Electromagnetic pulse(EMP) -- damaging factor nuclear weapons, as well as any other EMR sources(for example lightning, special electromagnetic weapons, short circuit in high power electrical equipment, or a nearby supernova explosion, etc.). Lethal effect electromagnetic pulse (EMP) is caused by the occurrence of induced voltages and currents in various conductors. The effect of EMR manifests itself primarily in relation to electrical and radio-electronic equipment. The most vulnerable are communication, signaling and control lines. In this case, insulation breakdown, damage to transformers, damage to semiconductor devices, etc. can occur. A high-altitude explosion can create interference in these lines over very large areas.

The nature of the electromagnetic pulse

A nuclear explosion produces huge amount ionized particles, strong currents and an electromagnetic field called electromagnetic pulse (EMP). It has no effect on humans (at least within the limits of what has been studied), but it damages electronic equipment. The large amount of ions left behind from the explosion interferes with shortwave communications and radar operation. The height of the explosion has a very significant influence on the formation of EMR. EMP is strong in explosions at altitudes below 4 km, and is especially strong at altitudes above 30 km, but is less significant for the range of 4-30 km. This is due to the fact that EMR is formed when gamma rays are asymmetrically absorbed in the atmosphere. And at medium altitudes, just such absorption occurs symmetrically and evenly, without causing large fluctuations in the distribution of ions. The origin of EMP begins with an extremely short but powerful emission of gamma rays from the reaction zone. Over the course of ~10 nanoseconds, 0.3% of the explosion energy is released in the form of gamma rays. A gamma quantum, colliding with an atom of any gas in the air, knocks out an electron from it, ionizing the atom. In turn, this electron itself is capable of knocking out its fellow from another atom. A cascade reaction occurs, accompanied by the formation of up to 30,000 electrons for each gamma ray. At low altitudes, gamma rays emitted towards the ground are absorbed by it without producing large quantity ions. Free electrons, being much lighter and more agile than atoms, quickly leave the region in which they originated. A very strong electromagnetic field is generated. This creates a very strong horizontal current, a spark that gives birth to a broadband electromagnetic radiation. At the same time, on the ground, under the explosion site, electrons are collected, “interested” in the accumulation of positively charged ions directly around the epicenter. Therefore, a strong field is also created along the Earth.

And although a very small part of the energy is emitted in the form of EMR - 1/3x10-10, this happens in a very short period of time. So the power it develops is enormous: 100,000 MW. On high altitudes ionization occurs below dense layers atmosphere. At cosmic altitudes (500 km), the region of such ionization reaches 2500 km. Its maximum thickness is up to 80 km. The Earth's magnetic field twists the trajectories of electrons into a spiral, forming a powerful electromagnetic pulse for several microseconds. Within a few minutes, a strong electrostatic field (20-50 kV/m) arises between the Earth’s surface and the ionized layer, until most electrons will not be absorbed due to recombination processes. Although the peak field strength during a high-altitude explosion is only 1-10% of the ground level, the formation of an EMP takes 100,000 more energy - 1/3x10-5 of the total released, the strength remains approximately constant under the entire ionized region.

Impact of EMR on equipment. The ultra-strong electromagnetic field induces high voltage in all conductors. Power lines will actually be giant antennas; the voltage induced in them will cause insulation breakdown and failure transformer substations. The majority of specially not protected semiconductor devices will fail. In this regard, microcircuits will give a big head start to the good old lamp technology, which does not care about either strong radiation or strong electric fields.

Introduction.

In order to understand the complexity of the problems of the EMP threat and measures to protect against it, it is necessary to briefly consider the history of the study of this physical phenomenon And current state knowledge in this area.

The fact that a nuclear explosion would necessarily be accompanied by electromagnetic radiation was clear to theoretical physicists even before the first test nuclear device in 1945. During the nuclear explosions in the atmosphere and outer space the presence of EMR was recorded experimentally.

However, the quantitative characteristics of the pulse were measured insufficiently, firstly, because there was no control and measuring equipment capable of recording extremely powerful electromagnetic radiation, which exists extremely short time(millionths of a second), secondly, because in those years in electronic equipment only electric vacuum devices were used, which were little susceptible to the effects of EMR, which reduced interest in its study. The creation of semiconductor devices, and then integrated circuits, especially digital devices based on them, and the widespread introduction of means into electronic military equipment forced military specialists to assess the threat of EMP differently.

Description of EMR physics.

