floating electrode insulating support 4. Precisely adjust the position of the floating electrode 3 so that the gap between the anode foil 1 and the corresponding circular hole in the floating electrode 3 is within 0.2 mm of the preset coaxial cathode-cathode gap. During the installation process, be careful to avoid scratching the anode foil 1 against the corresponding circular hole in the floating electrode 3, which could damage the anode foil 1. The circular hole in the floating electrode 3 serves as the cathode of the coaxial virtual cathode reflector transistor, which emits electrons inward. Together with the anode foil 1 mounted on the anode base 2, they form the first-stage coaxial virtual cathode reflector transistor array.

[0076] Step 5: Install the grounding outer cylinder 6 on the grounding end face of the pulse source through a flange, ensuring that it is coaxial with the anode base 2.

[0077] Step 6: Thread the remaining 15 anode foils 1 onto the corresponding positions of the floating electrode 3. Then, secure the grounded cathode 5 to the upper end of the grounded outer cylinder 6. Finely adjust the position of the grounded cathode 5 so that the gap between the corresponding circular holes in the anode foil 1 and the grounded cathode 6 is within 0.2 mm of the preset coaxial cathode-cathode gap. The circular holes in the grounded cathode 5 serve as the cathodes of the coaxial virtual cathode reflector transistors (CTs) that emit electrons inward. Together with the anode foil 1 mounted on the floating electrode 3, they form the second-stage coaxial virtual cathode reflector transistor array.

[0078] Step 7: Seal the anode foil 1, anode base 2, suspension electrode 3, suspension electrode insulation support 4, grounded cathode 5 and grounded outer cylinder 6 in a vacuum of 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 by: 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 to 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 one to one with 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 in the floating electrode (3), and the lower end is fixed to 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 one to one with the anode foils (1) of the second anode foil group (8); the upper ends of the anode foils (1) of the second anode foil group (8) pass through the corresponding circular holes on the grounded cathode (5), and the lower ends are fixed on the floating electrode (3); The electrons are gathered inside the anode foil (1) to form a virtual cathode (14), and the corresponding circular hole 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-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) form a second-stage 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 suspension electrode (3), and together constitute 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 evenly mounted on the upper end of the anode base (2) in a double ring shape.

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) is 30.

4. The 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 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 to an anode base (2) or a 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: Install n / 2 anode foils (1) on the anode base (2), then fix the suspension electrode (3) on the upper end surface of the suspension electrode insulation support (4), and precisely adjust 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 face of the pulse source, ensuring that it is coaxial with the anode base (2); Step 6: Mount the remaining n / 2 anode foils (1) on the suspended electrode (3), 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 corresponding circular holes on the anode foil (1) and the grounded cathode (5) and the preset coaxial anode-cathode gap is less than 0.2 mm; Step 7: Seal the anode foil (1), anode base (2), suspension electrode (3), suspension electrode insulation support (4), grounded cathode (5) and 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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