CN116243216A - Magnetic field probe for electromagnetic pulse measurement and electromagnetic pulse measurement method - Google Patents

Magnetic field probe for electromagnetic pulse measurement and electromagnetic pulse measurement method Download PDF

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Publication number
CN116243216A
CN116243216A CN202310471047.5A CN202310471047A CN116243216A CN 116243216 A CN116243216 A CN 116243216A CN 202310471047 A CN202310471047 A CN 202310471047A CN 116243216 A CN116243216 A CN 116243216A
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magnetic field
electromagnetic pulse
resistor
signal
circuit
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刘逸飞
吴伟
聂鑫
赵墨
王文兵
李进玺
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Northwest Institute of Nuclear Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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Abstract

The invention relates to an electromagnetic pulse measuring device and method, in particular to a magnetic field probe and an electromagnetic pulse measuring method for electromagnetic pulse measurement, which solve the technical problems that the existing magnetic field probe is easy to be interfered, the output differential signal has errors with an original signal after integration, and the two-time value integration is inconvenient to calculate or is not suitable for measuring a fast-forward pulse magnetic field signal. The magnetic field probe for electromagnetic pulse measurement provided by the invention comprises a coaxial cable with a gap, a shielding shell, an integrating circuit, a high input impedance amplifying circuit and an electro-optical conversion circuit, wherein the integrating circuit, the high input impedance amplifying circuit and the electro-optical conversion circuit are arranged in the shielding shell and are sequentially connected, and an output signal of the magnetic field probe is an original signal of a magnetic field waveform, so that the need of numerical integration reduction of the magnetic field waveform to be measured in differential measurement is avoided; the coaxial cable with the gap is semicircular, comprises an inner core and a shielding layer, wherein an annular gap is formed in the shielding layer along the circumferential direction, and two ends of the inner core are respectively connected with an integrating circuit and a load resistor, so that the capability of resisting electric field interference is strong.

Description

Magnetic field probe for electromagnetic pulse measurement and electromagnetic pulse measurement method
Technical Field
The invention relates to an electromagnetic pulse measuring device and an electromagnetic pulse measuring method, in particular to a magnetic field probe for electromagnetic pulse measurement and an electromagnetic pulse measuring method.
Background
The interference of high-altitude electromagnetic pulse or ultra-wideband electromagnetic pulse on electronic equipment is not ignored, so that the electric field and magnetic field energy of the electromagnetic pulse need to be monitored when the strong electromagnetic pulse effect test is performed.
The electromagnetic pulse is monitored by using a coil as a magnetic field probe, and the higher the inductance of the coil is, the poorer the high-frequency performance of the coil is. When the coil terminal load is far smaller than the coil self inductance, the voltage waveform on the load is consistent with the waveform of the magnetic field to be measured; when the coil terminal load is far larger than the coil self inductance, the voltage waveform on the load is the differential form of the magnetic field waveform to be measured. The rise time of the waveforms such as high-altitude electromagnetic pulse is in ns order, the corresponding high-frequency component can reach hundreds of MHz, and the inductance of the coil is required to be very small in order to ensure the high-frequency performance of the magnetic field probe. Only when the coil load is of mu omega magnitude, the load voltage is approximately consistent with the magnetic field waveform, but too small coil load can bring great difficulty to acquisition of the back-end signal. Therefore, the resistance value of the coil terminal load can be increased, the differential waveform of the magnetic field can be obtained, and the real magnetic field signal can be restored by adopting a numerical integration method. However, the coil of the magnetic field probe adopting the mode is easy to be interfered by a pulse electric field, so that errors exist between the integrated signal and a real magnetic field signal, and the integration of the two times of values brings certain inconvenience to engineering testers.
Chinese patent publication No. CN214845500U discloses a self-integrating time domain magnetic field probe, the coil of which is a winding coil, the self inductance is very large, and the measurement of high altitude electromagnetic pulse and other fast-forward magnetic field signals cannot be realized. The Chinese patent with publication number CN203572948U discloses a high-frequency magnetic field probe, the Chinese patent with publication number CN 107607888A discloses a three-dimensional transient magnetic field measurement system, both adopt a shield ring antenna with a notch, an inner core at one end of a shield ring of the high-frequency magnetic field probe and the shield ring antenna are connected with a shield layer, so that the impedance of a core wire terminal is not matched, the shield ring antenna forms reflection oscillation on a high-frequency signal, and a related matching circuit is not suitable for measuring a fast-forward pulse magnetic field signal.
