Coaxial S-waveband strong electromagnetic pulse suppressor based on plasma

Abstract

The invention belongs to the technical field of electromagnetic pulse suppressors, and particularly relates to a plasma-based coaxial S-waveband strong electromagnetic pulse suppressor which comprises an outer electrode, sealing windows, an inner electrode, a discharge electrode and a solder filling area, the sealing windows are installed on steps on the two sides of the outer electrode, an open hole is formed in the center of each sealing window, and the inner electrode is arranged in the open hole. The inner electrode is coaxially fixed in an open hole of the sealing window, the discharge electrode is welded on the outer electrode, filling gas is arranged in a sealed area enclosed by the outer electrode, the sealing window and the inner electrode, and a solder filling area is arranged between the outer electrode and the sealing window. The working frequency band of the coaxial plasma pulse suppressor is in the whole S wave band, and meanwhile, a dual impedance compensation structure is adopted on the suppressor shell, so that the insertion loss and the standing-wave ratio of the whole strong electromagnetic pulse suppressor are very small in a very wide broadband; and the broadband and low insertion loss indexes which are difficult to reach by the conventional waveguide type structure suppressor are obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic pulse suppressors, and in particular relates to a plasma-based coaxial S-band strong electromagnetic pulse suppressor. Background Art

[0002] Strong electromagnetic pulses are highly destructive due to their fast rise time and high instantaneous power. They enter the interior of the equipment through radiation or conduction coupling, causing performance degradation or even damage to sensitive circuits or devices in different forms such as short circuits, open circuits, insulation breakdown, impedance mutations, and burning. Electromagnetic pulse energy acts on the vulnerable parts of space structures such as semiconductor components and integrated circuits, causing soft damage such as coding disorder, sending erroneous information, and loss of stored information. In severe cases, it will cause electrical breakdown, thermal melting, or thermal stress damage to semiconductor devices and integrated circuits in the internal RF receiving front-end module, which will interfere with the operation of internal electronic components or even cause permanent damage.

[0003] Due to the interference of strong electromagnetic pulses, suppressors play a vital role in modern information and electronic warfare and electronic communication systems. With the development of high-power microwave weapon technology, it is particularly important to protect sensitive electronic equipment from damage by high-power microwaves. Suppressors can limit the entry of high-power signals into the system, prevent the system from being damaged by excessive power input, and ensure the normal operation of the equipment. Especially in battlefield environments, the ability of suppressors to counter enemy electronic attacks is crucial, and can effectively prevent radar, communication and navigation systems from failing or even being damaged due to strong interference signals.

[0004] Traditional waveguide plasma pulse suppressors use a multi-stage resonant structure to enhance gas discharge to increase the speed of plasma generation, so they have a narrow protection band, a large device size, and a high insertion loss, which easily causes signal loss. Summary of the invention

[0005] In view of the technical problem that the above-mentioned traditional waveguide plasma pulse suppressor easily causes signal loss, the present invention provides a plasma-based coaxial S-band strong electromagnetic pulse suppressor.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A plasma-based coaxial S-band strong electromagnetic pulse suppressor comprises an outer electrode, a sealing window, an inner electrode, a discharge electrode and a solder filling area, wherein the sealing window is mounted on steps on both sides of the outer electrode, an opening is arranged at the center of the sealing window, the inner electrode is coaxially fixed in the opening of the sealing window, the discharge electrode is welded to the outer electrode, a filling gas is arranged in the sealing area enclosed by the outer electrode, the sealing window and the inner electrode, a solder filling area is arranged between the outer electrode and the sealing window, a solder filling area is arranged between the sealing window and the inner electrode, and a solder filling area is arranged between the outer electrode and the discharge electrode.

[0008] The filling gas is pure argon or a neon-argon mixed gas, and the gas volume ratio of the neon-argon mixed gas is 1000:1.

[0009] The outer electrode is made of 4J33 alloy, the outer diameter of the outer electrode is 13mm, and the upper end of the outer electrode adopts a step structure for impedance compensation; the outer diameter of the inner electrode is 3mm, the inner diameter of the outer electrode is 7.6mm, and the inner electrode and the outer electrode form a coaxial structure with an impedance of 50Ω; the discharge electrode is made of metal molybdenum; the sealing window is made of 92 alumina ceramic, and the thickness of the sealing window is 1mm.

