P-band integrated vertical metamaterial high power klystron

Abstract

The application relates to the fields of vacuum electron devices and high-power microwave technology, and discloses a P-waveband integrated vertical metamaterial high-power klystron. The P-waveband integrated vertical metamaterial high-power klystron comprises an electron gun, an interaction resonant cavity chain, a collector, a multilayer annular magnetic field focusing assembly and an integrated electron gun oil cylinder. The interaction resonant cavity chain is arranged in the vertical direction along the axial direction, and at least one resonant cavity unit is loaded with a metamaterial unit. The electron gun comprises a cathode and an anode, and does not comprise a modulation anode. The integrated electron gun oil cylinder is integrated with the electron gun and a filament transformer. The application realizes the compactness of the interaction resonant cavity chain through the metamaterial, makes the P-waveband klystron more easily realize the vertical layout, eliminates the use of a voltage divider due to the configuration of the two-pole electron gun, and further simplifies the electron gun oil cylinder system after the built-in integration of the filament transformer, so that the klystron system finally greatly reduces the floor area and saves the cost.

Description

Technical Field

[0001] This application relates to the fields of vacuum electronic devices and high-power microwave technology, and in particular to a P-band integrated vertical metamaterial high-power klystron. Background Technology

[0002] Klystrons, as important high-power microwave amplification devices, are widely used in high-energy particle linear accelerators, radar, and high-power radio frequency sources. In applications such as proton accelerators, P-band klystrons typically feature high output power, high operating voltage, and large structural size. The P-band refers to the radio frequency band with operating frequencies between 230MHz and 1000MHz. This band is characterized by low frequency and long wavelength, making it suitable for high-power microwave devices. Due to the low frequency and long wavelength of this band (belonging to the decimeter-to-meter wave range), the physical size of traditional P-band klystrons and their resonant cavities is usually quite large.

[0003] On the one hand, due to the limitations of low-frequency resonance characteristics, traditional metal resonant cavities have a relatively large inherent volume in the P-band frequency range, which is a key factor restricting the reduction of the overall tube length. As a result, traditional P-band klystrons are huge in size, with a length generally exceeding 5 meters. To facilitate manufacturing, P-band klystrons currently adopt a horizontal structure layout, but this layout occupies a large area in practical engineering applications, which is not conducive to the miniaturization and high integration of the overall power source system, thus limiting its application in compact application scenarios.

[0004] On the other hand, traditional P-band klystrons generally adopt a triode electron gun structure, which includes a cathode, a modulation anode, and an anode. Although this structure can achieve good electron beam modulation performance, it requires a separate voltage divider modulator, making the external high-voltage system complex and bulky, increasing the difficulty of system design and the space required.

[0005] Therefore, improvements to existing technologies are necessary.

[0006] The above information is provided as background information only to aid in understanding this application and does not constitute an assertion or admission that any of the above content can be used as prior art relative to this application. Summary of the Invention

[0007] This application provides a P-band integrated vertical metamaterial high-power klystron to reduce the overall size and footprint while ensuring the klystron's performance.

[0008] To achieve the above objectives, this application provides the following technical solution: A P-band integrated vertical metamaterial high-power klystron includes: An electron gun is used to fire an electron beam. An interaction resonant cavity chain includes multiple resonant cavity units that are axially connected in sequence along the emission direction of the electron beam, used to modulate the electron beam and extract microwave energy from the electron beam; The collecting electrode is used to collect the electron beam that has been discarded after passing through the interaction resonant cavity chain. A multi-layer annular magnetic field focusing assembly includes multiple single annular focusing modules spaced apart along the axial direction of the interaction resonant cavity chain on the outer periphery of the interaction resonant cavity chain. Each single annular focusing module is provided with a focusing coil to generate a converging magnetic field along the direction of electron beam motion. In this embodiment, at least one of the resonant cavity units of the interaction resonant cavity chain is loaded with a metamaterial unit, and the axial direction of the interaction resonant cavity chain is arranged in a vertical direction. The electron gun and the collector are arranged opposite to each other at the bottom and top of the axial direction of the interaction resonant cavity chain, so that the electron beam emitted by the electron gun is transmitted vertically from bottom to top through the interaction resonant cavity chain and then enters the collector. The electron gun includes a cathode and an anode, but excludes a modulation anode; and the accelerating voltage range of the electron gun is 80kV to 120kV, corresponding to a beam current range of 10A to 60A.

[0009] Optionally, the accelerating voltage range of the electron gun is 90kV to 110kV, corresponding to a beam current range of 15A to 45A.

[0010] Optional, also includes: An integrated electron gun cylinder is located at the bottom of the multi-layer annular magnetic field focusing assembly. Its interior is used to hold insulating oil and includes a first cavity and a second cavity arranged side by side and connected in the horizontal direction, which are used to support the filament transformer and the electron gun, respectively. The filament transformer has its primary winding electrically connected to the electrical connection port on the integrated electron gun cylinder for connecting to an external power source, and its secondary winding electrically connected to the cathode of the electron gun. The electron gun is housed in the first cavity, the filament transformer is housed in the second cavity, and both the electron gun and the filament transformer are immersed in the insulating oil.

[0011] Optionally, each of the single-ring focusing modules is further provided with a cooling pipe for heat exchange with the corresponding focusing coil, and the two ends of the cooling pipe are respectively connected to the outlet of the liquid inlet pipe and the inlet of the liquid outlet pipe.

[0012] Optionally, the outlet of the top-level cooling pipe is connected to the outlet of the outlet pipe, and the inlet of the bottom-level cooling pipe is connected to the outlet of the inlet pipe; in two adjacent cooling pipes in the vertical direction, the inlet of the upper cooling pipe is connected to the outlet of the lower cooling pipe through a branch pipe, so as to form a cooling liquid path flowing from bottom to top in the multi-layer annular magnetic field focusing assembly.

