A mixed material input cavity for a pulsed magnetic field velocity modulation tube and an optimization method thereof

Abstract

The application discloses a mixed material input cavity for a pulse magnetic field klystron and an optimization method thereof. The mixed material input cavity comprises an inner conductor, a first outer conductor and a second outer conductor which are sleeved on the inner conductor. A drift tube cavity is formed between the outer wall of the inner conductor and the inner walls of the first outer conductor and the second outer conductor. An injection waveguide is formed between the first outer conductor and the second outer conductor. The injection waveguide and the drift tube cavity are communicated through an input cavity. The input cavity inner wall parts of the inner conductor, the first outer conductor and the second outer conductor are made of metal materials with different electric conductivities. The optimization method comprises optimizing the structure of the mixed material input cavity so that the response time of the metal materials with different electric conductivities to a magnetic field is as consistent as possible. The mixed material input cavity for the pulse magnetic field klystron aims to reduce microwave loss of injected microwaves and reduce eddy current loss.

Description

Technical Field

[0001] This invention relates to the field of high-power microwave technology, specifically to a hybrid material input cavity for a pulsed magnetic field klystron and its optimization method. Background Technology

[0002] High-power microwaves (HPM) typically refer to electromagnetic waves with peak power greater than 100 MW and frequencies between 0.1 GHz and 100 GHz. HPM technology is an interdisciplinary field that emerged in the 1970s, a product of the combination of traditional vacuum electronic devices and pulsed power technology. In the past two decades, driven by applications such as high-energy radio frequency accelerators, directed-energy weapons, and high-power radar, HPM technology has shown promising application prospects in both military and civilian fields and has experienced rapid development.

[0003] HPM devices are devices that convert the kinetic energy of an electron beam into microwave energy by utilizing the interaction mechanism between the high-current relativistic electron beam and its eigenmode in a vacuum high-frequency electromagnetic structure. High frequency, high power, high efficiency, long pulse, and high repetition rate are the goals that HPM technology continuously pursues. However, due to limitations imposed by the physical mechanisms of HPM generation, device fabrication processes, and material properties, further advancements in frequency, power, efficiency, pulse length, and repetition rate are hampered by physical obstacles such as strong electric field breakdown and shortened output microwave pulses, restricting further increases in the peak power of single-tube HPM devices. To meet practical application requirements, power combining of the output microwaves from multiple HPM devices has become a key focus and main direction for future HPM technology development. Among various power combining methods, spatial coherent power combining is advantageous because it can achieve N0 in the far field. 2 With a peak power density that is twice that of microwave generating devices (N being the number of microwave generating devices), it has a more attractive prospect.

[0004] To achieve high-efficiency spatial coherent power combining, the HPM devices involved in the combining process need to possess excellent frequency-locking and phase-locking characteristics, enabling precise control of the output microwave frequency and phase locking among multiple HPM generating devices. The relativistic klystron amplifier (RKA), as a microwave amplification device, offers advantages such as frequency stability and phase controllability, making it one of the ideal devices for spatial coherent power combining. The triaxial klystron amplifier (TKA) is an extension of the RKA to the higher frequency band, such as... Figure 1As shown, the TKA device consists of a cathode holder 101, an anode outer cylinder 102, a cathode 103, an inner conductor 104, an input cavity 105, a first modulation cavity 106, a second modulation cavity 107, an extraction cavity 108, a first reflector 109, a second reflector 110, a third reflector 111, an electron beam collector 112, an output port adjustment block 113, and an output waveguide 114. By introducing the inner conductor 104 and reasonably controlling the difference between the radii of the inner and outer conductors, the lateral operating mode of the device can be effectively blocked, allowing the device to have a larger radial dimension, which is beneficial to improving the space limit current and thus improving the output power. The injection of the input signal is the most fundamental and critical link in HPM spatial coherent power combining technology. The main function of the input cavity 105 is to achieve matched absorption of externally injected microwaves and complete the initial modulation of the electron beam, which is the first key structure to achieve high power and high efficiency output of TKA. The input cavity is mostly made of stainless steel. The inherent quality factor of the input cavity is positively correlated with the conductivity of the material. Therefore, using materials with higher conductivity (such as aluminum, copper, etc.) can improve the inherent quality factor of the input cavity, thereby reducing microwave loss of injected microwaves, enhancing the modulation of the electron beam by the input cavity, and improving the output power of the TKA.