The Chinese patent with publication number CN115032575A discloses a passive differential magnetic field probe based on differential double-loop and integrated balun structure, the Chinese patent with publication number CN113702878A discloses a miniaturized active differential magnetic field probe with high common-mode rejection ratio and high sensitivity, the two designs are based on a double-loop differential method, the interference of an electric field can be eliminated, but the output signal is still in the differential form of a magnetic field waveform to be detected, the scanning test of a near field magnetic field is relatively suitable, the numerical integration of measurement data is still required when the time-domain electromagnetic pulse magnetic field signal is measured, and the signal transmission link of a coaxial cable is easily subjected to the secondary interference of electromagnetic pulses.
Disclosure of Invention
The invention aims to solve the technical problems that the existing magnetic field probe is easy to be interfered, the output differential form signal has errors with the original signal after being integrated, the two-time value integration is inconvenient to calculate, or the magnetic field probe is not suitable for measuring the fast-forward pulse magnetic field signal, and provides a magnetic field probe for electromagnetic pulse measurement and an electromagnetic pulse measurement method.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the magnetic field probe for electromagnetic pulse measurement is characterized in that: the coaxial cable comprises a coaxial cable with a gap, a shielding shell, an integrating circuit, a high input impedance amplifying circuit, an electro-optical conversion circuit and a load resistor, wherein the integrating circuit, the high input impedance amplifying circuit, the electro-optical conversion circuit and the load resistor are arranged in the shielding shell;
two connectors for connecting the coaxial cables with gaps are formed in the shielding shell;
the coaxial cable with the gap is semicircular, and comprises an inner core and a shielding layer wrapped on the surface of the inner core, wherein an annular gap is formed in the shielding layer along the circumferential direction; two ends of the inner core extend into the shielding shell through two connectors respectively and are connected with the input end of the integrating circuit and one end of the load resistor respectively, and the other end of the load resistor is grounded;
the coaxial cable with the gap is used for inducing a magnetic field differential signal;
the integrating circuit is used for restoring the magnetic field differential signal sensed by the coaxial cable with the gap into a real magnetic field signal, and the output end of the integrating circuit is connected with the input end of the high input impedance amplifying circuit;
the high input impedance amplifying circuit is used for collecting and amplifying the real magnetic field signals, and the output end of the high input impedance amplifying circuit is connected with the input end of the electro-optical conversion circuit;
the electro-optical conversion circuit is used for converting a real magnetic field signal into an optical signal and outputting the optical signal.
Further, the integrating circuit comprises an input resistor R1, a current limiting resistor R2 and an integrating capacitor C1;
one end of the current limiting resistor R2 is connected with one end of the input resistor R1, is used as an input end of the integrating circuit, and is connected with one end of the inner core; the other end of the current limiting resistor R2 is connected with one side polar plate of the integrating capacitor C1, is used as the output end of the integrating circuit, and is connected with the input end of the high input impedance amplifying circuit;
the other end of the input resistor R1 is grounded, and the other side polar plate of the integrating capacitor C1 is grounded.
Further, the resistance of the current limiting resistor R2 is much larger than that of the input resistor R1.
Further, the characteristic impedance, the load resistance and the resistance of the input resistor R1 of the coaxial cable with the gap are consistent.
Further, the annular gap width of the gapped coaxial cable is less than 1mm.
Further, an output end of the electro-optical conversion circuit is connected with an optical fiber.
Furthermore, the electro-optical conversion circuit adopts a DFB laser, and the DFB laser has small volume and low power consumption.
Further, the high input impedance amplifying circuit comprises an operational amplifier, a ground resistor R3, a first adjusting resistor R4 and a second adjusting resistor R5;
the non-inverting input end of the operational amplifier is connected with the output end of the integrating circuit 3 and one end of the grounding resistor R3; the inverting input end of the operational amplifier is connected with one end of the first adjusting resistor R4 and one end of the second adjusting resistor R5, and the output end of the operational amplifier is connected with the input end of the electro-optical conversion circuit and the other end of the first adjusting resistor R4;
the other end of the grounding resistor R3 is grounded, and the other end of the second adjusting resistor R5 is grounded.
