Large-rotation magnetic control injection type electron gun

Abstract

The invention discloses a large-rotation magnetic control injection type electron gun which comprises a shell, a magnet assembly arranged on the outer circumferential face of the shell in a sleeving mode, a cathode assembly and an anode, wherein the cathode assembly and the anode are arranged in the shell. The cathode assembly comprises a first cathode, a second cathode and a third cathode which are coaxially nested from inside to outside; the first cathode and the shell are coaxially arranged, the first cathode comprises a first step surface, a second step surface and a transition inclined surface connecting the first step surface and the second step surface, and the second step surface is located on the side, close to the anode, of the first step surface; the surface of one side, close to the anode, of the second cathode is an emission surface, and the emission surface is an inclined surface formed by recessing in the direction away from the anode; the anode and the first cathode are coaxially arranged, the anode is an annular cylinder, and an electron beam channel for an electron beam to pass through is formed in the center of the anode; the end faces of the sides, close to each other, of the third cathode and the anode are both of a multi-face combined structure.

Description

Technical Field

[0001] The present invention relates to the technical field of high-power wave sources. More specifically, it relates to a large gyrotron magnetron injection gun. Background Art

[0002] High-power gyrotrons are widely used in advanced radars, microwave weapons, electronic countermeasures and jamming, nuclear fusion plasma heating and current drive, plasma diagnostics, high-density data communication, medical treatment, navigation and other fields. The gyrotron uses a magnetron injection gun, which can reduce the spread of electron beam parameters and push the performance of the gyrotron to a certain extreme. However, as the performance parameters of the gyrotron gradually advance towards high frequency, high efficiency, and wide bandwidth, its various performance parameters are approaching the limit parameters. The strong magnetic field is an important factor hindering the development of gyrotron devices towards higher frequencies. In the prior art, the performance of the gyrotron is generally improved by increasing the interaction harmonic number to reduce the magnetic field strength. However, increasing the interaction harmonic number will increase the risk of mode competition. Summary of the Invention

[0003] In view of the above problems, an object of the present invention is to provide a large gyrotron magnetron injection gun that can enable the gyrotron to operate stably at high power, high efficiency, and high frequency.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A large gyrotron magnetron injection gun, comprising:

[0006] A housing, a magnet assembly sleeved on the outer peripheral surface of the housing, and a cathode assembly and an anode disposed inside the housing;

[0007] The cathode assembly includes a first cathode, a second cathode, and a third cathode coaxially nested from the inside to the outside, and the end faces of the first cathode and the third cathode on the side away from the anode are flush;

[0008] The first cathode is coaxially arranged with the housing and includes a first stepped surface, a second stepped surface, and a transition inclined surface connecting the first stepped surface and the second stepped surface. The second stepped surface is located on the side of the first stepped surface close to the anode;

[0009] The surface of the second cathode close to the anode is an emission surface, and the emission surface is an inclined surface recessed in a direction away from the anode;

[0010] The anode is coaxially arranged with the first cathode, and the anode is a circular ring-shaped cylinder with an electron beam channel formed at its center for the electron beam to pass through;

[0011] The end faces of the third cathode and the anode close to each other are both multi-faceted combined structures,

[0012] In addition, as an alternative, the distance between the outer edge of the first stepped surface and the central axis of the first cathode is greater than the radius of the second stepped surface;

[0013] The sizes of the first stepped surface and the second stepped surface are both adjustable sizes, and the size of the transition inclined surface is adjusted as the relative positions of the first stepped surface and the second stepped surface change.

[0014] In addition, as an alternative, the third cathode is in a ring structure, and three sections of folded surfaces are provided on the end surface thereof close to the anode, and the end surface of the third cathode close to the anode is in a concave structure through these three sections of folded surfaces;

[0015] These three sections of folded surfaces are, in sequence from the outer wall to the inner wall of the third cathode, a first folded surface, a second folded surface, and a third folded surface. The first folded surface is a plane perpendicular to the central axis of the third cathode, and both the second folded surface and the third folded surface are inclined surfaces;

[0016] The sizes of the first folded surface, the second folded surface, and the third folded surface are all adjustable sizes.

[0017] In addition, as an alternative, the emission surface is connected to the end of the third folded surface of the first stepped surface and the third cathode that is far from the second folded surface.