[0010] A parameter calculation method for a plasma-based coaxial S-band strong electromagnetic pulse suppressor comprises the following steps:

[0011] S1. The frequency of electron oscillation in plasma is taken as the oscillation frequency of plasma. When calculating the plasma frequency, a simplified model, the Lorentz plasma model, is used.

[0012] S2. When electrons oscillate in plasma, it manifests as electrons moving a small distance as a whole in a certain area. Then, positive charges will appear on one side of the moving distance, and negative charges will appear on the other side. When the moving distance is very small, the electric field generated is similar to the electric field of a flat plate capacitor, so the electric field can be calculated;

[0013] S3. The force on the electron is -eE. Calculate the acceleration.

[0014] S4. The solution of the differential equation is in the form of simple harmonic oscillation x = x0sinω p t, calculate the oscillation frequency;

[0015] S5. Calculate the breakdown field strength of plasma at low pressure;

[0016] S6. Calculate the breakdown field strength under high pressure, and thus calculate the breakdown time of the gas;

[0017] S8. By solving the ionization equation, the electron number density is calculated, and finally the plasma formation time is obtained.

[0018] The method for calculating the electric field in S2 is:

[0019]

[0020] Where: e is the charge of the electron, E is the electric field strength, ε0 is the dielectric constant, N e is the amount of charge, and x is the vertical distance between the two plates.

[0021] The method for calculating the acceleration in S3 is:

[0022]

[0023] Where: m is the mass of the electron, e is the charge of the electron, ε0 is the dielectric constant, N e is the amount of charge, and x is the vertical distance between the two plates.

[0024] The method for calculating the oscillation frequency in S4 is:

[0025] The solution of the differential equation is in the form of simple harmonic oscillation x = x0sinω p t, its oscillation frequency is:

[0026]

[0027] Where: p is the oscillation angular frequency of the plasma, f p is the frequency of the plasma.

[0028] The method for calculating the breakdown field strength of plasma at low pressure in S5 is:

[0029]

[0030] Where: Λ is the characteristic diffusion length of the gas, σ is the collision cross section, k = 1.38 × 10 -23 J / K is the Boltzmann constant, T is the temperature, φ i Gas collision coefficient, p is the gas pressure, ω is the plasma frequency.

[0031] The method for calculating the breakdown time of the gas in S6 is:

[0032] The breakdown field strength under high pressure is:

[0033]

[0034] Where: v m is the gas collision frequency, φ i is the gas collision coefficient, which is related to the type of gas; M is the atomic mass of the gas;

[0035] The breakdown time of the gas is:

[0036]

[0037] Where: E is the field strength of the incident electromagnetic wave.

[0038] The method for obtaining the plasma formation time in S8 is: by solving the ionization equation, the electron number density is calculated, and the plasma formation time is finally obtained as:

[0039]

[0040] Where: N e0 is the electron number density in the initial gas, γ represents the quantum of electromagnetic radiation, and N is the number of electrons or ions in the plasma.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. Compared with the existing waveguide type plasma pulse suppressor, the present invention improves the suppressor design structure based on the coaxial plasma strong electromagnetic pulse suppressor, and has the characteristics of wide working frequency band and high power tolerance, and can realize broadband strong electromagnetic microwave pulse protection. The existing traditional waveguide type plasma suppressor has a narrow working frequency band, while the coaxial plasma pulse suppressor of the present invention has a working frequency band in the entire S band, and at the same time, a dual impedance compensation structure is adopted on the suppressor housing, so that the insertion loss and standing wave ratio of the entire strong electromagnetic pulse suppressor are very small in a very wide frequency band, and the broadband and low insertion loss indicators that are difficult to achieve with the traditional waveguide type suppressor are obtained.

[0043] 2. Compared with the traditional solid-state limiter, it can realize the protection of large pulse power, the time for gas ionization to generate plasma is short, and the influence of microwave power leakage caused by response time on the subsequent circuit is reduced. Compared with the hundreds of watts of the traditional solid-state limiter, the coaxial plasma suppressor of the present invention can withstand power of up to 200kW, which greatly improves the protection ability of the traditional limiter to the RF port.

[0044] 3. Compared with the existing traditional waveguide type plasma pulse suppressor, the invented suppressor is small in size, light in weight, easy to maintain and install. The existing waveguide type plasma suppressor is large in size, while the coaxial plasma pulse suppressor of the present invention greatly reduces the product size.