Further, since the input impedance of the FET-type operational amplifier is generally large and is generally larger than mΩ, the operational amplifier described in the present invention is a FET-type operational amplifier;
the resistance value of the ground resistor R3 is not smaller than 1MΩ;
the input impedance of the operational amplifier is not less than 10MΩ.
The invention also provides an electromagnetic pulse measuring method, which is characterized by comprising the following steps of:
step 1, the magnetic field probe for electromagnetic pulse measurement is placed in a magnetic field to be measured, a magnetic field differential signal of electromagnetic pulse is collected by a coaxial cable with a gap and is transmitted to an integrating circuit, and the relation between the magnetic field differential signal and a voltage difference generated between the gaps of the coaxial cable with the gap is expressed by the following formula:
Figure BDA0004203988270000041
wherein V is 0 H H is the magnetic field intensity, mu, which is the voltage difference generated between the gaps of the coaxial cable with the gaps 0 Is of vacuum permeability, A eq Is the equivalent area of the gapped coaxial cable loop,
Figure BDA0004203988270000042
is a magnetic field differential signal;
step 2, the integration circuit integrates the magnetic field differential signal to obtain a real magnetic field signal, and outputs the real magnetic field signal to the high input impedance amplifying circuit;
the true magnetic fieldSignal V out (t) is calculated by the following formula:
Figure BDA0004203988270000043
wherein τ is the time constant of the integrating circuit;
V in (t) is an input magnetic field differential signal,
Figure BDA0004203988270000044
step 3, amplifying the real magnetic field signal by the high input impedance amplifying circuit, and outputting the amplified real magnetic field signal to the electro-optical conversion circuit;
and 4, converting the amplified real magnetic field signal into an optical signal by the electro-optical conversion circuit and outputting the optical signal to finish the measurement of electromagnetic pulse.
Compared with the prior art, the invention has the following beneficial technical effects:
1. compared with a single loop antenna, the magnetic field probe for electromagnetic pulse measurement provided by the invention has stronger capacity of resisting electric field interference, and the inner core at one end of the coaxial cable with the gap is connected with a matched load resistor, so that reflection of high-frequency signals caused by impedance mismatch can be avoided;
2. the magnetic field probe for electromagnetic pulse measurement provided by the invention integrates the integrating circuit, the high input impedance amplifying circuit and the electro-optical conversion circuit in the shielding shell, and the output signal is the original signal of the magnetic field waveform, so that the numerical integration reduction of the magnetic field waveform to be measured required by differential measurement is avoided;
3. the magnetic field probe for electromagnetic pulse measurement provided by the invention has the advantages of high integration level and convenient engineering application, is especially suitable for measuring the waveform of the high-intensity electromagnetic pulse magnetic field with a fast front edge, and has application prospects in the fields of electromagnetic compatibility and the like;
4. compared with a coaxial cable, the optical fiber has the advantages of low remote transmission loss, light weight, strong electromagnetic interference resistance and the like.
Drawings
FIG. 1 is a schematic diagram of a magnetic field probe for electromagnetic pulse measurement according to the present invention;
FIG. 2 is a schematic diagram of an integrating circuit, a high input impedance amplifying circuit, and an electro-optic conversion circuit in an embodiment of a magnetic field probe for electromagnetic pulse measurement according to the present invention;
FIG. 3 is a graph showing the comparison of the waveform of the high altitude electromagnetic pulse magnetic field signal and the waveform of the pulse source measured under the TEM cell by the magnetic field probe for electromagnetic pulse measurement according to the embodiment of the present invention;
the reference numerals are explained as follows:
1-band gap coaxial cable, 11-inner core, 12-shielding layer, 2-shielding shell, 3-integrating circuit, 4-high input impedance amplifying circuit, 5-electro-optical conversion circuit, 6-optical fiber and 7-load resistor.
Detailed Description
To make the objects, advantages and features of the present invention more apparent, a magnetic field probe for electromagnetic pulse measurement according to the present invention will be described in further detail with reference to the accompanying drawings and specific examples.