[0018] In addition, as an alternative, both the angle between the emission surface and the central axis of the second cathode and the average value of the distances between the inner and outer edges of the emission surface and the central axis of the second cathode are adjustable sizes;

[0019] The angle between the emission surface and the central axis of the second cathode is greater than 40°, and the average value of the distances between the inner and outer edges of the emission surface and the central axis of the second cathode is greater than 10 mm.

[0020] In addition, as an alternative, the second cathode is in a thin-walled cylindrical structure, and the outer wall surface of the second cathode abuts against the inner wall surface of the third cathode;

[0021] One end of the second cathode close to the anode is folded inwards to form the emission surface, and the emission surface is coated with a cathode material.

[0022] In addition, as an alternative, the cathode assembly further includes a filament, and the filament is arranged on the side of the emission surface away from the anode and sleeved on the outer peripheral surface of the first cathode.

[0023] In addition, as an alternative, two sections of folded surfaces are provided on the inner wall of the anode, and the inner diameter of the electron beam channel corresponding to one section of the folded surface close to the cathode assembly is greater than the inner diameter of the electron beam channel corresponding to the other section of the folded surface.

[0024] In addition, as an alternative solution, one end face of the anode close to the cathode assembly is a stepped structure, including a first stepped surface, a second stepped surface, and a connecting inclined surface connecting the first stepped surface and the second stepped surface;

[0025] The first stepped surface and the second stepped surface are coaxially arranged. The second stepped surface protrudes from the first stepped surface towards the direction close to the cathode assembly, and the radius of the second stepped surface is smaller than the distance between the outer edge of the first stepped surface and the central axis of the anode.

[0026] In addition, as an alternative solution, the magnet assembly includes a first coil and a second coil wound around the outer wall surface of the housing in sequence along the axial direction of the housing, and an interval area is arranged between the first coil and the second coil;

[0027] The first coil is arranged corresponding to the cathode assembly, and the second coil is arranged corresponding to the anode;

[0028] The first coil and the second coil are energized in opposite directions and coaxially arranged, and the magnetic fields generated by the first coil and the second coil are superimposed to form a slowly varying magnetic field.

[0029] The beneficial effects of the present invention are as follows:

[0030] Aiming at the technical problems existing in the prior art, the present invention provides a large gyrotron magnetron injection electron gun provided by an embodiment of the present invention. Through the cooperative optimization of multiple cathodes and an anode with a specific structure, and the partial adjustability of the structural dimensions of the cathode assembly and the anode, the precise control of the initial electric field distribution is realized, the deviation of the electron emission position is reduced, the trajectory of the paraxial electron beam can be corrected, the axial magnetic field distribution is optimized, and the transverse velocity dispersion of the electron beam is suppressed; the slowly varying CUSP magnetic field with a length less than 14 mm is formed by the superposition of the first coil and the second coil to ensure that the magnetic field gradient is gentle and adapted to the geometric parameters of the second cathode; the synergistic effect of the magnetic field assembly, the cathode assembly and the anode generates a high-quality large gyrotron electron beam, greatly improving the mode partition ratio, reducing the risk of mode competition, and enabling the gyrotron to stably operate in the high-order harmonic and high-order mode states; and it can reduce the transverse and longitudinal velocity spreads of the electron beam to less than 5%, having the advantages of high automation, stable operation, good parameter consistency, high stability, low spread characteristics, meeting the working requirements of high-order harmonics, convenient operation, etc., and can be applied to fields such as high-power gyrotrons, millimeter-wave radars, and nuclear fusion heating devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The following further describes in detail the specific embodiments of the present invention with reference to the drawings.

[0032] Figure 1Shows the structural schematic diagram of the large gyrotron magnetron injection electron gun provided by the embodiments of the present invention.

[0033] Figure 2 Shows a quarter sectional view of the large gyrotron magnetron injection electron gun provided by the embodiments of the present invention.

[0034] Figure 3 Is Figure 2 The corresponding dimension and position point marking diagram. Detailed implementation manners

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that, for the sake of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0036] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected", "fixed" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0037] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them.

