A high-sensitivity low-noise fast-response magnetic fuze applied to a high-speed platform

Abstract

This invention discloses a highly sensitive, low-noise, and fast-response magnetic fuze applied to high-speed platforms. The magnetic fuze utilizes a differential method with two coils fixed in place to detect the residual magnetic field of a target. The two coils are differentially mounted on the high-speed platform, parallel to the platform's longitudinal axis, with the two coils 0.1m apart. This invention employs a dual-coil method, with the differential detection of the induced electromotive force generated by the ship's residual magnetism serving as the magnetic fuze's magnetic field detection mechanism. The two coils are arranged 0.1 meters apart along the torpedo's longitudinal axis. The differential induced electromotive force significantly eliminates noise generated by the Earth's magnetic field, ocean currents, and waves, reducing the noise amplitude by 20dB (100 times) and increasing the detection sensitivity to 10. ‑5 nTHz ‑1 / 2 With this, the response time of the induction coil can be increased to about 20µs (corresponding frequency 50kHz).

Description

Technical Field

[0001] This invention relates to the field of novel precision damage control technology, specifically to a highly sensitive, low-noise, and fast-response magnetic fuze applied to high-speed platforms. Background Technology

[0002] Magnetic fuses utilize the distortion of the Earth's magnetic field caused by ferromagnetic materials carried by the target. Through a quasi-static magnetic detection mechanism, the fuse activates when the distortion exceeds a certain threshold. Currently, most magnetic fuses employ a quasi-static magnetic field detection mechanism as their trigger condition. For example, the total remanent magnetic moment of a 3000-ton ship in the Earth's magnetic field is approximately 10⁻⁶. 5 Am 2 The remanent magnetic field at a distance of 20 meters from the ship's center of mass, perpendicular to the ship's direction of travel, is approximately:

[0003]

[0004] The remanent magnetic field component of a ship is superimposed on a component of the Earth's magnetic field, creating a distortion in the Earth's magnetic field. If the distortion threshold for the east-west component of the Earth's magnetic field is set to 5000 nT, then when a torpedo enters a range of 12.6 meters from the ship, the magnetic fuse will activate and detonate, launching an explosive attack on the ship. Assume the magnetic detector's x-axis points north-south, its y-axis points east-west, and its z-axis is perpendicular to the sea level and points downwards. The horizontal component of the Earth's magnetic field typically has a very large x-component, around 35000 nT, while the y-component is smaller, around 1000-2000 nT. If the magnetic fuse uses the detection of the Earth's magnetic field's y-component as its detection mechanism, with a threshold set at 2000 nT, a detected y-value exceeding 2000 nT indicates the torpedo is approaching the ship target, and exceeding 5000 nT indicates it is very close. When the magnetic detector rotates around its z-axis, the x and y components of the detector will exhibit significant numerical changes. However, when the attack platform launches an attack, its high speed causes vibrations in the overall azimuth angle of the platform (torpedo, interceptor), resulting in increased noise in the y-component of the magnetic field detection. When the azimuth angle deflects by 2 degrees, the detected value of the y-component increases by about 1220 nT. This is the noise amplitude of the torpedo's magnetic fuze. To reduce the noise amplitude of the torpedo's magnetic fuze, the detection of the geomagnetic scalar can be used as the working mechanism of the magnetic fuze. The total amount of the geomagnetic field generally changes only on the order of 10 nT. This reduces the noise amplitude of the geomagnetic field. Although the noise amplitude of the geomagnetic field is reduced, the torpedo's navigation in seawater and the circulation of seawater also cause changes in the total magnetic field. Moreover, the waves on the sea surface also bring short-term (10s), small-scale (10m) changes in the total magnetic field, with a noise amplitude of about 50 nT. The magnetic field detector of the magnetic fuze is also affected by the residual magnetic field of the torpedo platform itself. The magnetic fuze needs to undergo a relatively complex torpedo residual magnetic compensation operation before use. Furthermore, quasi-static magnetic field detectors typically have a low time response range, generally around 5 kHz. A too-high time response also reduces the detector's sensitivity. The sensitivity of a magnetic field detector is generally around 10 kHz. -2 nTHz -1 / 2 Approximately. A highly sensitive atomic magnetometer, with a sensitivity in the pTHz range. -1 / 2 However, atomic magnetic field detectors are too expensive to develop and are difficult to use widely. Summary of the Invention

[0005] To address the above technical problems, this invention provides a highly sensitive, low-noise, and fast-response magnetic fuze applicable to high-speed platforms:

[0006] A highly sensitive, low-noise, and fast-response magnetic fuze for use on high-speed platforms is provided. The magnetic fuze uses a differential method with two coils fixed together to form a detection mechanism for the residual magnetic field of the target.