The mechanism for generating EMR is as follows. During a nuclear explosion, gamma and x-ray radiation and a neutron flux is formed. Gamma radiation, interacting with molecules of atmospheric gases, knocks out so-called Compton electrons from them. If the explosion is carried out at an altitude of 20-40 km, then these electrons are captured by the Earth’s magnetic field and, rotating relative to power lines This field creates currents that generate EMR. In this case, the EMR field is coherently summed towards earth's surface, i.e. The Earth's magnetic field plays a role similar to a phased array antenna. As a result of this, the field strength sharply increases, and consequently the amplitude of the EMR in the areas south and north of the epicenter of the explosion. Duration this process from the moment of explosion from 1 - 3 to 100 ns.

At the next stage, lasting approximately from 1 μs to 1 s, EMR is created by Compton electrons knocked out of molecules by repeatedly reflected gamma radiation and due to the inelastic collision of these electrons with the flow of neutrons emitted during the explosion. In this case, the EMR intensity turns out to be approximately three orders of magnitude lower than at the first stage.

At the final stage, which takes a period of time after the explosion from 1 s to several minutes, the EMR is generated by the magnetohydrodynamic effect generated by disturbances magnetic field Earth is conductive fireball explosion. The intensity of EMR at this stage is very low and amounts to several tens of volts per kilometer.

The greatest danger to radio-electronic equipment is the first stage of EMR generation, at which, in accordance with the law, electromagnetic induction Due to the extremely rapid increase in the pulse amplitude (the maximum is reached 3 - 5 ns after the explosion), the induced voltage can reach tens of kilovolts per meter at the level of the earth's surface, gradually decreasing with distance from the epicenter of the explosion. In addition to temporary disruption of the functioning (functional suppression) of electronic devices, which allows for subsequent restoration of their functionality, EMP weapons can cause physical destruction (functional damage) of semiconductor elements of electronic devices, including those in the off state.

It should also be noted the possibility of damaging effects powerful radiation EMP weapons for electrical and electrical energy systems weapons and military equipment(VVT), electronic engine ignition systems internal combustion(Fig. 1). Currents excited by the electromagnetic field in the circuits of electric or radio fuses installed on ammunition can reach levels sufficient to trigger them. Streams high energy capable of initiating the detonation of explosives (HE) warheads of missiles, bombs and artillery shells, as well as non-contact detonation of mines within a radius of 50–60 m from the point of detonation of EMP ammunition of medium calibers (100–120 mm).

Fig. 1. Forced stopping of a car with electronic system ignition

With regard to the damaging effect of EMP weapons on personnel, as a rule, we're talking about about the effects of temporary disruption of adequate sensorimotority of a person, the occurrence of erroneous actions in his behavior and even loss of ability to work. It is important that the negative manifestations of the effects of powerful ultrashort microwave pulses are not necessarily associated with thermal destruction of living cells of biological objects. The damaging factor is often the high intensity of the electric field induced on cell membranes, comparable to the natural quasi-static intensity of the own electric field of intracellular charges. Experiments on animals have established that even at a density of pulse-modulated microwave irradiation on the surface of biological tissues of 1.5 mW/cm2 it has place reliable change electrical potentials brain Activity nerve cells changes under the influence of a single microwave pulse lasting from 0.1 to 100 ms, if the energy density in it reaches 100 mJ/cm2. Consequences similar influence on humans have not yet been studied much, but it is known that irradiation with microwave pulses sometimes gives rise to sound hallucinations, and with increased power, even loss of consciousness is possible.

The amplitude of the voltage induced by EMR in conductors is proportional to the length of the conductor located in its field and depends on its orientation relative to the electric field strength vector.

Thus, the EMR field strength in high-voltage power lines can reach 50 kV/m, which will lead to the appearance of currents of up to 12 thousand amperes in them.

EMPs are also generated during other types of nuclear explosions - air and ground. It has been theoretically established that in these cases its intensity depends on the degree of asymmetry of the spatial parameters of the explosion. Therefore, an air explosion is the least effective from the point of view of generating EMP. The EMR of a ground explosion will have a high intensity, but it quickly decreases as it moves away from the epicenter.

Since the collection of experimental data during underground exploration nuclear tests is technically very complex and expensive, then the solution to the data set is achieved by methods and means of physical modeling.

Sources of EMP (non-lethal weapons). EMP weapons can be created both in the form of stationary and mobile electronic directed radiation complexes, and in the form of electromagnetic ammunition (EMM), delivered to the target using artillery shells, mines, guided missiles (Fig. 2), aerial bombs, etc.

