RU2495439C1 - Measuring method of magnetic and charge components of signal at measurements of magnetic component of internal electromagnetic pulse - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: method is based on separation of the corresponding components of a signal shaped in a single-turn frame antenna. The latter has no direct galvanic coupling to the housing of the irradiated object; antenna beginning and end are closed through matching loads of an oscillograph, recording of signals from antenna outputs is performed via independent channels, and separation of magnetic and charge signal components is performed by means of subtraction or summation (respectively) of signals from the beginning and the end of frame antenna.

EFFECT: improving reliability of experimental investigations of internal electromagnetic pulses owing to obtaining quantitative data on physical effects, which determine shaping of the recorded signal and minimising the number of experiments.

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Description

The invention relates to the field of methodology for measuring the parameters of internal electromagnetic pulses (VEMI), formed in the equipment, under the action of ionizing radiation (AI). It can be used in studies of the mechanisms of formation of electromagnetic interference in the circuits of electronic equipment. The research results are necessary to increase the radiation and electromagnetic resistance of weapons and military equipment equipped with electronic equipment, spacecraft and other equipment subject to AI.

The need to develop this method is due to significant uncertainty in the physical nature of the formation of electrical pickups formed in the equipment circuits when ionizing radiation acts on its body. Crosstalk can be caused by both internal electromagnetic fields and the deposition (knocking out) of electrons on the elements of the equipment of the object of influence. Depending on the spectrum of the acting radiation, materials and the layout of the internal filling of the objects, the relationship between the amplitude values of the voltages generated by the above mechanisms can vary significantly. It should be noted that methods of protection against interference are largely determined by the nature of the formation of the latter. Therefore, when studying internal electromagnetic effects, it is unacceptable by hardware methods to exclude the contribution of any component to the signal generated in the primary converters.

As a rule, when conducting experimental studies of electromagnetic effects generated in the equipment enclosures, differential measurement schemes are used using shielding of electromagnetic field sensors, or, to eliminate spurious interference in the recorded signals, induction sensors with the opposite orientation of the windings are used, which are switched on according to the differential circuit and measure crosstalk caused only by VEMI fields [1, 2]. However, the use of additional screens leads to a distortion of the spatial distribution of electromagnetic and electronic fields in the volume under study. The use of differential circuits eliminates the signals generated due to the leakage (knocking out) of electrons on the sensors and the sensors surrounding the elements of the measuring circuit.

A technical solution is known for measuring the electrical component of VEMI, based on the use of two whip antennas, one of which is shielded from the electric field, and the signal from the other is determined by the total effect of all field and charge factors formed in the volume under study. The signal due to the action of only the electric field is determined by subtracting the signals from the antennas [3].

Closest to the technical solution of the problem (the prototype of the proposed method) is a method of measuring the magnetic component of the electromagnetic field by induction sensors [4].

The essence of the prototype method lies in the fact that as a primary transducer, two on-turn single-turn loop antennas are used, located at a fixed distance along the axis of symmetry parallel to each other. The antennas are connected to the oscilloscope through a system of cable lines so that the center conductor of one cable is connected to the shield of another cable and vice versa. These two cable sections are connected to the third cable of the same type, through which the signal is transmitted to the oscilloscope. With such a connection scheme, the antiphase - formed by the magnetic field and the in-phase subtraction of the components caused by other physical mechanisms are automatically added.

This method has a significant drawback, which consists in the hardware exclusion from the recorded signal of the component due to leakage (knocking out) of electrons.

The technical result to which the alleged invention is directed is to increase the reliability of experimental studies by obtaining quantitative data on physical effects that determine the formation of the recorded signal and minimize the number of experiments.

The technical result is achieved by isolating the corresponding components of the signal generated in a single-turn loop antenna that does not have direct galvanic connection with the body of the irradiated object, the beginning and end of the antenna are closed through matching loads of the oscilloscope, the signals from the antenna terminals are recorded via independent channels, and the magnetic and charge The components of the signal are produced by subtracting or adding (respectively) the signals from the beginning and end of the loop antenna.