[0013] Optionally, the multi-layer annular magnetic field focusing assembly further includes an upper annular magnetic shielding plate, a lower annular magnetic shielding plate, and several axial support columns; The upper annular magnetic shielding plate is disposed at the top of the multi-layer annular magnetic field focusing assembly, the lower annular magnetic shielding plate is disposed at the bottom of the multi-layer annular magnetic field focusing assembly, and each of the axial support columns surrounds the axial outer periphery of the multi-layer annular magnetic field focusing assembly. Each of the axial support columns is fixedly connected to the upper annular magnetic shielding plate and the lower annular magnetic shielding plate at both ends along the vertical direction; and each of the axial support columns is fixedly connected to each of the single annular focusing modules, so as to fix each of the single annular focusing modules, the upper annular magnetic shielding plate and the lower annular magnetic shielding plate into a whole.

[0014] Optionally, the interaction resonant cavity chain includes 5 or 6 resonant cavity units, which are formed from bottom to top as an input cavity, multiple intermediate focusing cavities and an output cavity; The input cavity and at least one intermediate focusing cavity are loaded with metamaterial units, and at least one intermediate focusing cavity is configured to operate in second harmonic mode.

[0015] Optionally, the metamaterial units are subwavelength structures with periodic or quasi-periodic distributions; or, the unit size, aperture angle, and / or spacing parameters of each metamaterial unit vary along the electron beam propagation direction.

[0016] Optionally, the resonant cavity unit includes: a cavity shielding shell, two drift tubes, a metamaterial unit, and a welding disk; The cavity shielding shell has a hollow cylindrical structure, forming an electromagnetic shielding cavity; The two drift tubes are arranged with a gap along the electron beam transmission direction and penetrate through the cavity shielding shell; The metamaterial unit is disposed inside the electromagnetic shielding cavity; The welding pads are respectively disposed on the outer sides of the axial ends of the cavity shielding shell, and are used to weld and fix to adjacent resonant cavity units so that multiple resonant cavity units are axially connected to form the interactive resonant cavity chain.

[0017] Optionally, in two adjacent resonant cavity units in the vertical direction, the upper end of the lower drift tube of the upper resonant cavity unit is provided with an outwardly convex annular step, and the lower end of the drift tube of the lower resonant cavity unit is provided with an inwardly concave annular groove. The annular step and the annular groove are interlocked to form a radial positioning and axial sealing fit.

[0018] Optionally, the anode of the electron gun includes a protruding structure that protrudes toward the cathode, formed by rotating and tangenting multiple circular arc segments; The electron gun also includes a control electrode surrounding the cathode and concentric with the cathode. The control electrode includes a protruding structure that protrudes toward the anode, formed by several segments of circular arcs that are tangent to each other end to end.

[0019] Compared with the prior art, this application has the following beneficial effects: A vertical layout is achieved through metamaterial resonant cavities, significantly reducing the footprint: In this embodiment, a metamaterial unit is loaded within at least one resonant cavity unit of the interaction resonant cavity chain. This metamaterial unit can significantly reduce the physical size of a single resonant cavity while maintaining the operating frequency, thereby greatly shortening the axial length of the entire interaction resonant cavity chain. Based on this length reduction, klystrons that were originally limited to a horizontal layout due to their large size (traditional P-band klystrons are generally longer than 5 meters) can be converted to a vertical layout, with the electron gun and collector positioned at the bottom and top, respectively. The vertical layout fundamentally solves the problem of the large footprint of horizontal structures, ensuring that the overall height of the klystron does not exceed 2.5 meters. Compared to traditional klystrons of the same power level, the footprint can be reduced by more than 60%, making it particularly suitable for space-constrained accelerator rooms or integrated radio frequency systems.

[0020] A bipolar electron gun simplifies the system structure while ensuring beam quality: Traditional tripolar electron guns include a cathode 12, a modulation anode, and an anode. The modulation anode requires an external voltage divider modulator to provide an independently adjustable voltage to control the electron beam current. Therefore, the presence of a modulation anode necessitates a separate voltage divider modulator, resulting in a complex and bulky external high-voltage system. This embodiment eliminates the modulation anode, employing a bipolar electron gun consisting only of a cathode 12 and an anode 11. Since the modulation anode is no longer present, a separate voltage divider modulator is unnecessary, significantly simplifying the external high-voltage system and further reducing equipment footprint and cost. Furthermore, it is important to emphasize that this embodiment does not simply omit the modulation anode and passively accept its functional deficiency. Instead, it actively compensates for the lack of electron beam quality through technical means: precise matching of parameters such as accelerating voltage (80kV~120kV) and beam current (10A~30A) ensures that the electron beam possesses good laminar flow characteristics and a small transverse velocity component upon exiting the electron gun, allowing it to directly enter the interaction region without pre-modulation by the modulation anode. In other words, this scheme uses a two-electrode electron gun with optimized parameter configuration to fundamentally replace the function of the modulated anode in the three-electrode gun, rather than leaving a performance gap by omitting it.

[0021] The design adopts an integrated electron gun cylinder with a built-in integrated filament transformer, further reducing the overall system footprint and cost. Traditionally, the filament transformer needs to be placed in a separate external cylinder or share a cylinder with the voltage divider. This design innovatively proposes to integrate the transformer and electron gun inside the cylinder of the klystron in the field of P-band integrated vertical metamaterial high-power klystron, further simplifying the complexity and space requirements of the klystron power source system and saving the cost of designing and developing a transformer separately.