A magnetic field probe for electromagnetic pulse measurement is shown in figure 1, and comprises a coaxial cable 1 with a gap, a shielding shell 2, an integrating circuit 3, a high input impedance amplifying circuit 4, an electro-optical conversion circuit 5 and a load resistor 7 which are arranged in the shielding shell 2, wherein output signals of the integrating circuit are original signals of magnetic field waveforms, and numerical integration reduction of the magnetic field waveforms to be measured required by differential measurement is avoided. The shielding shell 2 is provided with two connectors for connecting the coaxial cable 1 with the gap, the coaxial cable 1 with the gap is semicircular, the coaxial cable comprises an inner core 11 and a shielding layer 12 wrapped on the surface of the inner core 11, and an annular gap is formed in the shielding layer 12 along the circumferential direction. The smaller the value range of the annular gap, the better, in this embodiment, the annular gap is smaller than 1mm. Two ends of the inner core 11 extend into the shielding shell 2 through two connecting ports respectively and are connected with the input end of the integrating circuit 3 and one end of the load resistor 7 respectively, and the other end of the load resistor 7 is grounded. The coaxial cable 1 with gap is used for inducing magnetic field differential signals, one end inner core of the coaxial cable 1 is connected with a matched load resistor 7, reflection of high-frequency signals caused by impedance mismatch can be avoided, and compared with a single loop antenna, the coaxial cable 1 with gap has stronger capability of resisting electric field interference.
The integrating circuit 3 is used for restoring the magnetic field differential signal sensed by the gapped coaxial cable 1 into a real magnetic field signal, and the output end of the integrating circuit 3 is connected with the input end of the high input impedance amplifying circuit 4. The high input impedance amplifying circuit 4 is used for collecting and amplifying the real magnetic field signal, and the output end of the high input impedance amplifying circuit 4 is connected with the input end of the electro-optical conversion circuit 5. The electro-optical conversion circuit 5 is used for converting the real magnetic field signal into an optical signal and outputting the optical signal, and the output end of the electro-optical conversion circuit 5 is connected with the optical fiber 6. Because the optical fiber 6 has the advantages of low remote transmission loss, light weight, strong electromagnetic interference resistance and the like, the measuring signal of the magnetic field probe for electromagnetic pulse measurement provided by the invention is transmitted remotely through the optical fiber 6.
The coaxial cable 1 with the gap adopts an SR086-50 coaxial cable, the characteristic impedance is 50Ω, the cable is manufactured into a semicircle with the radius of 1.5cm, the middle is provided with a gap of 1mm, the two ends extend into the shielding shell 2, one end of the inner core at the two ends is connected with the integrating circuit 3, the other end is connected with the load resistor 7, and the input resistor of the integrating circuit 3 and the resistance value of the load resistor 7 are 50Ω.
When electromagnetic pulse irradiates the magnetic field probe, a loop formed by the coaxial cable with the gap and the shielding shell generates a voltage difference V between gaps of the coaxial cable with the gap due to magnetic flux change 0 H The method comprises the following steps:
Figure BDA0004203988270000071
wherein H is the magnetic field strength, mu 0 Is of vacuum permeability, A eq Is the equivalent area of the gapped coaxial cable loop. From the formula, it can be seen that the magnetic field differential signal is equal to V 0 H Proportional to the ratio.
