CN114236222A - Electrostatic probe current measuring device - Google Patents
Electrostatic probe current measuring device Download PDFInfo
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- CN114236222A CN114236222A CN202111465080.4A CN202111465080A CN114236222A CN 114236222 A CN114236222 A CN 114236222A CN 202111465080 A CN202111465080 A CN 202111465080A CN 114236222 A CN114236222 A CN 114236222A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/04—Voltage dividers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/22—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-emitting devices, e.g. LED, optocouplers
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
- G05B19/0423—Input/output
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Abstract
The invention relates to an electrostatic probe current measuring device, comprising: the sampling resistor (1) is used for collecting a signal fed back by the electrostatic probe; the amplifying circuit (2) is used for receiving and amplifying the signals collected by the sampling resistor (1); the collector (3) is used for carrying out analog-to-digital conversion on the amplified signals; the processor (4) is used for processing the signals subjected to the analog-to-digital conversion to obtain a measurement result; the amplifying circuit (2) amplifies received signals in a multi-path division mode according to measuring ranges, the collector (3) respectively carries out analog-to-digital conversion on the amplified multi-path signals, and the processor (4) carries out combination processing on the multi-path signals subjected to the analog-to-digital conversion. The measuring device can realize automatic measurement of signals with large dynamic range, ensure the precision of signal measurement, realize unattended automatic measurement, and is particularly suitable for unrepeatable tests with unknown signal size, and ensure complete measurement of signals.
Description
Technical Field
The invention relates to an electrostatic probe current measuring device.
Background
The static probe measuring system is mainly used for measuring the rapid space-time distribution of the electron density of the plasma in the ultra-high-speed flow field, a typical measuring object is a shock tube plasma flow field, and the plasma radial distribution of the cross section of the flow field is measured by adopting the transient array static probe measuring system. The electrostatic probe is a conductive metal needle inserted into the plasma, and the working mode of the electrostatic probe is that a probe control power supply applies a set voltage waveform to a needle point, weak current collected by the needle point is measured, and finally plasma parameters are calculated through a special algorithm of a voltage-current curve. During measurement, the scanning voltage phases of the electrostatic probes in each group are consistent, and the electron temperatures measured by the probe groups are ensured to be in the same time.
The voltage-current curve of the probe is S-shaped and can be divided into three regions, namely an ion saturation current region of microampere-level probe current, an electron saturation current region of milliamp-level probe current and a transition region between the two regions. For typical shock tube plasma parameters, the probe current increases with the scan voltage by about 6 orders of magnitude, and the test times are limited, and the single test time is short. Because of the large dynamic range of current (over 130dB) for one complete sample, the electrostatic probe must have a large dynamic range measurement capability for probe currents that span many orders of magnitude. Therefore, the conventional data collector has difficulty in meeting the test requirements. In order to accurately measure the current of the conventional large-dynamic-range probe current signal, the probe current signal is usually calculated and analyzed according to known test conditions, and the signal size is estimated, so that the measurement is completed by manually setting the measuring range, or the measurement is completed by manually or automatically setting the gear according to the previous test result in the next test, which is not applicable in the transient large-dynamic-range plasma parameter measurement process.
Disclosure of Invention
The invention aims to provide an electrostatic probe current measuring device.
In order to achieve the above object, the present invention provides an electrostatic probe current measuring apparatus, comprising:
the sampling resistor is used for collecting a signal fed back by the electrostatic probe;
the amplifying circuit is used for receiving and amplifying the signals collected by the sampling resistor;
the collector is used for carrying out analog-to-digital conversion on the amplified signals;
the processor is used for processing the signals subjected to the analog-to-digital conversion to obtain a measurement result;
the amplifying circuit amplifies the received signals in a multi-path division mode according to measuring ranges, the collector respectively carries out analog-to-digital conversion on the amplified multi-path signals, and the processor carries out combination processing on the multi-path signals subjected to the analog-to-digital conversion.
According to an aspect of the invention, the amplifying circuit includes:
the precise instrument amplifier is used for amplifying the signal input into the amplifying circuit;
and the sub-amplifying circuit is used for amplifying the signals output by the precision instrument amplifier by different times according to measuring ranges.
According to an aspect of the present invention, the sub-amplifying circuit includes:
the filtering module is used for carrying out low-pass filtering on the signals input into the sub-amplifying circuit;
the operational amplifier is used for amplifying the signal subjected to the low-pass filtering;
and the voltage division module is used for being connected with the operational amplifier in parallel to form a differential amplification circuit.
According to one aspect of the invention, the filtering module comprises a first filtering resistor, a second filtering resistor and a grounding line, wherein the first filtering resistor and the second filtering resistor are connected in series, and the grounding line is positioned between the first filtering resistor and the second filtering resistor and is provided with a filtering capacitor;
the voltage division module comprises a voltage division capacitor and a voltage division resistor which are connected in parallel.