[0045] 4. The present invention can realize the protection against front-door coupling of microwaves, etc., and the time for gas ionization to generate plasma is short, which reduces the influence of microwave power leakage caused by response time on the subsequent circuit, and the thermal and electrical effects of high-power microwaves have no obvious damage to plasma, so the operation is stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0047] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0048] Figure 1 The overall structural diagram of the present invention;

[0049] Figure 2 This is a diagram of the impedance compensation structure of the coaxial plasma pulse suppressor of the present invention;

[0050] Figure 3 is a schematic diagram of the structure of the inner electrode of the present invention;

[0051] Figure 4 It is a structural schematic diagram of the discharge electrode of the present invention;

[0052] Figure 5 The figure is a simulation result diagram of the initial electron density and the plasma formation time in the plasma of the present invention;

[0053] Figure 6 The relationship between the plasma formation time and the gas pressure of the present invention is shown in FIG.

[0054] Figure 7 is a graph showing the relationship between plasma formation time and incident pulse power of the present invention;

[0055] Figure 8 It is a graph showing the change of electron density over time in the present invention;

[0056] Fig. 9 This is a graph showing the change of electric field intensity over time according to the present invention.

[0057] Among them: 1 is the outer electrode, 2 is the sealing window, 3 is the inner electrode, 4 is the discharge electrode, and 5 is the solder filling area. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. These descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0059] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0060] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0061] Embodiment 1

[0062] A plasma-based coaxial S-band strong electromagnetic pulse suppressor, such as Figure 1-4 As shown, the outer electrode 1 is made of 4J33 alloy, with an outer diameter of 13mm, and a step structure is used for impedance compensation. The sealing window 2 is made of 92 alumina ceramic with a thickness of 1mm to ensure the gas tightness of the discharge cavity; the sealing window 2 is installed on the steps on both sides of the outer electrode 1, and the center of the sealing window 2 is opened to fix the inner electrode 3 in a coaxial position. The inner electrode 3 is made of 4J33 alloy and is located at the center of the suppressor. The outer diameter of the inner electrode 3 is 3mm, and the inner diameter of the outer electrode 4 is 7.6mm, forming a coaxial structure with an impedance of 50Ω. The sealing area enclosed by the outer electrode 1, the sealing window 2, and the inner electrode 3 is filled with a neon-argon mixed gas, and the gas volume ratio is 1000:1 for strong electromagnetic pulse excitation to form plasma. The discharge electrode 4 is made of metal molybdenum, one end of which is welded to the outer electrode 1, which is used to locally enhance the electric field strength and shorten the response time of the plasma pulse suppressor. A solder filling area 5 is provided between the outer electrode 1 and the sealing window 2, between the sealing window 2 and the inner electrode 3, and between the outer electrode 1 and the discharge electrode 4.

[0063] Embodiment 2

[0064] The structure is the same as that of the first embodiment, and the filling gas is pure argon to increase the breakdown field strength, thereby obtaining a higher ignition power than the first embodiment, and has been applied to an S-band RF port with a larger generating power.

[0065] Embodiment 3

[0066] The structure is the same as that of the first embodiment, and the filling gas is a neon-argon mixed gas, which increases the cavity structure size and the discharge electrode size, and improves the withstand power, which can reach 200kW.

[0067] The plasma-based coaxial S-band strong electromagnetic pulse suppressor of the present invention has the characteristics of wide protection bandwidth, high power tolerance, and fast response speed. It can suppress broadband pulses and effectively reduce the high-power microwave pulse energy coupled into the radio frequency channel by the antenna, protecting the frequency-using equipment from damage by high-power microwaves to meet the needs of complex application scenarios. The coaxial structure adopted improves the cavity structure design, while optimizing the performance, reducing the size and weight of the suppressor, which is convenient for integration and mobile application. Compared with traditional solid-state suppressors, the service life and protection stability of the device are improved, so that the coaxial plasma pulse suppressor has a more stable protection capability.