[0022] Verification has shown that, when applied to the P-band, the embodiments of this application can solve the land occupation problem by achieving a vertical layout through a metamaterial resonant cavity, while ensuring a peak output power of not less than 3MW and an electronic efficiency of not less than 50%, and simplify the system by using a bipolar electron gun to reduce complexity, thus demonstrating significant engineering application value.

[0023] This application has other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of this application. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a three-dimensional view of the P-band klystron provided in the embodiments of this application; Figure 2 This is an internal perspective view of the P-band klystron provided in the embodiments of this application; Figure 3 yes Figure 2 A cross-sectional view of the structure shown; Figure 4 This is an assembly structure diagram of the interactive resonant cavity chain and the multilayer annular magnetic field focusing assembly provided in the embodiments of this application; Figure 5 This is a perspective view of the multi-layer annular magnetic field focusing assembly provided in the embodiments of this application; Figure 6 This is a perspective view of the interactive resonant cavity chain provided in the embodiments of this application; Figure 7 This is a cross-sectional view of the interactive resonant cavity chain provided in the embodiments of this application; Figure 8 yes Figure 7 A magnified view of a portion of the structure shown. Figure 9 This is a cross-sectional view of a single resonant cavity unit provided in an embodiment of this application; Figure 10 This is a front view of the metamaterial unit provided in the embodiments of this application; Figure 11 This is a cross-sectional view of the electron gun provided in an embodiment of this application; Figure 12 This is the phase space distribution of the high-energy beam at different times when the P-band klystron provided in the embodiments of this application is outputting microwave energy at full power; Figure 13 This is a simulation of the output power and efficiency of the klystron provided in this application embodiment at different operating voltages.

[0026] Figure label: Electron gun 1, anode 11, control electrode 12, interaction resonant cavity chain 2, resonant cavity unit 21, cavity shielding shell 211, drift tube 212, metamaterial unit 213, welding disk 214, collecting electrode 3, multi-layer annular magnetic field focusing assembly 4, single annular focusing module 41, liquid inlet pipe 411, liquid outlet pipe 412, branch pipe 413; upper annular magnetic shielding plate 42, lower annular magnetic shielding plate 43, axial support column 44, integrated electron gun cylinder 5, filament transformer 6, input coupler 7, output coupler 8, external support frame 9. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] To reduce the footprint and overall volume of the P-band klystron and its supporting systems, while also lowering system complexity and improving adaptability to engineering applications, this invention provides a P-band integrated vertical metamaterial high-power klystron, which can significantly reduce the footprint and overall volume of the P-band klystron and its supporting systems, while also lowering system complexity and improving adaptability to engineering applications.

[0029] Please see Figures 1 to 10 The P-band integrated vertical metamaterial high-power klystron of this application embodiment includes: an electron gun 1, an interaction resonant cavity chain 2, a collector electrode 3, and a multilayer annular magnetic field focusing assembly 4.

[0030] Electron gun 1 is used to emit an electron beam that meets the working requirements, providing a basis for subsequent microwave energy extraction.

[0031] The interaction resonant cavity chain 2 includes multiple resonant cavity units 21 connected axially in sequence along the emission direction of the electron beam, used to modulate the electron beam and extract microwave energy from it. Arranged in sequence along the emission direction, these series-connected resonant cavity units 21 sequentially provide an input cavity, several intermediate focusing cavities, and an output cavity. The functions of each cavity are as follows: Input cavity: Serves as the signal input terminal of the klystron, connected to input coupler 7, used to receive external microwave signals, couple microwave energy into the cavity, and simultaneously perform preliminary modulation of the electron beam, laying the foundation for the subsequent interaction between the electron beam and the microwave field.

[0032] The intermediate focusing cavity consists of multiple resonant cavity units 21 connected in series, which are used to further modulate the speed and density of the electron beam, realize the focusing and energy exchange of the electron beam, and improve the microwave amplification efficiency. The output cavity, serving as the signal output terminal of the klystron, is connected to the output coupler 8. It is used to convert the kinetic energy of the electron beam into microwave energy, thereby realizing the output of a high-power microwave signal. At the same time, the amplified microwave signal is exported through the output coupler 8 for use by subsequent loads.

[0033] Collector 3 is used to collect the electron beam output after being processed by the interaction resonant cavity chain 2.

[0034] The multi-layer annular magnetic field focusing assembly 4 includes multiple single annular focusing modules 41 spaced apart along the axial direction of the interaction resonant cavity chain 2 on the outer periphery of the interaction resonant cavity chain 2. Each single annular focusing module 41 is provided with a focusing coil to generate a converging magnetic field along the direction of electron beam motion.

[0035] In this embodiment, at least one resonant cavity unit 21 of the interaction resonant cavity chain 2 is loaded with a metamaterial unit 213, and the axial direction of the interaction resonant cavity chain 2 is arranged in the vertical direction. The electron gun 1 and the collector 3 are arranged opposite to each other at the bottom and top of the axial direction of the interaction resonant cavity chain 2, so that the electron beam emitted by the electron gun 1 is transmitted vertically from bottom to top through the interaction resonant cavity chain 2 and then enters the collector 3.

[0036] The electron gun 1 is a two-stage electron gun 1, which includes only the cathode 12 and the anode 11, excluding the modulation anode; its operating parameters are precisely configured, with an accelerating voltage range of 80kV to 120kV and a corresponding beam current range of 10A to 60A.