A stationary generator allows you to reproduce EMR with horizontal polarization of the electric field. It includes a high voltage generator electrical impulses(4 MV), a symmetrical dipole radiating antenna on two masts and an open concrete test area. The installation ensures the formation above the test site (at heights of 3 and 10 m) of EMR with field strengths equal to 35 and 50 kV/m, respectively.

Mobile (Transportable) HPDII generator is designed to simulate horizontally polarized EMR. It includes a high-voltage pulse generator and a symmetrical dipole antenna mounted on a trailer platform, as well as data acquisition and processing equipment located in a separate van.

EMB is based on methods of converting the chemical energy of explosion, combustion and electrical energy DC into energy electromagnetic field high power. The solution to the problem of creating EMP ammunition is associated, first of all, with the presence of compact radiation sources that could be located in the warhead compartments of guided missiles, as well as in artillery shells.

The most compact energy sources for EMB today are considered to be spiral explosive magnetic generators (EMG), or generators with explosive compression of the magnetic field, having best performance specific gravity energy by mass (100 kJ/kg) and volume (10 kJ/cm3), as well as explosive magnetodynamic generators (EMDG). In VMG using explosive explosion energy is converted

into magnetic field energy with an efficiency of up to 10%, and with an optimal choice of VMG parameters – even up to 20%. This type of device is capable of generating pulses with an energy of tens of megajoules and a duration of up to 100 μs. Peak radiation power can reach 10 TW. EMGs can be used autonomously or as one of the cascades for pumping microwave generators. The limited spectral band of EMG radiation (up to several megahertz) makes their influence on the RES rather selective.

Fig.2. Design (a) and principle (b) combat use typical EMB.

As a result, the problem arises of creating compact antenna systems that are consistent with the parameters of the generated EMR. In VMDG, explosives or rocket fuel are used to generate a plasma flow, the rapid movement of which in a magnetic field leads to the generation of super-powerful currents with accompanying electromagnetic radiation.

The main advantage of the VMDG is its reusability, since cartridges with explosives or rocket fuel can be placed in the generator many times. However, its specific weight and size characteristics are 50 times lower than those of the VMG, and in addition, the VMG technology has not yet been sufficiently developed to rely on these energy sources in the near future.

During a nuclear explosion, strong electromagnetic radiation is generated in a wide range of waves with a maximum density in the region of 15-30 kHz.

Due to the short duration of action - tens of microseconds - this radiation is called an electromagnetic pulse (EMP).

The cause of EMR is an asymmetric electromagnetic field resulting from the interaction of gamma quanta with the environment.

The main parameters of EMR, as a damaging factor, are the strength of the electric and magnetic fields. During air and ground explosions, the dense atmosphere limits the area of ​​propagation of gamma rays, and the dimensions of the EMR source approximately coincide with the area of ​​action of penetrating radiation. In space, EMR can acquire the quality of one of the main damaging factors.

EMR does not have a direct effect on humans.

The effect of EMR manifests itself primarily on bodies that conduct electric current: overhead and underground communication and power lines, alarm and control systems, metal supports, pipelines, etc. At the moment of explosion, a current pulse appears in them and a high electrical potential is induced relative to the ground.

As a result, breakdown of cable insulation, damage to input devices of radio and electrical equipment, burnout of arresters and fuse-links, damage to transformers, and failure of semiconductor devices may occur.

Strong electromagnetic fields can damage equipment at control points and communication centers and create a danger of injury to operating personnel.

Protection against EMI is achieved by shielding individual units and components of radio and electrical equipment.

Chemical weapons.

Chemical weapons are toxic substances and means of their use. Applications include aerial bombs, cassettes, missile warheads, artillery shells, chemical mines, aircraft jet devices, aerosol generators, etc.

The basis of chemical weapons are toxic substances (CAS) chemical compounds, affecting people and animals, contaminating the air, terrain, water bodies, food and various items on the ground. Some chemical agents are designed to damage plants.

In chemical munitions and devices, agents are in liquid or solid state. At the time of use chemical weapons Agents transform into a combat state - vapor, aerosol or drops and affect people through the respiratory system or, if they come into contact with the human body, through the skin.

A characteristic of air contamination by vapors and fine aerosols is the concentration C = m/v, g/m3 - the amount “m” of OM per unit volume “v” of contaminated air.

A quantitative characteristic of the degree of contamination of various surfaces is the density of infection: d=m/s, g/m2 - i.e. the amount “m” of OM located per unit area “s” of the contaminated surface.