[0038] In the description of this embodiment, the orientation or positional relationship terms such as "above", "below", "left", "right", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0039] Research has found that when the large gyrotron electron beam effectively interacts with gyrotron-like devices, the harmonic order of the interaction must be consistent with the angular index of the operating mode, which can greatly improve the mode discrimination degree and thus reduce the risk of mode competition. Therefore, by providing a high-quality large gyrotron electron beam, the gyrotron can stably operate in the high-order harmonic and high-order mode states.

[0040] At present, high-quality large-cyclotron electron beams need to be obtained through an ideal CUSP magnetic field with harsh parameters, and it is very difficult to achieve in engineering. For the existing technology, it is extremely difficult to provide high-quality large-cyclotron electron beams that meet the requirements of beam-wave interaction in gyro-devices.

[0041] In view of the deficiencies of the existing technology, the present invention provides a large-cyclotron magnetron injection electron gun, which combines Figures 1 - 3 As shown in the figure, the electron gun includes a housing 1, a magnet assembly 2 sleeved on the outer peripheral surface of the housing 1, and a cathode assembly 3 and an anode 4 arranged in the housing 1. The housing 1 is made of insulating ceramic material.

[0042] The cathode assembly 3 includes a first cathode 31, a second cathode 32 and a third cathode 33 coaxially nested from the inside to the outside, and the end faces of the first cathode 31 and the third cathode 33 on the side far from the anode 4 are flush.

[0043] The axial direction of the housing 1 is the forward direction of the spiral movement of the electron beam. The first cathode 31 is coaxially arranged with the housing 1. The first cathode 31 includes a first step surface 311, a second step surface 312 and a transition inclined surface 313 connecting the first step surface 311 and the second step surface 312, wherein the second step surface 312 is located on the side of the first step surface 311 close to the anode 4.

[0044] The surface of the second cathode 32 close to the anode 4 is an emission surface 321, and the emission surface 32 is an inclined surface formed by being recessed in the direction away from the anode 4.

[0045] The anode 4 is coaxially arranged with the first cathode 31. The anode 4 is a circular ring-shaped cylinder, and an electron beam channel 5 for the electron beam to pass through is formed at its center.

[0046] The end faces of the third cathode 33 and the anode 4 close to each other are both multi-faceted combined structures.

[0047] As Figures 1 - 2 shown, the first cathode 31 is specifically an irregular frustum structure, and the second step surface 312 is the top surface of the irregular frustum structure. The axial direction of the first cathode 31 is the forward direction of the spiral movement of the electron beam. In a specific embodiment, the distance a between the outer edge of the first step surface 311 and the central axis of the first cathode 31 is greater than the radius r of the second step surface 312. Figure 2 and Figure 3 In the figure, the horizontal axis is the central axis of the housing 1, and the vertical axis represents the radius dimension. The dimensions of the first step surface 311 and the second step surface 312 are both adjustable dimensions, and the shape of the first cathode 31 can be locally optimized according to requirements and different electron beam parameters. Further, the dimension of the transition inclined surface 313 is adjusted as the relative positions of the first step surface 311 and the second step surface 312 change.

[0048] Specifically, in combination withFigure 2 and Figure 3 As shown in Figure 3 , the horizontal and vertical coordinate positions of the junction A between the second step surface 312 and the transition inclined surface 313 are adjustable, the horizontal and vertical coordinate positions of the junction B between the first step surface 311 and the transition inclined surface 313 are adjustable, and the horizontal and vertical coordinate positions of the junction C between the first step surface 311 and the emission surface 321 are adjustable. By changing the positions of the above position points, the shape of the first cathode 31 can be adjusted to meet the requirements of different electron beam parameters. It should be noted that when optimizing the shape and size of the first cathode 31, one or more of the above position points can be optimized according to the actual situation.

[0049] In this embodiment, by adjusting the shape of the first cathode 31 and cooperating with the anode 4, the specific electric field distribution in the cathode assembly region can be changed, the emission angle of the electron beam can be optimized, the initial motion trajectory of the electron beam can be corrected, the deviation of the electron emission position can be reduced, and the consistency of the electron beam can be better. It can preliminarily converge and guide the emitted electrons to form an electron beam with a certain shape and direction, improve the quality of the electron beam, and enable the electron beam to have a larger cyclotron radius. In the large cyclotron state, its cyclotron frequency is relatively high, which can generate high-order harmonics, expand the working frequency range of the device, and meet higher performance requirements.

