Rotary emission band multi-beam magnetic control injection electron gun of plane gyrotron traveling wave tube

Abstract

The invention discloses a rotary emission band multi-beam magnetic control injection electron gun structure applied to a plane gyrotron traveling wave tube, and relates to the technical field of microwaves, millimeter waves and electron optics. The structure comprises an anode and a cathode, the cathode is of a central symmetry structure and comprises a rear forming electrode, an emission band and a front forming electrode. Wherein the emission band is provided with an oval cambered surface electron emission area rotating by a certain angle, the electron emission area moves transversely, and meanwhile, the rear forming electrode and the front forming electrode are arranged to be of a special-shaped protruding structure so as to adjust electric field distribution. According to the invention, the forming track of the elliptical electron beam can be controlled to a certain extent, the speed dispersion of the formed electron beam is reduced, and the working current of the magnetic control injection electron gun is improved, so that the output power of the planar magnetic control injection electron gun is increased, and the efficiency of the planar gyrotron traveling wave tube is improved.

Description

Technical Field

[0001] The invention belongs to the fields of microwave, millimeter wave technology and electronic optics, and in particular relates to a rotating emission band multi-injection magnetron injection electron gun structure applied to a planar cyclotron traveling wave tube. Background Art

[0002] A gyrotron traveling wave tube is a vacuum amplification device that works based on the instability mechanism of electron cyclotron maser. It has the characteristics of high frequency, wide bandwidth, and high power, and has important application prospects in the technical fields of electronic countermeasures and radar imaging. With the increasing performance requirements of microwave systems, the research and development of high-frequency gyrotron traveling wave tubes has also received widespread attention.

[0003] The traditional cyclotron traveling wave tube is mainly composed of a magnetron injection electron gun, a high-frequency interaction structure, a collector, and a microwave input and output system. Electrons are first emitted from the magnetron injection electron gun under the action of an orthogonal electromagnetic field, and then perform cyclotron motion along the longitudinal magnetic field. At the high-frequency interaction structure, the cyclotron electrons exchange energy with the microwaves injected from the input system, and the amplified microwaves are output longitudinally along the collector and the output system. The remaining electrons after the injection-wave interaction are intercepted by the collector. Subject to challenges such as current density and thermal power capacity, the pulse power of the traditional Ka-band cyclotron traveling wave tube is between 100 and 150 kW. As the output power of cyclotron traveling wave tubes develops towards the MW level, a planar cyclotron electron injector has been proposed. Compared with the traditional circularly symmetric electron beam, the main technical feature of the planar cyclotron electron beam is that it has a large aspect ratio. The electron beam can have a small size in one direction to match the high-frequency wavelength, and a larger size in the other direction according to the output power requirements of the device. In this way, by increasing the electron beam cross-section while keeping the total current constant, the space charge effect and current density can be reduced, ensuring a sufficiently large output power, improving the high-frequency interaction efficiency of the electron beam, and thus achieving a higher output efficiency. Therefore, the planar cyclotron electron beam has the advantages of small space charge force, small current density, and large lateral size. The planar cyclotron electron beam has great potential for the development of new vacuum electronic devices with high power, high frequency, and high efficiency.

[0004] However, it is difficult to shape a planar cyclotron electron beam, and it is difficult to design the corresponding planar magnetron injection electron gun. Unlike traditional circular cyclotron traveling wave tubes, when a planar cyclotron electron beam is transmitted in a focused magnetic field, there is velocity shear caused by the space charge field and the external magnetic field between the beams, which causes them to kink and break, the so-called Diocotron instability. As the electron beam current density increases, the Diocotron instability becomes more serious. When an elliptical ribbon electron beam is transmitted in a focused magnetic field, the beam will rotate because the two ends of the beam along the x-direction are subjected to magnetic field forces in opposite directions. In the uniform region where the magnetic field remains unchanged, the rotation of the electron beam can be suppressed by reducing the distance between the electron beam and the waveguide wall. However, there is currently no good suppression measure in the process of electron beam shaping. As a result of the rotation of the electron beam, the formed electron beam has a certain angle with the x-axis, so that the beams in different parts of the planar cavity have significantly different beam-wave interaction conditions, which leads to a decrease in the efficiency of the planar cyclotron and a deterioration in the output characteristics. If the rotation angle of the electron beam is too large, the height of the electron beam will be greater than the narrow side length of the high-frequency interaction channel, which will cause some electrons to be intercepted by the high-frequency interaction channel.