[0037] Please see Figures 1 to 3In the P-band integrated vertical metamaterial high-power klystron provided in this embodiment of the invention, the cathode inside the electron gun 1 emits an electron beam under the heating effect of the filament. Because the cathode is connected to a pulsed negative high voltage (80kV~120kV), a high-energy electron beam is formed under the action of a strong electric field, propagating vertically from bottom to top. This electron beam first enters the input cavity, which receives the external microwave signal to be amplified through the input coupler 7. Within the cavity, the electron beam passing through the gap is velocity-modulated, with some electrons accelerating and others decelerating. Subsequently, the velocity-modulated electron beam drifts in the drift tubes 212 between the various resonant cavity units 21, gradually converting velocity modulation into density modulation. When the electron beam enters the intermediate focusing cavity, the radio frequency electric field induced in each cavity further remodulates the electron beam, continuously enhancing the density focusing of the electron beam. As the electron beam propagates vertically upward through multiple intermediate focusing cavities, the beam current is gradually compressed into a high-density periodic electron beam cluster. Finally, the highly focused electron beam enters the output cavity. The electron beam is modulated by the cavity field in the gap between the output cavities, and its kinetic energy is converted into microwave field energy, amplifying the high-power microwave signal. The amplified microwave signal is output through the output coupler 8 and supplied to the subsequent load. After completing the energy exchange, the electron beam velocity decreases and continues to propagate upwards into the collector 3. Its remaining kinetic energy is converted into heat energy and carried away by the cooling water in the water jacket outside the collector 3. Throughout the process, the multi-layer annular magnetic field focusing component 4 generates a converging magnetic field along the direction of electron beam motion, constraining the electron beam to maintain a stable beam radius, preventing beam divergence or wall collision, and ensuring that the electron beam can pass through the interaction resonant cavity chain 2 efficiently and stably.

[0038] Compared with traditional technologies, the embodiments of this application have the following characteristics: A vertical layout is achieved through metamaterial resonant cavities, significantly reducing the footprint: In this embodiment, a metamaterial unit 213 is loaded within at least one resonant cavity unit 21 of the interaction resonant cavity chain 2. This metamaterial unit 213 can significantly reduce the physical size of a single resonant cavity while maintaining the operating frequency, thereby greatly shortening the axial length of the entire interaction resonant cavity chain 2. Based on this length reduction, klystrons that were originally limited to a horizontal layout due to their large size (traditional P-band klystrons are generally longer than 5 meters) can be converted to a vertical layout, with the electron gun 1 and collector 3 positioned at the bottom and top, respectively. The vertical layout fundamentally solves the problem of the large footprint of horizontal structures, ensuring that the overall height of the klystron does not exceed 2.5 meters. Compared to traditional klystrons of the same power level, the footprint can be reduced by more than 60%, making it particularly suitable for space-constrained accelerator rooms or integrated radio frequency systems.

[0039] A bipolar electron gun 1 simplifies the system structure while ensuring beam quality: A traditional tripolar electron gun 1 includes a cathode 12, a modulation anode, and an anode 11. The modulation anode requires an external voltage divider modulator to provide an independently adjustable voltage to control the electron beam current. Therefore, whenever a modulation anode exists, a separate voltage divider modulator is necessary, resulting in a complex and bulky external high-voltage system. This embodiment eliminates the modulation anode, employing a bipolar electron gun 1 containing only a cathode 12 and an anode 11. Since the modulation anode is no longer present, a separate voltage divider modulator is unnecessary, greatly simplifying the external high-voltage system and further reducing equipment footprint and cost. Meanwhile, it is important to emphasize that the embodiments of this application do not simply omit the modulation anode and passively accept its functional deficiency. Instead, they ensure electron beam quality through active technical compensation: by precisely matching the accelerating voltage (80kV~120kV) and beam current (10A~60A) parameters, the electron beam possesses good laminar flow characteristics and a small transverse velocity component upon leaving the electron gun 1, allowing it to directly enter the interaction region without pre-modulation by the modulation anode. In other words, this solution, with a two-electrode electron gun 1 and optimized parameter configuration, fundamentally replaces the function of the modulation anode in a three-electrode gun, rather than leaving a performance gap after omission.

[0040] Verification has shown that, when applied to the P-band, the embodiments of this application can solve the land occupation problem by achieving a vertical layout through a metamaterial resonant cavity, while ensuring a peak output power of not less than 3MW and an electronic efficiency of not less than 50%, and simplify the system by using a bipolar electron gun 1 to reduce complexity, thus demonstrating significant engineering application value.

[0041] Furthermore, in one optional embodiment, the accelerating voltage range of the electron gun 1 is 90kV to 110kV, corresponding to a beam current range of 15A to 45A. This parameter range is an optimal range obtained through optimized matching under typical operating conditions of a P-band high-power klystron. Within this range, the laminar flow characteristics of the electron beam are optimal, the transverse velocity component is minimal, and it can enter the interaction resonant cavity chain 2 with a lower beam emittance, thereby reducing the transmission loss of the electron beam in the drift tube 212. Secondly, this voltage and current range keeps the conductivity of the electron gun 1 within a suitable range, avoiding the problems of beam focusing difficulties due to excessively low voltage and increased insulation breakdown risk due to excessively high voltage, achieving a good balance between output power and system reliability.

[0042] Based on the control of the above key parameters, when the length of the drift tube 212 or the key dimension deviation of the resonant cavity is controlled within ±0.5mm, the klystron can still maintain a stable working state, causing only a limited range of frequency and output power changes, thereby meeting the engineering manufacturing feasibility requirements.

[0043] Optionally, the cathode 12 is a coated impregnated hot cathode with a cathode load not exceeding 5 A / cm². The coated impregnated cathode 12 has the characteristics of low work function and high emission uniformity. Combined with a cathode load not exceeding 5 A / cm², it can ensure that the cathode 12 operates within its economic life range, effectively suppress the consumption of active material, extend the overall life of the klystron, and at the same time ensure the stability and uniformity of electron beam emission.