[0050] In a specific embodiment, the third cathode 33 is of a ring structure, and its axial direction is the advancing direction of the spiral motion of the electron beam. One end face of the third cathode 33 close to the anode 4 is provided with three folded surfaces, and the three folded surfaces form a multi-surface combination structure, and this end face is integrally concave through the three folded surfaces.

[0051] The three folded surfaces are, in sequence from the outer wall of the third cathode 33 to the inner wall of the third cathode 33, the first folded surface 331, the second folded surface 332, and the third folded surface 333. In one embodiment, the first folded surface 331 is a plane perpendicular to the central axis of the third cathode 33, and the second folded surface 332 and the third folded surface 333 are both inclined surfaces.

[0052] The outer wall of the third cathode 33 is in contact with the inner wall of the housing 1, and the sizes of the first folded surface 331, the second folded surface 332, and the third folded surface 333 are all adjustable sizes.

[0053] Specifically, in combination with Figure 2 and Figure 3As shown in the figure, the horizontal and vertical axis positions of the connection point E between the third folding surface 333 and the second folding surface 332 are adjustable; the horizontal and vertical axis positions of the connection point F between the second folding surface 332 and the first folding surface 331 are adjustable; the horizontal axis position of the contact position G between the first folding surface 331 and the inner wall of the housing 1 is adjustable, and the vertical axis position is limited by the size of the housing 1. Further, the first folding surface 331 can be adjusted to an inclined surface by changing the position point G. By changing the positions of the above position points, the shape of the third cathode 33 can be adjusted. Cooperating with the anode 4, the generated electric field can correct the paraxial trajectory of the electron beam, suppress the eccentricity of the electron beam, and improve the quality of the electron beam. It should be noted that when optimizing the shape and size of the third cathode 33, one or more of the above position points can be optimized according to the actual situation.

[0054] In a specific embodiment, the emission surface 321 is located between the first cathode 31 and the third cathode 33, and the third folding surface 333 connecting the first step surface 311 and the third cathode 33 is at the end far from the second folding surface 332.

[0055] Further, the angle between the emission surface 321 and the central axis of the second cathode 32 (i.e., the inclination angle β of the emission surface 321) and the average value of the distances between the inner and outer edges of the emission surface 321 and the central axis of the second cathode 32 are adjustable dimensions. Specifically, on the premise that the shape of the first cathode 31 is optimized, by adjusting the horizontal and vertical axis positions of the contact position D between the emission surface 321 and the third cathode 33, the adjustment of the angle between the emission surface 321 and the central axis of the second cathode 32 and the average value of the distances between the inner and outer edges of the emission surface 321 and the central axis of the second cathode 32 can be achieved.

[0056] Specifically, the distance between the inner edge of the emission surface 321 and the central axis of the second cathode 32 is the distance a between the outer edge of the first step surface 311 and the central axis of the first cathode 31, and the distance between the outer edge of the emission surface 321 and the central axis of the second cathode 32 is b. Therefore, the average value of the distances between the inner and outer edges of the emission surface 321 and the central axis of the second cathode 32 is 1 / 2(a + b).

[0057] The second cathode 32 emits a high-current electron beam in a temperature-limited manner. By adopting a large radius, the length of the second cathode 32 is reduced. Specifically, to ensure that the emission surface 321 can emit a high-quality electron beam, the angle between the emission surface 321 and the central axis of the second cathode 32 needs to be greater than 40°. To prevent the large current emitted from the emission surface 321 from getting out of control or even causing breakdown, the average value of the distances between both ends of the emission surface 321 and the central axis of the second cathode 32 needs to be greater than 10 mm, that is, 1 / 2(a + b) > 10 mm. In addition, the limitation of the above values can be adapted to the slowly varying magnetic field generated by the magnet assembly 2, improving the consistency of the transverse and longitudinal velocity ratios of the electron beam.

[0058] In one embodiment, the second cathode 32 is a hollow annular cylinder, and its axial direction is the advancing direction of the helical movement of the electron beam. Further, as Figure 1 shown, in the embodiment of the present invention, the second cathode 32 is a thin-walled cylindrical structure, sleeved outside the first cathode 31, and the outer wall surface of the second cathode 32 abuts against the inner wall surface of the third cathode 33. One end of the second cathode 32 close to the anode 4 is folded inward to form an emission surface 321. The emission surface 321 is coated with a cathode material, and an electron beam can be emitted by heating with a heat source, and the heating temperature is between 1000°C and 1300°C. Specifically, the cathode material is barium tungsten cathode, coated cathode (such as Sc2O3 / W), etc.

