GENERAL PROVISIONS FOR PRESERVING THE SURVIVABILITY AND PROTECTION OF RADIOELECTRONIC EQUIPMENT FROM THE EFFECTS OF ELECTROMAGNETIC WEAPONS AND ELECTRONIC TERRORISM.

GENERAL PROVISIONS FOR PRESERVING THE SURVIVABILITY AND ENSURING THE PROTECTION OF RADIOELECTRONIC EQUIPMENT FROM THE EFFECTS OF ELECTROMAGNETIC WEAPONS AND ELECTRONIC TERRORISM..

GENERAL PROVISIONS FOR PRESERVING THE SURVIVABILITY AND PROTECTION OF RADIOELECTRONIC EQUIPMENT FROM THE EFFECTS OF ELECTROMAGNETIC WEAPONS AND ELECTRONIC TERRORISM

All modern power engineering facilities, communications facilities, transport control systems and life support facilities contain radio-electronic equipment (REF), therefore, the urgent problem is the task of ensuring the reliability and resistance of REF to external influencing factors. This work does not address the issues of protection against software corruption and information “viruses” in REF – known manifestations of criminal activity, the fight against which is currently organized and carried out by government services. The problems of electronic terrorism associated with the impact of high-intensity electromagnetic pulses (EMP) on REF are considered.

Sources of EMI are numerous electromagnetic factors of natural and artificial origin: lightning and static electricity (SE) discharges, radiation from radar and radio transmitting equipment (RLS and RPS), short circuits in power equipment, in power transmission lines, etc., resistance to the effects of which is provided for in the design process of modern RPE and is monitored on special stands simulating electromagnetic factors (EF).

Successes in the creation of effective energy sources and the development of new methods for generating powerful EMPs with a high rate of increase and long duration have led to the creation in the United States and Russia of new electromagnetic weapons (EMW), which are intended primarily to disable RES by affecting vulnerable parts of RES with EMPs and microwave EMPs. It is reported [1, 2] that EMPs may be adopted for service in this decade. The availability of EMPs or their components on the arms market will lead to the criminal use of these means in the process of competitive “showdowns”, terrorist and vandalistic acts by certain groups of people.

Specialists involved in assessing the resistance of RES to the impact of electromagnetic factors, electromagnetic compatibility can always find a “weak link” in the equipment complex and select the appropriate technical means of electromagnetic radiation (EMR), damaging RES in a non-contact way — remotely. Such EMR generators can be made in the form of portable, mobile, flying and shooting devices.

An EMR radiation generator contains a power source, a modulator and a field-forming device — an antenna. Familiar household appliances can be parts of such generators and used for electromagnetic “household” terrorism [3].

EMI and microwave EMI radiation can affect both individual devices of the radio electronic system and strategic area facilities, electric power facilities.

The cost of manufacturing such generators, intended for various applications, can be in the range from 5 to 50 thousand US dollars. The costs of eliminating the consequences of the impact of EMI on the radio electronic system are 5-10 times higher due to the search, detection, repair and additional control of the radio electronic system, if these impacts did not cause an explosion, fire with associated human casualties.

The costs of carrying out work related to ensuring the resistance of RES to the effects of EMI, at the early stages of design make up no more than 2% of the development cost, and the cost of a protected RES increases by no more than 3 — 5%. However, the costs increase by more than an order of magnitude if measures to protect RES from the effects of EMI are carried out at the later stages of design.

According to experimental data, the ratio of the cost of replacing a damaged “weak link” in a RES, for example, an electronic product (EP) during incoming inspection, after mounting on a printed circuit board under production conditions and during RES operation is 2:5:50. Even a single exposure of the EP terminals to a voltage exceeding the “permissible value of static potential” (according to the technical conditions for EP from 2 to 600 V) causes degradation of the EP parameters (increase in reverse current, change in input characteristics, etc.), which leads to a decrease in the threshold of resistance to the effects of subsequent interference pulses, a decrease in resistance to the effects of climatic, mechanical and radiation factors, a significant decrease in the residual life of the EP (up to 102 — 103 hours).

The impact of electromagnetic weapons causes voltage pulses from 100 to 10,000 V in the circuits of the electronic equipment and on the terminals of the electronic equipment. Mass sparking of cable sheaths to the equipment body and the ground, breakdowns in the mounting blocks, connectors and air gaps up to 50 mm in size between the components of the electronic equipment structure are observed. In this case, the energy of spark breakdowns is from 0.1 to 100 mJ. This energy is sufficient to cause failures of electronic equipment in the electronic equipment, short circuits in power supply circuits, fires and explosions of flammable substances, since the energy of initiation of an explosion of many dust-gas-air mixtures is in the range from 20 to 1 mJ, paint and varnish and gasoline vapors from 1 to 0.01 mJ, damage to semiconductor structures — from 1 to 0.001 mJ.

