Internal and external cascade relativistic klystron amplifier and use method thereof

Abstract

The invention relates to an internal and external cascade relativistic klystron amplifier and a use method thereof, and belongs to the technical field of high-power microwaves, and the internal and external cascade relativistic klystron amplifier comprises an electron beam emission unit which is used for generating electron beams; the electron beam modulation unit is used for modulation and bunching of electron beams and comprises an internal relativistic klystron amplifier and an external relativistic klystron amplifier which are sleeved and coaxially arranged; the output end of the internal relativistic klystron amplifier is connected with the input end of the external relativistic klystron amplifier; the input coaxial transmission line is used for introducing a seed source microwave signal into the input end of the internal relativistic klystron amplifier; according to the relativistic klystron amplifier, the technical problems that in the prior art, a relativistic klystron amplifier is low in gain, large in input signal power requirement, large in power consumption and large in size can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of high-power microwaves, and in particular relates to an internal-external cascade relativistic klystron amplifier and a use method thereof. Background Art

[0002] High-power microwaves refer to electromagnetic waves with a peak power greater than 100MW and a frequency range of 1GHz-100GHz. Since high-power microwave technology has important application prospects in many fields, it has attracted widespread attention from researchers at home and abroad and has developed rapidly. Various types of high-power microwave sources have been developed one after another. Since relativistic klystrons have the characteristics of stable frequency and phase, high gain, high peak power, and high efficiency, they are widely used in new accelerators, high-power radars, new communication systems and other fields, making them a very potential type of high-power microwave source. In order to meet the development needs of high-power microwave systems, breakthroughs are urgently needed in the miniaturization and reliability of relativistic klystron amplifiers.

[0003] The gain index of a relativistic klystron amplifier is a very important index for measuring the amplifier. The gain of a traditional relativistic klystron amplifier is generally less than 55dB. In order to achieve gigawatt-level high-power microwave amplification, the input signal generally requires tens of kilowatts. The volume, weight, and power consumption of a seed source of tens of kW are often large, which is not conducive to the development of the system towards miniaturization and low power consumption. In addition, the input of tens of kW signals requires a rectangular waveguide with high power capacity for transmission. The input coupler composed of the rectangular waveguide has a large turning radius and its own large size, which leads to an increase in the lateral size of the device. It is necessary to increase the inner diameter of the focusing magnet to accommodate the input coupler system, resulting in an increase in the volume and power consumption of the focusing magnet. Therefore, how to meet the needs of the relativistic klystron amplifier to develop in the direction of miniaturization, low power consumption, and high gain is a technical problem that technicians in this field urgently need to solve. Summary of the invention

[0004] In view of various deficiencies in the prior art, an internal-external cascade relativistic klystron amplifier and a method of using the same are proposed to solve the technical problems of low gain, large input signal power requirement, high power consumption and large size of the prior art relativistic klystron amplifier.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides an internal-external cascade relativistic klystron amplifier, comprising:

[0007] An electron beam emitting unit, used for generating an electron beam;

[0008] An electron beam modulation unit, used for modulation and grouping of electron beams, wherein the input end of the electron beam modulation unit is connected to the output end of the electron beam emission unit, and the electron beam modulation unit comprises an internal relativistic klystron amplifier and an external relativistic klystron amplifier which are nested and coaxially arranged, and the output end of the internal relativistic klystron amplifier is connected to the input end of the external relativistic klystron amplifier;

[0009] An input coaxial transmission line, used to introduce a seed source microwave signal into an input end of the internal relativistic klystron amplifier;

[0010] and an output waveguide for transmitting the amplified microwave signal to an external radiation system.

[0011] The technical solution is further configured as follows: the internal relativistic klystron amplifier includes an internal device electron beam channel, the internal device electron beam channel is located on the central axis of the electron beam modulation unit, and an internal device input cavity, an internal device intermediate cavity and an internal device output cavity are sequentially provided from the entrance end to the exit end of the internal device electron beam channel, the internal device input cavity is connected to the input coaxial transmission line, and the internal device output cavity is connected to the input end of the external relativistic klystron amplifier.