[0005] The performance optimization of planar cyclotron electron beams also faces challenges. In the two transverse dimensions of a circular electron beam, the angular dimension is uniform, and only the radial dimension is non-uniform; however, the two transverse dimensions of a planar electron beam are non-uniform, so the transverse non-uniformity of a planar electron beam is stronger than that of a circular electron beam, which leads to a worsening of the velocity discreteness of the electron beam.

[0006] The Russian Academy of Sciences has designed a planar magnetron injection gun for a 140 GHz cyclotron oscillator tube. Figure 1 As shown in the figure, under the conditions of working voltage of 50kV and current of 30A, a rectangular electron beam with a velocity ratio of 1.3, a velocity dispersion of 24%, a length of 30mm, and a width of 1.8mm is formed, the interaction efficiency is 20%, and the output power is 300kW. At present, the research on planar cyclotron traveling wave tubes is mainly focused on lower currents, and there are fewer studies on high currents. The main reason is that large currents lead to excessive Diocotron instability, which will increase the difficulty of forming and focusing the planar electron beam, and will also affect the efficiency of the beam-wave interaction, thereby affecting the output power. The planar magnetron injection electron guns reported in the current research are mostly used in planar cyclotron oscillator tubes. Planar cyclotron traveling wave tubes have higher requirements for the stability of the electron beam and more stringent design requirements for magnetron injection electron guns. Therefore, research in this area is still very lacking. At present, there is no structural case that can compensate for the Diocotron instability in the process of planar cyclotron electron beam forming and the lateral inconsistency of the planar cyclotron electron beam. Summary of the invention

[0007] Aiming at the problems of shaping and speed discrete optimization of existing Ka-band planar cyclotron electron beam, the present invention proposes a rotating emission band multi-injection magnetron injection electron gun for a planar cyclotron traveling wave tube. The electron gun of the present invention can control the shaping trajectory of the elliptical electron beam to a certain extent and reduce the speed discreteness of the shaped electron beam.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] A rotating emission band multi-injection magnetron injection electron gun of a planar cyclotron traveling wave tube comprises an anode and a cathode arranged inside the anode, wherein a certain distance exists between the anode and the cathode;

[0010] The cathode is characterized in that the overall structure is rotationally symmetrical about the z-axis by 180 degrees, and includes a rear-shaped electrode, an emission band, and a front-shaped electrode arranged in sequence along the z-axis;

[0011] The post-forming pole is a special-shaped racetrack-shaped column having the same shape in any section along the z-axis;

[0012] The special-shaped runway-shaped column is composed of a rectangular column part, a semi-cylindrical part arranged on both sides of its short side, and a special-shaped convex part arranged on both sides of its long side, wherein the long side of the rectangular column part is parallel to the x-axis, and the short side is parallel to the y-axis; the outer side surface of the special-shaped convex part is divided into four planes connected in sequence, wherein the first surface is inclined outward, the second surface is a parallel surface, the third surface is inclined outward, and the fourth surface is a transition connection surface;

[0013] The emission belt, any section along the z-axis is a racetrack-shaped structure, and the size along the z-axis gradually decreases, forming an inclined emission belt; two electron emission regions coated with emission coatings are arranged on the emission belt, the electron emission regions are elliptical and located in the central area of ​​the projection of the first to third surfaces of the special-shaped protrusion on the xy plane, and the side close to the vertex of the special-shaped protrusion is inclined toward the rear forming pole, and the other side is inclined toward the front forming pole;

[0014] The front forming pole has an irregular racetrack shape in any section along the z-axis, and the top is chamfered to form a smooth arc surface.

[0015] Furthermore, the distance between the midpoint of the electron emission region and the cathode centerline in the x direction is d, and the projection of the transition connection surface of the special-shaped protrusion on the x axis is 2d; the value of d is determined by the difference between the trajectories of the upper and lower electron beams.

[0016] Furthermore, the emission belt is a curved emission belt.

[0017] Furthermore, the inclination angles of the first inclined surface and the third inclined surface of the special-shaped protruding portion are the same or different, and the projection lengths on the x-axis are the same or different; when the projection areas of the first inclined surface and the third inclined surface on the x-axis are different, the electric field matching requirements can be met by changing the boundary positions on both sides of the parallel surfaces.

[0018] Furthermore, a rear-forming pole transition section is provided between the rear-forming pole and the emission band to achieve a transition connection between the two; a front-forming pole transition section is provided between the front-forming pole and the emission band to achieve a transition connection between the two.