The damaging effect of EMP is achieved by the action of an electromagnetic field (EMF) on the RES, which has a high rate of increase of the magnetic and electric components of the EMP, creating high values ​​of the spatial distribution of the field potential gradient in the surrounding airspace and in the ground, a long pulse duration and repetition frequency. The main criterion for the resistance of the RES complex to the effects of EMP is such an intensity of the electromagnetic radiation field, when the interference intensity in the circuits of vulnerable elements reaches an acceptable level. An additional criterion may be the field intensity, when the beginning of spark breakdowns in the outer covers of the equipment is registered.

The damaging properties of EMF are increased by 2-4 times due to non-optimal design of RES, which have external electromagnetic shields with sharp angles, protruding parts and local inhomogeneities, irrational layout of external cables, internal circuits, grounding and protection systems. The shape of the external electromagnetic shield is of great importance for the resistance of RES. For example, when EMF impacts electromagnetic shields made in the form of a sphere and a parallelepiped of the same volume, the beginning of sparking on the surface of the latter occurs at an EMF intensity 3 times less than when EMF impacts a sphere.

The main methods of designing ground-based technical equipment resistant to compromise conditions of exposure to EMI, lightning discharges and static electricity are given in OST 107.420082.031-97. The structural diagram of ensuring electromagnetic safety (EMS) is shown in Fig. 1 [3].

Fig. 1. Ensuring EMS
EMC – electromagnetic compatibility
EF – electromagnetic factor

Rational indirect methods of testing a complex of RES for resistance to the effects of EMI (and lightning discharges) by passing a current through the outer covers of the RES, equivalent to external field effects of EMI, and calculated and experimental estimates of the resistance of fragments of the RES, are given in OST 107.20.57.002-88. These indirect methods of operational testing of RES have been developed in accordance with the materials of seven author's certificates. The effectiveness of indirect methods has been confirmed by the results of testing many samples of technical equipment. The cost of testing RES and their components by indirect methods is at least 10 times lower than the cost of testing RES by field methods given in individual current GOSTs [4].

The indicator of the resistance of the RES to the effects of EF is the maximum EF level at which the criterion of the resistance of the RES to the effects of EF is still met. The criteria of the resistance of the RES in a de-energized state to the effects of EMI are the absence of irreversible failures and unacceptable changes in the parameters of the RES established in the regulatory documentation (RD) or technical conditions (TC) for them. The criterion of the resistance of the electronic equipment in this case is the non-exceedance of the interference voltage in the vulnerable circuits connected to the terminals of the electronic equipment, the permissible Uо additional, established in the RD (TC) for the electronic equipment according to the parameter «resistance to static electricity».

The criterion for the resistance of energized electronic equipment to the effects of electromagnetic radiation is the absence of irreversible and reversible failures (malfunctions) at the time of or after exposure to electromagnetic radiation. The criterion for resistance to reversible failures is non-exceedance of the interference voltage in vulnerable circuits connected to the terminals of electronic equipment, permissible Uт доп, established in the ND (TU) for electronic equipment by the parameter “pulse interference immunity”.

Research has shown that for digital circuits of electronic equipment to which power source voltages are applied, the amplitude of the switching voltage of the circuit at which a failure occurs is Uтдоп ~ 0.01 Uо доп with the same pulse duration. Accordingly, the ratio of the threshold values ​​for the energy of the interference pulse is 103 – 104 times. There is information on the creation of electronic equipment with a switching energy of 10-14 J.

An analysis of information sources since the 1960s devoted to the issues of the immunity of electronic equipment to the effects of pulsed interference shows that for typical products used in digital circuits, the amplitude of the permissible interference pulse voltage Uо доп decreases by 2–4 times, and the energy of the switching threshold of the circuit – by up to 80 times in each subsequent decade [5].

The impact of EMI by physical mechanism and degree of danger for RES is divided into three categories:

Category I— the impact of interference voltages on the circuits of functional and structural parts (FSP) as a result of current passing through resistive, capacitive and inductive elements connected to the circuits of the input-output connectors of the RES;

Category II — the impact of interference voltages in the FSP circuits induced by electric and magnetic fields arising at the location of this FSP at the time of exposure to EMI;

Category III– the impact of interference voltage on the terminals of the FCC, caused by the spread of current along the structural elements, cable screens and ground (housing) circuits of this FCC at the moment of exposure to electromagnetic radiation – the spread of EMI current along the outer coverings of the RES.

The assessment of the damaging effect of various sources: radar, RPS, MR, SE is carried out by testing the RES for resistance to the impact of significant indicators and maximum intensity levels of these sources. The testing regulations do not contain equivalent recalculations in the RES failure criteria of pulse and harmonic interference, various pulse shapes, duration, interference voltage in circuits and the intensity of EMI fields — magnetic and electrical components, etc.

Developers and manufacturers of RES find themselves in a difficult situation, who, in order to comply with the provisions of RD-50-697-90 on mandatory certification of products, for example, in accordance with GOST 29280-92 (IEC-1000-4-91) «Noise Immunity Tests», must conduct 23 tests of RES for resistance to interference in power and control circuits using the methods of this ND. Therefore, the RES developer services, constrained in funds, are forced to ignore these control procedures or choose such ND, the methods of which do not require large expenditures, but ensure compatibility of the requirements of all impacts, including the impact of EMI fields and induced EMI currents.