[0012] The technical solution is further configured such that the input coaxial transmission line is located at the output end of the electron beam modulation unit, a first end of the input coaxial transmission line passes through the coupling region between the internal relativistic klystron amplifier and the external relativistic klystron amplifier, and is connected to the internal device input cavity, and a second end of the input coaxial transmission line is connected to a microwave seed source.

[0013] The technical solution is further configured such that the inner device middle cavity is provided with a plurality of levels.

[0014] The technical solution is further configured as follows: the external relativistic klystron amplifier includes an external device multi-beam electron beam channel, the external device multi-beam electron beam channel is coaxially arranged with the electron beam modulation unit, an external device input cavity, an external device intermediate cavity and an external device output cavity are sequentially arranged from the entrance end to the exit end of the external device multi-beam electron beam channel, the external device input cavity is connected to the internal device output cavity, and the external device output cavity is connected to the output waveguide.

[0015] The technical solution is further configured that an internal device output coupler is provided on the cavity wall of the internal device output cavity, and the internal device output coupler is connected to the external device input cavity through a transmission coaxial waveguide.

[0016] The technical solution is further configured such that the internal device output coupler is composed of a plurality of fan-shaped waveguides arranged on the cavity wall of the internal device output cavity.

[0017] The technical solution is further configured such that the range of values ​​of the central angle of the fan-shaped waveguide is determined based on the cutoff frequency condition and the single-mode transmission condition of the fan-shaped waveguide.

[0018] The technical solution is further configured such that the plurality of fan-shaped waveguides leave a clearance channel for the input coaxial transmission line in an angular direction.

[0019] In a second aspect, the present invention provides a method for using an internal-external cascade relativistic klystron amplifier, comprising the following steps:

[0020] S100, based on the seed source microwave signal input through the coaxial transmission line, the internal relativistic klystron amplifier modulates the electron beam and converts the energy of the modulated electron beam into microwave energy to achieve primary microwave signal amplification, and the microwave signal after primary amplification is transmitted to the external relativistic klystron amplifier;

[0021] S200. Based on the microwave signal after primary amplification, the external relativistic klystron amplifier modulates the electron beam and converts the energy of the modulated electron beam into microwave energy to achieve secondary microwave signal amplification. The microwave signal after secondary amplification is transmitted to the external radiation system through the output waveguide.

[0022] The beneficial effects of the present invention are:

[0023] By setting up an internal relativistic klystron amplifier and an external relativistic klystron amplifier in cascade inner and outer configurations, ultra-high gain of microwave signals is achieved; the axial length is shortened, and the miniaturization of the relativistic klystron amplifier is achieved; the input power of the seed source microwave signal is reduced to the watt level, and the miniaturization and low power consumption of the microwave seed source driven by the relativistic klystron amplifier are achieved; an angularly uniform TEM mode is achieved, thereby suppressing the generation of self-excited oscillation, which is conducive to stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of an internal and external cascade relativistic klystron amplifier in an embodiment of the present invention;

[0025] Figure 2 yes Figure 1 Schematic diagram of the EE cross section;

[0026] Figure 3 yes Figure 1 Schematic diagram of the FF cross section;

[0027] Figure 4 It is a flow chart of a method for using an internal and external cascade relativistic klystron amplifier in an embodiment of the present invention.

[0028] In the attached drawings: 1. diode; 2. external device multi-beam electron beam emitter; 3. internal device electron beam emitter; 4. internal device electron beam channel; 5. external device multi-beam electron beam channel; 6. input coaxial transmission line; 7. internal device input cavity; 8. internal device intermediate cavity I; 9. internal device intermediate cavity II; 10. internal device output cavity; 11. internal device output coupler; 12. transmission coaxial waveguide; 13. external device input cavity; 14. external device intermediate cavity; 15. external device output cavity; 16. output waveguide;

[0029] 100. Electron beam emitting unit; 200. Electron beam modulating unit. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the embodiments in this application, other similar embodiments obtained by ordinary technicians in this field without making creative work should all fall within the scope of protection of this application. In addition, the directional words mentioned in the following embodiments, such as "up", "down", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional words used are used to illustrate rather than limit the invention.