[0005] During TKA operation, the electron beam exhibits significant divergence due to the presence of space charge force. Therefore, an external guiding magnetic field is required to guide and focus the electron beam, enhancing beam-wave interaction and improving microwave output efficiency. The pulsed magnetic field generated by capacitor discharge through a solenoid offers advantages such as compact structure, low heat generation, and low power consumption, and has been widely used in HPM (High-Performance Microwave) applications. However, under pulsed magnetic fields, materials with high conductivity experience significant eddy current losses. This leads to a decrease in magnetic field strength at the input cavity location where high conductivity is used, increasing the power consumption of the pulsed magnetic field and failing to achieve the optimal effect of saving magnetic field energy. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a hybrid material input cavity for a pulsed magnetic field klystron and its optimization method, in view of the above-mentioned problems of the prior art. The present invention aims to reduce microwave loss of injected microwaves and reduce eddy current loss.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A hybrid material input cavity for a pulsed magnetic field klystron includes an inner conductor and a first outer conductor and a second outer conductor respectively sleeved on the inner conductor. A drift cavity is formed between the outer wall of the inner conductor and the inner walls of the first and second outer conductors. An injection waveguide is formed between the first and second outer conductors. The injection waveguide and the drift cavity are connected through an input cavity. The inner wall portion of the input cavity of the inner conductor, the first outer conductor, and the second outer conductor is made of a metal material with different conductivity than the rest, and the conductivity of the inner wall portion of the metal material is higher than that of the rest portion of the metal material.

[0009] Optionally, the inner conductor, the first outer conductor, and the second outer conductor are rotationally symmetric about the central axis OO′ of the inner conductor.

[0010] Optionally, the input cavity is a re-entrant coaxial resonant cavity structure, which includes an input cavity gap and a re-entrant structure. The re-entrant structure is arranged along the length of the drift cavity, and the middle part of the re-entrant structure is connected to the injection waveguide, and one end is connected to the input cavity gap. The input cavity gap includes a pair of grooves formed on the inner walls of both sides of the drift cavity.

[0011] Optionally, the inner conductor has a three-section structure, and the metal material used in the middle section is different from that used in the other two sections. A groove forming the inner side of the input cavity gap is located on the middle section of the inner conductor. The injection waveguide has a rectangular cross-section. The first outer conductor has an L-shaped first mounting groove on the side near the injection waveguide. The first mounting groove has a first L-shaped inner wall with its inner corner facing the injection waveguide. The middle part of the first L-shaped inner wall is arranged opposite to the injection waveguide, and the shorter end has an extension parallel to the longer end. The extension extends to align with the edge of the injection waveguide; the second outer conductor has an L-shaped second mounting groove on the side near the injection waveguide, and the second mounting groove has a second L-shaped inner wall with its inner corner facing the drift cavity. The shorter end of the second L-shaped inner wall contacts the bottom of the second mounting groove, and the longer end aligns with the edge of the injection waveguide. The gap between the longer end of the first L-shaped inner wall and the shorter end of the second L-shaped inner wall forms the outer part of the input cavity gap, and the outer part of the input cavity gap is aligned with the inner part of the input cavity gap.

[0012] Optionally, the outer ends of the first outer conductor, the second outer conductor, and the inner conductor are all made of stainless steel, and the middle section of the first L-shaped inner wall, the second L-shaped inner wall, and the inner conductor is made of aluminum. The thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall is 6.5 mm, so that the response time of the inner wall portion of the input cavity to the magnetic field is the same as or the difference is less than a set value.

[0013] Optionally, the length L8 of the second L-shaped inner wall is 22 mm; the length L7 of the first L-shaped inner wall is 20 mm; the width L3 of the injection waveguide is 2 mm; the distance L4 between the longer end of the first L-shaped inner wall and the input cavity gap is 7.3 mm; the length L2 of the re-entry structure is 17.5 mm; the width L1 of the input cavity gap is 5 mm; the thickness L6 of the middle section of the inner conductor near the first outer conductor and the portion between it and the input cavity gap is 7 mm; the length L5 of the middle section of the inner conductor is 21 mm; the groove depth H1 on the inner conductor forming the inner portion of the input cavity gap is 4.3 mm; the groove depth H2 between the first and second outer conductors forming the outer portion of the input cavity gap is 4.5 mm; and the width H3 of the re-entry structure is 2.5 mm.