[0059] In a specific embodiment, the cathode assembly 3 further includes a filament 34. The filament 34 is arranged on the side of the emission surface 321 away from the anode 4 and sleeved on the outer peripheral surface of the first cathode 31. The filament 34 is used to heat the cathode material coated on the emission surface 321 to emit an electron beam.

[0060] In a specific embodiment, the second cathode 32 should satisfy the following relational expression:

[0061]

[0062] where α is the transverse and longitudinal velocity ratio of the electron beam, γ is the relativistic factor, U0 is the electron beam voltage, m0 is the rest mass of the electron, e is the electron charge, B z0 is the axial magnetic field strength at the exit of the electron gun, B zc is the central longitudinal magnetic field strength of the second cathode 32, and r c is the central radius of the second cathode 32.

[0063] During design, it is necessary to adjust the size of the emission surface 321 according to the required transverse and longitudinal velocity ratio α of the electron beam, so that the axial magnetic field strength B z0 at the exit of the electron gun and the central longitudinal magnetic field strength B zc of the second cathode 32 can make the transverse and longitudinal velocity ratio α of the electron beam meet the set value.

[0064] In a specific embodiment, the anode 4 has a single-anode structure. For example, Figure 1 as shown, two folding surfaces are provided on the inner wall of the anode 4. The inner diameter of the electron beam channel 5 corresponding to one folding surface close to the cathode assembly 3 is larger than that of the electron beam channel 5 corresponding to the other folding surface. The electron beam channel 5 with two folding surfaces provided on the anode 4 can expand the coverage range of the electric field in the near-cathode region, reduce the transverse velocity dispersion of the electron beam, and improve the quality of the electron beam.

[0065] In a specific embodiment, for example, Figures 1 - 3 as shown, one end face of the anode 4 close to the cathode assembly 3 has a stepped structure, including a first stepped surface 41, a second stepped surface 42, and a connecting inclined surface 43 connecting the first stepped surface 41 and the second stepped surface 42.

[0066] The first stepped surface 41 and the second stepped surface 42 are coaxially arranged. The second stepped surface 42 protrudes from the first stepped surface 41 in the direction close to the cathode assembly 3. The distance c between the outer edge of the second stepped surface 42 and the central axis of the anode 4 is smaller than the distance d between the outer edge of the first stepped surface 41 and the central axis of the anode 4. The first stepped surface 41 and the second stepped surface 42 can be flat surfaces or inclined surfaces, and the sizes of the first stepped surface 41 and the second stepped surface 42 are both adjustable sizes. Through the size optimization of the first stepped surface 41 and the second stepped surface 42, the structure of the anode 4 can be optimized so that it can cooperate with the cathode assembly 3 to form the electric field distribution required for generating a high-quality large gyration electron beam in the entire gun region, optimize the axial electric field distribution, and suppress the transverse velocity dispersion of the electron beam.

[0067] Specifically, in combination with Figures 2 - 3 as shown, the horizontal coordinate position and the vertical coordinate position of the inner edge J of the second stepped surface 42 are adjustable; the horizontal coordinate position and the vertical coordinate position of the connection point I between the second stepped surface 42 and the connecting inclined surface 43 are adjustable; the horizontal coordinate position and the vertical coordinate position of the connection point H between the first stepped surface 41 and the connecting inclined surface 43 are adjustable. By changing the positions of the above position points, the specific shape of one end face of the anode 4 close to the cathode assembly 3 can be adjusted so that it can cooperate with the cathode assembly 3 to form the required electric field distribution in the entire gun region. It should be noted that when optimizing the shape and size of the anode 4, one or more of the above position points can be optimized according to the actual situation.

[0068] In a specific embodiment, the magnetic field assembly 2 includes a first coil 21 and a second coil 22 that are sequentially wound around the outer wall surface of the housing 1 along the axial direction of the housing. The first coil 21 and the second coil 22 are coaxially arranged, and their axial direction is the advancing direction of the helical motion of the electron beam.

