A Cherenkov oscillator implementing S, C band selection

Abstract

The application relates to a Cherenkov oscillator realizing S and C band selection, which comprises an oscillator cavity and a solenoid magnetic field arranged outside the oscillator cavity, wherein the oscillator cavity comprises an anode outer cylinder, a cutoff neck, a resonant reflection cavity, a slow wave structure and an output waveguide arranged in sequence; a cathode is arranged in the anode outer cylinder; the slow wave structure is composed of six rectangular slow wave vanes with the same parameters and is connected by a ring between every two rectangular slow wave vanes. The application utilizes the principle of electron cyclotron resonance absorption, so that the device can output different frequency microwaves when different guiding magnetic field strengths are adopted on the same device. The function of adjusting the output wave band of the device can be realized by only changing the current size of the driving external guiding magnetic field. The device has clear principle, simple structure and easy processing, and has the advantages of innovation and usability, so it is a better multi-wave band Cherenkov oscillator scheme.

Description

TECHNICAL FIELD

[0001] The present application relates to a microwave source device in the field of high power microwave technology, in particular to a Cherenkov oscillator for realizing S and C band selection by using the principle of cyclotron resonance absorption, and belongs to the field of high power microwave technology. BACKGROUND

[0002] High power microwave generally refers to electromagnetic waves with a peak power greater than 100 MW and a frequency of 1 GHz-300 GHz. High power microwave technology is a newly emerging research field along with the development of pulse power technology, plasma physics and electric vacuum technology. It has bright application prospects in plasma heating, high power radar, particle radio frequency acceleration and future space energy utilization.

[0003] A high power microwave source is a core device of a high power microwave system, and its operation is based on coherent radiation of an electron beam. The coherent radiation mechanism of the electron beam is divided into three categories: Cherenkov radiation, transition radiation and Bremsstrahlung radiation. The high power microwave source based on the Cherenkov radiation mechanism mainly includes a relativistic Cherenkov oscillator and a relativistic Cherenkov amplifier. The high power microwave source based on the transition radiation mechanism mainly includes a relativistic klystron oscillator and a relativistic klystron amplifier. The high power microwave source based on the Bremsstrahlung radiation mechanism mainly includes a free electron laser and a virtual cathode.

[0004] The relativistic Cherenkov oscillator is one of the most potential high power microwave source devices at present. It utilizes the interaction between a relativistic electron beam and an electromagnetic wave mode (structure wave) in a slow wave structure to produce self-oscillation and amplification, form coherent microwave radiation, and has the characteristics of high power, high efficiency and suitability for repeated frequency operation.

[0005] We call a Cherenkov device that produces non-single frequency in the same device by using various methods a multi-band Cherenkov device. Due to the wide range of applications of the multi-band Cherenkov oscillator in electromagnetic attack and defense, information frequency hopping transmission and other aspects, the multi-band Cherenkov oscillator has become a research hotspot in recent years. There are several methods for realizing multi-band of the same device, including but not limited to multi-cavity, mechanical tuning, electric tuning, magnetic field tuning and the like. The magnetic field tuning technology utilizes the principle of cyclotron resonance absorption of electrons, changes the microwave frequency of the device by changing the magnetic field strength through the different characteristics of the cyclotron resonance absorption magnetic field of the electrons corresponding to different wave bands. It can reduce the steps and difficulty required for changing the wave band. SUMMARY

[0006] The technical problem solved by the present application is: the present application provides a Cherenkov oscillator for realizing S and C band selection by using the principle of cyclotron resonance absorption. The present application uses the principle of cyclotron resonance absorption of electrons to achieve the effect of outputting different frequency microwaves by the device when different guiding magnetic field strengths are used on the same device. The function of adjusting the output band of the device can be realized by only changing the current size of the driving external guiding magnetic field. The device principle is clear, the structure is simple and easy to process, and the innovation and usability are considered, which is a good multi-band Cherenkov oscillator scheme.