[0044] In traditional P-band klystrons, the filament transformer 6 is typically mounted independently outside the electron gun 1, requiring a long-distance high-voltage cable connection and occupying additional equipment space. For this purpose, please refer to... Figures 1 to 3 The high-power klystron in this embodiment of the application further includes: An integrated electron gun cylinder 5 is located at the bottom of a multi-layer annular magnetic field focusing assembly 4. Its interior is used to hold insulating oil and includes a first cavity and a second cavity arranged side by side and connected in the horizontal direction. The filament transformer 6 has its primary side electrically connected to the electrical connection port on the integrated electron gun cylinder 5 for connecting to an external power source, and its secondary side electrically connected to the cathode 12 of the electron gun 1. The electron gun 1 is housed in the first cavity, and the filament transformer 6 is housed in the second cavity. Both the electron gun 1 and the filament transformer 6 can be immersed in insulating oil.

[0045] This embodiment of the application sets up a first cavity and a second cavity arranged side by side and connected in the horizontal direction, housing the electron gun 1 in the first cavity and the filament transformer 6 in the second cavity, so that the two are integrated in the same integrated electron gun cylinder 5 unit, which can greatly reduce the number and volume of external accessories and is conducive to the miniaturization of the overall power source system.

[0046] When the electron gun 1 operates, it is in a pulsed negative high-voltage state (e.g., 80kV~120kV), requiring a high-insulation environment to prevent breakdown. The secondary winding of the filament transformer 6 is directly connected to the cathode 12 and is also at a high potential. In this application, the electron gun 1 and the filament transformer 6 are both immersed in the insulating oil within the same integrated electron gun cylinder 5. This utilizes the high withstand voltage characteristics of the insulating oil to achieve high-voltage insulation, and the shared oil circuit simplifies the cooling and sealing structure, reducing system complexity.

[0047] Furthermore, the first and second cavities are arranged side-by-side in a horizontal direction, making the electron gun 1 and the filament transformer 6 spatially independent. Compared to a stacked layout, this structure facilitates the separate disassembly and maintenance of the electron gun 1 or the filament transformer 6, while also promoting the convective circulation and heat dissipation of the insulating oil.

[0048] Overall, the use of an integrated electron gun cylinder 5 with a built-in integrated filament transformer 6 further reduces the footprint and cost of the entire system. Traditionally, the filament transformer 6 needs to be placed in a separate external cylinder or share a cylinder with the voltage divider. This application innovatively proposes to integrate the filament transformer 6 and the electron gun 5 inside the cylinder of the klystron in the field of P-band integrated vertical metamaterial high-power klystron, which further simplifies the complexity and footprint of the klystron power source system and saves the cost of designing and developing the filament transformer 6 separately.

[0049] When a high-power P-band klystron is operating, a large current is passed through the focusing coil to generate a converging magnetic field. Due to the coil's resistance, significant Joule heating is generated. If this heat cannot be dissipated in time, the coil temperature will rise excessively, causing the following problems: increased power consumption, impaired electron beam focusing stability, accelerated insulation aging, and even coil burnout. Therefore, please refer to [further details needed]. Figure 5 In this embodiment of the application, each single ring focusing module 41 is further provided with a cooling pipe for exchanging heat with the corresponding focusing coil. The two ends of the cooling pipe are connected to the outlet of the liquid inlet pipe 411 and the inlet of the liquid outlet pipe 412, respectively, so as to cool the focusing coil through the coolant in the cooling pipe.

[0050] In one alternative embodiment, the outlet of the top-level cooling pipe is connected to the outlet of the outlet pipe 412, and the inlet of the bottom-level cooling pipe is connected to the outlet of the inlet pipe 411. In two adjacent cooling pipes in the vertical direction, the inlet of the upper cooling pipe is connected to the outlet of the lower cooling pipe through a branch pipe 413, so as to form a cooling fluid path flowing from bottom to top in the multi-layer annular magnetic field focusing assembly 4.

[0051] In other words, this embodiment employs a bottom-up series cooling method: the coolant enters from the bottommost cooling pipe, flows through each of the middle cooling pipes in sequence, and exits from the topmost cooling pipe. Of course, in other embodiments, a parallel method or a combination of series and parallel methods can also be used.

[0052] The series cooling method not only ensures that the coolant flow rate in each layer of cooling pipes is exactly the same, eliminating the problem of uneven flow distribution and achieving balanced cooling of each layer of focusing coils, but also ensures that the coolant flows from bottom to top, making the coolant flow direction consistent with the direction of the ambient temperature gradient (temperature rises from bottom to top), which can naturally form temperature matching and improve heat exchange efficiency. In addition, the series method only requires one inlet pipe 411 and one outlet pipe 412, and each layer of modules is connected in sequence through branch pipes 413, which greatly reduces the number of pipe joints, facilitates simple layout, and simplifies the assembly process.

[0053] Please see Figure 4 and Figure 5The multi-layer annular magnetic field focusing assembly 4 also includes an upper annular magnetic shielding plate 42, a lower annular magnetic shielding plate 43, and several axial support columns 44. The upper annular magnetic shielding plate 42 is located at the top of the multi-layer annular magnetic field focusing assembly 4, the lower annular magnetic shielding plate 43 is located at the bottom of the multi-layer annular magnetic field focusing assembly 4, and each axial support column 44 surrounds the axial outer periphery of the multi-layer annular magnetic field focusing assembly 4. Each axial support column 44 has an upper annular magnetic shielding plate 42 and a lower annular magnetic shielding plate 43 fixedly connected to its two ends along the vertical direction, and each axial support column 44 is fixedly connected to each single annular focusing module 41, so as to fix each single annular focusing module 41, the upper annular magnetic shielding plate 42 and the lower annular magnetic shielding plate 43 into a whole.