[0068] From the energy point of view, the gas filled in the plasma limiter has a certain breakdown threshold. When the incident electromagnetic wave is higher than this threshold, the gas is broken down to form plasma. A part of the incident electromagnetic wave is reflected at the interface, and it will be absorbed and attenuated in the plasma. When the attenuation is sufficient to ensure the normal operation of the subsequent circuit, it will achieve the protection effect. From the frequency domain, after the plasma is formed, there will be a plasma frequency, which is a certain value. When the frequency of the incident electromagnetic wave is less than this frequency, it can hardly propagate in the plasma. This characteristic can also be understood as the shielding behavior of the plasma against the electric field of this frequency. When it is greater than this frequency, it can propagate in the plasma. Therefore, it is proposed to use the plasma limiter as a means of protection for high-power microwaves. Whether the plasma can limit the incident electromagnetic wave is mainly determined by the relationship between the plasma frequency and the frequency of the incident electromagnetic wave. Therefore, to ensure that the incident electromagnetic wave cannot pass through the limiter, a reasonable plasma frequency should be designed, that is, for high-power microwaves (need to be limited), its frequency should be lower than the plasma frequency so that it cannot propagate in the plasma.

[0069] For plasma pulse suppressors, the frequency of plasma, the absorption field strength of the inert gas and the plasma generation time are three important parameters.

[0070] Generally speaking, the density of plasma is uniformly distributed from a macroscopic perspective, but from a microscopic perspective, its density distribution varies, and this density variation is oscillatory. The mass of ions is three or four orders of magnitude higher than that of electrons, and their response times to plasma oscillations vary greatly. Therefore, the frequency of electron oscillations in plasma can be taken as the oscillation frequency of plasma. Therefore, when calculating the plasma frequency, a simplified model—the Lorentz plasma model—is used, which assumes that the mass of ions in plasma is much greater than that of electrons, and that heavy ions are considered to be stationary and uniformly distributed. When electrons oscillate in a plasma, it manifests as the overall movement of electrons in a certain area for a small distance. Then, positive charges will appear on one side of this moving distance, and negative charges will appear on the other side. When the moving distance is very small, the electric field they generate is similar to the electric field of a flat plate capacitor, so the electric field can be obtained as:

[0071]

[0072] The force on the electron is -eE, so the acceleration can be expressed as:

[0073]

[0074] Where m is the mass of the electron and e is the charge of the electron.

[0075] The solution of the differential equation is in the form of simple harmonic oscillation x = x0sinω p t, its oscillation frequency is:

[0076]

[0077] ω p is the oscillation angular frequency of the plasma, f p is the frequency of the plasma.

[0078] The breakdown field strength of plasma at low pressure (0.1Torr~1Torr) is:

[0079]

[0080] Where Λ is the characteristic diffusion length of the gas, σ is the collision cross section, and k = 1.38×10 -23 J / K is the Boltzmann constant, T represents the temperature (unit: K) is the ionization energy required for gas atoms to be ionized.

[0081] The breakdown field strength under high pressure (10Torr ~ 1000Torr) is

[0082]

[0083] where v mis the gas collision frequency, φ i is the gas collision coefficient, which is related to the type of gas. M is the atomic mass of the gas.

[0084] The breakdown time of the gas is:

[0085]

[0086] Where E is the field intensity of the incident electromagnetic wave. By solving the ionization equation, the electron number density is calculated, and the plasma formation time is finally obtained as:

[0087]

[0088] Where N e0 is the electron number density in the initial gas.

[0089] The simulation results of plasma production time, initial electron density, gas pressure and incident pulse power are shown in Figure 2. Figure 5-7 shown.

[0090] The plasma pulse suppressor of the present invention is simulated with a pulse frequency of 2.5 GHz and a pulse power of 10 kW. The initial electron number density of the plasma pulse suppressor is 10 13 m -3 , the gas pressure is 10Torr, the change of electron density with time and the change of electric field distribution with time are as follows Figure 8 and Fig. 9 shown.

[0091] Only the preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention, and various changes should be included in the protection scope of the present invention.

Claims

1. A plasma-based coaxial S-band strong electromagnetic pulse suppressor, characterized in that: The invention comprises an outer electrode (1), a sealing window (2), an inner electrode (3), a discharge electrode (4) and a solder filling area (5), wherein the sealing window (2) is mounted on steps on both sides of the outer electrode (1), an opening is provided at the center of the sealing window (2), the inner electrode (3) is coaxially fixed in the opening of the sealing window (2), the discharge electrode (4) is welded to the outer electrode (1), a filling gas is provided in the sealing area enclosed by the outer electrode (1), the sealing window (2) and the inner electrode (3), a solder filling area (5) is provided between the outer electrode (1) and the sealing window (2), a solder filling area (5) is provided between the sealing window (2) and the inner electrode (3), and a solder filling area (5) is provided between the outer electrode (1) and the discharge electrode (4).