[0031] According to an embodiment of the present invention, there is provided an internal and external cascade relativistic klystron amplifier, referring to Figures 1 to 3 ,include:

[0032] The electron beam emitting unit 100 is used to generate an electron beam;

[0033] An electron beam modulation unit 200 is used for modulation and grouping of electron beams. The input end of the electron beam modulation unit 200 is connected to the output end of the electron beam emission unit 100. The electron beam modulation unit 200 includes an internal relativistic klystron amplifier and an external relativistic klystron amplifier which are nested and coaxially arranged. The output end of the internal relativistic klystron amplifier is connected to the input end of the external relativistic klystron amplifier.

[0034] An input coaxial transmission line 6, used to introduce the seed source microwave signal into the input end of the internal relativistic klystron amplifier;

[0035] And an output waveguide 16 is used to transmit the amplified microwave signal to an external radiation system.

[0036] It should be noted that by arranging an internal relativistic klystron amplifier and an external relativistic klystron amplifier in cascade inner and outer configurations, an ultra-high gain of the microwave signal is achieved; the axial length is shortened, and the miniaturization of the relativistic klystron amplifier is achieved; the input power of the seed source microwave signal is reduced to the watt level, and the miniaturization and low power consumption of the relativistic klystron amplifier-driven microwave seed source are achieved; an angularly uniform TEM mode is achieved, thereby suppressing the generation of self-excited oscillation, which is conducive to stable operation.

[0037] Specifically, the axial lengths of the internal relativistic klystron amplifier and the external relativistic klystron amplifier are equal, thereby making full use of the structural space and maximizing the utilization rate of the magnetic space of the required focusing system.

[0038] In this embodiment, the internal and external cascade relativistic klystron amplifier is shown in Figures 1 to 3 The internal relativistic klystron amplifier includes an internal device electron beam channel 4, which is located on the central axis of the electron beam modulation unit 200. From the entrance end to the exit end of the internal device electron beam channel 4, an internal device input cavity 7, an internal device intermediate cavity and an internal device output cavity 10 are sequentially arranged. The internal device input cavity 7 is connected to the input coaxial transmission line 6, and the internal device output cavity 110 is connected to the input end of the external relativistic klystron amplifier.

[0039] Specifically, the inlet end of the internal device electron beam channel 4 is used as the input end of the internal relativistic klystron amplifier, and the outlet end of the internal device electron beam channel 4 is used as the output end of the internal relativistic klystron amplifier. The electron beam emitting unit 100 includes a diode 1, on which an internal device electron beam emitter 3 is provided, and the internal device electron beam emitter 3 is arranged corresponding to the internal device electron beam channel 4.

[0040] It should be noted that the internal relativistic klystron amplifier modulates the electron beam emitted by the internal device electron beam emitter 3 on the diode 1 based on the seed source microwave signal input by the input coaxial transmission line 6, and converts the energy of the modulated corresponding electron beam into microwave energy, realizes primary microwave signal amplification, and transmits the primary amplified microwave signal to the external relativistic klystron amplifier. In addition, the internal device input cavity 7 is excited by a coaxial transmission line, the lateral size of the coaxial transmission line is much smaller than the rectangular waveguide of the same frequency band, and the coaxial transmission line is a flexible component, which is easy to integrate and miniaturize.

[0041] In this embodiment, the internal and external cascade relativistic klystron amplifier is shown in Figures 1 to 3 The input coaxial transmission line 6 is located at the output end of the electron beam modulation unit 200, a first end of which passes through the coupling region between the internal relativistic klystron amplifier and the external relativistic klystron amplifier, and is connected to the internal device input cavity 7, and a second end of which is connected to the microwave seed source.