[0007] Optionally, the dual-coil differential mounting is performed on the high-speed platform, with the differential mounting parallel to the longitudinal axis of the high-speed platform and the two coils 0.1m apart.

[0008] The induced electromotive force generated by the coils as they move with the platform is obtained by differentially mounting two coils on the high-speed platform:

[0009]

[0010] in, It is the relative permeability of the coil core; It is the total magnetic field passing through the electromagnetic coil; This represents the distribution of the Earth's background magnetic field near the Earth's surface or sea level and its changes over time.

[0011] Optionally, the method for calculating the remanent magnetic field of the target body is as follows:

[0012]

[0013] in, for, The number of turns of the electromagnetic coil. It is the cross-sectional area of ​​the coil. The velocity of the target body, Let be the gradient tensor of the magnetic field.

[0014] Optionally, the differential calculation method using a dual-coil fixed connection is as follows:

[0015]

[0016] in, , which are the normal directions of the cross-sectional area of ​​the first coil and the normal methods of the cross-sectional area of ​​the second coil, respectively;

[0017] Because the two coils are fixedly connected, the coils move synchronously and in phase with the platform's oscillation, and The difference in induced electromotive force is obtained as follows:

[0018]

[0019] The signal of the novel magnetic fuze is obtained based on the difference in the induced electromotive force.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention employs a dual-induction coil method. The difference in induced electromotive force generated by the residual magnetism of a ship serves as the magnetic field detection mechanism for the magnetic fuse. The two coils are arranged 0.1 meters apart along the longitudinal axis of the torpedo. The difference in induced electromotive force significantly eliminates noise generated by the geomagnetic field, ocean currents, and waves, reducing the noise amplitude by 20 dB (100 times). That is, the magnetic detection noise is reduced from 50 nTHz. -1 / 2 Reduced to 0.5 nTHz -1 / 2 The detection sensitivity has been increased to 10. -5 nTHz -1 / 2 With this, the response time of the induction coil can be increased to about 20µs (corresponding frequency 50kHz). Attached Figure Description

[0022] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the predicted trajectory supplied to a target ship by a highly sensitive, low-noise, and fast-response magnetic fuze torpedo applied to a high-speed platform, according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of noise suppression using a differential magnetic induction coil for a high-sensitivity, low-noise, and fast-response magnetic fuze applied to a high-speed platform, according to an embodiment of the present invention.

[0025] Figure 3 This invention relates to the installation of a dual-coil induced electromotive force differential magnetic fuze, which is a high-sensitivity, low-noise, and fast-response magnetic fuze applied to a high-speed platform, on a torpedo.

[0026] Figure 4 This is a schematic diagram of an armored battlefield environment for a high-sensitivity, low-noise, fast-response magnetic fuze applied to a high-speed platform, according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the differential induction coil magnetic fuze layout for a high-sensitivity, low-noise, and fast-response magnetic fuze applied to a high-speed platform, according to an embodiment of the present invention.

[0028] Attached image description: Figure 4 In the diagram, A represents the enemy tank, B represents the tank lying dormant on the battlefield, and C represents the tank that fired armor-piercing shells. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1:

[0032] In this embodiment, a highly sensitive, low-noise, and fast-response magnetic fuze is applied to a high-speed platform. The magnetic fuze uses a differential method with two coils fixed together to form a detection mechanism for the residual magnetic field of the target body.

[0033] Optionally, the dual-coil differential mounting is performed on the high-speed platform, with the differential mounting parallel to the longitudinal axis of the high-speed platform and the two coils 0.1m apart; the induced electromotive force differential reduces noise by 20dB.

[0034] The induced electromotive force generated by the coils as they move with the platform is obtained by differentially mounting two coils on the high-speed platform:

[0035]

[0036] in, It is the relative permeability of the coil core; It is the total magnetic field passing through the electromagnetic coil; This represents the distribution of the Earth's background magnetic field near the Earth's surface or sea level and its changes over time.

[0037] Optionally, the method for calculating the remanent magnetic field of the target body is as follows:

[0038]

[0039] in, for, The number of turns of the electromagnetic coil. It is the cross-sectional area of ​​the coil. The velocity of the target body, Let be the gradient tensor of the magnetic field.

[0040] Optionally, the differential calculation method using a dual-coil fixed connection is as follows:

[0041]

[0042] in, , which are the normal directions of the cross-sectional area of ​​the first coil and the normal methods of the cross-sectional area of ​​the second coil, respectively;

[0043] Because the two coils are fixedly connected, the coils move synchronously and in phase with the platform's oscillation, and The difference in induced electromotive force is obtained as follows:

[0044]

[0045] The signal of the novel magnetic fuze is obtained based on the difference in the induced electromotive force.