[0069] A spacing region is provided between the first coil 21 and the second coil 22. By changing the size e of the spacing region, the magnetic field synthesized by the first coil 21 and the second coil 22 can satisfy the interaction requirements for the magnetic field at the electron beam outlet.

[0070] In this embodiment, the first coil 21 corresponds to the cathode assembly 3, and the second coil 22 corresponds to the anode 4.

[0071] The first coil 21 and the second coil 22 are energized in opposite directions, and the generated magnetic fields are in opposite directions. The magnetic fields generated by the first coil 21 and the second coil 22 are superimposed to form a slowly varying magnetic field. Specifically, the superimposition method is carried out according to the CUSP length being less than 14 mm. The magnetic field intensity at the center of the second cathode 32 is not greater than 70 Gs, and the minimum magnetic field of the synthesized magnetic field is greater than -180 GS.

[0072] The magnet assembly 2 provided in the embodiment of the present invention adopts a fully slowly varying magnetic field configuration. By restricting the length of the CUSP section, the superimposition position of the magnetic fields generated by the first coil 21 and the second coil 22 is limited, so that the synthesized slowly varying magnetic field configuration is consistent with the inclination angle of the emission surface 321 of the second cathode 32.

[0073] In a specific embodiment, the axial magnetic field distributions of the first coil 21 and the second coil 22 satisfy the following formula:

[0074]

[0075] Among them, B z is the axial magnetic field of the first coil 21 or the second coil 22, μ0 is the magnetic permeability in vacuum, R is the inner diameter of the coil winding, I is the direct current of the coil, and r0 is the distance from the field point of the axial magnetic field to the center of the coil.

[0076] Through the above formula, when the axial magnetic field distribution of the required coil is known, the values of the direct current of the coil and the distance from the field point of the axial magnetic field to the center of the coil can be taken to ensure that the generated magnetic field gradient is gentle and adapted to the geometric parameters of the second cathode.

[0077] In a specific embodiment, the inner diameter of the coil winding needs to be determined according to the outer diameter of the third cathode 33. Exemplarily, the inner diameter of the coil winding is 5 - 10 mm larger than the outer diameter of the third cathode 33.

[0078] During actual use, after the size e of the spacing region is adjusted, the magnet assembly 2 is loaded on the outer wall surface of the housing 1, and the overall axial position of the magnet assembly 2 is adjusted so that the length of the slowly varying CUSP magnetic field for the large gyration electron beam with the required parameters is less than 14 mm.

[0079] For each component of the large-cyclotron magnetron-injected electron gun provided by the embodiments of the present invention, there are requirements for the shape and relative position. Among them, the error precision of the shape and position of the second cathode 32 and the anode 4 is 0.1 mm; the magnetic field precision error of the magnet assembly 2 needs to be less than 5 Gs, and the position precision is 0.1 mm.

[0080] The large-cyclotron magnetron-injected electron gun provided by the embodiments of the present invention realizes precise control of the initial electric field distribution through the collaborative optimization of multiple cathodes and the anode with a specific structure, and the structural dimensions of the cathode assembly and the anode are partially adjustable, reducing the deviation of the electron emission position, being able to correct the near-axis electron beam trajectory, optimize the axial magnetic field distribution, and suppress the transverse velocity dispersion of the electron beam; a slowly varying CUSP magnetic field with a length less than 14 mm is formed by superimposing the first coil and the second coil to ensure a gentle magnetic field gradient and adapt to the geometric parameters of the second cathode; through the synergistic effect of the magnetic field assembly, the cathode assembly and the anode, a high-quality large-cyclotron electron beam is generated, greatly improving the mode partition ratio, reducing the risk of mode competition, and enabling the gyrotron to operate stably in the high-order harmonic and high-order mode states; moreover, the transverse and longitudinal velocity spreads of the electron beam can be reduced to less than 5%, having the advantages of high automation, stable operation, good parameter consistency, high stability, low spread characteristics, meeting the working requirements of high-order harmonics, convenient operation, etc., and can be applied to fields such as high-power gyrotrons, millimeter-wave radars, and nuclear fusion heating devices.