Electric field in electromagnetic pulseThe components will create a voltage difference between the gaps of the gapped coaxial cable 1, breaking the electric field components into an electric field E perpendicular to the gapped coaxial cable gaps ⊥ And an electric field E parallel to the gap of the gapped coaxial cable ∥ 。E ⊥ The voltages generated across the gap being common mode voltages of the same direction, E ∥ The voltage generated across the gap is a reverse differential mode voltage, so the voltage difference between the gaps is only equal to E ∥ Related to the following. E due to the presence of the shielding shell, according to the limit of the boundary conditions of the electromagnetic field ∥ Is distributed in standing wave at the interface of the shell and E at the interface ∥ Equal to zero. E when the height of the coaxial cable with the gap is smaller than the wavelength of electromagnetic waves to be detected ∥ The electric field strength at the gap position is still small, so that the influence on the voltage difference between the gaps is negligible, and the total voltage between the gaps of the coaxial cable with the gaps is still approximate to V 0 H . The gap forms an electric field due to the existence of voltage difference, and the electric field acts on the inner core of the coaxial cable 1 with the gap to form a point voltage source with the size approximately equal to V 0 H . The two ends of the inner core 11 are respectively connected with the input resistor R1 and the load resistor 7 of the integrating circuit 3, the characteristic impedance of the input resistor R1, the load resistor 7 and the gapped coaxial cable 1 is the same, so that good matching is formed, high-frequency reflection is not formed, and the voltage on each load is V 0 H /2。
As shown in fig. 2, the integrating circuit 3 includes an input resistor R1, a current limiting resistor R2, and an integrating capacitor C1. One end of the current limiting resistor R2 is connected to one end of the input resistor R1, serves as an input end of the integrating circuit, and is connected to one end of the inner core 11. The other end of the current limiting resistor R2 is connected to one side plate of the integrating capacitor C1, and is used as the output end of the integrating circuit 3, and is connected to the input end of the high input impedance amplifying circuit 4. The other end of the input resistor R1 is grounded, and the other side polar plate of the integrating capacitor C1 is grounded. The resistance of the current limiting resistor R2 is much larger than that of the input resistor R1. The characteristic impedance of the coaxial cable 1 with the gap, the load resistor 7 and the input resistor R1 have the same resistance value.
The integrating circuit 3 integrates the sensed magnetic field differential signal, and the input resistor R1 of the integrating circuit 3The resistance value (namely, the antenna load) is 50Ω, the current limiting resistor R2 is 1kΩ, and the integrating capacitor C1 is 1nf. The time constant of the integrating circuit 3 is r2.c1=1μs, and when the width of the pulse waveform to be measured is much smaller than 1 μs, the voltage V on the capacitor C1 out (t) is the input voltage V in (t) integration over time t, i.e
Figure BDA0004203988270000081
The high input impedance amplifying circuit 4 includes an FET-type operational amplifier, a ground resistance R3, a first adjustment resistance R4, and a second adjustment resistance R5. The non-inverting input terminal of the FET-type operational amplifier is connected to the output terminal of the integrating circuit 3 and one terminal of the ground resistor R3. The inverting input terminal of the FET-type operational amplifier is connected to one end of the first adjustment resistor R4 and one end of the second adjustment resistor R5, and the output terminal of the FET-type operational amplifier is connected to the input terminal of the electro-optical conversion circuit 5 and the other end of the first adjustment resistor R4. The other end of the grounding resistor R3 is grounded, and the other end of the second adjusting resistor R5 is grounded. The high input impedance amplifying circuit 4 further comprises two capacitors, wherein one side polar plate of one capacitor is connected with the positive end of the power input of the FET type operational amplifier, and the other side polar plate is grounded; one side polar plate of the other capacitor is connected with the negative end of the power input of the FET type operational amplifier, and the other side polar plate is grounded.
The FET type operational amplifier avoids the abnormal operation of the FET type operational amplifier caused by the fact that no direct current path exists at the input end through the parallel connection of the grounding resistor R3, and the resistance value of the grounding resistor R3 is not smaller than 1MΩ. The high input impedance amplifying circuit 4 is used for collecting the voltage on a capacitor C1 in the integrating circuit, the circuit takes an FET type operational amplifier as a core, the forward input end of the circuit is taken as a signal input end, the input impedance can reach more than GΩ, the parallel ground resistor R3 takes 1MΩ, and the input impedance of the circuit is approximate to the resistance value of R4. Taking r4=r5 as 150Ω, the FET-type operational amplifier amplifies the input signal by a factor of 2.
The electro-optical conversion circuit 5 includes a DFB laser, a resistor R6, a resistor R7, and a capacitor C2. One end of the resistor R6 is an input end of the electro-optical conversion circuit 5, is connected with an output end of the FET type operational amplifier, and the other end of the resistor R6 is connected with one side polar plate of the capacitor C2. The other side polar plate of the capacitor C2 is connected with one end of a resistor R7 and the anode of the DFB laser, the other end of the resistor R7 is connected with a power supply, and the cathode of the DFB laser is grounded.
The output end of the electro-optical conversion circuit 5 is connected with an optical fiber, and the signal output by the high input impedance amplifying circuit is transmitted through the optical fiber by using a DFB laser, so that the transmission link is prevented from being interfered by strong electromagnetic pulse.