According to an aspect of the invention, the sub-amplifying circuit further comprises:
the linear optical coupling module is used for transmitting the signal output by the differential amplification circuit in an optical coupling mode;
and the connector is used for outputting the signal transmitted by the linear optical coupling module.
According to one aspect of the invention, the merging process is performed by analyzing through upper computer software, specifically, the data size measured under the maximum measuring range of the collector is analyzed through processor software, the measuring range interval where the collector is located is determined, and the measuring data in the corresponding measuring range interval is selected as the measuring result.
According to one aspect of the invention, the collector is a 16-bit data collection card and the processor is an upper computer.
According to one aspect of the invention, the amplification circuit amplifies the signal by 100 times and 1 time, respectively.
According to the concept of the invention, the invention provides a high-precision large-dynamic-range probe current measuring device which comprises a sampling resistor, an amplifying circuit, a double-channel data acquisition unit and a processor. The device can be combined with multiple paths of signals acquired in different ranges to be integrated, automatically judges and selects output signals, realizes automatic measurement of signals in a large dynamic range, has the characteristics of large range and high precision of signal measurement, can realize unattended automatic measurement, is particularly suitable for non-repeatable tests with unknown signal sizes, and ensures complete measurement of signals.
According to one scheme of the invention, the sub-amplification circuits with different ranges and amplification factors are utilized in the amplification circuit to automatically amplify the input signals, so that a plurality of paths of signals with different ranges can be output. In addition, the sub-amplification circuit forms a differential amplification circuit with a high common-mode rejection ratio by utilizing the cooperation of the operational amplifier, the voltage-dividing resistor and the voltage-dividing capacitor, so that the precision of signal amplification is ensured.
According to one scheme of the invention, the two-channel data acquisition device can simultaneously perform analog-to-digital conversion on the amplified signals, and finally, the processor integrates the data according to the measuring range, wherein one integration scheme is as follows: when the large range and the small range are not overloaded, the small range value is taken during integration, and when the small range is overloaded and the large range is not overloaded, the large range value is selected during integration, so that the best acquisition data is output.
Drawings
FIG. 1 is a schematic diagram showing the components and signal transmission of an electrostatic probe current measuring apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic block diagram of a high common mode rejection ratio differential amplifier circuit of an electrostatic probe current measurement apparatus according to an embodiment of the present invention;
FIG. 3 schematically illustrates a two-channel data acquisition range setting diagram for an electrostatic probe current measurement apparatus according to an embodiment of the present invention;
fig. 4 is a schematic diagram showing a high common mode rejection ratio differential amplifier circuit of an electrostatic probe current measuring apparatus according to an embodiment of the present invention.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
In describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship that is based on the orientation or positional relationship shown in the associated drawings, which is for convenience and simplicity of description only, and does not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, the above-described terms should not be construed as limiting the present invention.
The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.
Fig. 1 also shows a current wide channel conditioning scheme, and as shown in fig. 1, the electrostatic probe current measuring device of the present invention includes a sampling resistor 1, an amplifying circuit 2, a collector 3 and a processor 4. The sampling resistor 1 is used for collecting signals fed back by the electrostatic probe, the amplifying circuit 2 is used for receiving the signals collected by the sampling resistor 1 and carrying out operational amplification, the collector 3 is used for carrying out analog-to-digital conversion on the signals subjected to operational amplification, and the processor 4 is used for processing the signals subjected to analog-to-digital conversion to obtain a measurement result. According to the concept of the invention, the amplifying circuit 2 amplifies the received signals in a multi-path way according to the measuring range, the collector 3 respectively carries out analog-to-digital conversion on the multi-path signals output by the amplifying circuit 2, and finally the processor 4 carries out combination processing on the multi-path signals after the analog-to-digital conversion to obtain the final measuring result. Therefore, the invention adopts a multi-channel AD acquisition mode to be applied to the process of measuring the plasma parameters by the probe, solves the measurement problem that the measurement times are limited under the environment similar to shock wave plasma, and the density range of the plasma is greatly changed in the single measurement process, and realizes the accurate measurement of the plasma current under the condition of large current range span.