[0019] Furthermore, the post-forming pole transition section is divided into an arcuate transition section and a linear transition section along the z-axis; the front-forming pole transition section is divided into a linear transition section and an arcuate transition section along the z-axis; the two-stage transition can make the electric field change smoother and is also easier to process.

[0020] Furthermore, the electron emission region is tangent to the upper and lower boundaries of the emission band respectively, so as to reduce the size in the z-axis direction and make the structure more compact.

[0021] Principles and beneficial effects of the present invention:

[0022] 1) A planar cyclotron electron beam can have a small size in one direction that matches the high-frequency wavelength, and a larger size in the other direction according to the output power requirements of the device, thereby maintaining a higher total current while maintaining a smaller space charge force within the beam, ensuring a sufficiently large output power, and improving the high-frequency interaction efficiency of the electron beam, thereby achieving a higher output efficiency.

[0023] 2) The present invention sets the electron emission region to an elliptical shape and rotates the electron emission region to control the angular trajectory of the electron beam, compensate for the influence of the Diocotron instability of the band electron beam, and improve the beam-wave interaction efficiency.

[0024] 3) The present invention places the electron emission region toward The lateral displacement in the direction is used to control the lateral trajectory of the electron beam, thereby eliminating the lateral drift caused by the electric field and the axial magnetic field in the gun area of ​​the electron gun, making the positions of the upper and lower strip electron beams consistent, reducing the difficulty of subsequent mode synthesis.

[0025] 4) The present invention adjusts the electric field distribution on the emission belt by adjusting the parameters of the front and rear forming pole profiled protrusions, and compensates for the electromagnetic field inconsistency caused by the rotating emission belt and the high aspect ratio emission belt, thereby optimizing the speed discreteness of the electron beam and improving the performance of the electron beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is a planar magnetron injection gun designed by the Russian Academy of Sciences.

[0027] Figure 2 1 is a schematic diagram of the cathode structure of a multi-injection planar magnetron injection electron gun with a Ka-band rotating emission band in an embodiment.

[0028] Figure 3 It is a front view and a side view of the cathode structure of a multi-injection planar magnetron injection electron gun with a Ka-band rotating emission band in an embodiment, and a schematic diagram of the corresponding cross-sectional position.

[0029] Figure 4 It is a cross-sectional schematic diagram corresponding to the cathode structure of the multi-injection planar magnetron injection electron gun in the Ka-band rotating emission band in the embodiment.

[0030] Figure 5 It is a schematic diagram of the structure of the emission band of the Ka-band rotating emission band multi-injection planar magnetron injection electron gun in the embodiment.

[0031] Figure 6 It is a structural schematic diagram of the yz cross section of the emission band of the Ka-band rotating emission band multi-injection planar magnetron injection electron gun in the embodiment.

[0032] Figure 7 It is a structural schematic diagram of the Ka-band rotating emission band multi-injection planar magnetron injection electron gun structure and the electron injection yz cross section in the embodiment.

[0033] Figure 8 It is a schematic structural diagram of the Ka-band rotating emission band multi-injection planar magnetron injection electron gun structure and the electron injection xz cross section in the embodiment.

[0034] Fig. 9 This is a cross-sectional view of the output electron beam of the Ka-band rotated emission band multi-beam planar magnetron injection electron gun at the electron gun outlet in the embodiment. The left figure is a cross-sectional view of the output electron beam without rotating the emission band and without lateral displacement of the emission band, and the right figure is a cross-sectional view of the output electron beam with rotation and lateral displacement of the emission band.

[0035] Fig.10 This is a long-axis electromagnetic field distribution diagram of the elliptical emission band of the Ka-band rotating emission band multi-injection planar magnetron injection electron gun in the embodiment. The left figure is the electromagnetic field distribution without a step structure, and the right figure is the electromagnetic field distribution with a step structure.

[0036] Fig.11 This is a diagram showing the result of the injection-wave interaction of a planar cyclotron electron beam output by a multi-beam planar magnetron injection electron gun with a Ka-band rotating emission band in an embodiment.