OM is classified according to physiological effects per person, tactical purpose, speed of onset and duration of the damaging effect, toxicological properties, etc.

According to their physiological effects on the human body, chemical agents are divided into the following groups:

1) Nerve agents - sarin, soman, Vx (VI-ix). They cause nervous system dysfunction, muscle cramps, paralysis and death.

2) Agent of blister action - mustard gas. Affects the skin, eyes, respiratory and digestive organs if ingested.

3) Generally toxic agents - hydrocyanic acid and cyanogen chloride. In case of poisoning, severe shortness of breath, a feeling of fear, convulsions, and paralysis appear.

4) Asphyxiating agent - phosgene. It affects the lungs, causing swelling and suffocation.

5) OM of psycho-chemical action - BZ (Bizet). Affects through the respiratory system. Impairs coordination of movements, causes hallucinations and mental disorders.

6) irritant agents - chloroacetophenone, adamsite, CS (Ci-S) and CR (Ci-Er). These chemical agents cause irritation to the respiratory and visual organs.

Nerve agents, blister agents, generally poisonous and asphyxiating agents are lethal agents. Agents of psycho-chemical and irritating action - temporarily incapacitate people.

Based on the speed of onset of the damaging effect, a distinction is made between fast-acting agents (sarin, soman, hydrocyanic acid, CS, SR) and slow-acting agents (V-X, mustard gas, phosgene, Bi-zet).

According to duration, OBs are divided into persistent and unstable. Persistent ones retain their damaging effect for several hours or days. Unstable - several tens of minutes.

Toxodose is the amount of agent required to obtain a certain effect of damage: T=c*t (g*min)/m3, where: c is the concentration of agent in the air, g/m3; t is the time a person spends in contaminated air, min.

When using chemical munitions, a primary cloud of chemical agents is formed. Under the influence of moving air masses, the OM spreads in a certain space, forming a zone of chemical contamination.

Zone of chemical contamination refers to the area that was directly exposed to chemical weapons, and the territory over which a cloud contaminated with chemical agents with damaging concentrations has spread.

Foci of chemical damage may occur in the zone of chemical contamination.

Site of chemical damage- this is the territory within which, as a result of the influence of chemical weapons, occurred mass casualties people, farm animals and plants.

Protection against toxic substances is achieved by using individual respiratory and skin protective equipment, as well as collective means.

Special groups of chemical weapons include binary chemical munitions, which are two containers with different gases - not poisonous in their pure form, but when they are displaced during an explosion, a toxic mixture is obtained.

Electromagnetic pulse

Shock wave

Shock wave (SW)- an area of ​​sharply compressed air, spreading in all directions from the center of the explosion at supersonic speed.

Hot vapors and gases, trying to expand, produce a sharp blow to the surrounding layers of air, compress them to high pressures and densities and heat them to high temperature(several tens of thousands of degrees). This layer of compressed air represents a shock wave. The front boundary of the compressed air layer is usually called the shock wave front. The shock front is followed by a region of rarefaction, where the pressure is below atmospheric. Near the center of the explosion, the speed of propagation of shock waves is several times higher than the speed of sound. As the distance from the explosion increases, the speed of wave propagation quickly decreases. On long distances its speed approaches the speed of sound in air.

The shock wave of medium-power ammunition travels: the first kilometer in 1.4 s; the second - in 4 s; fifth - in 12 s.

The damaging effect of hydrocarbons on people, equipment, buildings and structures is characterized by: velocity pressure; excess pressure in the front of the shock wave movement and the time of its impact on the object (compression phase).

The impact of hydrocarbons on people should be direct and indirect. With direct impact, the cause of injury is an instantaneous increase in air pressure, which is perceived as a sharp blow, leading to fractures, damage internal organs, rupture of blood vessels. With indirect exposure, people are affected by flying debris from buildings and structures, stones, trees, broken glass and other objects. Indirect impact reaches 80% of all lesions.

With an excess pressure of 20-40 kPa (0.2-0.4 kgf/cm2), unprotected people can suffer minor injuries (minor bruises and contusions). Exposure to hydrocarbons with excess pressure of 40-60 kPa leads to moderate damage: loss of consciousness, damage to the hearing organs, severe dislocations of the limbs, damage to internal organs. Extremely severe lesions, often with fatal, are observed at excess pressure above 100 kPa.

Degree of damage shock wave various objects depends on the power and type of explosion, mechanical strength (stability of the object), as well as on the distance at which the explosion occurred, the terrain and the position of objects on the ground.