The magnetic field probe for electromagnetic pulse measurement has good electric field interference resistance, the internal integrating circuit 3 and the matched high input impedance amplifying circuit 4 can convert differential signals induced by an antenna into real magnetic field signals and transmit the signals out through optical fibers, and the magnetic field probe for electromagnetic pulse measurement can prevent a transmission link from being subjected to secondary interference of electromagnetic pulses and has the advantages of convenience in use, high integration level, convenience in engineering application and the like.
As shown in fig. 3, in order to show a comparison graph of a waveform of a high-altitude electromagnetic pulse magnetic field signal and a waveform of a pulse source measured by the magnetic field probe for electromagnetic pulse measurement provided by the invention under a TEM cell, it can be seen that the waveform measured by the magnetic field probe for electromagnetic pulse measurement provided by the invention has good compliance with the waveform of the pulse source, and the magnetic field probe for electromagnetic pulse measurement provided by the invention has the characteristic of strong anti-electric field interference capability, and is suitable for measuring a fast-front pulse magnetic field signal.
The embodiment also provides an electromagnetic pulse measuring method, which comprises the following steps:
step 1, the magnetic field probe for electromagnetic pulse measurement is placed in a magnetic field to be measured, the magnetic field differential signal of the electromagnetic pulse is collected by the coaxial cable 1 with gap and transmitted to the integrating circuit 3, and the relationship between the magnetic field differential signal and the voltage difference generated between the gaps of the coaxial cable 1 with gap is expressed by the following formula:
Figure BDA0004203988270000101
wherein V is 0 H H is the magnetic field intensity, mu, which is the voltage difference generated between the gaps of the coaxial cable 1 with the gaps 0 Is of vacuum permeability, A eq Is the equivalent area of the gapped coaxial cable loop,
Figure BDA0004203988270000102
as a magnetic field differential signal, as an input signal V to the integrating circuit 3 in (t), let->
Figure BDA0004203988270000103
Step 2, the integration circuit 3 integrates the magnetic field differential signal to obtain a real magnetic field signal, and outputs the real magnetic field signal to the high input impedance amplifying circuit 4;
the true magnetic field signal V out (t) is calculated by the following formula:
Figure BDA0004203988270000104
where τ is the time constant of the integrating circuit 3;
V in (t) is an input magnetic field differential signal,
Figure BDA0004203988270000105
step 3, amplifying the real magnetic field signal by the high input impedance amplifying circuit 4, and outputting the amplified real magnetic field signal to the electro-optical conversion circuit 5;
and 4, the electro-optical conversion circuit 5 converts the amplified real magnetic field signal into an optical signal and outputs the optical signal to finish the measurement of electromagnetic pulse.

Claims (10)

1. A magnetic field probe for electromagnetic pulse measurement, characterized by: comprises a coaxial cable (1) with a gap, a shielding shell (2), an integrating circuit (3), a high input impedance amplifying circuit (4), an electro-optical conversion circuit (5) and a load resistor (7) which are arranged in the shielding shell (2);
two connectors for connecting the coaxial cable (1) with the gap are formed in the shielding shell (2);
the coaxial cable (1) with the gap is semicircular and comprises an inner core (11) and a shielding layer (12) wrapped on the surface of the inner core (11), wherein an annular gap is formed in the shielding layer (12) along the circumferential direction; two ends of the inner core (11) extend into the shielding shell (2) through two connecting ports respectively and are connected with the input end of the integrating circuit (3) and one end of the load resistor (7) respectively, and the other end of the load resistor (7) is grounded;
the coaxial cable (1) with the gap is used for inducing a magnetic field differential signal;
the integrating circuit (3) is used for restoring a magnetic field differential signal sensed by the coaxial cable (1) with a gap into a real magnetic field signal, and the output end of the integrating circuit (3) is connected with the input end of the high input impedance amplifying circuit (4);
the high input impedance amplifying circuit (4) is used for collecting and amplifying real magnetic field signals, and the output end of the high input impedance amplifying circuit (4) is connected with the input end of the electro-optical conversion circuit (5);
the electro-optical conversion circuit (5) is used for converting a real magnetic field signal into an optical signal and outputting the optical signal.