[0042] It should be noted that the input coaxial transmission line 6 enters the internal relativistic klystron amplifier from the end of the electron beam modulation unit 200, which greatly reduces the lateral size and reduces the inner diameter of the focusing system. The reduction in the inner diameter of the focusing system leads to a square reduction in the outer diameter, which greatly reduces the weight of the focusing system and achieves miniaturization. In the internal and external cascade relativistic klystron amplifier of this embodiment, please refer to Figures 1 to 3 The inner device middle cavity 8 is provided with several levels.

[0043] It should be noted that the gain of the amplifier is determined by the number of stages of the inner device intermediate cavity 8. In this embodiment, the inner device intermediate cavity 8 has two stages, namely, the inner device intermediate cavity I 8 and the inner device intermediate cavity II 9.

[0044] In this embodiment, the internal and external cascade relativistic klystron amplifier is shown in Figures 1 to 3 The external relativistic klystron amplifier includes an external device multi-beam electron beam channel 5, which is coaxially arranged with the electron beam modulation unit 200. From the entrance end to the exit end of the external device multi-beam electron beam channel 5, an external device input cavity 13, an external device intermediate cavity 14 and an external device output cavity 15 are sequentially arranged. The external device input cavity 13 is connected to the internal device output cavity 10, and the external device output cavity 15 is connected to the output waveguide 16.

[0045] Specifically, the inlet end of the external device multi-beam electron beam channel 5 is used as the input end of the external relativistic klystron amplifier, and the outlet end of the external device multi-beam electron beam channel 5 is used as the output end of the external relativistic klystron amplifier. The electron beam emitting unit 100 includes a diode 1, on which an external device multi-beam electron beam emitter 2 is provided, and the external device multi-beam electron beam emitter 2 is arranged corresponding to the external device multi-beam electron beam channel 5.

[0046] It should be noted that the external relativistic klystron amplifier completes the modulation of the electron beam emitted by the external device multi-injection electron beam emitter 2 on the diode 1 based on the microwave energy output by the internal relativistic klystron amplifier, and converts the energy of the modulated corresponding electron beam into microwave energy to achieve secondary microwave signal amplification, and transmits the amplified microwave signal to the external radiation system through the output waveguide 16.

[0047] In this embodiment, the internal and external cascade relativistic klystron amplifier is shown in Figures 1 to 3 An internal device output coupler 11 is provided on the cavity wall of the internal device output cavity 10 , and the internal device output coupler 11 is connected to the external device input cavity 13 through a transmission coaxial waveguide 12 .

[0048] Specifically, the internal device output coupler 11 is composed of a plurality of fan-shaped waveguides arranged on the cavity wall of the internal device output cavity 10, and the central angle value range of the fan-shaped waveguide is determined based on the cutoff frequency condition and the single-mode transmission condition of the fan-shaped waveguide. At the same time, the plurality of fan-shaped waveguides leave a clearance channel for the input coaxial transmission line 6 in the angular direction.

[0049] It should be noted that the fan-shaped waveguide can transmit the operating frequency f, and the central angle Ang of the fan-shaped waveguide satisfies two conditions: first, the cutoff frequency condition determines the central angle Ang1 of the fan-shaped waveguide; the fan-shaped waveguide can only transmit the fundamental mode (TE11 mode), and the single-mode transmission condition determines the angle Ang2 of the fan-shaped waveguide. Therefore, the central angle of the fan-shaped waveguide can be any value within the range of Ang1<Ang<Ang2; the length of the fan-shaped waveguide (L) determines the angular uniformity of the TEM mode coupled to the transmission coaxial waveguide 12.

[0050] Specifically, the external device multi-beam electron beam emitter 2 and the external device multi-beam electron beam channel 5 can be a separate emitter and a separate electron beam channel, respectively. Alternatively, the external device multi-beam electron beam emitter 2 and the external device multi-beam electron beam channel 5 can also be an annular electron beam and an annular electron beam channel, and accordingly, the external device input cavity 13, the external device intermediate cavity 14 and the external device output cavity 15 need to be configured as a coaxial resonant cavity.