[0046] Example 2

[0047] Most current magnetic fuses employ quasi-static magnetic field component or total magnetic field detection mechanisms as detectors to sense the target's magnetic field. In naval warfare, torpedoes and interceptor missiles in tank active defense systems operating in complex battlefield environments mostly utilize magnetic fuses or combination fuses that integrate magnetic fuzes. These detonate when the torpedo approaches the target ship or the interceptor missile approaches an incoming armor-piercing projectile, damaging the enemy ship or the projectile. Torpedoes and interceptor missiles travel at high speeds towards their targets. This high-speed motion introduces additional interference and noise to conventional magnetic fuses. The high-speed motion of torpedoes (greater than 45 m / s) further exacerbates this problem. -1 The movement of a torpedo in seawater causes mutual vibrations between its components, which can lead to changes in the magnitude and direction of its remanent magnetic moment over time. This presents significant challenges and additional power consumption for remanent magnetization compensation. High-speed torpedoes moving in seawater can also cause changes in their overall pitch, azimuth, and even rotation around their longitudinal axis. These overall angular changes also result in variations in the detected values ​​of individual magnetic field components. These changes constitute the noise of the magnetic fuze. To eliminate this noise, wavelet transform methods are often used. This requires increasing the computational power and noise reduction model algorithms for the magnetic fuze, as well as adding electronic hardware units and noise reduction software. The complex battlefield environment in tank warfare, such as a damaged tank lying in wait on the battlefield, can lead to significant remanent magnetization, potentially interfering with the magnetic fuze of an interceptor missile. Furthermore, interceptor missiles are difficult to move away from a stationary tank. This can cause premature detonation of the interceptor missile, reducing the probability of intercepting an incoming armor-piercing projectile. If the interceptor missile flies parallel to the incoming armor-piercing projectile, and if the interceptor missile's sensitivity is increased—that is, detonating at a distance of 3 meters from the incoming armor-piercing projectile—its fragments and blast wave can destroy the incoming projectile or change its flight path. This greatly increases the probability of actively intercepting an incoming armor-piercing projectile. The interceptor missile's flight speed is approximately 700 m / s. -1 The incoming armor-piercing projectile has a flight speed of approximately 1000 m / s. -1 The relative speed between the two is greater than 1500 ms -1 .

[0048] Basic Principles of Novel High-Sensitivity, Low-Noise, Fast-Response Magnetic Fuzes on High-Speed ​​Platforms

[0049] Assume the high-speed platform moves at a velocity of 0 in the stationary coordinate system O(x, y, z) on the ground. The initial normal direction of an electromagnetic induction coil is perpendicular to the z-axis of the stationary coordinate system. .in The Z-axis is the coordinate system O'(X, Y, Z) fixed to the platform. Initially, the three axes of both coordinate systems are parallel. The induced electromotive force in the electromagnetic induction coil during platform movement...

[0050]

[0051] in, It is a micro-business that passes through the magnetic flux of an electromagnetic coil; It is the local derivative of the magnetic flux passing through the electromagnetic coil, or the partial derivative of the magnetic flux with respect to time t; It refers to the migration and change of magnetic flux through the electromagnetic coil as the platform moves, or the migration of micro-businesses. In a stationary coordinate system, it varies with spatial coordinates , a function of the time coordinate t.

[0052]

[0053] in, It is the number of turns of the electromagnetic coil. It is the cross-sectional area of ​​the coil. It is the direction of the normal to the cross-sectional area of ​​the coil. It is the relative permeability of the coil core. This is the total magnetic field passing through the electromagnetic coil. Therefore, the induced electromotive force generated when the coil moves with the platform...

[0054]

[0055] All quantities in equation (A) are in a stationary coordinate system. Among them:

[0056]

[0057] The distribution and temporal variation of the Earth's background magnetic field near the Earth's surface or sea level. (This is relevant to the last 1000 seconds of a torpedo attack on a ship.) Within a range of 1000 m, the Earth's background magnetic field can be considered uniform, meaning the gradient of the geomagnetic field is less than [missing value]. During a magnetically still day, the change in the geomagnetic field over time is less than 1 nTs⁻¹. Only during a strong geomagnetic storm, with a Dst exponent of approximately -2000 nT and an initial phase of about 30 minutes, can a change in the geomagnetic field over time exceeding 1 nTs⁻¹ occur. Such intense geomagnetic storms have only occurred once or twice in the 300-year recorded history. Therefore, the change in the geomagnetic field over time can be ignored. In the application of magnetic fuses, the background geomagnetic field can be considered constant. , , .

[0058] This refers to the distribution of the remanent magnetic field of minerals (such as iron ore and nickel ore) in the Earth's crust. If a mineral has not been mined on a large scale, its remanent magnetic field remains largely unchanged over time. Although the spatial gradient of the remanent magnetic field of a mineral is greater than the spatial gradient of the Earth's magnetic field, it varies significantly over time. Within a range of 1000 (m), less than During the first 20 seconds of operation of the magnetic fuze, the residual magnetic interference from crustal minerals can be ignored. , , .