[0054] Since the strong magnetic field generated by the focusing coil could interfere with external electronic equipment if it were to leak directly to the outside, this embodiment of the application uses the upper and lower magnetic shielding plates and the axial support column 44 to form a nearly closed magnetic circuit structure, which confines the magnetic field mainly inside the multi-layer annular magnetic field focusing assembly 4, reduces external radiation, and improves the electromagnetic compatibility of the system.

[0055] Meanwhile, in this embodiment, each axial support column 44 is arranged around the axial outer periphery of the focusing component, and the upper and lower magnetic shielding plates are fixedly connected in the vertical direction, and fixedly connected to the single ring focusing module 41 of each layer, thereby integrating multiple independent single ring modules into a rigid whole, improving the vibration and impact resistance, and making it suitable for on-site transportation and long-term operation.

[0056] To further enhance stability, such as Figure 1 As shown, the klystron in this embodiment of the application also includes an external support frame 9, which is fastened to the collecting electrode 3, the multi-layer annular magnetic field focusing assembly 4 and the integrated electron gun cylinder 5 to achieve an overall stable support effect.

[0057] The number of resonant cavity units 21 provided by the interacting resonant cavity chain 2 can be selected from 4 to 8, preferably 5 to 6, such as... Figure 6 and Figure 7 As shown, from bottom to top, it forms an input cavity, multiple intermediate focusing cavities, and an output cavity.

[0058] In one alternative embodiment, metamaterial units 213 are loaded inside the input cavity and at least one intermediate focusing cavity, such as... Figure 10As shown, the metamaterial unit can specifically be of the CeSRR type. The metamaterial unit 213 is a subwavelength structure with a periodic or quasi-periodic distribution. By changing its geometry, opening shape, and arrangement, equivalent capacitance and equivalent inductance are introduced into the resonant cavity, thereby controlling the equivalent electromagnetic parameters of the cavity. Overall, this method can effectively reduce the size of the resonant cavity while maintaining the target resonant frequency. Specifically, by loading the metamaterial unit 213, the effective characteristic impedance of a single resonant cavity can be increased, and the drift distance required to achieve the same modulation depth can be shortened, thereby reducing the overall resonant cavity chain length by 20% to 40% compared to the traditional structure.

[0059] At least one intermediate focusing cavity is configured to operate in the second harmonic mode, i.e. without the loading of metamaterial unit 213. The purpose of this design is to enhance the focusing of the electron beam and improve the beam energy exchange efficiency.

[0060] The output cavity preferably adopts a structure without loaded metamaterials, which can reduce the local electric field concentration effect under high power operation, thereby improving the device's breakdown resistance. Under rated operating conditions, the maximum electric field strength inside the cavity is lower than the vacuum breakdown threshold at the corresponding frequency.

[0061] In this embodiment, the interacting resonant cavity chain 2 can adopt a non-uniform structure design, that is, different resonant cavity units 21 can adopt different types of structural forms, including: some cavities are loaded with metamaterial units 213; some cavities adopt a traditional resonant cavity structure; or, different sizes and different loading quantities of metamaterial units 213 are combined. In practical applications, the design type can be selected according to the requirements.

[0062] The hybrid structure design described above enables the klystron to achieve both miniaturization and high reliability under high-power operation. For example, the metamaterial loading is reduced or eliminated in the cavity near the output end to reduce the electric field concentration effect, while the metamaterial loading is enhanced at the input end and in the focusing cavity to improve modulation efficiency.

[0063] Optionally, the electron beam is focused within the interaction region by an axial magnetic field with a strength of 150G to 350G. By appropriately selecting the magnetic field strength, the electron beam radius can be made smaller than the inner diameter of the drift tube 212, maintaining a stable transmission state and avoiding electron backflow or target hitting.

[0064] In one alternative implementation, please refer to Figure 9 A single resonant cavity unit 21 includes: a cavity shielding shell 211, two drift tubes 212, a metamaterial unit 213, and a welding disk 214; The cavity shielding shell 211 is a hollow cylindrical structure that forms an electromagnetic shielding cavity. Two drift tubes 212 are arranged with gaps along the electron beam transmission direction and pass through the cavity shielding shell 211. Metamaterial units 213 are disposed inside the electromagnetic shielding cavity. Welding pads 214 are respectively disposed on the outside of the two axial ends of the cavity shielding shell 211 for welding and fixing with adjacent resonant cavity units 21, so that multiple resonant cavity units 21 are axially connected to form an interactive resonant cavity chain 2.

[0065] In this embodiment, the metamaterial unit 213 is a subwavelength structure with a periodic or quasi-periodic distribution. By changing its geometric dimensions, opening shape, and arrangement, equivalent capacitance and equivalent inductance can be introduced into the resonant cavity, thereby controlling the equivalent electromagnetic parameters of the cavity. In this way, the size of the resonant cavity can be reduced while keeping the target resonant frequency constant.

[0066] In another alternative implementation, the metamaterial units 213 are no longer limited to a regular periodic distribution, but can be arranged in a gradually varying manner. That is, the unit size, opening angle, or spacing is gradually changed along the electron beam transmission direction, thereby achieving a spatially gradual change in the equivalent electromagnetic parameters. This structure is beneficial for achieving a smooth transition in the electron beam modulation process and reducing the risk of reflection and parasitic oscillations.