[0051] According to an embodiment of the present invention, a method for using an internal and external cascade relativistic klystron amplifier is provided. Figure 4 , including the following steps:

[0052] S100, based on the seed source microwave signal input by the input coaxial transmission line 6, the internal relativistic klystron amplifier modulates the electron beam and converts the energy of the modulated electron beam into microwave energy to achieve primary microwave signal amplification, and the primary amplified microwave signal is transmitted to the external relativistic klystron amplifier;

[0053] S200. Based on the microwave signal after primary amplification, the external relativistic klystron amplifier modulates the electron beam and converts the energy of the modulated electron beam into microwave energy to achieve secondary microwave signal amplification. The microwave signal after secondary amplification is transmitted to the external radiation system through the output waveguide.

[0054] Specifically, the high-frequency signal output by the microwave seed source is fed into the input coaxial transmission line 6 and transmitted to the internal device input cavity 7, where the internal device input cavity 7 excites and generates an angularly uniform TM01 mode electric field. The input coaxial transmission line 6 can be turned according to structural requirements, greatly reducing the complexity of the system.

[0055] When the DC electron beam emitted by the inner device electron beam emitter 3 passes through the gap of the inner device input cavity 7 under the constraint of the axial magnetic field, the speed is modulated under the action of the electric field of the TM01 mode in the inner device input cavity 7, and the drift tube after the electron beam with modulated speed enters the inner device input cavity 7 is density clustered. After the initial modulation, the electron beam is further velocity modulated in the inner device middle cavity, and density modulation occurs at the same time. After a series of modulation electron beam modulation current depth amplification, the modulation ratio can reach 100% or more, and finally the electron beam after deep modulation generates an induced current in the inner device output cavity 10, and the induced current establishes a high-frequency field in the inner device output cavity 10. The energy of the high-frequency field is coupled to the transmission coaxial waveguide 12 through the inner device output coupler 11 on the cavity wall of the inner device output cavity 10, realizing the primary microwave signal amplification, and the output power reaches the MW level.

[0056] The microwave power output by the internal relativistic klystron amplifier is injected into the external device input cavity 13 through the transmission coaxial waveguide 12, and the electric field of the angular uniform TM01 mode is excited in the coaxial resonant cavity. The DC electron beam emitted by the external device multi-beam electron beam emitter 2 enters the external device multi-beam electron beam channel 5 under the constraint of the axial magnetic field and passes through the gap of the external device input cavity 13. The velocity of the electron beam modulated at the gap of the external device input cavity 13 is modulated by the electric field of the TM01 mode. The drift tube after the velocity modulated electron beam enters the external device input cavity 13 obtains the density After clustering and preliminary modulation, the electron beam is further speed modulated in the middle cavity 14 of the external device, and density modulation occurs at the same time. After a series of modulations, the modulation current is deeply amplified, and the modulation ratio of the outer electron beam can reach 100% or more. Finally, the electron beam generates an induced current in the output cavity 15 of the external device after deep modulation. The induced current establishes a high-frequency field in the output cavity 15 of the external device. The energy of the high-frequency field is coupled to the output waveguide 16 through the output cavity 15 of the external device, and finally radiated to the free space through the circular waveguide and the radiating antenna of the external radiation system.

[0057] In summary, the internal relativistic klystron amplifier adopts a multi-cavity fundamental mode working mode, which can achieve 40-60dB signal amplification and amplify the small signal of external input to the megawatt level. The megawatt power output by the internal device output cavity 10 is coupled to the transmission coaxial waveguide 12 of TEM transmission through the internal device output coupler 11. At the same time, the internal device output coupler 11 provides an input channel for the input coaxial transmission line 6 in the angular direction. When the megawatt signal drives the external relativistic klystron amplifier, only 10-30dB is needed to immediately achieve high-power microwave output of hundreds of megawatts to several gigawatts.