[0007] The technical solution of the present application is: the present application is a Cherenkov oscillator for realizing S and C band selection, and the special feature is that: the Cherenkov oscillator for realizing S and C band selection comprises an oscillator cavity and a solenoid magnetic field arranged outside the oscillator cavity, and the oscillator cavity comprises an anode outer cylinder, a cutoff neck, a resonant reflection cavity, a slow wave structure and an output waveguide arranged in sequence; a cathode is arranged in the anode outer cylinder, and the slow wave structure is composed of six rectangular slow wave blades with the same parameters, and each two rectangular slow wave blades are connected by a circular ring.

[0008] Further, the cathode is a thin-walled cylinder, the wall thickness is 2mm, the inner radius R1 is equal to the electron beam radius, and the anode outer cylinder is a metal shell with an inner radius R2.

[0009] Further, the cutoff neck is disc-shaped, the inner radius is R3, R3>R1, the length is L2, the length L1 between the cutoff neck and the cathode is the anode-cathode spacing, and L1 is greater than 2cm.

[0010] Further, the resonant reflection cavity is disc-shaped, the inner radius R3 and the outer radius R4 satisfy R4>R3, and the length L3 is 0.4-0.5 times the working wavelength λ.

[0011] Further, the distance from the resonant reflection cavity is L4, which is the slow wave structure, and L4 is 0.2-0.3 times the working wavelength λ.

[0012] Further, each two trapezoidal slow wave blades are connected by a circular ring with a length of L5 and an inner radius of R3, and each slow wave blade has a length of L5 and a radius of R5.

[0013] Further, the slow wave structure is connected with the output waveguide with a radius of the inner radius R3 of the slow wave structure.

[0014] Further, the anode outer cylinder, the cutoff neck, the resonant reflection cavity, the slow wave structure and the output waveguide are all made of stainless steel, the cathode is made of graphite, and the solenoid magnetic field is made of copper wire.

[0015] Compared with the prior art, the present application can achieve the following technical effects:

[0016] This invention provides a Cherenkov oscillator for S-C band selection, which utilizes the principle of cyclotron resonance absorption to achieve S-C band selection. Its main functions are as follows:

[0017] In relativistic Cherenkov devices, cyclotron resonance absorption occurs when the electron beam electrical parameters and the guiding magnetic field meet the cyclotron resonance absorption condition. This excites the cyclotron resonance absorption mode within the device, causing a sharp increase in the oscillation current, which can damage the device's operating state or even render it inoperable. Therefore, for general Cherenkov oscillators, cyclotron resonance absorption is a phenomenon that should be avoided when selecting a magnetic field.

[0018] However, for devices that utilize the cyclotron resonance absorption principle to achieve frequency selection, the cyclotron resonance absorption phenomenon is an advantage rather than a hindrance. Generally speaking, there are two cyclotron resonance absorption regions:

[0019]

[0020]

[0021] Since the slow wave period L is related to the frequency of the output microwave, different frequencies can have different cyclotron resonance absorption regions. By carefully designing, we can make the cyclotron resonance absorption region corresponding to a certain frequency the saturation region of another frequency, and the cyclotron resonance absorption region corresponding to another frequency the saturation region of the former frequency. By adjusting the magnetic field strength, we can adjust the microwave output frequency.

[0022] Specifically: Due to the design of the slow-wave structure, the S-band structure wave with a frequency of 2.31 GHz and the C-band structure wave with a frequency of 4.62 GHz can be excited simultaneously because their frequencies are harmonics. Observe the relationship between the microwave output power and the magnitude of the guiding magnetic field in the C-band and S-band diagrams (…). Figure 3 It can be seen that when the magnetic field strength is 0.8T, microwaves with a C-band frequency of 4.62GHz cannot be generated normally due to the electron beam being in the cyclotron resonance absorption region. However, at this time, microwaves with an S-band frequency of 2.31GHz are in a saturated state. Therefore, the device can only output 2.31GHz S-band microwaves. Similarly, when the magnetic field strength is 1.3T, microwaves with a S-band frequency of 2.31GHz cannot be generated normally due to the electron beam being in the cyclotron resonance absorption region. However, at this time, microwaves with a C-band frequency of 4.62GHz are in a saturated state. Therefore, the device can only output 4.62GHz C-band microwaves.