[0059] This refers to the magnetic field distribution in the battlefield environment. The magnetic fields generated by ocean currents and waves can interfere with the magnetic fuze. Seawater contains 3.5% salt, which completely dissociates into Na+ and Cl- ions. Seawater has a certain degree of electrical conductivity. The average conductivity of seawater is approximately 4.5 Sm⁻¹. S is the Siemens unit of conductivity. The reciprocal of the Siemens unit is the ohm, the unit of electrical resistance. Ocean currents generate seawater that moves perpendicular to the Earth's magnetic field, inducing an electric current within it. This current, in turn, generates a magnetic field. Ocean waves are caused by sea winds exciting KH instabilities on the sea surface, creating uneven wave troughs and crests. Wave crests, propelled by the wind, move in the direction of the wind, generating an electric current perpendicular to the Earth's magnetic field. This current induces a magnetic field, which varies with time and space, increasing the noise of the magnetic fuze. The magnetic fields induced by the currents from ocean currents and waves produce noise in the magnetic fuze of the induction coil. This noise amplitude is around 20 nT, with a timescale in the order of seconds. In a tank battlefield environment, the remanent magnetization of a stationary tank is on the order of 1000 am², and the remanent magnetic field generated at a distance of 10 meters from the tank's center of mass...

[0060]

[0061] The remanent magnetic moment of the incoming armor-piercing projectile is approximately 15 Am², and the remanent magnetic field generated at a distance of 3 m from the projectile is approximately:

[0062]

[0063] In other words, the residual magnetic field at a distance of 10 units from the damaged tank is greater than the residual magnetic field at a distance of 10 units from the incoming armor-piercing projectile. If the interceptor uses a quasi-static magnetic field detector as its magnetic fuse detection mechanism, it may malfunction, causing the interceptor to detonate due to the damaged tank, thus reducing the probability of intercepting the incoming armor-piercing projectile. In this invention, the magnetic fuse uses an induction coil on a high-speed moving platform, whose induced electromotive force...

[0064]

[0065] Residual magnetic field of the battlefield environment It does not change over time, therefore

[0066]

[0067] If a differential mode of induced electromotive force using a fixed dual-coil is adopted...

[0068]

[0069] The two coils are fixedly connected, and the coils swing synchronously and in phase with the platform. ,and The difference in induced electromotive force

[0070]

[0071] The differential induced electromotive force of the dual coils, which is the signal of the novel magnetic fuze, is described by equation (B). From equation (B), it can be seen that the detection signal of the novel magnetic fuze... Proportional to the velocity of the high-speed moving platform relative to the target body This is proportional to the gradient of the target's remanent magnetic field in the direction of relative velocity. Assume the interceptor's velocity is... The speed of the incoming armor-piercing projectile is . and Parallel, but in opposite directions. Here, it is assumed that the velocity of the armor-piercing projectile is 1.5 times that of the interceptor projectile. For example, if the velocity of the armor-piercing projectile is 1050 m / s and the velocity of the interceptor projectile is 700 m / s, the relative velocity is 1750 m / s. The difference in the remanent magnetic field gradient of the armor-piercing projectile is:

[0072]

[0073] The residual magnetic field gradient difference of the damaged tank in the environment

[0074]

[0075] The difference in induced electromotive force generated by the interceptor missile in the residual magnetic field of the damaged tank.

[0076]

[0077] The induced electromotive force difference generated by the residual magnetic field of the armor-piercing projectile is divided into

[0078]

[0079] The above analysis and calculation results show that, although the residual magnetic field of a destroyed and lying tank is much greater than that of an incoming armor-piercing projectile on the battlefield, the differential signal of the induced electromotive force of the dual coil is much greater than the residual magnetic interference of the destroyed tank. This is mainly because the difference in induced electromotive force is proportional to the relative velocity, and this factor plays an important role in improving the signal-to-noise ratio of dual-coil differential detection.

