RU1841366C - Method for anti-radar camouflage of a hypersonic body entering the atmosphere - Google Patents

Abstract

FIELD: means of protecting ballistic missile.

SUBSTANCE: invention relates to the field of creating means of protecting ballistic missile warheads and can be used in complexes of means of overcoming missile defense in the atmospheric section of the trajectory to conceal the true value of the aerodynamic drag area of the body, determined by radar methods by the velocity of gas in the wake. The claimed method of anti-radar masking of a hypersonic body entering the atmosphere is based on distortion of measurements of the velocity characteristics of the satellite wake. In the method, the trace regions are shielded from the passage of radio waves by artificially increasing the electron concentration in the trace region to a value exceeding the critical value for the wavelength of the radar observing the body.

EFFECT: technical result is a decrease in the measured value of the aerodynamic drag area of the body.

1 cl, 1 dwg

Description

The proposed invention relates to the field of creating means of protecting the warheads of ballistic missiles and can be used in complexes of means of overcoming missile defense (CSP) in the atmospheric part of the trajectory to hide the true value of the aerodynamic drag area of the body, determined by radar methods from the gas velocity in the wake.

Aerodynamic drag area characterizes the size and shape of the body, and is one of the main parameters used for selecting targets in the atmospheric part of the trajectory. Having determined the ballistic coefficient of the body from the amount of braking and knowing the value , you can estimate the mass of the flying body and classify the observed object.

Parameter Definition produced in a number of ways, usually using the relationship between the value of this parameter and the EPR value of the body or the EPR distribution in time or frequency. In this regard, in the development of CSP devices, devices for distorting the amplitude characteristics of missile warheads (MC) are known and widely used. All these devices usually create an EPR that is larger than the EPR of the head part and provide masking of the amplitude characteristics of the MS.

The development of radar technology has led to the creation of radar stations (radars) with simultaneous resolution of targets in range and speed, which have great capabilities for target selection. In particular, these stations make it possible, in principle, to determine the value body without using the amplitude characteristics of the radio signal scattered by the target.

This method is based on the relationship between the quantity with the gas velocity on the axis of the turbulent wake and in a section separated by a distance from body:

where k is the coefficient.

For determining According to this method, it is sufficient that the reflection from a section of the trace located at a selected distance from the warhead exceeds the noise level. The magnitude of the reflected signal does not matter. In this regard, masking the true value for this type of radar requires the use of new methods.

There is a known method for increasing when blowing substance [I] into the trace. However, its use for warheads turns out to be unprofitable (especially at low altitudes - <40-60 km), since it requires a lot of weight. A more effective method of distorting measurements of the speed characteristics of a body wake is known [2], which can be considered as a prototype of the proposed method.

According to method [2], masking the true value of a quantity body is carried out by creating, next to the natural wake of the warhead, artificial plasma trails that have increased radio-reflective properties than the wake of the warhead. At the same time, the reflective properties of the natural trail behind the warhead are reduced as much as possible by introducing plasma-quenching substances into this trail.

The radar station, observing both natural and artificial wakes at the same time, measures the speed of the artificial wake, for which the value of the equivalent is chosen significantly less than for MS.

In the proposed method, just like the prototype, it is possible to use a source of artificial plasma. However, its purpose and use differ in significant ways.

The main disadvantage of the known methods of protection is that although they make it difficult to determine the size and shape of the body, if there is a priori data or improvements in radars, they do not exclude the possibility of such a determination.

The disadvantages of the method [2] include the need to move the plasma source away from the longitudinal axis of the MS. This requires the use of some kind of brackets (pylons) or other devices that divert the plasma source to the required distance from the MS. To maintain the centering of the head part of such sources there must be several (two or more) with an axisymmetric arrangement. In addition, to extinguish the plasma in the MS’s own trail, it is necessary to use a device for introducing plasma-quenching substances into the trail. All this makes the camouflage device heavier.

The purpose of the present invention is to eliminate these disadvantages of the prototype and reduce weight costs.

The essence of the invention is to increase the electron concentration in the MS trace to a supercritical value over a sufficiently extended area. The value of the critical electron concentration is calculated using the formula

Where - radar wavelength, measured in cm.

This achieves shielding of the internal areas of the trace from the penetration of radio waves into them. The above formula (I) to determine the value valid only for the axis of the turbulent wake. At the boundary of the wake, the gas flow velocity turns out to be significantly lower. When shielding the inside of the track, the radar will measure lower velocities than on the axis, which will lead to a decrease in the detected value bodies.

The length of the section of the created supercritical wake (a wake filled with plasma with an electron concentration above the critical one) is determined by the speed resolution of the radar. It is advisable to choose the length of the supercritical section of the wake equal to the distance at which the gas velocity on the wake axis drops to the value of one or two velocity resolving elements. Length regulation is achieved by changing the number of electrons introduced into the trace, that is, the productivity of the source.

To illustrate the quantitative side of the proposed invention, a figure taken from [3] is provided.

The figure shows the dependence of the decrease in the measured relative value on the degree of filling of the wake cross section with supercritical plasma.

,

Where

)

- measured value by radar ;

- actual value bodies;

- electron concentration on the trace axis;

- the value of the critical electron concentration.

At ≤0 the trace is completely subcritical, with =I - completely supercritical. As can be seen from the figure, filling the cross section of the trace with supercritical plasma reduces the measurable value by an order of magnitude or more bodies.

The implementation of the proposed method depends on the conditions of use of the ballistic body and the radar parameters. As is known, the missile defense system uses centimeter range radars, for which the critical electron concentration is 10 ¹¹ - 10 ¹² I/cm ³ . The creation of extended traces with an electron concentration exceeding this value is possible by using sources of artificial plasma formed during the combustion of solid fuel compositions containing alkali metals (for example, cesium). Such sources are used for plasma decoys in the atmospheric part of the trajectory and, as flight tests have shown, create trails up to several kilometers long.

According to the proposed method, the plasma source, unlike the prototype, is located in the central part of the bottom of the MS and is turned on at an altitude of about 70 km, where the formation of a turbulent wake is possible.

Using the proposed method for masking the value body compared to the known ones has the following advantages:

The main advantage of the proposed method is that when it is used, the area of the wake, the gas velocity in which characterizes the size and shape of the body, is shielded from the passage of radio waves, and this completely eliminates the possibility of measuring the gas velocity in the wake (and the resistance area of the body) by radar methods.

In addition, the device that implements this method is simplified, since instead of several sources for plasma injection and plasma-quenching liquid injection equipment, only one plasma source is used, and the placement of the device on the MS is simplified.

Claims (1)

A method of anti-radar camouflage of a hypersonic body entering the atmosphere, based on distortion of measurements of the speed characteristics of the wake, characterized in that, in order to reduce the measured value of the body's aerodynamic drag area, the wake areas are screened from the passage of radio waves by artificially increasing the electron concentration in the wake area to a value exceeding the critical wavelength of the radar observing the body.

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