Referring to fig. 2, the sampling resistor 1 of the present invention is mainly used for converting a current signal into a voltage signal. Specifically, the sampling resistor 1 adopts a high-precision and high-temperature stable resistor, so that high-precision conversion of electric signals is ensured, and the sampling resistance value and the ambient temperature are accurately measured. Of course, the temperature it collects also needs to be corrected by the subsequent processor 4. The amplifying circuit 2 includes a precision instrumentation amplifier 21 and a sub-amplifying circuit 22. As shown in fig. 2, the precision instrumentation amplifier 21 is used to extract and amplify the voltage signal of the sampling resistor 1 for output, and the acquired signal is also the signal input to the amplifying circuit 2. The present embodiment has two sub-amplification circuits 22 for amplifying the signal output from the precision instrumentation amplifier 21 by different times according to the measurement range. In fact, the sub-amplifier circuit 22 in the amplifier circuit 2 plays a main role of signal amplification, and the precise instrument amplifier 21 performs low-power signal amplification to form signal isolation and avoid the signal at the probe side from interfering with the instrument side.
With continued reference to fig. 2, the collector 3 of the present invention is a 16-bit data collection card, and the processor 4 is an upper computer. In this embodiment, the collector 3 is a dual-channel collector, i.e. can receive signals of two different ranges at the same time. Specifically, as can be seen from fig. 2, the precision sampling resistor 1 collects the plasma current with a collection precision of 0.1 μ a to 400mA, and the precision sampling resistor amplifies the signal by the precision instrumentation amplifier 21 to output a voltage with a precision of 2 μ V to 8V. Because the post-stage processing adopts the cascade connection of double 16-bit acquisition cards, the signal can be divided by taking 2mV as a limit, 2 mV-8V signals are directly acquired through a +/-10V large range, and tiny voltage signals of 2 muV-2 mV in a small signal range of a current channel are amplified into 200 muV-200 mV signals through a 100-time high-speed precision amplifier (namely a precision voltage amplifying circuit) and then input into a +/-200 mV small-range channel for acquisition. The merging processing operation is realized by software in the upper computer, and the specific logic is that the range interval where the collector 3 is located is judged according to the size of the data measured under the maximum range, and the measured data in the corresponding range interval is selected as the measuring result, so that the optimal collected data can be obtained.
Referring to fig. 3, it can be seen from the above that the use of the dual-channel collector of the present invention considers both the characteristics of large range and high precision. Specifically, for a 16-bit AD acquisition card, the first-gear dynamic range is only 80dB, and in consideration of overlapping of measurement ranges, about 5 measurement ranges are required to be set in the range of 160 dB. For an electrostatic probe measurement system, a dynamic range of about 130dB is required, but 2 ranges are still required in this range. Therefore, the dual-channel data conditioning collector can meet the range of 130dB in one measuring range, so that the measurement is simpler, the measurement result precision is better, and the advantages are obvious.
Referring to fig. 4, the sub-amplifying circuit 22 of the present invention includes a filtering module 221, an operational amplifier 222, and a voltage dividing module 223. The filtering module 221 is configured to perform low-pass filtering on the signal input to the sub-amplifying circuit 22. Specifically, the filtering module 221 includes a first filtering resistor 221a and a second filtering resistor 221b connected in series, and a ground line 221c located between the first filtering resistor 221a and the second filtering resistor 221b, and a filtering capacitor 221d is disposed on the ground line 221 c. The operational amplifier 222 is configured to amplify the low-pass filtered signal, and the amplifier is a wideband transimpedance amplifier, and is connected in parallel with the voltage dividing module 223 to form a differential amplifier circuit with a high common mode rejection ratio. The voltage dividing module 223 includes a voltage dividing capacitor 223a and a voltage dividing resistor 223b connected in parallel, and specifically, an AD8065 with low bias current and high input impedance may be used for the design of the transimpedance sampling amplifying circuit. Therefore, the amplifying circuit 2 of the invention has the characteristic of high common mode rejection ratio differential amplification. Thus, the signal input into the amplifying circuit 2 is subjected to the preliminary amplification of the signal by the precision instrument amplifier 21 to form a current measuring signal, and then is output after the low-pass filtering and differential amplification of the filtering module 221, so that the accuracy of the large dynamic range measurement can be ensured. In addition, in order to ensure high speed of signal transmission, the sub-amplification circuit 22 of the present invention further includes a linear optical coupling module 224. The module can enable the signal output by the differential amplification circuit to be transmitted to a subsequent connector 225 in an optical coupling mode at a high speed, and then the signal is output by a cable. From this, the linear optical coupler module 224 actually forms a high-speed operational amplifier together with the differential amplifier circuit.
In summary, the circuit of the electrostatic probe current measuring device of the present invention is a large dynamic range current testing circuit with a dual-channel data collector, and can collect probe signals according to the magnitude of input current signals by using two-channel signal analog-to-digital converters with different gains, i.e. automatically amplify the same signal according to the input signal, simultaneously perform analog-to-digital conversion on the amplified signal by using two-channel or multi-channel data conditioning collectors, and then automatically determine and select an output signal, thereby realizing automatic measurement of large dynamic range signals, ensuring the precision of signal measurement, realizing unattended automatic measurement, being especially suitable for unrepeatable tests with unknown signal magnitude, and ensuring complete measurement of signals.