[0080] Example 3

[0081] Realization of a High-Sensitivity, Low-Noise, Fast-Response Magnetic Fuze

[0082] This invention employs a differential method with dual coils fixed in place to implement a magnetic fuze mechanism for detecting the remanent magnetic field of a target. The signal calculation for the magnetic fuze is described by equation (B):

[0083]

[0084] in, These represent the positions of the two coils in a stationary coordinate system. On a torpedo, the dual coils are differentially mounted 0.1m apart in the direction parallel to the torpedo's longitudinal axis; on a 105mm interceptor missile, they are mounted 0.1m apart in the direction perpendicular to the interceptor's longitudinal axis. The torpedo reaches a velocity of 45ms⁻¹ in the final stage of entering its attack range. The difference in the remanent magnetic field near the target ship on the two coils is also shown. It is the core contributing factor to the differential electromotive force induced by the induction coil. If the near-field remanent magnetic field of the target object is in If the difference between two points is zero or extremely small, this invention cannot be applied. However, it can be increased... The difference in the remanent magnetic field is increased by the distance between two points. Increase The distance between two points cannot be increased indefinitely; as the distance increases, the noise level on the magnetic fuze also increases. Generally... A distance of 0.1m between the two points can significantly reduce interference noise from ocean currents, waves, and the residual magnetic fields of tanks damaged on the battlefield. At closer distances, the spatial distribution of the target's residual magnetic field more closely resembles the magnetic field configuration of a magnetic quadrupole or higher-order octupole, resulting in a larger magnetic field difference at 0.1m. Reducing the noise of the differential signal of the induced electromotive force between the two coils requires decreasing the distance between them. At smaller distances, ambient noise is particularly low. This is one reason for the low noise of the magnetic fuze in this invention. While reducing environmental noise, the inductive magnetic fuze also needs high sensitivity. Improving sensitivity involves increasing the amplitude of the induced electromotive force signal from the induction coil. A smaller differential residual magnetic field of the target is used to suppress noise. At that time, increasing the induced electromotive force of the induction coil can be achieved by increasing... This is achieved by using a high-permeability material for the magnetic core, thereby increasing the relative permeability of the core material. Increase the number of turns N of the coil; increase the cross-sectional area s of the induction coil and increase the speed of the mounting platform. This invention increases the induced electromotive force (EMF) by using amorphous permalloy strip coiled into a magnetic core. The induction coil itself possesses a high response frequency to changes in the magnetic field; the induced EMF is directly proportional to the frequency of the disturbance signal in the measured magnetic field. In other words, the higher the frequency of the disturbance magnetic field, the stronger the induced EMF signal of the electromagnetic coil. Therefore, the magnetic fuze of this invention has the advantages of low noise, high sensitivity, and fast response.

[0085] Example 4

[0086] In this embodiment, the main application scenario involves a high-speed torpedo hurtling towards an enemy ship at the end of its attack. The differential electromotive force induced by the near-field remanent magnetic field of the ship in a dual-coil system is used as a magnetic fuze. When the signal exceeds a certain threshold, the torpedo warhead detonates. This creates an explosive shockwave at the bottom of the ship, destroying it.

[0087] A schematic diagram of the installation of a dual-coil induced electromotive force differential magnetic fuze on a torpedo is shown below. Figure 3 As shown, two identical electromagnetic induction coils are fixed to an aluminum alloy plate, which is placed in the thunder head on the XY plane.

[0088] 1. Noise Analysis and Suppression of High-Speed ​​Torpedoes

[0089] When the torpedo enters the near-field of the target ship (within 1000m of the target ship, the torpedo only needs about 22 seconds to approach the target ship at a speed of 45ms⁻¹), the magnetic field of the target ship does not change over time, that is... The magnetic field gradient of the target ship is the target sensed by the torpedo's magnetic fuse. As the torpedo gets closer to the target ship, the gradient of the target ship's remanent magnetic field increases, and the induced electromotive force (EMF) is proportional to the product of the magnetic field gradient and the torpedo's velocity. When the induced EMF exceeds a certain threshold, the magnetic fuse activates, igniting and detonating the torpedo. A schematic diagram of the predicted trajectory of a torpedo attacking a target ship within a 10-meter underwater plane is shown below. Figure 1 As shown:

[0090] Total magnetic field on the magnetic fuze induction coil

[0091]

[0092] in, It is the Earth's background magnetic field near the sea surface, assuming it is within 1000 meters of the target ship. This means that the background geomagnetic field near the sea surface does not change with time and space. The scale of change in the Earth's intrinsic background magnetic field is on the order of 100 years, and the currently obtained range of changes in the intrinsic background magnetic field is 5% within 100 years. During the 20 seconds of a torpedo attack on a target ship, the change of the Earth's intrinsic magnetic field over time can be completely ignored; with the Earth's rotation, the Earth's background magnetic field will exhibit diurnal variation, with a rate of change of about 2-3 nT per hour, and the geomagnetic variation in the 20-second interval can also be ignored. If there are no geomagnetic storms or substorms in the Earth's magnetosphere and ionosphere, the Earth's background magnetic field will also not change with time, that is, during a geomagnetic quiescent day, the Earth's background magnetic field remains basically unchanged. During small geomagnetic storms, the geomagnetic field near the Earth's surface will exhibit a geomagnetic field variation of 20-50 nTh⁻¹. During the 20-second interval, the geomagnetic variation can be ignored. However, during large geomagnetic storms, the geomagnetic variation of 600-2000 nTh⁻¹ in the 20-second interval may be similar to the gradient change of the target ship, becoming one of the important interference factors for the magnetic fuse. If the target ship is within 1000 meters of the magnetically still day, the Earth's background magnetic field can be considered to remain unchanged over a 25-second interval during a torpedo attack. Only during the half-hour interval following a sudden strong magnetic storm can the change in the geomagnetic field over time cause a strong disturbance in the induced electromotive force on the torpedo's magnetic fuse (not the change in induced electromotive force caused by the magnetic field gradient of the target ship).