[0081] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A large cyclotron magnetron injection electron gun, characterized in that: It comprises a shell, a magnet assembly sleeved on the outer circumference of the shell, and a cathode assembly and an anode arranged in the shell; The cathode assembly comprises a first cathode, a second cathode and a third cathode coaxially nested from inside to outside, and the end surfaces of the first cathode and the third cathode on a side away from the anode are arranged flush; The first cathode and the housing are coaxially arranged, and include a first step surface, a second step surface, and a transition slope connecting the first step surface and the second step surface, wherein the second step surface is located on a side of the first step surface close to the anode; A surface of the second cathode close to the anode is an emission surface, and the emission surface is an inclined surface that is concave in a direction away from the anode; The anode and the first cathode are coaxially arranged, the anode is a circular cylinder, and an electron injection channel is formed at the center thereof for electron injection to pass through; The end surfaces of the third cathode and the anode close to each other are both multi-faceted combined structures.

2. The large cyclotron magnetron injection electron gun according to claim 1, characterized in that: The distance between the outer edge of the first step surface and the central axis of the first cathode is greater than the radius of the second step surface; The size of the first step surface and the size of the second step surface are both adjustable sizes, and the size of the transition slope is adjusted as the relative position of the first step surface and the second step surface changes.

3. The large cyclotron magnetron injection electron gun according to claim 1, characterized in that: The third cathode is a circular ring structure, and its end surface close to the anode is provided with three sections of folded surfaces, and the end surface of the third cathode close to the anode is in a concave structure through the three sections of folded surfaces; The three folding surfaces are sequentially a first folding surface, a second folding surface and a third folding surface from the outer wall of the third cathode to the inner wall of the third cathode, the first folding surface is a plane perpendicular to the central axis of the third cathode, and the second folding surface and the third folding surface are both inclined surfaces; The sizes of the first folding surface, the second folding surface and the third folding surface are all adjustable.

4. The large cyclotron magnetron injection electron gun according to claim 3, characterized in that: The emission surface connects the first step surface and an end of the third folded surface of the third cathode away from the second folded surface.

5. The large cyclotron magnetron injection electron gun according to claim 4, characterized in that: The angle between the emission surface and the central axis of the second cathode and the average value of the distance between the inner and outer edges of the emission surface and the central axis of the second cathode are both adjustable dimensions; The angle between the emission surface and the central axis of the second cathode is greater than 40°, and the average value of the distances between the inner and outer edges of the emission surface and the central axis of the second cathode is greater than 10 mm.

6. The large cyclotron magnetron injection electron gun according to claim 1, characterized in that: The second cathode is a thin-walled cylindrical structure, and the outer wall surface of the second cathode abuts against the inner wall surface of the third cathode; One end of the second cathode close to the anode is folded inward to form the emission surface, and the emission surface is coated with cathode material.

7. The large cyclotron magnetron injection electron gun according to claim 1, characterized in that: The cathode assembly further comprises a filament, which is arranged on a side of the emitting surface away from the anode and sleeved on the outer peripheral surface of the first cathode.

8. The large cyclotron magnetron injection electron gun according to claim 1, characterized in that: The inner wall of the anode is provided with two folded surfaces, and the inner diameter of the electron injection channel corresponding to one folded surface close to the cathode assembly is larger than the inner diameter of the electron injection channel corresponding to the other folded surface.

9. The large cyclotron magnetron injection electron gun according to claim 1, characterized in that: The end surface of the anode on one side close to the cathode assembly is a stepped structure, including a first stepped surface, a second stepped surface, and a connecting inclined surface connecting the first stepped surface and the second stepped surface; The first step surface and the second step surface are coaxially arranged, the second step surface is formed by the first step surface protruding toward the cathode assembly, and the radius of the second step surface is smaller than the distance between the outer edge of the first step surface and the central axis of the anode.

10. The large cyclotron magnetron injection electron gun according to claim 1, characterized in that: The magnet assembly comprises a first coil and a second coil which are sequentially wound around the outer wall surface of the shell along the axial direction of the shell, and a spacing area is provided between the first coil and the second coil; The first coil is arranged corresponding to the cathode assembly, and the second coil is arranged corresponding to the anode assembly; The first coil and the second coil are energized in opposite directions and are coaxially arranged, and the magnetic fields generated by the first coil and the second coil are superimposed to form a slowly varying magnetic field.

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