[0014] Optionally, the inner conductor has bolted connection structures at both ends for connecting to the front end structure and the rear end structure of the input cavity, and the outer end faces of the first and second outer conductors have bolted connection structures for connecting to the front end structure or the rear end structure of the input cavity.

[0015] Optionally, the inner wall portions of the first and second outer conductors, made of aluminum, are embedded in the remaining portions made of stainless steel.

[0016] A triaxial relativistic klystron amplifier includes a triaxial relativistic klystron amplifier body and an input cavity disposed at the front end of the triaxial relativistic klystron amplifier body, wherein the input cavity is the aforementioned hybrid material input cavity for a pulse magnetic field klystron.

[0017] An optimization method for the aforementioned hybrid material input cavity of a pulsed magnetic field klystron includes:

[0018] S101, Determine the length of the mixed material input cavity, wherein the length of the mixed material input cavity is greater than 10 times the radius R2 between the central axis OO′ of the inner conductor and the outer wall of the drift cavity;

[0019] S102, Based on the length of the hybrid material input cavity, determine the response time of the first outer conductor, the second outer conductor, and the rest of the inner conductor to the magnetic field;

[0020] S103, adjust the thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall, calculate the response time of the inner wall portion of the input cavity to the magnetic field, and determine whether the response time of the inner wall portion of the input cavity to the magnetic field is the same as or the difference is less than the set value. If not, jump to step S103 to continue optimizing and adjusting the thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall; otherwise, determine that the final thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall is the optimal thickness.

[0021] Compared with the prior art, the present invention has the following advantages: The present invention includes an inner conductor and a first outer conductor and a second outer conductor respectively sleeved on the inner conductor. A drift cavity is formed between the outer wall of the inner conductor and the inner walls of the first and second outer conductors. An injection waveguide is formed between the first and second outer conductors. The injection waveguide and the drift cavity are connected through an input cavity. The inner wall portion of the input cavity of the inner conductor, the first outer conductor, and the second outer conductor and the remaining portion are made of metal materials with different conductivity, forming a hybrid material input cavity structure. As mentioned earlier, using materials with high conductivity can improve the quality factor of the injection cavity and reduce microwave loss. However, in the application of pulsed magnetic fields, because the magnetic field has a frequency, eddy current losses will be generated in the metal, and the higher the conductivity, the greater the eddy current loss. Based on the existence of the above two contradictory factors, the hybrid material input cavity structure of this invention uses two metal materials with different conductivity, and the conductivity of the inner wall metal material is higher than that of the rest of the metal material. Therefore, the metal material with higher conductivity inside (surrounding the injection cavity structure) is beneficial to improving the quality factor of the injection cavity, while the metal material with lower conductivity on the outside is used to minimize eddy current loss (compared with the single metal material structure). This can effectively improve the inherent quality factor of the input cavity, reduce microwave loss, reduce eddy current loss, enhance the modulation of the electron beam by the input cavity, and improve the output power of the triaxial relativistic klystron amplifier (TKA). This lays the technical foundation for HPM devices to achieve high power and high efficiency microwave output. Attached Figure Description

[0022] Figure 1 It is an X-band triaxial relativistic klystron amplifier in the existing technology.

[0023] Figure 2 This is a schematic diagram of the stainless steel-aluminum hybrid input cavity in an embodiment of the present invention.

[0024] Figure 3 The simulation results show the response time of the two metal materials to the magnetic field in this embodiment of the invention.