Therefore, the invention breaks through the thinking constraint that one signal only adopts one data acquisition, each signal is synchronously sampled by using two or more data acquisition channels, and each data acquisition is preceded by different but fixed amplification factors, so that digital signals for measurement under multiple ranges are simultaneously obtained, then the signals of proper channels are judged and selected according to the measurement result of a wider range channel for processing and analysis, finally, a plurality of digital signals across ranges are integrated by a processor, the size of the signal is preliminarily determined by using the measurement data of the maximum range, and then the data which can meet the measurement under the optimal range of the signal size is selected as final acquisition data, thereby ensuring the large dynamic range measurement of the current signal.
Therefore, the invention is not only suitable for the electrostatic probe test of the supersonic plasma, but also can be applied to the large dynamic range test of voltage and current in other plasma tests. The wide-range test method has the advantages of simple structure, high reliability and high precision, and can be popularized to the test of other electric signals and non-electric signals. The characteristics also enable the scheme to be used for testing the space plasma probe, improving the precision of the space plasma probe, increasing the capabilities of space detection, spacecraft state monitoring and self-protection, being beneficial to improving the efficiency and precision of plasma equipment, having wide application prospects in the fields of space tasks and general plasma application, and being capable of converting into mass production and sale of products to generate remarkable economic benefits and social benefits.
The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and it is apparent to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. An electrostatic probe current measurement apparatus comprising:
the sampling resistor (1) is used for collecting a signal fed back by the electrostatic probe;
the amplifying circuit (2) is used for receiving and amplifying the signals collected by the sampling resistor (1);
the collector (3) is used for carrying out analog-to-digital conversion on the amplified signals;
the processor (4) is used for processing the signals subjected to the analog-to-digital conversion to obtain a measurement result;
it is characterized in that the preparation method is characterized in that,
the amplifying circuit (2) amplifies received signals in a multi-path division mode according to measuring ranges, the collector (3) respectively carries out analog-to-digital conversion on the amplified multi-path signals, and the processor (4) carries out combination processing on the multi-path signals subjected to the analog-to-digital conversion.
2. The electrostatic probe current measuring device according to claim 1, wherein the amplifying circuit (2) comprises:
a precision instrument amplifier (21) for amplifying the signal inputted to the amplifying circuit (2);
and the sub-amplification circuit (22) is used for amplifying the signal output by the precision instrument amplifier (21) by different times according to measuring ranges.
3. The electrostatic probe current measuring device according to claim 2, wherein the sub amplification circuit (22) comprises:
a filtering module (221) for low-pass filtering the signal input to the sub-amplifying circuit (22);
an op-amp (222) for amplifying the low-pass filtered signal;
and the voltage division module (223) is used for being connected with the operational amplifier (222) in parallel to form a differential amplification circuit.
4. The electrostatic probe current measuring device according to claim 3, wherein the filter module (221) comprises a first filter resistor (221 a), a second filter resistor (221 b) connected in series and a ground line (221c) located between the first filter resistor (221 a) and the second filter resistor (221 b), and a filter capacitor (221d) is arranged on the ground line (221 c);
the voltage division module (223) comprises a voltage division capacitor (223a) and a voltage division resistor (223b) which are connected in parallel.
5. The electrostatic probe current measuring device according to claim 3, wherein the sub amplification circuit (22) further comprises:
a linear optical coupler module (224) for transmitting the signal output by the differential amplification circuit in an optical coupler form;
a connector (225) for outputting the signal transmitted by the linear optical coupling module (224).
6. The electrostatic probe current measuring device according to claim 1, wherein the merging process is performed by analyzing through upper computer software, determining a range interval where the collector (3) is located according to the size of data measured under the maximum range, and selecting the measured data in the corresponding range interval as the measurement result.
7. The electrostatic probe current measuring device according to claim 1, wherein the collector (3) is a 16-bit data acquisition card, and the processor (4) is an upper computer.
8. The electrostatic probe current measuring device according to claim 2, wherein the amplification circuit (2) amplifies the signal by 100 times and 1 time, respectively.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111465080.4A CN114236222A (en) | 2021-12-03 | 2021-12-03 | Electrostatic probe current measuring device |
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| CN202111465080.4A CN114236222A (en) | 2021-12-03 | 2021-12-03 | Electrostatic probe current measuring device |
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| CN114236222A true CN114236222A (en) | 2022-03-25 |
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| CN202111465080.4A Pending CN114236222A (en) | 2021-12-03 | 2021-12-03 | Electrostatic probe current measuring device |
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Cited By (1)
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| CN115575688A (en) * | 2022-09-29 | 2023-01-06 | 北京航天计量测试技术研究所 | Weak current detection circuit |
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