[0093] It is the remanent magnetic field of minerals in the Earth's crust. Mining is extremely rare underwater, therefore... It does not change over time. The gradient of the mineral magnetic anomaly distribution in the Earth's crust is much smaller than the magnetic field gradient of the target ship, so the interference signal amplitude generated by the remanent magnetic anomaly gradient of the Earth's crustal minerals is very small.

[0094] This refers to the torpedo's own remanent magnetic field. The torpedo's pump-jet propeller generates shaft-frequency magnetic disturbances during rotation, which can be eliminated using a bandpass filter. If the torpedo moves without relative motion between itself and other components, its remanent magnetic field will not change over time. The torpedo's remanent magnetic field moves with the torpedo and has no relative velocity with respect to the magnetic fuze induction coil. Therefore, the gradient term of the torpedo's remanent magnetic field does not generate an induced electromotive force.

[0095] This is the magnetic field generated by ocean currents and the sheer volume of water. Seawater contains approximately 3.5% dissolved salt, and its density is approximately 1035 kg m⁻³. When NaCl salt completely dissolves in seawater, it forms Na⁺ and Cl⁻ ions, which act as charge carriers. Seawater has a certain degree of electrical conductivity, approximately 4.5%. Seawater is magnetized by the Earth's magnetic field. Assuming ocean currents move parallel to the sea surface, the vertical component of the Earth's magnetic field acts on the Lorentz force of ions moving with the current, causing positive and negative ions to separate, forming an electric current. This current generates an induced magnetic field. However, the spatial gradient of the induced magnetic field generated by the ocean current is small, producing only a small-amplitude electromotive force interference in the magnetic fuze's induction coil. Sea winds create waves on the sea surface due to KH instability. The undulating structure of these waves also leads to a magnetic field that varies with time and space. This is a significant part of the interference noise from torpedo magnetic fuzes, especially under adverse sea conditions. High waves and high horizontal speeds result in a large interference electromotive force for the torpedo magnetic fuze.

[0096] This refers to the distribution of the target ship's remanent magnetic field, which is also the main component sensed by the magnetic fuze. When the torpedo enters the near-field region of the target ship, the target ship's remanent magnetic field can be considered to be constant over time. The induced electromotive force of the magnetic fuze's electromagnetic coil is:

[0097]

[0098] This is the main signal of the magnetic fuse; all other signals are interference signals.

[0099] When a torpedo is moving at a high horizontal speed of 45 m / s (162 km / h), relative vibrations will occur between the various components of the torpedo. This causes the distribution of the torpedo's remanent magnetic field to no longer be a constant over time. In addition to the rotation of the pump-jet propeller, there is also vibration between various components. This introduces additional interference.

[0100] When a torpedo moves at high speed, in addition to the vibration between its components, there is also non-stationary motion of the torpedo as a whole. For example, there is rotational vibration around the torpedo's longitudinal axis, that is, the torpedo rotates left and right around the X-axis of its fixed coordinate system O'(X, Y, Z). This causes the normal vector of the electromagnetic induction coil of the magnetic fuze to... It is no longer a constant in the static geographic coordinate system O(x,y,zt).

[0101]

[0102] It is the vibration spectrum of the normal vector of the electromagnetic coil. The left and right vibration of the normal vector introduces a disturbance term into the induced electromotive force.

[0103]

[0104] The vertical component of the Earth's magnetic field is located in mid-to-high latitude regions (25–60°N). o The torpedo's rotation angle is relatively large, approximately 20,000 nT. Although the torpedo's high-speed movement causes a very small lateral rotation angle, assuming it's only 2-5... o However, the vibration frequency is relatively fast, around 100Hz, which causes a large amount of interference signal.

[0105] Similarly, a high-speed torpedo causes it to oscillate up and down around the fixed Y-axis. The oscillation frequency is on the order of 10 Hz, and assuming the oscillation angle is only 2-5 degrees, this is also a noise factor. Although the forward direction of a high-speed torpedo also oscillates, it does not cause a change in the normal vector of the electromagnetic coil. Therefore, the oscillation in the forward direction does not cause signal noise to the horizontal electromagnetic induction coil. The orientation of the electromagnetic coil plane has different effects on the noise of the induced electromotive force. A horizontal orientation of the coil plane is relatively better, resulting in lower noise.