[0037] Explanation of the accompanying drawings: 1. rear formed pole, 2. emission belt, 3. front formed pole, 4. electron gun anode shell, 5. belt-shaped electron injection, 6. transition connection structure, 7. semi-conical structure, 8. anode partition, 11. first surface of rear formed pole, 12. second surface of rear formed pole, 13. third surface of rear formed pole, 14. fourth surface of rear formed pole, 21. first surface of front formed pole, 22. second surface of front formed pole, 23. third surface of front formed pole, 24. fourth surface of front formed pole. DETAILED DESCRIPTION

[0038] The following is a further detailed description of the technical solution of the present invention by taking the Ka-band rotating emission band multi-beam planar magnetron injection electron gun as an example in conjunction with the accompanying drawings:

[0039] This embodiment provides a rotating emission band multi-injection planar magnetron injection electron gun structure working in the Ka band, and the working mode is rectangular waveguide TE 01 mold.

[0040] The electron gun of this embodiment includes an anode and a cathode disposed inside the anode, and an axial distance of 12.2 mm exists between the anode and the cathode.

[0041] The anode is a centrally symmetrical metal shell structure, and any cross section along the z-axis is a rectangle with a constant wide side and a narrow side that decreases along the z-axis. A partition is provided in the middle of the narrow side at the front end to separate the upper and lower electron beams and reduce the influence of the space charge effect.

[0042] like Figure 2-5 As shown, the cathode in this embodiment is a centrally symmetrical structure, including a rear forming pole, an emission band, and a front forming pole arranged in sequence along the z-axis.

[0043] The post-forming pole is a special-shaped racetrack-shaped column with the same shape in any section along the z-axis.

[0044] The emission belt has a runway-like structure in any section along the z-axis, and the size along the z-axis gradually decreases, forming an inclined arc-surface emission belt; two electron emission regions coated with emission coatings are arranged on the emission belt, and the electron emission region is elliptical and located in the central area of ​​the projection of the first to third surfaces of the special-shaped protrusion on the xy plane, and the side close to the vertex of the special-shaped protrusion is inclined toward the rear forming pole, and the other side is inclined toward the front forming pole. The distance between the midpoint of the electron emission region and the central axis of the cathode in the x direction is d; the value of d is determined by the difference in the trajectories of the upper and lower electron beams. The electron emission region is tangent to the upper and lower boundaries of the emission belt respectively to reduce the size in the z-axis direction and make the structure more compact.

[0045] The front forming pole has an irregular racetrack shape in any section along the z-axis, and the top is chamfered to form a smooth arc surface.

[0046] The special-shaped runway-shaped column is composed of a rectangular column part, a semi-cylindrical part arranged on both sides of its short side and a special-shaped convex part arranged on both sides of its long side, wherein the long side of the rectangular column part is parallel to the x-axis, and the short side is parallel to the y-axis; the outer side surface of the special-shaped convex part is divided into four planes connected in sequence, wherein the first surface is inclined outward, the second surface is a parallel surface, the third surface is inclined outward, and the fourth surface is a transition connection surface.

[0047] A rear-forming pole transition section is provided between the rear-forming pole and the emission belt to achieve a transition connection between the two; a front-forming pole transition section is provided between the front-forming pole and the emission belt to achieve a transition connection between the two.

[0048] The post-forming pole transition section is divided into an arc transition section and a linear transition section along the z-axis; the front-forming pole transition section is divided into a linear transition section and an arc transition section along the z-axis; the two-stage transition can make the electric field change smoother and is also easier to process.

[0049] In the post-forming pole, the length of the first surface projected on the x-axis is db4=52mm, and the length of the projection on the y-axis is db2=0.864mm; the length of the second surface projected on the x-axis is db5=1mm; the length of the third surface projected on the x-axis is db3=56mm, and the length of the projection on the y-axis is db1=0.672mm; the length of the fourth surface projected on the x-axis is 2d=14mm.

[0050] In the front forming pole, the shape of any cross section along the z-axis is the same as the shape of any cross section of the rear forming pole along the z-axis, and the sizes are proportionally reduced, where df1=0.672mm, df2=0.864mm, df3=56mm, df4=52mm, and df5=1mm.

[0051] The special-shaped racetrack column can enhance the electric field of the emission band in the left half (corresponding area of ​​the third face) and weaken the electric field of the emission band in the right half (corresponding area of ​​the first face), thereby realizing the regulation of the electric field on the surface of the emission band, reducing the speed discreteness of the electron beam, and improving the performance of the electron beam.