[0025] Legend: 201, Inner conductor; 202, First outer conductor; 203, Second outer conductor; 211, Input cavity; 2111, Input cavity gap; 2112, Reentrant structure; 212, Injection waveguide; 213, Drift cavity. Detailed Implementation

[0026] like Figure 2 As shown, this embodiment provides a hybrid material input cavity for a pulsed magnetic field klystron, including an inner conductor 201 and a first outer conductor 202 and a second outer conductor 203 respectively sleeved on the inner conductor 201. A drift cavity 213 is formed between the outer wall of the inner conductor 201 and the inner walls of the first outer conductor 202 and the second outer conductor 203. An injection waveguide 212 is formed between the first outer conductor 202 and the second outer conductor 203. The injection waveguide 212 and the drift cavity 213 are connected through an input cavity 211. The inner wall portion of the input cavity 211 of the inner conductor 201, the first outer conductor 202, and the second outer conductor 203 and the remaining portion are made of metal materials with different electrical conductivities, and the electrical conductivity of the inner wall portion of the metal material is higher than that of the remaining portion of the metal material. Considering factors such as material conductivity, hardness, and cost-effectiveness, in this embodiment, the inner wall of the input cavity 211 of the inner conductor 201, the first outer conductor 202, and the second outer conductor 203 is made of aluminum, while the remaining parts are made of stainless steel, forming a stainless steel-aluminum hybrid input cavity structure. The base material is stainless steel, and the cavity surface material is aluminum, which reduces microwave loss during injection and also reduces eddy current loss. The drift cavity 213 is the channel for electron beam transmission, and its structure is an annular cavity between the inner conductor 4 and the first and second outer conductors 202 and 203 of the input cavity.

[0027] like Figure 2 As shown, in this embodiment, the inner conductor 201, the first outer conductor 202, and the second outer conductor 203 are rotationally symmetric structures about the central axis OO′ of the inner conductor 201. For ease of description, the end near the inlet of the drift cavity 213 is defined as the left side, the end connected to the cluster cavity of the triaxial relativistic klystron amplifier is defined as the right side, the side closer to the central axis OO′ is defined as the inner side, and the side farther from the central axis OO′ is defined as the outer side.

[0028] Input cavity 211 is the core structure of the hybrid material input cavity used in the pulse magnetic field klystron of this embodiment. See also Figure 2In this embodiment, the input cavity 211 is a re-entry coaxial resonant cavity structure. The re-entry coaxial resonant cavity structure includes an input cavity gap 2111 and a re-entry structure 2112. The re-entry structure 2112 is arranged along the length of the drift cavity 213, and its middle part is connected to the injection waveguide 212, and one end is connected to the input cavity gap 2111. The input cavity gap 2111 includes a pair of grooves formed on the inner walls of both sides of the drift cavity 213. The gap between the inner conductor 201 and the second outer conductor 203 of the input cavity, the groove on the outside of the inner conductor 201, and the groove on the inside of the second outer conductor 203 of the input cavity constitute the input cavity gap 2111. The outer side of the aluminum is made of stainless steel. Since stainless steel is the base material of the entire TKA, the present invention will not make special descriptions of the base material. The gap between the first outer conductor 202 and the second outer conductor 203 of the input cavity constitutes the re-entry structure 2112.

[0029] like Figure 2 As shown, the inner conductor 201 in this embodiment has a three-section structure, and the metal material used in the middle section is different from that used in the other two sections. The groove forming the inner part of the input cavity gap 2111 on the inner conductor 201 is provided on the middle section. Specifically, in this embodiment, the inner conductor 201 has a three-section structure, including a stainless steel section, an aluminum section, and a stainless steel section connected in sequence. The groove forming the re-entry structure 2112 on the inner conductor 201 is provided on the aluminum section. That is, the inner conductor 201 is processed in sections, connected in series with screws, and the outermost layer is fixed with a nut, so that the middle layer can be clamped.

[0030] Injection waveguide 212 is the structure for injecting microwaves into input cavity 211, see [link / reference]. Figure 2 In this embodiment, the injection waveguide 212 has a rectangular cross-section and is composed of the gap between the first outer conductor 202 of the input cavity and the second outer conductor 203 of the input cavity.