[0067] Furthermore, the resonant cavities are connected via drift tubes 212, and the drift distance is optimized and matched according to the electron velocity and operating frequency. Please refer to [link / reference]. Figure 8 In two adjacent resonant cavity units 21 in the vertical direction, the upper end of the lower drift tube 212 of the upper resonant cavity unit 21 is provided with an outwardly convex annular step, and the lower end of the drift tube 212 of the lower resonant cavity unit 21 is provided with an inwardly concave annular groove. The annular step and the annular groove are interlocked to form a radial positioning and axial sealing fit. In this embodiment, the interlocking connection between adjacent resonant cavity units 21 using annular steps and annular grooves not only ensures coaxial transmission of the electron beam and improves sealing reliability, but also has strong vibration resistance, high overall mechanical reliability, and a smooth transition of the inner wall, reducing the risk of electron beam arcing.

[0068] The transit gap length of each resonant cavity is designed based on the electron beam energy and synchronization conditions, ensuring that the electron beam is in a decelerating phase at the input cavity, thus achieving velocity modulation; during the subsequent drift process, density modulation is gradually formed, and energy release is completed at the output cavity. Through the coordinated optimization of gap length, cavity spacing, and resonant parameters, a high-density beam-focusing structure can be formed at the output cavity, thereby achieving high energy conversion efficiency.

[0069] In one alternative implementation, please refer to Figure 11The bipolar electron gun of this embodiment mainly comprises an anode 11 and a cathode 12. The cathode 12 and the control electrode 13 are concentric and connected at the same potential behind each other, thus considered as one electrode. When the electron gun is operating, the cathode 12 (control electrode 13) is directly connected to an externally supplied pulsed negative high voltage, such as 80-120kV. The anode 11 is at the same potential as the klystron's external shield, which is 0. Therefore, a strong potential difference is formed between the anode 11 and the cathode 12, which enables the cathode 12 to emit a high-energy electron beam. Figure 11 The anode 11 in the cathode 12 has a main structural feature: a protruding structure convex towards the cathode 12, formed by multiple rotating tangential arcs (e.g., two rotating tangential arcs at 110 degrees). This ensures a more uniform electric field distribution on the surface, making it less prone to breakdown and arcing. Similarly, the control electrode 13 also includes a protruding structure convex towards the anode 11, formed by several rotating tangential arcs. This protruding structure is approximately an annular ring that encloses the cathode 12 in its center. The chevron shape of the control electrode 13's protruding structure is primarily for modulating the electric field distribution on the cathode 12 surface, thereby controlling the emission characteristics of the high-energy electron beam.

[0070] In this embodiment of the application, the P-band high-power klystron operates at a frequency ranging from 300MHz to 900MHz, preferably around 648MHz. Under rated operating conditions, the klystron can achieve megawatt-level output power, with an electronic efficiency preferably not less than 50%. Furthermore, under different operating voltage conditions, the output power exhibits a monotonic relationship with voltage changes, thus providing a certain range of power regulation capability.

[0071] Figure 12 The figure shows the simulation results of the phase space distribution of the high-energy beam at different times when the P-band klystron outputs microwave energy at full power. As can be seen from the figure, the electron beam output from the electron gun has low velocity dispersion and good laminar flow characteristics before entering the interaction region. In the input cavity and the intermediate focusing cavity, the electron beam is modulated by the radio frequency electric field, and its velocity changes periodically and gradually forms a focused beam. After entering the output cavity, the kinetic energy of the electron beam is efficiently converted into microwave energy, which verifies that the electron beam has good transmission stability and beam-wave interaction efficiency under the synergistic design of the two-stage electron gun, metamaterial resonant cavity and focusing component in the embodiment of this application.

[0072] Figure 13 The figure shows the output power and electronic efficiency of the klystron as a function of operating voltage under a fixed conductivity coefficient. As can be seen from the figure, within the preferred operating voltage range of this invention (80–110 kV), the output power steadily increases with increasing beam voltage, achieving megawatt-level output. The electronic efficiency remains above 55% within this range, with a peak efficiency of approximately 60%. This verifies the effectiveness of the two-stage electron gun parameter matching scheme in this application, demonstrating that while simplifying the system structure, it still ensures the high power and high efficiency output performance of the klystron.

[0073] In summary, the embodiments of this application, through the synergistic design of the bipolar electron gun structure and the loaded metamaterial resonant cavity, reduce system complexity while achieving miniaturization, high efficiency, and high power output of the klystron, and have good prospects for engineering applications.

[0074] Finally, it should be noted that although the above embodiments have been described in the text and drawings of this application, this should not limit the scope of patent protection of this application. Any technical solutions that are based on the essential concept of this application and utilize the content described in the text and drawings of this application, resulting in equivalent structural or procedural substitutions or modifications, as well as the direct or indirect application of the technical solutions of the above embodiments to other related technical fields, are all included within the scope of patent protection of this application.

Claims

1. A P-band integrated vertical metamaterial high-power klystron, characterized in that, include: Electron gun (1), used to emit an electron beam; The interaction resonant cavity chain (2) includes a plurality of resonant cavity units (21) connected axially in sequence in the emission direction of the electron beam, for modulating the electron beam and extracting microwave energy from the electron beam; The collecting electrode (3) is used to collect the electron beam output after being acted upon by the interaction resonant cavity chain (2); The multi-layer ring magnetic field focusing assembly (4) includes multiple single ring focusing modules (41) spaced apart along the axial direction of the interaction resonant cavity chain (2) on the outer periphery of the interaction resonant cavity chain (2). Each single ring focusing module (41) is provided with a focusing coil to generate a converging magnetic field along the direction of electron beam movement. In this embodiment, at least one of the resonant cavity units (21) of the interaction resonant cavity chain (2) is loaded with a metamaterial unit (213), and the axial direction of the interaction resonant cavity chain (2) is arranged vertically. The electron gun (1) and the collecting electrode (3) are arranged opposite to each other at the bottom and top of the axial direction of the interaction resonant cavity chain (2), so that the electron beam emitted by the electron gun (1) is transmitted vertically from bottom to top through the interaction resonant cavity chain (2) and then enters the collecting electrode (3). The electron gun (1) includes a cathode (12) and an anode (11), but does not include a modulation anode; and the accelerating voltage range of the electron gun (1) is 80kV to 120kV, corresponding to a beam current range of 10A to 60A.