[0052] like Figure 5 As shown, two elliptical arc electron emission zones with a certain rotation angle are distributed symmetrically in the electron gun, the major axis a of the elliptical emission zone is 50 mm, the minor axis b is 2.5 mm, the emission zone rotation angle θ is 4°, the overall length of the emission zone (i.e., the length of the projection of the first to third surfaces on the x-axis) is L=109 mm, and the emission zone is offset from the center of the electron gun by d=7 mm. The rotated emission zone can effectively control the trajectory of the electron beam, so that the electron beam enters the high-frequency structure in a horizontal state, thereby improving the interaction efficiency between the electron beam and the electromagnetic wave.

[0053] like Figure 6As shown, the surface of the emission belt is an arc surface with a radius of r=185 mm. The arc surface emission belt design helps to reduce the inconsistency of the electric field on the surface of the emission belt and improve the electron injection performance.

[0054] like Figure 7 , Figure 8 As shown, two planar electron beams are emitted from the cathode. The cyclotron electrons pass through the acceleration region and the adiabatic region. Through magnetic adiabatic compression, the longitudinal energy is converted into transverse energy.

[0055] In terms of trajectory control of planar cyclotron electron beam, the trajectory of electron beam can be well controlled due to the design of emission band. Fig. 9 It can be obtained that the electron beam of the electron emission zone that has not been rotated and shifted has a certain angle θ2=4.6° with the horizontal plane at the exit of the electron gun, and the upper and lower emission bands have a certain position difference d1=5.2mm in the x-axis direction. The electron beam of the electron emission zone that has been rotated and shifted has an angle θ2=0.2° with the horizontal plane at the exit of the electron gun, which is greatly reduced compared with the current planar magnetron injection electron gun, where the angle θ2==1.71° between the generated electron beam and the horizontal plane. The length of the electron beam is 30mm, and the width of the electron beam is 2mm. And due to the design of the lateral displacement of the emission band, the positions of the upper and lower electron beams in the x-direction are consistent, which is conducive to the subsequent power synthesis.

[0056] In terms of speed dispersion optimization of planar cyclotron electron beams, the rotation of the electron gun emission belt and the design of the high aspect ratio emission belt will increase the difference in electromagnetic field distribution on the long axis of the emission belt, resulting in a deterioration of speed dispersion. Fig.10 As shown, the electric field of the emission zone without the special-shaped protrusion shows a trend of being high on the left and low on the right, which is opposite to the trend of the magnetic field being low on the left and high on the right. In addition, since the magnetic field is the smallest at the highest point of the electric field on the left end, it is very easy to cause insufficient magnetic field confinement, electron escape, and limit the improvement of the magnetic pressure ratio. However, the present invention significantly reduces the electric field on the left end of the emission band and increases the electric field on the right end by setting a special-shaped protrusion structure, which conforms to the trend of magnetic field changes. The speed discreteness of the electron beam is reduced from 6.53% to 3.33%, and the electron beam performance is optimized. Compared with the current planar magnetron injection electron gun speed discreteness of 25% to 30%, under the same speed discreteness algorithm, the electron beam equivalent speed discreteness of this embodiment is 6.7%, and the electron beam performance is improved.

[0057] In the beam-wave interaction of planar cyclotron electron beams, for example Fig.11 As shown, in the case of a single electron injection, TE 01 The output power of the mode is about 535kW, and the injection-wave interaction efficiency is 35%. Therefore, at 34GHz, the total output power of the two high-frequency structures is 1.070MW, which is much greater than the output power of a traditional circular gyrotron traveling wave tube.

[0058] Table 1

[0059]

[0060] As shown in Table 1, the Ka-band rotating emission band multi-injection planar magnetron injection electron gun of this embodiment has a single electron emission area of ​​S1=392mm 2 , the single electron beam current is I1 = 25A, and the emission band current density is J C1 =6.36A / cm 2 , the electron injection area at the exit is S2 = 47.1 mm 2 , the corresponding current density is J 01 =53.05A / cm 2 The traditional Ka-band exit injection electron gun has an operating current of I2=10A and an emission band current density of J C1 =11.2A / cm 2 , the current density at the electron gun exit is J 01 =78.9A / cm 2 . In contrast, the total working current of the dual electron emission region of the present invention is 50A, which is increased to 5 times, the current density of the emission region is reduced to 0.56 times, and the current density at the electron gun outlet is reduced to 0.67 times; the final electron beam velocity ratio is 1.43, and the velocity dispersion is 3.33%. It can be obtained that the present invention can significantly increase the output power of the electron gun, reduce the current density of the electron beam, and reduce the space charge effect of the electron beam.