[0023] As described above, based on the principle that the electron beam cyclotron resonance absorption region differs at different frequencies, the output microwave frequency of the device can be changed simply by altering the magnitude of the guiding magnetic field, i.e., by changing only the magnitude of the current passing through the guiding magnetic field solenoid coil. This method is simple in principle, involves a single variable, and is easy to change. Attached Figure Description

[0024] Figure 1 This is a cross-sectional perspective view of a preferred embodiment of a Cherenkov oscillator for S-C band selection provided by the present invention.

[0025] Figure 2 A cross-sectional view of a preferred embodiment of a Cherenkov oscillator for S-C band selection provided by the present invention;

[0026] Figure 3 A comparison diagram of the output power of S-band microwave and C-band microwave under different magnetic field magnitudes in a preferred embodiment of a Cherenkov oscillator for S-band and C-band selection provided by the present invention.

[0027] The annotations in the attached figures are explained as follows:

[0028] 101. Cathode; 102. Anode outer cylinder; 103. Cutoff neck; 104. Resonant reflection cavity; 105. Slow wave structure; 106. Output waveguide; 107. Solenoid magnetic field; 108. Oscillator cavity. Detailed Implementation

[0029] The overall solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0030] See Figure 1 , 2 The present invention provides a specific embodiment of a Cherenkov oscillator for S-C band selection, comprising an oscillator cavity 108 and a solenoid magnetic field 107 surrounding the oscillator cavity 108. The oscillator cavity 108 includes, in sequence, an anode outer cylinder 102, a cutoff neck 103, a resonant reflection cavity 104, a slow wave structure 105, and an output waveguide 106. A cathode 101 is disposed inside the anode outer cylinder 102. The entire structure is rotationally symmetrical about a central axis. The left end of the cathode 101 is externally connected to the inner conductor of a pulse power source, the left end of the anode outer cylinder 102 is externally connected to the anode of the pulse power source, and the right end of the output waveguide 106 is connected to a mode converter and an antenna. The solenoid magnetic field 107 is mounted on a magnetic field support, wherein:

[0031] Cathode 101 is a thin-walled cylinder with a wall thickness of 2 mm and an inner radius R1 equal to the electron beam radius;

[0032] The anode outer cylinder 102 is a metal shell with an inner radius of R2, and the anode of the pulse power source is connected to the left end.

[0033] The cutoff neck 103 is disc-shaped, with an inner radius R3, R3>R1, and a length L2. The length L1 between the cutoff neck 103 and the cathode 101 is referred to as the anode-cathode spacing. If L1 is too small, the cathode plasma will expand to the anode too early, resulting in a shortened anode-cathode closing pulse. Therefore, L1 is generally greater than 2 cm.

[0034] The resonant reflector 104 is disc-shaped, with an inner radius R3 and an outer radius R4, R4>R3. The length L3 is generally 0.4-0.5 times the working wavelength λ.

[0035] The length L4 from the resonant reflector 104 is the slow wave structure 305. L4 is generally 0.2-0.3 times the working wavelength λ.

[0036] The slow wave structure 105 is composed of six rectangular slow wave vanes with the same parameters. The length of the connecting circular ring is L5, and the inner radius is R3.

[0037] Each slow wave vane has a length L5 and a radius R5.

[0038] The slow wave structure 105 is followed by an output waveguide 106 with a radius equal to the inner radius R3 of the slow wave structure. The right end of the output waveguide 106 is connected to a mode converter and an antenna.

[0039] The anode outer cylinder 102, the cutoff neck 103, the resonant reflector 104, the slow wave structure 105, and the output waveguide 106 are all made of stainless steel. The cathode 101 is made of graphite, and the solenoid magnetic field 107 is made of copper wire.