To protect against the effects of hydrocarbons, the following should be used: trenches, cracks and trenches, reducing this effect by 1.5-2 times; dugouts - 2-3 times; shelters - 3-5 times; basements of houses (buildings); terrain (forest, ravines, hollows, etc.).

Electromagnetic pulse (EMP) is a set of electric and magnetic fields resulting from the ionization of atoms of the medium under the influence of gamma radiation. Its duration of action is several milliseconds.

The main parameters of EMR are those induced in wires and cable lines currents and voltages that can lead to damage and failure of electronic equipment, and sometimes to damage to people working with the equipment.

In ground and air explosions, the damaging effect of the electromagnetic pulse is observed at a distance of several kilometers from the center nuclear explosion.

The most effective protection against electromagnetic pulses is shielding of power supply and control lines, as well as radio and electrical equipment.

The situation that arises when nuclear weapons are used in areas of destruction.

Hearth nuclear destruction- this is the territory within which, as a result of the use of nuclear weapons, there were mass casualties and deaths of people, farm animals and plants, destruction and damage to buildings and structures, utility, energy and technological networks and lines, transport communications and other objects.

Electromagnetic pulse - concept and types. Classification and features of the category "Electromagnetic impulse" 2017, 2018.

The damaging effect of an electromagnetic pulse (EMP) is caused by the occurrence of induced voltages and currents in various conductors. The effect of EMR manifests itself primarily in relation to electrical and radio-electronic equipment. The most vulnerable are communication, signaling and control lines. In this case, insulation breakdown, damage to transformers, damage to semiconductor devices, etc. may occur.

HISTORY OF THE ISSUE AND THE CURRENT STATE OF KNOWLEDGE IN THE FIELD OF EMP

In order to understand the complexity of the problems of the EMP threat and measures to protect against it, it is necessary to briefly consider the history of the study of this physical phenomenon and the current state of knowledge in this area.

The fact that a nuclear explosion would necessarily be accompanied by electromagnetic radiation was clear to theoretical physicists even before the first test of a nuclear device in 1945. During nuclear explosions in the atmosphere and outer space carried out in the late 50s - early 60s, the presence of EMR was recorded experimentally. However, the quantitative characteristics of the pulse were measured insufficiently, firstly, because there was no control and measuring equipment capable of recording extremely powerful electromagnetic radiation, existing for an extremely short time (millionths of a second), secondly, because in those years in radio-electronic equipment only electro-vacuum devices were used, which were little susceptible to the effects of EMR, which reduced interest in its study.

The creation of semiconductor devices, and then integrated circuits, especially digital devices based on them, and the widespread introduction of means into electronic military equipment forced military specialists to assess the threat of EMP differently. Since 1970, issues of protecting weapons and military equipment from EMP began to be considered by the Ministry of Defense as having the highest priority.

The mechanism for generating EMR is as follows. During a nuclear explosion, gamma and X-ray radiation are generated and a flux of neutrons is formed. Gamma radiation, interacting with molecules of atmospheric gases, knocks out so-called Compton electrons from them. If the explosion is carried out at an altitude of 20-40 km, then these electrons are captured by the Earth's magnetic field and, rotating relative to the lines of force of this field, create currents that generate EMR. In this case, the EMR field is coherently summed towards the earth’s surface, i.e. The Earth's magnetic field plays a role similar to a phased array antenna. As a result of this, the field strength and, consequently, the amplitude of the EMR sharply increases in the areas south and north of the explosion epicenter. The duration of this process from the moment of explosion is from 1 - 3 to 100 ns.

At the next stage, lasting approximately from 1 μs to 1 s, EMR is created by Compton electrons knocked out of molecules by repeatedly reflected gamma radiation and due to the inelastic collision of these electrons with the flow of neutrons emitted during the explosion.

In this case, the EMR intensity turns out to be approximately three orders of magnitude lower than at the first stage.

At the final stage, which takes a period of time after the explosion from 1 s to several minutes, EMR is generated by the magnetohydrodynamic effect generated by disturbances of the Earth's magnetic field by the conductive fireball of the explosion. The intensity of EMR at this stage is very low and amounts to several tens of volts per kilometer.

The greatest danger for radio-electronic equipment is the first stage of EMR generation, at which, in accordance with the law of electromagnetic induction, due to the extremely rapid increase in the pulse amplitude (the maximum is reached 3 - 5 ns after the explosion), the induced voltage can reach tens of kilovolts per meter at the level of the earth's surface , gradually decreasing as it moves away from the epicenter of the explosion.