[0106] 2. Dual-coil induced electromotive force differential magnetic fuze

[0107] Magnetic detection of high-speed moving platforms is affected by complex sea conditions and platform vibration, resulting in low signal-to-noise ratio and short detection range. To significantly reduce the noise of torpedo magnetic fuses, such as... Figure 2 As shown, this invention employs a dual-sensor differential mode, meaning two identical electromagnetic induction coils are fixedly mounted on an aluminum alloy plate. Rubber pads are used for vibration damping between the aluminum alloy plate and the torpedo structure. The vibrations generated by the torpedo's high-speed movement do not cause relative vibration of the aluminum alloy plate; instead, the plate vibrates along with the torpedo. Thus, during high-speed torpedo movement, the torpedo's overall oscillation around the X-axis and Y-axis causes the normal vectors of the two electromagnetic induction coils to... The oscillations are in phase and at the same frequency. The resulting induced electromotive force interference signal is completely eliminated after differential processing. The centers of the two identical electromagnetic induction coils are 0.1m apart, and the radius of the coils is generally less than 0.02m. Using this dual-sensor differential mode, the noise of the torpedo magnetic fuze can be significantly reduced. Two coils 10cm apart can sense the gradient difference of the ship's remanent magnetic field at a distance of 12m from the target ship, thus providing a sensing signal for detonating the torpedo.

[0108] The target ship is constructed of steel and possesses both hard remanence and soft remanence in the Earth's magnetic field. The remanent magnetic moment of a 3000t ship is approximately 10⁵ Am², and it generally coincides with the ship's longitudinal direction. The remanent magnetic field gradient is minimum in the vertical longitudinal direction. Two identical electromagnetic coils, 0.1m apart, have a differential induced electromotive force of approximately [value missing].

[0109]

[0110]

[0111] The negative sign of the gradient indicates that the magnetic field is enhanced as the torpedo gets closer to the target ship.

[0112] The remanent magnetic field at a distance of 12m from the target ship (3000t) is approximately:

[0113]

[0114] The gradient difference between the two identical electromagnetic coils is approximately 1446.7 nTm. -1 This is the difference in magnetic field gradient on the plane passing through the magnetic moment vector, which is much greater than the noise of the differential signal. In reality, the remanent magnetic field at a distance of 12 meters from the target ship's center of mass is no longer a dipole magnetic moment magnetic field, but may be a magnetic quadrupole magnetic field. The magnetic field decays with the fifth power of distance, and the magnetic field gradient is even greater. Therefore, estimating the target ship's magnetic field gradient based on the magnetic dipole magnetic field will not lead to a revolutionary result; it simply means that the magnetic field gradient of a magnetic dipole is smaller than that of a magnetic quadrupole.

[0115] 3. Noise attenuation of high-speed torpedo magnetic fuzes

[0116] In magnetic fuses employing quasi-static magnetic field detection, even those employing total magnetic field detection, the noise level is approximately 50 nTHz. -1 / 2 This noise is mainly caused by the induced magnetic field generated by ocean currents and waves. The magnetic fuze using a dual-coil induced electromotive force differential detection has a noise level of 0.5 nTHz. -1 / 2 The noise amplitude was attenuated by a factor of 100, or 20 dB. A magnetic fuze employing a differential induced electromotive force using a dual-coil system has the following signal:

[0117]

[0118] The induced magnetic fields generated by ocean currents and waves have very small amplitude differences over a distance of 0.1m, which are eliminated by the differential electromotive force induced by the dual coils. Therefore, the noise amplitude is also very small, only 0.5 nTHz. -1 / 2 .

[0119] Example 5

[0120] Another application scenario is the interceptor missiles launched by tank active protection systems, in order to... The interceptor missile flies towards the incoming armor-piercing projectile at high speed. When it passes within 3 meters of the projectile, the dual coils induce a differential electromotive force signal. Sensing that the gradient signal of the projectile's near-field residual magnetic field exceeds a certain threshold, the interceptor missile detonates. Through explosive fragments and the shockwave, it destroys the projectile or alters its flight path, providing active protection for our tanks. The interceptor missile's interception area is approximately 28 square meters.

[0121] Armored battlefield environment diagram as follows Figure 4 As shown, Tank C launches an active protection interceptor missile to intercept the attack of an armor-piercing projectile. The elliptical rings represent the magnetic field lines of the residual magnetic field that caused the incoming armor-piercing projectile to destroy the stationary tank.