[0040] This embodiment realizes a C-band Cherenkov oscillator with a center frequency of 4.26 GHz (corresponding to a microwave wavelength λ=7 cm). The corresponding size design is: R1=27 mm, R2=80 mm, R3=50 mm, R4=61 mm, R5=58 mm; L1=21 mm, L2=44 mm, L3=31 mm, L4=22 mm, L5=22 mm. In particle simulation, when the magnetic field is 0.8 T, the output S-band microwave power frequency is 2.31 GHz, and the power is 1.22 GW. When the magnetic field is 1.3 T, the output C-band microwave power frequency is 4.62 GHz, and the power is 2.10 GW, realizing the effect of changing the output microwave frequency by changing the guiding magnetic field size.

[0041] Referring to Figure 3 , the principle of electron cyclotron resonance absorption is used to realize the effect of outputting S-band microwaves when the magnetic field is 0.8 T and outputting C-band microwaves when the magnetic field is 1.3 T.

[0042] Of course, in the preferred embodiment, other connection modes can also be adopted between the cutoff neck 103, the resonant reflection cavity 104, the slow wave structure 105 and the output waveguide 106, and other material processing can also be adopted for the device structure. The above description is only the preferred embodiment of the present application, and the protection scope of the present application is not limited to the above-described embodiment. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application.

[0043] The technical content not specifically described in the summary of the present application and the above-described embodiments is the same as the prior art.

[0044] The above is only the specific implementation of the present application, but the protection scope of the present application is not limited to this. The protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A Cherenkov oscillator implementing S, C band selection, characterized in that: The Cherenkov oscillator realizing S, C band selection comprises an oscillator cavity and a solenoid magnetic field arranged outside the oscillator cavity, the oscillator cavity comprises an anode outer cylinder, a cutoff neck, a resonant reflection cavity, a slow wave structure and an output waveguide arranged in sequence; the anode outer cylinder is internally provided with a cathode, the slow wave structure is composed of six rows of rectangular slow wave blades with same parameters, and each two rectangular slow wave blades are connected by a circular ring.

2. The Cherenkov oscillator implementing S, C band selection according to claim 1, characterized in that: The cathode is a thin-walled cylinder with a wall thickness of 2 mm and an inner radius R1 equal to the electron beam radius, and the anode outer cylinder is a metal shell with an inner radius R2.

3. The Cherenkov oscillator enabling S, C band selection according to claim 2, characterized in that: The cutoff neck is disc-shaped with an inner radius R3 and a length L2, R3>R1, and the length L1 between the cutoff neck and the cathode is the anode-cathode spacing, L1 is greater than 2 cm.

4. The Cherenkov oscillator enabling S, C band selection according to claim 3, characterized in that: The resonant reflection cavity is disc-shaped with an inner radius R3 and an outer radius R4 satisfying R4>R3, and the length L3 is 0.4-0.5 times the working wavelength λ.

5. The Cherenkov oscillator enabling S, C band selection according to claim 4, characterized in that: The slow wave structure is at a distance L4 from the resonant reflection cavity, and L4 is 0.2-0.3 times the working wavelength λ.

6. The Cherenkov oscillator implementing S, C band selection according to claim 5, characterized in that: Each two rectangular slow wave blades are connected by a circular ring with a length L5 and an inner radius R3, each slow wave blade has a length L5 and a radius R5.

7. The Cherenkov oscillator implementing S, C band selection according to claim 6, characterized in that: The slow wave structure is followed by an output waveguide with a radius equal to the inner radius R3 of the slow wave structure.

8. The Cherenkov oscillator enabling S, C band selection according to any of claims 1 to 7, characterized in that: The anode outer cylinder, the cutoff neck, the resonant reflection cavity, the slow wave structure and the output waveguide are all made of stainless steel, the cathode is made of graphite, and the solenoid magnetic field is made of copper wire.

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