[0031] In this embodiment, the first outer conductor 202 is provided with an L-shaped first mounting groove on the side near the injection waveguide 212. The first mounting groove has a first L-shaped inner wall with its inner corner facing the injection waveguide 212. The middle part of the first L-shaped inner wall is arranged opposite to the injection waveguide 212, and the shorter end has an extension arranged parallel to the longer end. The extension extends to be aligned with the edge of the injection waveguide 212. The second outer conductor 203 is provided with an L-shaped second mounting groove on the side near the injection waveguide 212. The second mounting groove has a second L-shaped inner wall with its inner corner facing the drift cavity 213. The shorter end of the second L-shaped inner wall is in contact with the bottom of the second mounting groove, and the longer end is aligned with the edge of the injection waveguide 212. The gap between the longer end of the first L-shaped inner wall and the shorter end of the second L-shaped inner wall forms the outer part of the input cavity gap 2111, and the outer part of the input cavity gap 2111 is aligned with the inner part of the input cavity gap 2111.

[0032] For the hybrid material input cavity, the response time of the two materials with different conductivities to the magnetic field still differs, which seriously affects the synchronization of the device at this location, impacts beam-wave interaction, and ultimately affects the efficiency of the TKA (Telematics Kinematic Amplifier). To address these technical problems, reduce the difference in response time between stainless steel and aluminum materials to the magnetic field, and minimize the impact on the operation of the TKA, the structure of the input cavity 211 is optimized in this embodiment. For example... Figure 2 As shown, in this embodiment, the outer ends of the first outer conductor 202, the second outer conductor 203, and the inner conductor 201 are all made of stainless steel, while the first L-shaped inner wall, the second L-shaped inner wall, and the middle section of the inner conductor 201 are made of aluminum. The thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall is 6.5 mm, ensuring that the response time of the inner wall portion of the input cavity 211 to the magnetic field is the same as or less than a set value as the response time of the remaining portions of the first outer conductor 202, the second outer conductor 203, and the inner conductor 201. For example, in this embodiment, the thickness of the surface material—aluminum—around the input cavity gap 2111 is optimized based on the magnetic field charging time. To reduce the influence of the injection waveguide on the angular uniformity of the input cavity operating mode, the axial position of the injection waveguide 212 needs to be optimized. In principle, the greater the distance between the injection waveguide and the input cavity, the smaller the influence of the injection waveguide on the angular uniformity of the input cavity's operating mode. However, the longer the distance, the more competing modes may exist in the input cavity.