2. The magnetic field probe for electromagnetic pulse measurement according to claim 1, wherein: the integrating circuit (3) comprises an input resistor R1, a current limiting resistor R2 and an integrating capacitor C1;
one end of the current limiting resistor R2 is connected with one end of the input resistor R1, is used as an input end of the integrating circuit (3), and is connected with one end of the inner core (11); the other end of the current limiting resistor R2 is connected with one side polar plate of the integrating capacitor C1, is used as the output end of the integrating circuit (3), and is connected with the input end of the high input impedance amplifying circuit (4);
the other end of the input resistor R1 is grounded, and the other side polar plate of the integrating capacitor C1 is grounded.
3. The magnetic field probe for electromagnetic pulse measurement according to claim 2, wherein: the resistance of the current limiting resistor R2 is far greater than that of the input resistor R1.
4. A magnetic field probe for electromagnetic pulse measurement according to claim 3, characterized in that: the characteristic impedance and the load resistance (7) of the coaxial cable (1) with the gap are consistent with the resistance value of the input resistance R1.
5. A magnetic field probe for electromagnetic pulse measurement according to any of claims 1-4, characterized in that: the annular gap of the gapped coaxial cable (1) is less than 1mm.
6. The magnetic field probe for electromagnetic pulse measurement of claim 5, wherein: the output end of the electro-optical conversion circuit (5) is connected with an optical fiber (6).
7. The magnetic field probe for electromagnetic pulse measurement of claim 6, wherein: the electro-optical conversion circuit (5) adopts a DFB laser.
8. The magnetic field probe for electromagnetic pulse measurement of claim 7, wherein: the high input impedance amplifying circuit (4) comprises an operational amplifier, a ground resistor R3, a first adjusting resistor R4 and a second adjusting resistor R5;
the non-inverting input end of the operational amplifier is connected with the output end of the integrating circuit (3) and one end of the ground resistor R3; the inverting input end of the operational amplifier is connected with one end of a first adjusting resistor R4 and one end of a second adjusting resistor R5, and the output end of the operational amplifier is connected with the input end of the electro-optical conversion circuit (5) and the other end of the first adjusting resistor R4;
the other end of the grounding resistor R3 is grounded, and the other end of the second adjusting resistor R5 is grounded.
9. The magnetic field probe for electromagnetic pulse measurement of claim 8, wherein: the operational amplifier is an FET type operational amplifier;
the resistance value of the ground resistor R3 is not smaller than 1MΩ;
the input impedance of the operational amplifier is not less than 10MΩ.
10. An electromagnetic pulse measurement method, characterized by comprising the steps of:
step 1, placing the magnetic field probe for electromagnetic pulse measurement according to any one of claims 1-9 in a magnetic field to be measured, and the magnetic field differential signal of the electromagnetic pulse is collected by the gapped coaxial cable (1) and transmitted to the integrating circuit (3), wherein the relationship between the magnetic field differential signal and the voltage difference generated between the gaps of the gapped coaxial cable (1) is expressed by the following formula:
Figure FDA0004203988260000031
in the method, in the process of the invention,
Figure FDA0004203988260000032
h is the magnetic field intensity, mu, which is the voltage difference generated between the gaps of the coaxial cable (1) with the gaps 0 Is of vacuum permeability, A eq For equivalent area of gapped coaxial cable loop, +.>
Figure FDA0004203988260000033
Is a magnetic field differential signal;
step 2, an integrating circuit (3) integrates the magnetic field differential signal to obtain a real magnetic field signal, and the real magnetic field signal is output to a high input impedance amplifying circuit (4);
the true magnetic field signal V out (t) is calculated by the following formula:
Figure FDA0004203988260000034
wherein τ is the time constant of the integrating circuit (3);
V in (t) is an input magnetic field differential signal,
Figure FDA0004203988260000035
step 3, amplifying the real magnetic field signal by the high input impedance amplifying circuit (4), and outputting the amplified real magnetic field signal to the electro-optical conversion circuit (5);
and 4, converting the amplified real magnetic field signal into an optical signal by an electro-optical conversion circuit (5) and outputting the optical signal to finish the measurement of electromagnetic pulse.
CN202310471047.5A 2023-04-27 2023-04-27 Magnetic field probe for electromagnetic pulse measurement and electromagnetic pulse measurement method Pending CN116243216A (en)

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