It is possible to reduce the costs by at least an order of magnitude by using modified models of failures of vulnerable parts of RES: charging, speed and energy [4]. The results of tests of various electronic means in different organizations confirmed the correctness of the presented approaches to assessing the stability of RES.

To assess the resistance of the radio-electronic equipment to the effects of electromagnetic radiation by indirect methods directly at the place of standard placement, a portable EMI voltage generator and miniature autonomous pulse voltage recorders (ARIN) with memory are used, connected to the input of vulnerable control circuits of the radio-electronic equipment. At present, the method of assessing permissible pulse interference in vulnerable circuits from the effects of switching power equipment using ARIN is used to assess the electromagnetic compatibility of control equipment, automation and safety of electric power plants and substations and their resistance to EMI in organizations of RAO «UES of Russia».

Protection of RES from the effects of electromagnetic weapons is performed by methods of rational design using known shielding methods, limiting interference levels in circuits, using various grounding systems, etc. To protect broadband signal receivers from the effects of EMI and lightning discharges, a shielding device for equipment with nonlinear properties was used — transmitting a weak signal and shielding high-intensity EMI (A.S. N 999185 dated 20.03.81). The protective shell was made of three layers. The two outer layers were made of radio-transparent material, and the cavity between them contained gas that was ionized when exposed to high-intensity EMF and shielded the antenna from interference energy (Fig. 2).

Fig. 2.

1 — shell;
2 — cavity filled with easily ionizing dielectric material or gas;
3 and 4 — outer layers of the shell;
5 — collector;
6 — screen;
7 — Protected equipment

In addition to this device, a device with nonlinear properties was developed and tested, which was a metal grid, in the generators of which diodes were included, for closing the grid cells when exposed to powerful EMF radiation.

It is known that when a person stays in a shielded room for a long time, his/her performance decreases and his/her health indicators deteriorate. The reason for this is the decrease in natural electromagnetic factors in the room: geomagnetic field, electric field, Schumann waves, etc. In accordance with the State Sanitary and Epidemiological Surveillance Guide R.2.2.755-99, the level of geomagnetic field reduction at industrial workplaces is included in the list of electromagnetic factors subject to mandatory periodic monitoring.

The use of non-linear material for shielding workplaces solves this problem: natural fields are not weakened, and powerful man-made impacts are shielded.

At present, theoretical prerequisites for the creation of a sheet composite material with an internal barrier layer with nonlinear properties have been developed. The main objectives of developing such a material are: technological support for specified frequency and amplitude characteristics, manufacturing the material in one technological pass, so that the material is inexpensive and suitable for mass use in radio electronic equipment. At present, the first samples of such a material have been manufactured and tested. It can be used not only to protect radio electronic equipment from the effects of EMI and microwave EMI, but also to protect humans from radiation from radars, radio-electronic means, cell phone radiation, the creation of threshold sensors and recorders of powerful EMI radiation, etc. However, due to lack of funding, work on creating a nonlinear material has been suspended.

Electromagnetic terrorism can be aimed not only at damaging technical equipment, but also directly at human health. For example, the energy of an electrical discharge of about 0.8 joules through the human body causes shock, and 80 joules leads to death. At present, the results of biological studies have been obtained and a regulatory document is being developed, where the dose exposure to powerful EMPs is opposed to a reduction in human lifespan by one year. It seems that accessible human protection from such unauthorized impacts can be implemented using nonlinear materials.

The spread of EMF creation technologies and the availability of elements of EMP generating devices puts on the agenda the protection of RES, control systems of energy and information facilities and humans from the effects of electromagnetic factors of natural and man-made origin and domestic terrorism, capable of causing great economic damage due to failures of electronic systems, communication devices, explosions and fires of flammable substances and short circuits of electrical wiring. Therefore, the problems of increasing the resistance of RES from the effects of EMP, the development of nonlinear materials are an urgent task of the present time.

1. Kadukov A.E., Razumov A.V. “Fundamentals of the technical and operational-tactical use of electromagnetic weapons”. Petersburg Journal of Electronics, issue. 2, 2000.
2. “Russia Puts Weapons of the Future on the Market”, Nezavisimoye Voyennoye Obozreniye newspaper, No. 39 (261), October 19–25, 2001.
3. Ryabov Yu.G. et al. “Problems of Electromagnetic Safety and Compatibility of Products and Workplaces”. New in EMC, issue 4, 1998.
4. Ryabov Yu.G., Lopatkin S.M. “Basic Principles of Monitoring Electromagnetic Stability of Radio-Electronic Equipment”. Radio Industry, issue 2, 1994.
5. Ryabov Yu.G., Baburin V.M., Stavinsky V.N. “Problems of Ensuring Electrostatic and Electromagnetic Safety of Workplaces”. Standards and Quality, issue 4, 1996.