[0061] In summary, the present invention can control the shaping trajectory of the planar cyclotron electron beam to a certain extent, reduce the speed discreteness of the shaped electron beam, thereby increasing the working current of the magnetron injection electron gun, increasing the output power of the magnetron injection electron gun, and improving the efficiency of the planar cyclotron traveling wave tube. At present, the output power of the planar magnetron injection electron gun is 300kW and the efficiency is 20%. The total output power of the embodiment of the present invention reaches the MW level and the efficiency is 35%. In addition, the present invention has a simple and compact structure and has a high application and promotion value.

[0062] The above examples are only for the convenience of explaining the present invention. The present invention proposes a rotating emission band multi-injection magnetron injection electron gun structure applied to a planar cyclotron traveling wave tube. It is also applicable to other frequency bands and larger working currents. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principle of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A rotating emission band multi-injection magnetron injection electron gun of a planar cyclotron traveling wave tube, comprising an anode and a cathode arranged inside the anode, with a certain distance between the anode and the cathode; It is characterized in that The cathode has an overall structure that is rotationally symmetrical 180 degrees around the z-axis, and includes a rear-forming electrode, an emission band, and a front-forming electrode that are sequentially arranged along the z-axis; The post-forming pole is a special-shaped racetrack-shaped column having the same shape in any section along the z-axis; The special-shaped runway-shaped column is composed of a rectangular column part, a semi-cylindrical part arranged on both sides of its short side, and a special-shaped convex part arranged on both sides of its long side, wherein the long side of the rectangular column part is parallel to the x-axis, and the short side is parallel to the y-axis; the outer side surface of the special-shaped convex part is divided into four planes connected in sequence, wherein the first surface is inclined outward, the second surface is a parallel surface, the third surface is inclined outward, and the fourth surface is a transition connection surface; The emission belt, any section along the z-axis is a racetrack-shaped structure, and the size along the z-axis gradually decreases, forming an inclined emission belt; two electron emission regions coated with emission coatings are arranged on the emission belt, the electron emission regions are elliptical and located in the central area of ​​the projection of the first to third surfaces of the special-shaped protrusion on the xy plane, and the side close to the vertex of the special-shaped protrusion is inclined toward the rear forming pole, and the other side is inclined toward the front forming pole; The front forming pole has an irregular racetrack shape in any section along the z-axis, and the top is chamfered to form a smooth arc surface.

2. The rotating emission band multi-injection magnetron injection electron gun of a planar cyclotron traveling wave tube as claimed in claim 1, characterized in that: The distance between the midpoint of the electron emission region and the cathode centerline in the x direction is d, and the projection of the transition connection surface of the special-shaped protrusion on the x axis is 2d; the value of d is determined by the difference between the trajectories of the upper and lower electron beams.

3. The rotating emission band multi-injection magnetron injection electron gun of a planar cyclotron traveling wave tube as claimed in claim 2, characterized in that: The emission belt is a curved surface emission belt.

4. The rotating emission band multi-injection magnetron injection electron gun of a planar cyclotron traveling wave tube as claimed in claim 3, characterized in that: A rear-forming pole transition section is provided between the rear-forming pole and the emission belt to achieve a transition connection between the two; a front-forming pole transition section is provided between the front-forming pole and the emission belt to achieve a transition connection between the two.

5. The rotating emission band multi-injection magnetron injection electron gun of a planar cyclotron traveling wave tube as claimed in claim 4, characterized in that: The post-forming pole transition section is divided into an arc transition section and a linear transition section along the z-axis; the front-forming pole transition section is divided into a linear transition section and an arc transition section along the z-axis; the two-stage transition can make the electric field change smoother and is also easier to process.

6. A rotating emission band multi-injection magnetron injection electron gun for a planar cyclotron traveling wave tube as claimed in claim 4 or 5, characterized in that: The inclination angles of the first inclined surface and the third inclined surface of the special-shaped protruding part are the same or different, and the projection lengths on the x-axis are the same or different; when the projection areas of the first inclined surface and the third inclined surface on the x-axis are different, the electric field matching requirements are met by changing the boundary positions on both sides of the parallel surfaces.

7. The rotating emission band multi-injection magnetron injection electron gun of a planar cyclotron traveling wave tube as claimed in claim 6, characterized in that: The electron emission regions are tangent to the upper and lower boundaries of the emission band respectively.

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