2. The plasma-based coaxial S-band strong electromagnetic pulse suppressor according to claim 1, characterized in that: The filling gas is pure argon or a neon-argon mixed gas, and the gas volume ratio of the neon-argon mixed gas is 1000:

1.

3. The plasma-based coaxial S-band strong electromagnetic pulse suppressor according to claim 1, characterized in that: The outer electrode (1) is made of 4J33 alloy, the outer diameter of the outer electrode (1) is 13 mm, and the upper end of the outer electrode (1) adopts a step structure for impedance compensation; the outer diameter of the inner electrode (3) is 3 mm, the inner diameter of the outer electrode (1) is 7.6 mm, and the inner electrode (3) and the outer electrode (1) form a coaxial structure with an impedance of 50Ω; the discharge electrode (4) is made of metal molybdenum; the sealing window (2) is made of 92 alumina ceramic, and the thickness of the sealing window (2) is 1 mm.

4. A parameter calculation method for a plasma-based coaxial S-band strong electromagnetic pulse suppressor according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. The frequency of electron oscillation in plasma is taken as the oscillation frequency of plasma. When calculating the plasma frequency, a simplified model, the Lorentz plasma model, is used. S2. When electrons oscillate in plasma, it manifests as electrons moving a small distance as a whole in a certain area. Then, positive charges will appear on one side of the moving distance, and negative charges will appear on the other side. When the moving distance is very small, the electric field generated is similar to the electric field of a flat plate capacitor, so the electric field can be calculated; S3. The force on the electron is -eE. Calculate the acceleration. S4. The solution of the differential equation is in the form of simple harmonic oscillation x = x0sinω p t, calculate the oscillation frequency; S5. Calculate the breakdown field strength of plasma at low pressure; S6. Calculate the breakdown field strength under high pressure, and thus calculate the breakdown time of the gas; S8. By solving the ionization equation, the electron number density is calculated, and finally the plasma formation time is obtained.

5. The parameter calculation method of a plasma-based coaxial S-band strong electromagnetic pulse suppressor according to claim 4 is characterized in that: The method for calculating the electric field in S2 is: Where: e is the charge of the electron, E is the electric field strength, ε0 is the dielectric constant, N e is the amount of charge, and x is the vertical distance between the two plates.

6. The parameter calculation method of a plasma-based coaxial S-band strong electromagnetic pulse suppressor according to claim 4 is characterized in that: The method for calculating the acceleration in S3 is: Where: m is the mass of the electron, e is the charge of the electron, ε0 is the dielectric constant, N e is the amount of charge, and x is the vertical distance between the two plates.

7. The parameter calculation method of a plasma-based coaxial S-band strong electromagnetic pulse suppressor according to claim 4 is characterized in that: The method for calculating the oscillation frequency in S4 is: The solution of the differential equation is in the form of simple harmonic oscillation x = x0sinω p t, its oscillation frequency is: Where: p is the oscillation angular frequency of the plasma, f p is the frequency of the plasma.

8. The parameter calculation method of a plasma-based coaxial S-band strong electromagnetic pulse suppressor according to claim 4 is characterized in that: The method for calculating the breakdown field strength of plasma at low pressure in S5 is: Where: Λ is the characteristic diffusion length of the gas, σ is the collision cross section, k = 1.38 × 10 -23 J / K is the Boltzmann constant, T is the temperature, φ i Gas collision coefficient, p is the gas pressure, ω is the plasma frequency.

9. The parameter calculation method of a plasma-based coaxial S-band strong electromagnetic pulse suppressor according to claim 4 is characterized in that: The method for calculating the breakdown time of the gas in S6 is: The breakdown field strength under high pressure is: Where: v m is the gas collision frequency, φ i is the gas collision coefficient, which is related to the type of gas; M is the atomic mass of the gas; The breakdown time of the gas is: Where: E is the field intensity of the incident electromagnetic wave.

10. The parameter calculation method of a plasma-based coaxial S-band strong electromagnetic pulse suppressor according to claim 4 is characterized in that: The method for obtaining the plasma formation time in S8 is: by solving the ionization equation, the electron number density is calculated, and the plasma formation time is finally obtained as: Where: N e0 is the electron number density in the initial gas, γ represents the quantum of electromagnetic radiation, and N is the number of electrons or ions in the plasma.

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