[0033] like Figure 2As shown, in this embodiment, the length L8 of the second L-shaped inner wall is 22 mm; the length L7 of the first L-shaped inner wall is 20 mm; the width L3 of the injection waveguide 212 is 2 mm; the distance L4 between the longer end of the first L-shaped inner wall and the input cavity gap 2111 is 7.3 mm; the length L2 of the re-entry structure 2112 is 17.5 mm; the width L1 of the input cavity gap 2111 is 5 mm; the thickness L6 of the middle section of the inner conductor 201 near the first outer conductor 202 and the portion between it and the input cavity gap 2111 is 7 mm; the length L5 of the middle section of the inner conductor 201 is 21 mm; the groove depth H1 on the inner conductor 201 forming the inner portion of the input cavity gap 2111 is 4.3 mm; the groove depth H2 between the first outer conductor 202 and the second outer conductor 203 forming the outer portion of the input cavity gap 2111 is 4.5 mm; and the width H3 of the re-entry structure 2112 is 2.5 mm. Furthermore, see also... Figure 2 In this embodiment, the length L7 of the aluminum portion in the first outer conductor 202 is 20 mm; the width L3 of the injection waveguide 212 is 2 mm; the length L4 of the aluminum portion in the second outer conductor 203 from the end near the injection waveguide 212 to the input cavity gap 2111 is 7.3 mm; the length L2 of the re-entry structure 2112 is 17.5 mm; the width L1 of the input cavity gap 2111 is 5 mm; the thickness L6 of the aluminum portion in the inner conductor 201 from the side near the first outer conductor 202 to the input cavity gap 2111 is 7 mm; and the length L5 of the aluminum portion in the second outer conductor 203 from the input cavity gap 2111 to the end near the second outer conductor 203 is 21 mm. mm; the depth H1 of the groove forming the input cavity gap 2111 on the inner conductor 201 is 4.3 mm, the depth H2 of the groove forming the input cavity gap 2111 on the second outer conductor 203 is 4.5 mm, the width H3 of the re-entry structure 2112 is 2.5 mm, and the thickness H4 of the aluminum portion on the first outer conductor 202 and the second outer conductor 203 is 6.5 mm. This ensures that the response time of the aluminum portion of the inner wall structure of the input cavity 211 to the magnetic field is the same as or less than the response time of the stainless steel material to the magnetic field, thereby reducing the difference in response time between the stainless steel and aluminum materials to the magnetic field and reducing the impact on the operation of the triaxial relativistic klystron amplifier (TKA). See Figure 2In this embodiment, the inner cavity depth of the input cavity gap 2111 is H1, and the length is L1. The outer cavity depth is H2, and the length is L1. The sharp corners are chamfered to prevent electric field concentration. The re-entry structure 2112 is rotationally symmetrical about the central axis (i.e., the OO′ axis), with a length of L2 and a width of H3. The sharp corners are also chamfered. H1 = 4.3 mm, L1 = 5 mm, H2 = 4.5 mm, L2 = 17.5 mm, H3 = 2.5 mm. The injection waveguide 212 is rectangular and consists of the gap between the first outer conductor 202 and the second outer conductor 203 of the input cavity. The length of the injection waveguide 212 is L3, and its distance from the input cavity gap 2111 is L4. The sharp corners are also chamfered. L3 = 2 mm, L4 = 7.3 mm. The inner conductor 201 is a cylindrical structure with a radius of R1. A groove within the inner conductor 201 forms the input cavity gap 2111. The portion of the inner conductor 201 made of aluminum (the section with the single diagonal line in the diagram) has a length of L5, and its distance from the left side to the input cavity gap 2111 is L6. R1 = 34 mm, L5 = 21 mm, L6 = 7 mm. In the first outer conductor 202 of the input cavity, the portion made of aluminum (the section with the single diagonal line in the diagram) has a length of L7 and a thickness of H4. In the second outer conductor 203 of the input cavity, the portion made of aluminum (the section with the single diagonal line in the diagram) has a length of L8 and a thickness of H4. L7 = 20 mm, H4 = 6.5 mm, L8 = 22 mm.

[0034] like Figure 3 As shown, after structural optimization in this embodiment, the response times of stainless steel and aluminum to the magnetic field differ by approximately 2-3 milliseconds, making them almost simultaneous, and the magnitudes of the generated magnetic fields are also roughly the same, achieving the expected effect. For other materials with different conductivity, optimization can also be performed to make the response times of the two materials to the magnetic field almost simultaneous.

[0035] In this embodiment, the inner conductor 201 has bolt connection structures (omitted in the figure) at both ends for connecting with the front end structure and the rear end structure of the input cavity. The outer end faces of the first outer conductor 202 and the second outer conductor 203 have bolt connection structures (omitted in the figure) for connecting with the front end structure or the rear end structure of the input cavity.

[0036] In this embodiment, the inner wall portions of the first outer conductor (202) and the second outer conductor (203) made of aluminum are embedded in the remaining portions made of stainless steel.

[0037] This embodiment also provides a triaxial relativistic klystron amplifier, including a triaxial relativistic klystron amplifier body and an input cavity disposed at the front end of the triaxial relativistic klystron amplifier body. The input cavity is the aforementioned hybrid material input cavity for a pulse magnetic field klystron.

[0038] This embodiment also provides an optimization method for the aforementioned hybrid material input cavity of a pulsed magnetic field klystron, comprising:

[0039] S101, determine the length of the mixed material input cavity, the length of the mixed material input cavity is greater than 10 times the radius R2 between the central axis OO′ of the inner conductor 201 and the outer wall of the drift cavity 213;

[0040] S102, based on the length of the hybrid material input cavity, determine the response time of the first outer conductor 202, the second outer conductor 203, and the remaining portion of the inner conductor 201 to the magnetic field;

[0041] S103, adjust the thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall, calculate the response time of the inner wall portion of the input cavity 211 to the magnetic field, and determine whether the response time of the inner wall portion of the input cavity 211 to the magnetic field is the same as or the difference is less than the set value. If not, jump to step S103 to continue optimizing and adjusting the thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall; otherwise, determine that the final thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall is the optimal thickness.