[0122] 1. Differential signal of induced electromotive force from dual coils on the interceptor missile

[0123] The battlefield environment of armored warfare, such as Figure 4 As shown, in 2000 The ambient geomagnetic field within a 2000m range can be considered uniform and unchanging over time. Besides the strong remanent magnetic fields of friendly tank C and enemy tank A, the interceptor missile encounters remanent magnetic fields in the battlefield environment after launch, including those from the incoming armor-piercing projectile and potentially damaged, stationary tanks. The dual-coil induced electromotive force differential magnetic fuze on the interceptor missile is positioned on the cross-section of the interceptor missile's warhead, such as... Figure 5 As shown, Tank C launches an active protection interceptor missile to intercept the attack of an armor-piercing projectile. The elliptical rings represent the magnetic field lines of the residual magnetic field that caused the incoming armor-piercing projectile to destroy the stationary tank.

[0124] The surface material of the fuze section is made of aluminum alloy, titanium alloy, or non-metallic non-magnetic material to avoid the magnetic shielding effect of ferromagnetic materials. In the coordinate system O(x, y, z) fixed to the interceptor missile, the induced electromotive force difference of the dual coils is divided into:

[0125]

[0126] in, It is the x-component of the relative velocity between the interceptor missile and the remanent magnetic field of the object it encounters. It refers to the normal direction of the double coil, which is important when installing the coil. That is, the normal direction of the coil is perpendicular to the longitudinal axis of the interceptor missile. direction, It is the x-component of the total magnetic field at coil 1. This is the x-component of the total magnetic field at point 2 of the coil. Therefore, the difference in the induced electromotive force between the two coils is:

[0127]

[0128] in It is the vertical component of the total magnetic field at coil 1 in the fixed coordinate system of the interceptor missile. The vertical component of the total magnetic field at coil 2.

[0129] 2. Suppression of interference signals

[0130] In a battlefield environment, the Earth's magnetic field can be considered uniform and unchanging over time. The gradient of the remanent magnetic field in the Earth's crust is extremely small and negligible. The interceptor's own remanent magnetic field does not move relative to the dual coils, therefore it does not generate an induced electromotive force (EMF). Only the residual magnetism of the incoming armor-piercing projectile and the damaged, stationary tank on the battlefield contributes to the differential EMF induced by the dual coils. Because the relative velocity between the incoming armor-piercing projectile and the interceptor is much greater than the relative velocity of the interceptor relative to the stationary tank, the differential EMF signal generated by the incoming armor-piercing projectile is greater than the interference signal from the damaged, stationary tank on the battlefield. This is mainly due to the difference in relative velocity suppressing the interference from the remanent magnetic field of the damaged, stationary tank on the battlefield.

[0131] In this embodiment of the dual-coil induced electromotive force differential magnetic fuze, an original approach is adopted to utilize the staggered arrangement of identical dual coils, using the gradient of the near-field remanent magnetic field of the target as the detection signal of the magnetic fuze. This forms a highly sensitive, low-noise, and fast-response magnetic fuze unit, reducing noise signals by 20dB. It eliminates the need for remanent magnetization compensation on high-speed mounting platforms, significantly reducing the cost of mass production of magnetic fuzes. This invention will provide a highly sensitive, low-noise, fast-response, and low-cost technical approach for magnetic fuzes in Chinese weaponry.

[0132] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A highly sensitive, low-noise, fast-response magnetic fuze for use on high-speed platforms, characterized in that, The magnetic fuze is formed by detecting the residual magnetic field of the target body using a differential method with two coils fixed together; The differential calculation method using a dual-coil fixed connection is as follows: ； in, It is the relative permeability of the coil core; This represents the number of turns of the electromagnetic coil; It is the cross-sectional area of ​​the coil; , which are the normal directions of the cross-sectional areas of the first coil and the second coil, respectively; It is the residual magnetic field of the battlefield environment; The velocity of the target body; Because the two coils are fixedly connected, the coils move synchronously and in phase with the platform's oscillation, and The difference in induced electromotive force is obtained as follows: ； The signal of the novel magnetic fuze is obtained based on the difference in the induced electromotive force.

2. The high-sensitivity, low-noise, fast-response magnetic fuze for high-speed platforms according to claim 1, characterized in that, The dual-coil differential mounting is performed on the high-speed platform in such a way that the two coils are installed parallel to the longitudinal axis of the high-speed platform, with a distance of 0.1m between them.

3. The high-sensitivity, low-noise, fast-response magnetic fuze for high-speed platforms according to claim 2, characterized in that, The induced electromotive force generated by the coils as they move with the platform is obtained by differentially mounting two coils on the high-speed platform: ； wherein, is the normal vector to the electromagnetic induction coil of the magnetic fuze; is the total magnetic field crossing the electromagnetic coil.

4. The high sensitivity low noise fast response magnetic fuze applied to high speed platform according to claim 3, characterized in that, The method for calculating the remanent magnetic field of the target body is as follows: ； wherein is the gradient tensor of the magnetic field.

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