[0058] The total gain of the internal and external cascaded relativistic klystron amplifiers can reach an ultra-high gain of more than 70dB. Since both the internal and external relativistic klystron amplifiers operate at relatively low gains, self-oscillation problems are not easily generated. The ultra-high gain device greatly reduces the power of the seed source microwave signal, so that the power of the microwave seed source driving the relativistic klystron amplifier is reduced to the watt level, greatly reducing the system volume, weight and power consumption of the microwave seed source. In addition, the axial length of the entire device is very short compared with traditional low-gain devices, saving system volume and weight. Specific embodiment:

[0060] The center radius of the external device multi-beam electron beam channel 5 is 30mm, which is composed of 30 drift tubes uniformly distributed in the angular direction, the drift tube radius is 2mm, and the radius of the internal device electron beam channel 4 (drift tube) is 1.6mm. The outer conductor radius of the input coaxial transmission line 6 is 1mm, and its inner conductor radius is 0.5mm. The outer radius of the internal device input cavity 7 is 4.15mm, the cavity length is 4.3mm, the cavity height is 2mm, and the gap width is 2.0mm. The distance between the internal device input cavity 7 and the internal device intermediate cavity I 8 is 30mm. The outer radius of the internal device intermediate cavity I 8 is 3.984mm, and the gap width is 2.2mm. The distance between the internal device intermediate cavity I 8 and the internal device intermediate cavity II 9 is 24mm. The outer radius of the internal device intermediate cavity II 9 is 3.997mm, and the gap width is 2.0mm. The distance between the internal device intermediate cavity II 9 and the internal device output cavity 10 is 20mm. The outer radius of the inner device output cavity 10 is 4.2mm, the cavity length is 6.36mm, the cavity height is 2mm, and the gap width is 2.4mm. The outer radius of the inner device output coupler 11 is 10.7mm, the width is 1.5mm, the central angle of the fan-shaped waveguide is 37°, the number of fan-shaped waveguides is 6, the fan-shaped waveguide length is 6mm, the outer radius of the fan-shaped waveguide is 10.7mm, and the inner radius of the fan-shaped waveguide is 9.5mm. The outer radius of the transmission coaxial waveguide 12 is 10.7mm, and the inner radius is 8.7mm.

[0061] The outer radius of the external device input cavity 13 is 33mm, the inner radius is 23.75mm, the gap width is 1.5mm, the cavity length is 2.93mm, and the cavity height is 2mm. The distance between the external device input cavity 13 and the external device intermediate cavity 14 is 45mm. The outer radius of the external device intermediate cavity 14 is 32.931mm, the inner radius is 27.069mm, and the gap width is 1.6mm. The distance between the external device intermediate cavity 14 and the external device output cavity 15 is 22mm. The outer radius of the gap of the external device output cavity 15 is 33.6mm, the inner radius is 26.45mm, the gap width is 2mm, the interval between the gaps is 1mm, and the number of gaps is 4. The outer radius of the external device output cavity 15 is 26.45mm, the inner radius is 21.55mm, and the width is 1.2mm. The output coupling tapered waveguide has an outer radius of 22.55 mm at the input end and an inner radius of 21.55 mm at the output end, an outer radius of 22.55 mm at the output end, an inner radius of 19.05 mm, and a length of 10.24 mm. The output waveguide 16 has an outer radius of 22.55 mm and an inner radius of 19.05 mm.

[0062] The total length from the external device input cavity 13 to the external device output cavity 15 is 85 mm, and the total length from the internal device input cavity 7 to the internal device output cavity 10 is 76.5 mm. The total length difference is 8.5 mm. The overall length of the electron beam modulation unit 200 is controlled at about 85 mm.

[0063] The electron beam voltage is 380 kV, the current emitted by the inner device electron beam emitter 3 is 110 A, and the current emitted by the outer device multi-beam electron beam emitter 2 is 110 A*30 beams=3.3 kA. A 50 W high frequency signal is injected through the inner device input cavity 7, the inner device intermediate cavity I 8, the inner device intermediate cavity II 9, and the inner device output cavity 10 to generate a microwave power output of 11 MW, which is coupled to the outer device input cavity 13, and then through the outer device intermediate cavity 14 and the outer device output cavity 15, the microwave power is finally generated to reach 530 MW, the output microwave frequency is Ka band, the internal relativistic klystron amplifier gain is 53.4 dB, the external relativistic klystron amplifier gain is 16.8 dB, and the total gain after two-stage amplification reaches 70.2 dB.