The amplitude of the voltage induced by EMR in conductors is proportional to the length of the conductor located in its field and depends on its orientation relative to the electric field strength vector. Thus, the EMR field strength in high-voltage power lines can reach 50 kV/m, which will lead to the appearance of currents of up to 12 thousand amperes in them.

EMPs are also generated during other types of nuclear explosions - air and ground. It has been theoretically established that in these cases its intensity depends on the degree of asymmetry of the spatial parameters of the explosion. Therefore, an air explosion is the least effective from the point of view of generating EMP. The EMR of a ground explosion will have a high intensity, but it quickly decreases as it moves away from the epicenter.

Since low-current circuits and electronic devices operate normally at voltages of several volts and currents up to several tens of milliamperes, then for them absolutely reliable protection EMI is required to ensure a reduction in the magnitude of currents and voltages in cables by up to six orders of magnitude.

POSSIBLE WAYS TO SOLUTION THE PROBLEM OF EMP PROTECTION

The ideal protection against EMR would be to completely cover the room in which the radio-electronic equipment is located with a metal screen. At the same time, it is clear that it is practically impossible to provide such protection in some cases, because For equipment to operate, it is often necessary to provide electrical communication with external devices. Therefore, less reliable means of protection are used, such as conductive mesh or film coverings for windows, honeycomb metal structures for air intakes and ventilation openings, and contact spring gaskets placed around the perimeter of doors and hatches.

More complex technical problem protection against the penetration of EMR into equipment through various cable entries is considered. A radical solution to this problem could be a transition from electrical networks connection to fiber-optic fibers practically not affected by EMR. However, replacing semiconductor devices in the entire range of functions they perform with electro-optical devices is possible only in the distant future. Therefore, at present, filters, including fiber filters, as well as spark gaps, metal oxide varistors and high-speed Zener diodes, are most widely used as means of protecting cable entries.

All these means have both advantages and disadvantages. Thus, capacitive-inductive filters are quite effective for protection against low-intensity EMI, and fiber filters protect in a relatively narrow range above high frequencies.Spark gaps have significant inertia and are mainly suitable for protection against overloads arising under the influence of voltages and currents induced in the aircraft skin, equipment casing and cable sheath.

Metal oxide varistors are semiconductor devices that sharply increase their conductivity at high voltage. However, when using these devices as means of protection against EMI, one should take into account their insufficient performance and deterioration of characteristics under repeated exposure to loads. These disadvantages are absent in high-speed Zener diodes, the action of which is based on a sharp avalanche-like change in resistance from relatively high value almost to zero when the voltage applied to them exceeds a certain threshold value. In addition, unlike varistors, the characteristics of Zener diodes do not deteriorate after repeated exposure to high voltages and mode switching.

The most rational approach to designing means of protection against EMI of cable glands is to create such connectors, the design of which includes special measures to ensure the formation of filter elements and the installation of built-in Zener diodes. Similar solution helps to obtain very small values ​​of capacitance and inductance, which is necessary to provide protection against pulses that have a short duration and, therefore, a powerful high-frequency component. The use of connectors of this design will solve the problem of limiting the weight and size characteristics of the protection device.

Faraday cage- a device for shielding equipment from external electromagnetic fields. Usually it is a grounded cage made of highly conductive material.

The principle of operation of a Faraday cage is very simple - when a closed electrically conductive shell enters an electric field free electrons the shells begin to move under the influence of this field. As a result opposite sides cells acquire charges, the field of which compensates for the external field.

A Faraday cage only protects against electric fields. The static magnetic field will penetrate inside. A changing electric field creates a changing magnetic field, which in turn creates a changing electric field. Therefore, if a changing electric field is blocked using a Faraday cage, then a changing magnetic field will not be generated either.

However, in the high-frequency region, the action of such a screen is based on reflection electromagnetic waves from the surface of the screen and the attenuation of high-frequency energy in its thickness due to heat losses due to eddy currents.

The ability of a Faraday cage to shield electromagnetic radiation is determined by:
the thickness of the material from which it is made;
depth of surface effect;
the ratio of the size of the openings in it to the wavelength of external radiation.
To shield a cable, it is necessary to create a Faraday cage with a highly conductive surface along the entire length of the shielded conductors. In order for a Faraday cage to work effectively, the size of the grid cell must be significantly smaller than the wavelength of the radiation from which protection is required. The operating principle of the device is based on the redistribution of electrons in a conductor under the influence of an electromagnetic field.