2. The P-band integrated vertical metamaterial high-power klystron according to claim 1, characterized in that, The accelerating voltage range of the electron gun (1) is 90kV to 110kV, and the corresponding beam current range is 15A to 45A.

3. The P-band integrated vertical metamaterial high-power klystron according to claim 1, characterized in that, Also includes: An integrated electron gun cylinder (5) is located at the bottom of the multi-layer annular magnetic field focusing assembly (4). Its interior is used to hold insulating oil and includes a first cavity and a second cavity arranged in parallel and connected in the horizontal direction, which are used to support the filament transformer and the electron gun, respectively. The primary winding of the filament transformer (6) is electrically connected to the electrical connection port on the integrated electron gun cylinder (5) for connecting to an external power source, and the secondary winding is electrically connected to the cathode (12) of the electron gun (1). The electron gun (1) is housed in the first cavity, the filament transformer (6) is housed in the second cavity, and both the electron gun (1) and the filament transformer (6) are immersed in the insulating oil.

4. The P-band integrated vertical metamaterial high-power klystron according to claim 1, characterized in that, Each of the single-ring focusing modules (41) is also provided with a cooling pipe for exchanging heat with the corresponding focusing coil. The two ends of the cooling pipe are connected to the outlet of the liquid inlet pipe (411) and the inlet of the liquid outlet pipe (412), respectively.

5. The P-band integrated vertical metamaterial high-power klystron according to claim 4, characterized in that, The outlet of the top-level cooling pipe is connected to the outlet of the outlet pipe (412), and the inlet of the bottom-level cooling pipe is connected to the outlet of the inlet pipe (411). In two adjacent cooling pipes in the vertical direction, the inlet of the upper cooling pipe is connected to the outlet of the lower cooling pipe through a branch pipe (413) to form a cooling liquid path flowing from bottom to top in the multi-layer annular magnetic field focusing assembly (4).

6. The P-band integrated vertical metamaterial high-power klystron according to claim 1, characterized in that, The multi-layer annular magnetic field focusing assembly (4) also includes an upper annular magnetic shielding plate (42), a lower annular magnetic shielding plate (43), and several axial support columns (44). The upper annular magnetic shielding plate (42) is located at the top of the multi-layer annular magnetic field focusing assembly (4), the lower annular magnetic shielding plate (43) is located at the bottom of the multi-layer annular magnetic field focusing assembly (4), and each of the axial support columns (44) surrounds the axial outer periphery of the multi-layer annular magnetic field focusing assembly (4). Each of the axial support columns (44) is fixedly connected to the upper annular magnetic shielding plate (42) and the lower annular magnetic shielding plate (43) at both ends along the vertical direction; and each of the axial support columns (44) is fixedly connected to each of the single annular focusing modules (41) to fix each of the single annular focusing modules (41), the upper annular magnetic shielding plate (42) and the lower annular magnetic shielding plate (43) into a whole.

7. The P-band integrated vertical metamaterial high-power klystron according to claim 1, characterized in that, The interaction resonant cavity chain (2) includes 5 or 6 resonant cavity units (21), which are formed from bottom to top as an input cavity, multiple intermediate focusing cavities and an output cavity; The input cavity and at least one of the intermediate focusing cavities are loaded with metamaterial units (213), and at least one of the intermediate focusing cavities is configured to operate in the second harmonic mode.

8. The P-band integrated vertical metamaterial high-power klystron according to claim 7, characterized in that, The metamaterial unit (213) is a subwavelength structure with a periodic or quasi-periodic distribution; or, the unit size, opening angle and / or spacing parameters of each metamaterial unit (213) vary along the electron beam transmission direction.

9. The P-band integrated vertical metamaterial high-power klystron according to claim 7, characterized in that, The resonant cavity unit (21) includes: a cavity shielding shell (211), two drift tubes (212), a metamaterial unit (213), and a welding disk (214). The cavity shielding shell (211) has a hollow cylindrical structure, forming an electromagnetic shielding cavity; The two drift tubes (212) are arranged with a gap along the electron beam transmission direction and are disposed through the cavity shielding shell (211). The metamaterial unit (213) is disposed inside the electromagnetic shielding cavity; The welding disks (214) are respectively disposed on the outer sides of the cavity shield shell (211) at both ends, and are used to weld and fix with adjacent resonant cavity units (21) so that multiple resonant cavity units (21) are axially connected to form the interactive resonant cavity chain (2).

10. The P-band integrated vertical metamaterial high-power klystron according to claim 9, characterized in that, In two adjacent resonant cavity units (21) in the vertical direction, the upper end of the lower drift tube (212) of the upper resonant cavity unit (21) is provided with an outwardly convex annular step, and the lower end of the drift tube (212) of the lower resonant cavity unit (21) is provided with an inwardly concave annular groove. The annular step and the annular groove are interlocked to form a radial positioning and axial sealing fit.

11. The P-band integrated vertical metamaterial high-power klystron according to claim 1, characterized in that, The anode (11) of the electron gun (1) includes a protruding structure that protrudes toward the cathode (12) formed by multiple segments of circular arcs rotating tangentially; The electron gun (1) also includes a control electrode (13) surrounding the cathode (12) and concentric with the cathode (12). The control electrode (13) includes a protruding structure formed by several arc segments tangent to each other at the beginning and end, protruding toward the anode (11).

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