[0064] The present invention has been described in detail above. The above description is only a preferred embodiment of the present invention and should not limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made within the scope of this application should still fall within the scope of the present invention.

Claims

1. An internal and external cascade relativistic klystron amplifier, characterized in that: include: An electron beam emitting unit, used for generating an electron beam; An electron beam modulation unit, used for modulation and grouping of electron beams, wherein the input end of the electron beam modulation unit is connected to the output end of the electron beam emission unit, and the electron beam modulation unit comprises an internal relativistic klystron amplifier and an external relativistic klystron amplifier which are nested and coaxially arranged, and the output end of the internal relativistic klystron amplifier is connected to the input end of the external relativistic klystron amplifier; An input coaxial transmission line, used to introduce a seed source microwave signal into an input end of the internal relativistic klystron amplifier; and an output waveguide for transmitting the amplified microwave signal to an external radiation system.

2. The internal-external cascade relativistic klystron amplifier according to claim 1, characterized in that: The internal relativistic klystron amplifier comprises an internal device electron beam channel, which is located on the central axis of the electron beam modulation unit. An internal device input cavity, an internal device intermediate cavity and an internal device output cavity are sequentially arranged from the inlet end to the outlet end of the internal device electron beam channel. The internal device input cavity is connected to the input coaxial transmission line, and the internal device output cavity is connected to the input end of the external relativistic klystron amplifier.

3. The internal-external cascade relativistic klystron amplifier according to claim 2, characterized in that: The input coaxial transmission line is located at the output end of the electron beam modulation unit, a first end of which runs through the coupling region between the internal relativistic klystron amplifier and the external relativistic klystron amplifier and is connected to the internal device input cavity, and a second end of which is connected to a microwave seed source.

4. The internal-external cascade relativistic klystron amplifier according to claim 2 or 3, characterized in that: The inner device middle cavity is provided with several levels.

5. The internal-external cascade relativistic klystron amplifier according to claim 2, characterized in that: The external relativistic klystron amplifier comprises an external device multi-beam electron beam channel, which is coaxially arranged with the electron beam modulation unit. An external device input cavity, an external device intermediate cavity and an external device output cavity are sequentially arranged from the inlet end to the outlet end of the external device multi-beam electron beam channel. The external device input cavity is connected to the internal device output cavity, and the external device output cavity is connected to the output waveguide.

6. The internal-external cascade relativistic klystron amplifier according to claim 5, characterized in that: An internal device output coupler is arranged on the cavity wall of the internal device output cavity, and the internal device output coupler is connected to the external device input cavity through a transmission coaxial waveguide.

7. The internal-external cascade relativistic klystron amplifier according to claim 6, characterized in that: The internal device output coupler is composed of a plurality of fan-shaped waveguides arranged on the cavity wall of the internal device output cavity.

8. The internal-external cascade relativistic klystron amplifier according to claim 7, characterized in that: The range of the central angle of the fan-shaped waveguide is determined based on the cutoff frequency condition and the single-mode transmission condition of the fan-shaped waveguide.

9. The internal-external cascade relativistic klystron amplifier according to claim 7 or 8, characterized in that: The plurality of fan-shaped waveguides leave a clearance channel for the input coaxial transmission line in an angular direction.

10. A method for using the internal-external cascade relativistic klystron amplifier according to any one of claims 1 to 9, characterized in that: The following steps are involved: S100, based on the seed source microwave signal input through the coaxial transmission line, the internal relativistic klystron amplifier modulates the electron beam and converts the energy of the modulated electron beam into microwave energy to achieve primary microwave signal amplification, and the microwave signal after primary amplification is transmitted to the external relativistic klystron amplifier; S200. Based on the microwave signal after primary amplification, the external relativistic klystron amplifier modulates the electron beam and converts the energy of the modulated electron beam into microwave energy to achieve secondary microwave signal amplification. The microwave signal after secondary amplification is transmitted to the external radiation system through the output waveguide.

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