[0042] The function expression for calculating the response time to the magnetic field is as follows:

[0043] ωt max = nπ - arctan(1 / (ωG)),

[0044] In the above formula, ω is the oscillation period of the magnetic field (the oscillation period of the charging current), and t MAX Let n be the moment when the magnetic field strength is maximum, n be a positive integer, and G be a relevant characteristic of the material parameters, and we have:

[0045]

[0046] In the above formula, μ0 is the free permeability, and D i t is the diameter of the inner wall of the drift cavity 213. G For the metal wall thickness (the metal circular waveguide is coaxial with the magnetic field coil, and its length is much greater than its diameter), ρ G The resistivity of the waveguide material.

[0047] Assuming the waveguide is a standard and complete circular waveguide, then the diameter D of the inner wall of the drift cavity 213 is... i Given that the repetition frequency magnetic field frequency is 50Hz and the desired magnetic field strength is 0.45T (i.e., B), the magnetic field strength is 0.45T. z0 Under the condition of 0.45T, according to the attenuation coefficient The attenuation coefficient of stainless steel within a thickness of 20mm is approximately 100%, meaning the loss of stainless steel is essentially negligible. At this thickness, the response time of stainless steel is approximately 8.4ms. Similarly, using... Under the same conditions, when the aluminum thickness is less than 2.4 mm, the aluminum loss is less than 20%. However, 2.4 mm aluminum is relatively thin, which is not conducive to processing and results in a more pronounced skin effect. Since 2.4 mm is close to H2-H3 (2 mm), and H3 (2.5 mm) is basically hollow (re-entry structure), increasing the aluminum thickness to H2 (4.5 mm) has little impact on the loss. Considering the influence of the hollow part of the injected waveguide 212, in this embodiment, the aluminum thickness can be increased to H4 = 6 mm (the volume of the hollow part is converted into an aluminum thickness of approximately 1.5 mm). At this point, the aluminum response time is approximately 8.3 ms. Therefore, in simulation optimization, optimization can be performed with 6 mm as the center. The best effect is achieved when the thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall is 6.5 mm.

[0048] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A hybrid material input cavity for a pulsed magnetic field klystron, characterized in that, The device includes an inner conductor (201) and a first outer conductor (202) and a second outer conductor (203) respectively sleeved on the inner conductor (201). A drift cavity (213) is formed between the outer wall of the inner conductor (201) and the inner walls of the first outer conductor (202) and the second outer conductor (203). An injection waveguide (212) is formed between the first outer conductor (202) and the second outer conductor (203). The injection waveguide (212) and the drift cavity (213) are connected through an input cavity (211). The inner wall portion of the input cavity (211) of the inner conductor (201), the first outer conductor (202) and the second outer conductor (203) are made of metal materials with different electrical conductivity than the rest of the metal materials. The electrical conductivity of the metal material in the inner wall portion is higher than that of the metal material in the rest portion.

2. The hybrid material input cavity for a pulse magnetic field klystron according to claim 1, characterized in that, The inner conductor (201), the first outer conductor (202), and the second outer conductor (203) are a rotating body structure that is rotationally symmetric about the central axis OO′ of the inner conductor (201).

3. The hybrid material input cavity for a pulse magnetic field klystron according to claim 1, characterized in that, The input cavity (211) is a re-entrant coaxial resonant cavity structure. The re-entrant coaxial resonant cavity structure includes an input cavity gap (2111) and a re-entrant structure (2112). The re-entrant structure (2112) is arranged along the length of the drift cavity (213). The middle part of the re-entrant structure (2112) is connected to the injection waveguide (212), and one end is connected to the input cavity gap (2111). The input cavity gap (2111) includes a pair of grooves formed on the inner walls of both sides of the drift cavity (213).