Thus, the structural differences of the proposed method are:

- use of one single-turn loop antenna;

- lack of direct galvanic connection of the antenna with the housing;

- the lack of a differential circuit for registering a signal.

A significant difference is the possibility of studying the amplitude-time characteristics of the magnetic component of VEMI and pickups due to charge imbalance.

Schematic diagram illustrating the essence of the method shown in Fig-1, where

i _s is the charge component of the current in the frame;

i _m is the magnetic component of the current in the frame;

U ₁ , U ₂ - signals recorded in the channels of the oscilloscope;

R ₁ , R ₂ - matching the load of the oscilloscope (R ₁ = R ₂ = 50 Ohms).

When generating VEMI fields, any field sensor placed inside the volume under investigation is exposed to at least three factors simultaneously:

- electromagnetic field;

- an external current of electrons knocked out from the internal surfaces of the sample;

- ionizing radiation.

In a loop antenna, an electromagnetic field generates an EMF proportional to the time derivative of the magnetic field strength. As a result of this, a current is formed in the frame, indicated on the circuit as i _m (magnetic component of the current in the frame).

Electrons knocked out from the internal surfaces of the object, falling on the conductive material of the frame, create an uncompensated excess negative charge in it, which flows from the frame through matching loads of the registration system.

Ionizing radiation does not change the electrical properties of the metal of the frame (unlike semiconductors and dielectrics), but knocks electrons from the surface of the frame into the surrounding space, creating an uncompensated excess positive charge in the antenna, which also flows through the matching loads of the registration system.

Thus, there are two competing processes of creating uncompensated charges of different signs in the frame. Depending on the values of the electron exit coefficients from the materials of the object’s frame and body, depending on the energy of the primary quanta, a charge of any sign can be formed on the antenna that cannot be shielded, because the inner surface of the screen itself is a source of external current. The resulting currents arising in the frame loads due to these processes are indicated on the diagram as i _z1 and i _z2 . Their sum i _z can be called the charge component of the current in the frame. In the case of symmetric loads and symmetrical frames can assume that i ≈i _{P1 P2.} The registered signals in the first and second channels of registration of the oscilloscope can be represented in the form U ₁ = (i _z1 -i _m ) / R ₁ and U ₂ = (i _z2 -i _m ) / R ₂ . Summing the registered signals will allow us to determine the magnitude of the current from an uncompensated charge, and subtracting it from the time derivative of the magnetic field strength.

The efficiency and information content of the proposed method is confirmed during experimental work using ionizing radiation of various spectral composition. The experimental results are in good agreement with the data of theoretical calculations.

The positive effect of the invention is to increase the reliability of experimental studies of VEMI by obtaining quantitative data on the physical effects that determine the formation of the recorded signal and minimize the number of experiments.

Information sources

1. V.V. Panin, B.M. Stepanov. Practical magnetometry. M. "Mechanical Engineering", 1978, p. 54.

2. “Measuring equipment”, M. No. 5, 1977, p. 75.

3. A.P. Stepovik, V.V. Ostavnov, et al. On measurements of the electrical component of VEMI using pin antennas. Scientific and technical collection "Radiation resistance of electronic systems-Resistance-2010". - M.: NRNU MEPhI, 2010, pp. 143-144.

4. "Probe for measuring magnetic fields with subnanosecond resolution." "Rev. Sci. Jnstrum ", 1975, 46, No. 7, pp. 886-880. Russian translation - “Instruments for scientific research”, M., No. 7, 1975, pp. 88-91.

Claims (1)

A method of measuring the magnetic and charge components of a signal when measuring the magnetic component of an internal electromagnetic pulse to study the mechanisms of formation of radiation-stimulated electromagnetic effects, based on the selection of the corresponding components of the signal generated in a single-turn loop antenna, characterized in that the loop antenna does not have direct galvanic communication with the body of the irradiated object, the beginning and end of the antenna is closed through the matching load of the oscilloscope, registration The signals from the antenna terminals are produced through independent channels, and the magnetic and charge components of the signal are extracted by subtracting or adding (respectively) the signals from the beginning and end of the loop antenna.