4. The hybrid material input cavity for a pulse magnetic field klystron according to claim 3, characterized in that, The inner conductor (201) has a three-section structure, and the metal material used in the middle section is different from that used in the other two sections. A groove forming the inner part of the input cavity gap (2111) is located on the middle section of the inner conductor (201). The injection waveguide (212) has a rectangular cross-section. An L-shaped first mounting groove is provided on the side of the first outer conductor (202) near the injection waveguide (212). The first mounting groove contains a first L-shaped inner wall with its inner corner facing the injection waveguide (212). The middle part of the first L-shaped inner wall is arranged opposite to the injection waveguide (212), and the shorter end has an extension parallel to the longer end. The extension extends to align with the edge of the injection waveguide (212); the second outer conductor (203) is provided with an L-shaped second mounting groove on the side near the injection waveguide (212), and the second mounting groove is provided with a second L-shaped inner wall with its inner corner facing the drift cavity (213). The shorter end of the second L-shaped inner wall contacts the bottom of the second mounting groove, and the longer end aligns with the edge of the injection waveguide (212). The gap between the longer end of the first L-shaped inner wall and the shorter end of the second L-shaped inner wall forms the outer part of the input cavity gap (2111), and the outer part of the input cavity gap (2111) is aligned with the inner part of the input cavity gap (2111).

5. The hybrid material input cavity for a pulsed magnetic field klystron according to claim 4, characterized in that, The outer ends of the first outer conductor (202), the second outer conductor (203), and the inner conductor (201) are all made of stainless steel. The middle section of the first L-shaped inner wall, the second L-shaped inner wall, and the inner conductor (201) is made of aluminum. The thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall is 6.5 mm, so that the response time of the inner wall of the input cavity (211) to the magnetic field is the same as or the difference is less than the set value.

6. The hybrid material input cavity for a pulse magnetic field klystron according to claim 5, characterized in that, The length L8 of the second L-shaped inner wall is 22 mm; the length L7 of the first L-shaped inner wall is 20 mm; the width L3 of the injection waveguide (212) is 2 mm; the distance L4 between the longer end of the first L-shaped inner wall and the input cavity gap (2111) is 7.3 mm; the length L2 of the re-entry structure (2112) is 17.5 mm; the width L1 of the input cavity gap (2111) is 5 mm; and the middle section of the inner conductor (201) is near the first outer conductor (202). The thickness L6 of the portion between the inner conductor (201) and the input cavity gap (2111) is 7 mm; the length L5 of the middle section of the inner conductor (201) is 21 mm; the groove depth H1 of the inner conductor (201) forming the inner part of the input cavity gap (2111) is 4.3 mm; the groove depth H2 between the first outer conductor (202) and the second outer conductor (203) forming the outer part of the input cavity gap (2111) is 4.5 mm; and the width H3 of the re-entry structure (2112) is 2.5 mm.

7. The hybrid material input cavity for a pulse magnetic field klystron according to claim 6, characterized in that, The inner conductor (201) has bolted connection structures at both ends for connecting to the front end structure and the rear end structure of the input cavity. The outer end faces of the first outer conductor (202) and the second outer conductor (203) have bolted connection structures for connecting to the front end structure or the rear end structure of the input cavity.

8. The hybrid material input cavity for a pulse magnetic field klystron according to claim 7, characterized in that, The inner wall portions of the first outer conductor (202) and the second outer conductor (203) are made of aluminum and are embedded in the remaining portions made of stainless steel.

9. A triaxial relativistic klystron amplifier, comprising a triaxial relativistic klystron amplifier body and an input cavity disposed at the front end of the triaxial relativistic klystron amplifier body, characterized in that, The input cavity is the hybrid material input cavity for a pulse magnetic field klystron as described in any one of claims 1 to 8.

10. The method for optimizing the hybrid material input cavity of a pulse magnetic field klystron according to any one of claims 1 to 8, characterized in that, include: S101, determine the length of the mixed material input cavity, the length of which is greater than 10 times the radius R2 between the central axis OO′ of the inner conductor (201) and the outer wall of the drift cavity (213); S102, based on the length of the hybrid material input cavity, determine the response time of the first outer conductor (202), the second outer conductor (203), and the remaining portion of the inner conductor (201) to the magnetic field; S103, adjust the thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall, calculate the response time of the inner wall of the input cavity (211) to the magnetic field, and determine whether the response time of the inner wall of the input cavity (211) to the magnetic field is the same as or the difference is less than the set value. If not, jump to step S103 to continue to optimize and adjust the thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall; otherwise, determine that the final thickness H4 of the first L-shaped inner wall and the second L-shaped inner wall is the optimal thickness.

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